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Differential climate–growth relationships in Abies alba Mill. and Fagus sylvatica L. in Mediterranean mountain forests
Accepted Manuscript Title: Differential climate-growth relationships in Abies alba Mill. and Fagus sylvatica L. in Mediterranean mountain forests Author: Angelo Rita Tiziana Gentilesca Francesco Ripullone Luigi Todaro Marco Borghetti PII: DOI: Reference:
S1125-7865(14)00031-9 http://dx.doi.org/doi:10.1016/j.dendro.2014.04.001 DENDRO 25277
To appear in: Received date: Revised date: Accepted date:
15-11-2012 4-2-2014 1-4-2014
Please cite this article as: Rita, A., Gentilesca, T., Ripullone, F., Todaro, L., Borghetti, M.,Differential climate-growth relationships in Abies alba Mill. and Fagus sylvatica L. in Mediterranean mountain forests, Dendrochronologia (2014), http://dx.doi.org/10.1016/j.dendro.2014.04.001 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Differential climate-growth relationships in Abies alba Mill. and Fagus sylvatica
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L. in Mediterranean mountain forests
3 Angelo Rita, Tiziana Gentilesca, Francesco Ripullone, Luigi Todaro, Marco Borghetti
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School of Agricultural, Forest, Food and Environmental Sciences, University of
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Basilicata
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Viale dell’Ateneo Lucano 10, 85100 Potenza (Italy)
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9 Corresponding author: Angelo Rita
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email address: [email protected]
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phone: 0039-3284737527; fax: 0039-0971-205378
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Keywords: Common beech, Dendrochronology, Mixed forests, Silver fir, Tree rings.
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Abstract
Pointer year analysis, simple correlations, and response functions were combined in a
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dendroecological study to evaluate climate-growth relationships over the last century
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in two Abies alba Mill. and Fagus sylvatica L. mixed stands in Southern Italy
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mountainous areas. Analyses revealed species-specific attributes at the two study
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sites, i.e. Molise and Basilicata. Growth divergence between the two species emerged
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based on three primary climatic drivers, including drought stress and spring warmer
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temperatures during the current growing season for F. sylvatica, and water availability
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in the previous growing season for A. alba. However, despite the microclimatic
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differences between the two study sites, F. sylvatica showed similar climate-growth
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patterns, while differences were indicated for A. alba, due to its minor susceptibility
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to drought stress during the current growing season at the Basilicata site. Indeed, at
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the southernmost geographic limits of A. alba drought avoidance mechanisms were
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confirmed, consistent with traits considered diagnostic for the species in the
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Mediterranean
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Introduction
3 Changes in tree-growth response to temporal climatic variability have the potential to
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modify forest ecosystem equilibrium by altering plant phenological traits, ecological
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species-specific amplitude and community composition dynamics.
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The Mediterranean region is one of the most valuable ecological systems on earth,
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rich in biodiversity, but also fragile, and therefore extremely vulnerable to the
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consequences of climate change (Sitch et al., 2008). However, climate change will
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indirectly contribute to an increase in drought events, consistent with a potential
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decline of 4–27% of precipitation (Christensen et al., 2007; Ripullone et al., 2009)
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primarily in summer (e.g. Gao and Giorgi 2008, Sitch et al. 2008). Furthermore, the
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rise in average temperatures recorded during the last decades is expected to exhibit
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further increases by 2.2-5.1 °C by 2100 (IPCC, 2007), with significant impacts on
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forest ecosystems (Mátyás et al., 2009; Boden et al., 2010).
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Therefore, deep concerns exist regarding the effects of climate change on the growth
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1996) constitutes a powerful tool to understand forest dynamics under uncertain
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climate change scenarios. Species-specific studies performed in Mediterranean areas
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demonstrated a decline in F. sylvatica vitality (Jump et al., 2006; Piovesan et al.,
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2008). Results emphasized that even small increases in drought stress reduced F.
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and distribution of species along altitudinal gradients (Lenoir et al., 2008), particularly in Mediterranean environments. One of the primary issue regarding Mediterranean forests is their southernmost distributional limit where these communities experienced increased sensitivity to summer drought stress. Detecting differential growth responses to climate (Fritts, 1976; Schweingruber,
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sylvatica growth, suggesting possible competitive replacement from other tree
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species, e.g. Quercus petraea and Q. cerris (Vitale et al., 2012). Geßler et al. (2007)
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showed that F. sylvatica might lose dominance towards more drought-tolerant tree
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species largely on low water availability soils. However, Dittmar et al. (2003)
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reported that F. sylvatica exhibits tolerance in dry areas. A. alba site specific studies
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conducted at a regional scale confirmed the species sensitivity to decreased soil-water
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availability (Aussenac, 2002). A decline in A. alba growth at its southern and lower
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geographic range has been reported (Peguero-Pina et al., 2007; Battipaglia et al.,
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2009; Cailleret and Davi, 2010). However, Rovelli (1995) indicated A. alba remains
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in a few relicts stands along the Italian Apennine Mountains, probably due to climatic
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and anthropogenic factors; and in some cases the species co-occurs with F. sylvatica.
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The climatic factors influencing F. sylvatica (Dittmar et al., 2003; Piovesan et al.,
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2003, 2005) and A. alba (Rolland, 1993; Manetti and Cutini, 2006; Gentilesca and
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Todaro, 2008) growth have been reported, but very few studies have been conducted
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in stands where the two species grow sympatrically (Kern and Popa, 2007; Cailleret
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and Davi, 2010).
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Therefore, the objectives of our study were to identify the primary climatic factors
influencing radial growth in A. alba and F. sylvatica mixed stands, and to ascertain the presence or absence of species-specific responses to climatic variation during the
last century. Two mixed stands of A. alba and F. sylvatica along the Italian Apennines
Mountains were evaluated. Dendroclimatic analysis was conducted by developing 90-
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year climate-growth relationships for tree-ring chronologies and species-specific
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responses between the two sites. In addition to correlation and response function
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analyses, we performed a pointer year analysis to detect years with extreme growth
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deviations.
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Materials and methods
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4 Site characteristics
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One study site is located at Bosco Pantano (1500 m a.s.l.) (Fig. 1) within Pollino
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National Park in the municipality of Terranova del Pollino (Basilicata Region,
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Southern Italy). Mesozoic limestone and dolomite formations constitute the
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orographic relief structure. The lower Calabro-Lucanian massif slopes are
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characterized by Eocene flysch formations comprised of sandstone and limestone; the
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soils are a slightly leached calcareous matrix.
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The study site was classified according to Mayr-Pavari (De Philippis, 1937) in the
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cold Fagetum phytoclimatic zone. F. sylvatica dominates the mesic forest in this
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altitudinal belt, primarily forming pure stands, or mixed with A. alba and other tree
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species, including Ulmus minor Mill., Acer pseudoplatanus L. and Taxus baccata L.
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Sampling was performed in a plot (about 0.5 ha) where A. alba accounts for 41% of
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A. alba prevails (Ferrari and Wolf, 1970). The entire region is included in the
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Fagetum phytoclimatic zone, which is further supported by the understory species
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composition. Field work was carried out in a plot (about 0.5 ha), where A. alba is the
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dominant tree species, accounting for 50% of the total growing stock (Lombardi et al.,
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the total growing stock (Guarino et al. unpublished), and is easily observed within the
dense F. sylvatica canopy cover in the form of majestic specimens.
The second study site, Abeti Soprani (1490 m a.s.l.) (Fig. 1) is located in the
Pescopennataro municipality (Molise Region, Central Italy). The pedology is
characterized by Rendzina, Miocenic-clay soils, and Cretacic white limestone, where
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2011), mixed with F. sylvatica, and occasionally other species, including Pyrus
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communis L., T. baccata L., Fraxinus ornus L., A. pseudo-platanus L., A. campestre
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L., Carpinus betulus L., and Sorbus torminalis Crantz. This community is considered
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a relict, representative of past A. alba Apennine stands, surviving only in small glacial
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refugia in the Italian peninsula (Ciancio et al., 1985).
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Selected sites exhibited fairly similar characteristics (Table 1). Both localities are
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included in Natura 2000 sites, where A. alba is an endangered species included in a
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priority habitat (code 9220*) (European Commission, 2003). The natural forest
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structure was historically disturbed by anthropogenic activities; in particular, forest
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management during the twentieth century was based on A. alba timber exploitation
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through selective felling, particularly during World War II (Di Martino 1988; Todaro
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et al. 2007).
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13 Tree-ring width chronologies
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Tree-ring samples were collected for each stand in 2010, following standard
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dendrochronological procedures (Schweingruber et al., 1990). Two cores per
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dominant tree were collected at breast height (1.3 m) in opposite directions, perpendicular to slope, from each of 33 F. sylvatica trees [17 trees from Basilicata
(FGBas) and 16 trees from Molise (FGMol)], and 32 A. alba trees [15 trees from Basilicata (ABBas) and 17 trees from Molise (ABMol)], respectively. Each core was dried, mounted on wooden slats, and polished with progressively finer sandpaper.
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Ring width samples, previously visually cross-dated (Yamaguchi, 1991), were
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measured using the incremental measuring table SMIL3 (Corona et al., 1989), with
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0.01 mm accuracy. Measured tree-ring width series were statistically verified using
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COFECHA software (Holmes, 1983), and the two tree-ring series from every tree
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were averaged.
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Age-related growth trends were removed by standardizing the raw chronologies in
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detrended (Dt) using ARSTAN software (Cook et al., 2007) with a cubic spline curve
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function, with 50% frequency cut-off, to amplify the climatic (high frequency), and
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remove the non-climatic (low frequency) signals. Approximately two-thirds of the
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mean length of time span was applied to estimate the function (Cook and Kairiukstis,
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1990): 70-years cubic smoothing spline for ABBas, ABMol, and FGMol, and a 32-
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years cubic smoothing spline for FGBas chronologies.
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Each final residual tree-ring series (Rs) was modeled through an autoregressive
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process, where the individual series order was selected by searching the first
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minimum of the Akaike Information Criterion (AIC). A biweight robust mean was
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calculated to reduce the influence of outliers (Cook and Briffa, 1990). Residual tree-
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ring width chronologies for each species were used to evaluate relationships between
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radial growth and climate (Cook and Briffa, 1990). The following statistical
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parameters commonly used in dendrochronology were computed from the tree-ring
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series: the mean sensitivity (MS), as a measure of the degree of relative interannual variation in ring width (Fritts, 1976); first-order autocorrelation (AC1) (Fritts, 1976), which reflects the influence of the previous ring on the current year's growth; the
signal-to-noise ratio (SNR ratio) as an expression of the common signal strength among trees; and the expressed population signal (EPS), which quantifies the site-
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specific common variability among tree-ring series, based on a threshold value of 0.85
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(Wigley et al., 1984). Spatial similarity between series and climatic areas was
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evaluated by the Pearson correlation coefficient using SPSS software (IBM Corp.).
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1 Climatic data
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We used monthly precipitation (P), minimum (Tmin) and maximum (Tmax)
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temperatures recorded from climatic reference stations; the dataset was acquired from
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the Annual Hydrological Bulletin (Servizio Idrografico e Mareografico Italiano).
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Bosco Pantano (Bas): temperature (T) series was recorded at Castrovillari (343 m
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a.s.l.) from 1924 to 2010, and precipitation (P) was recorded at Terranova di Pollino
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(1232 m a.s.l) from 1923 to 2010. Missing P values were estimated by linear
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regression (R2 = 0.75), with a series recorded at San Lorenzo Bellizzi meteorological
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station (851 m a.s.l.). Annual T and P patterns showed high summer temperatures, and
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irregular precipitation distribution throughout the year. Mean annual precipitation was
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1083 mm, distributed as follows: 39.5% in winter, 23.7% in spring, 29.2% in autumn,
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and 7.6% in summer; snow cover typically persists from November to the end of
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May, with the highest persistence values between January and February.
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Abeti Soprani (Mol): T and P were recorded at Pescopennataro (1290 m a.s.l.) from
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1924 to 2010 and 1918 to 2010, respectively. Missing T and P values were estimated
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by linear regression with a series recorded at Agnone (for T) (806 m a.s.l.) and
Capracotta (for P) (1004 m a.s.l.), the nearest meteorological stations (R2 = 0.99, R2 = 0.98, R2 = 0.68, respectively for Tmax, Tmin, and P). The area is characterized by
respective mean annual temperature and precipitation of 9.4 °C and 1030 mm. January was recorded as the coldest month (mean 1.5 °C), and August the warmest
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(mean 23.1 °C). Temperature values for the two study sites were estimated by
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applying a reduction coefficient of 0.7 °C for every 100 m of altitude.
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The climatic data showed a general tendency for increased temperatures, most evident
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in the last 30 years (Fig. 2), particularly in minimum autumn-winter season values
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(Brunetti et al. 2012). Annual precipitation exhibited a non-significant decreased
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tendency during the last century at both sites (Caloiero et al. 2011; Brunetti et al.
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2012), while a general increase in summer precipitation was observed after 1980 (Fig.
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2).
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5 Climate-growth relationships
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Climate-growth relationships were assessed using DENDROCLIM2002 software
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(Biondi and Waikul, 2004), applying bootstrapped confidence intervals to estimate the
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significance of both correlation and response function coefficients. Correlation
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(Pcorr) and response functions (RRFF) for P < 0.05 were evaluated by concurrent
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temperature (T) and precipitation (P) iterations. Ring width indices (Rs) and
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meteorological parameters (monthly P, Tmin, and Tmax) were analyzed for the 1925 to
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2010 period; the time window considered for climate correlations was set from
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previous year July to current years October as reported as reported in Serre-Bachet
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(1982) and Savidge (2001) for Mediterranean areas.
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Temporal variability in growth-climate relationships was tested by calculating
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correlation functions from 1920 to 2010 in moving time windows of 30 years, in
consecutive shifts of five years.
Pointer year analysis
Pointer year analysis was performed to determine whether climatic factors were
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responsible for conspicuously smaller or larger tree-ring increments as described by
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Schweingruber et al. (1990a).
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Species and site specific pointer years were calculated on residual (Rs) series using
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the software Weiser (Gonzales, 2001), by applying a 7-year time window and ±1.0σ
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as local threshold. A given year was considered as pointer year when it was depicted
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by more than eight trees (> 75%) per species and site.
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To evaluate the impact of summer water availability on the occurrence of pointer
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years, averaged monthly precipitation (from June to August) versus pointer years
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were processed in superposed epoch analysis (SEA), over the common period 1925-
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2010, by using EVENT Version 6.02P program (Holmes, 1999). An 11-year interval
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(5 years before to 5 years after each event) was used as the time window. In this
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analysis, windows for each event are superimposed and averaged, and the average
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patterns emerging examined for statistically significant differences through 1000
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random simulations that provide 95% bootstrap confidence intervals.
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Tree-ring series (Fig. 3) were successfully cross-dated in both species and sites.
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Statistical parameters associated with tree-ring residual (Rs), detrended (Dt), were in
considerable agreement with those reported in other studies (Gentilesca and Todaro, 2008; Gallucci and Urbinati, 2009; Carrer et al., 2010). Summary results are as follows: 1) FGBas MS values were lower than other studies for Mediterranean species (Serre-Bachet, 1982; Tessier, 1982); 2) ABBas exhibited
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the highest AC1 (Dt) value compared to the other chronologies; 3) F. sylvatica
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chronologies showed a higher SNR compared to A. alba, and the signals were
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strongest for the Molise site; 4) in all chronologies the EPS values (Table 2) were
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higher than the threshold level (≥ 0.85, Wigley et al. (1984)) for the climate analysis
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time span.
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The correlation between residual chronologies (Table 3) showed species-specific
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variation at the Basilicata site. FGMol-FGBas Rs chronologies showed high
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significant correlations, despite the clear geographic disjunction between the sites.
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The dendroclimatic output (Fig. 4) showed negative response functions (RRFF) in
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ABBas for T(max) in August(t-1), and August(t), and positive RRFF for December(t-1). A
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positive correlation (Pcorr) for T(min) was found during the winter season (Dec(t-1),
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Feb(t)). A positive (Pcorr and RRFF) and negative (Pcorr) correlation were
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respectively depicted for precipitation in August(t-1) and in January(t).
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No correlation was detected for T(max) in FGBas. However, a positive correlation
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(Pcorr) for T(min) in May(t) was observed. Further, a positive Pcorr and RRFF in June(t)
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and Aug(t-1) were identified for precipitation.
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ABMol showed a positive Pcorr for T(max) in May(t), and a negative Pcorr and RRFF
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for Sep(t-1). Negative Pcorr for T(min) in Sept(t-1), Oct(t-1 ), Jul(t), and Aug(t), and negative
RRFF for Sept(t-1) were detected. Precipitation showed positive Pcorr for Sept(t-1), June(t), July(t), August(t), and a negative RRFF in Jan(t).
FGMol exhibited a positive Pcorr for T(max) in May(t), and a negative Pcorr in Aug(t). Positive Pcorr for T(min) in May(t), and positive Pcorr for precipitation in June(t) and July(t) were also observed.
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Temporal changes in climate-growth relationships
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Calculation of moving correlation functions between residual chronologies and
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climate parameters revealed temporal trends (Fig. 5) in August and September of the
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previous year (year(t-1)), and in summer months of the current year (year(t)), i.e. June,
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July, August, and September.
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Results showed temporal variation, particularly interesting in A. alba at both study
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sites. Growth of ABBas appeared strongly and stable influenced by precipitation (P)
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in August(t-1) from 1940 on. For the recent decades 1980-2010 also temperature (T) in
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August(t-1) showed significant but negative correlations with ABBas growth.
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In ABMol, an increased P influence on radial growth was observed for year(t-1), which
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was more pronounced in September; however, a decreasing trend was indicated in the
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final decades of the last century, particularly during summer (year(t)), e.g. June, July,
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and August. In addition, influence of June T on growth of ABMol changed from a
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significant negative correlation during the first half of the last century to a significant
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positive correlation from 1960 on.
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During the entire period analyzed, the temporal variability in climate-growth
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relationships resolved for F. sylvatica was consistent with the long-term correlations
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depicted in Figure 5; temporal variation between study sites was not evident.
Pointer years analysis
Generally, for all chronologies, negative pointer years were more frequent than positive. In detail, F. sylvatica chronologies showed the highest number of pointer
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years (19 for FGBas and 22 for FGMol). Compared to Fagus, a minor number of
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pointer years were detected for Abies. In fact, ABMol showed a total of 13 pointer
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years, while few pointer years were detected for the ABBas chronology (3 positives
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and 6 negatives), and most occurred during the last 30 years, including 1967, 1981,
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1986, and 2008, which were identified as narrow rings, and 1930 and 1990 as wide
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rings.
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Concurrence between species in the extreme growth deviations was found in 1930 and
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1981 at the Basilicata site, and in 1931, 1974 and 1994 at the Molise site (Fig. 3).
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Superposed epoch analysis (SEA) revealed significant influence (p < 0.05) of drought
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on the occurrence of pointer years for all chronologies, excepted ABBas (Fig. 6A). In
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particular, specie-specific correspondence in negative departures for FGBas and
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FGMol was found, while site-specific correspondence in negative departures was
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found at the Molise site (Fig. 6B).
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Long-term climate-growth relationships
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In our study, a high correlation between residual F. sylvatica chronologies from two
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different sites suggested a common climatic influence along the Mediterranean
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Apennine (Piovesan et al. 2003). However, similar evidence was not revealed following a comparison of A. alba chronologies. The positive FGMol growth response to May temperatures (Fig. 4) during the current
growth year was supported by previous studies (Dittmar et al., 2003; Di Filippo et al., 2007). In general, at this elevation a warmer May is associated with a positive
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influence on metabolic activity and biochemical reactions at the onset of vegetative
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activity (Cufar et al., 2008). Higher temperatures in spring might allow trees to limit
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physiological damage by late frosts, inducing positive growth influences (Di Filippo
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et al. 2007). Instead June precipitation showed a positive influence on growth at both
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sites, congruent with previous reports from the Apennine Mountains (Piovesan et al.,
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2003; Di Filippo et al., 2007), and other European sites (Dittmar et al., 2003;
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Szabados, 2006).
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Late summer temperatures (Aug(t)) negatively influenced tree ring growth in FGMol,
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likely due to increased water stress. On the other hand, FGBas showed heightened
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resistance to drought stress, probably influenced by the previous year’s precipitation
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(Aug(t-1)), consistent with other Mediterranean stand studies (Dittmar et al., 2003;
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Nahm et al., 2006), and attributed to more efficient internal stomatal regulation
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mechanisms (García-Plazaola et al., 2000).
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Milder winter temperatures favored A. alba (Fig. 4), which was particularly evident at
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ABBas. Several dendroecological investigations (Desplanque, 1997; Manetti and
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Cutini, 2006; Kern and Popa, 2007) concomitantly demonstrated the importance of
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above-average winter temperatures for growth of A. alba. Moreover, mild winters
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might cause a two-fold effect on thermal amplitude reduction and photosynthetic
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capacity (Aussenac, 2002), in addition to limiting winter frost damage (Desplanque et
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al., 1999).
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Consistent with reports by Romagnoli and Schirone (1992), our results suggested ABMol was more susceptible, compared to ABBas, to drought stress during the
current growing season, indicated by positive relationships with June(t)-July(t)August(t) precipitation, and negative relationships with minimum July(t)-August(t) temperatures. Furthermore, our results suggested benefits to June precipitation, as the
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cambium is fully active (Gricar and Kufar, 2008), and the number of tracheids has
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quadupled (Freni, 1955; Rossi et al., 2006). September(t-1) showed a marked affect on
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ABMol growth; in fact, precipitation exhibited positive and temperature negative
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effects.
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The marked effect of September(t-1) on ABMol growth suggested that climatic
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conditions of the previous year strongly influenced growth during the following
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growing season (Pallardy, 2007). Gaudinski et al. (2009) showed that one-third of the
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carbon employed in new root tissue formation was derived from the photosynthate
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fixed prior to the start of the current growing season. The precipitation effects from
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the previous year are often more pronounced than the effects of the current year.
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These results were confirmed by other findings on the same species growing in the
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Pyrenees (Tardif et al., 2003; Marcias et al., 2006) and Alps (Rolland, 1993; Cailleret
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et al., 2010).
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Our results showed that water balance from the previous summer exerted more
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influence on ABBas. In fact, the absence of factors indicating drought stress in the
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current year was explained as a result of an efficient stress avoidance strategy
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(Aussenac, 2002; Pallardy, 2007; Carrer et al., 2010). Linares et al. (2012) observed
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that drought avoidance mechanisms in A. pinsapo (Boiss.) might prevent functional
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damage; however, the tradeoff was a substantial compromise in tree growth, which
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might result in an influence on species strength competition.
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Temporal changes in climate-growth relationships Moving correlation functions provided a dynamic view on the evolution of tree growth response to climate. F. sylvatica exhibited relatively similar temporal trends (Fig. 5) at both sites, reinforcing the results obtained by long-term climate-growth
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relationships (Fig. 4), and confirming the previous summer water availability
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requirements for FGBas.
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A. alba exhibited a clear divergence in growth-climate relationships among sites. In
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particular, June(t) response in ABMol showed a peculiar reversal trend between
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temperature and precipitation. Precipitation strongly and positively influenced tree
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growth since 1920, while it was no longer a limiting growth factor from 1950 to 2010.
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Conversely, during the same month, temperature correlations exhibited an inverse
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trend compared with precipitation, and positively influenced tree growth during the
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second half of the twentieth century, having had a negative impact on tree growth
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during the first half. This decreasing influence of precipitation on growth in July(t) and
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Aug(t) is probably due to the observed increasing trend in summer precipitation,
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recently demonstrated by Brunetti et al. (2012). Alternatively, the significant
9
influence of September(t-1) precipitation on growth of ABMol could be considered as a
10
driver for growth pattern change, noted from 1970-2010, showing an adaptive
11
response to changing climatic conditions.
12
Indeed, by dividing the summer months of the current year into two time periods, it
13
might be possible to differentiate ABMol (Fig. 5) into a first period (1923-1960),
14
where an accentuated precipitation influence was evident, and a second time period
15
(1961-2008), where precipitation progressively decreased in significance, in contrast
16
to temperatures. Therefore, increasing temperatures could play an important future
18 19 20 21
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1
role with the effects of enhancing drought conditions or leading to changes in growing
season length as recently demonstrated for A. alba (Vitasse et al., 2009), and A.
pinsapo (Linares et al., 2012) in Mediterranean areas.
Pointer years evidence
22
The pointer years analysis provides complementary information regarding response to
23
climate over the last century. Pointer years were more frequent in F. sylvatica than in
24
A. alba chronologies, both for Basilicata and Molise sites. SEA analysis suggests that
25
the relative abundance of summer precipitations led to positive pointer years for
16
Page 16 of 40
ABMol and FGMol (Fig. 6B). On the contrary, low precipitation in summer caused
2
negative pointer years exclusively for F. sylvatica, at both sites. This is in accordance
3
to Dittmar and Elling (2003), who explain the most of the strong negative growth
4
deviations in F. sylvatica forests with dry conditions.
5
Accordingly, the narrow tree rings coincided with the some of the driest summer in
6
the Mediterranean region (e.g. 1931, 1939, 1946, and 1988). In particular, the year
7
1931 was one of the driest years in the last century, characterized by a summer
8
precipitation deficit of 95% compared to the long-term average.
9
Moreover, the occurrence of positive pointer years reflected the site-specific
10
precipitation regime: most of the positive pointer years at Molise site were associated
11
with exceptionally high summer precipitation (e.g. 1940, 1959, 1964, and 1976).
12
Finally, pointer years had a variable temporal pattern throughout time. Our results,
13
calculated over a 10-year time window (data not shown), indicated a slight increase in
14
the number of pointer years in all chronologies, likely attributable to the increasing in
15
extreme precipitation events (IPCC, 2007) during the last decades. This is in
16
accordance to Piovesan et al. (2003) who observed an increasing frequency of
18 19 20 21
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negative pointer years during the last decades for high elevation F. sylvatica chronologies.
Conclusions
22 23
The influence of climate on A. alba and F. sylvatica radial growth was investigated
24
using chronologies developed from two mixed stands of the abovementioned species
25
from the Southern Apennines mountains growing under fairly similar conditions.
17
Page 17 of 40
Dendroecological approaches revealed differential climate-growth responses. These
2
differences are obviously site and specie-dependent, and mostly related to the water
3
availability.
4
Overall, growth patterns were highly responsive to summer water stress, with the
5
exception of ABBas, where growth was strongly influenced by climatic conditions
6
during the previous growing season, suggesting substantial investment from nutrient
7
reserves formed during the actual year of ring formation.
8
At Molise, current summer water stress exhibited control on Fagus and Abies growth.
9
Basilicata favored both species growth due to decreased temperature amplitude in
10
spring, and a reported upward summer precipitation trend, which slightly alleviated
11
drought stress. Furthermore, A. alba at its southernmost distribution confirmed these
12
drought avoidance mechanisms.
13
Analysis of temporal changes in climate-growth relationships emphasized the
14
increasing influence of precipitation levels from the previous year on growth in both
15
species at the Basilicata site. A. alba at the Molise site demonstrated a reverse growth
16
tendency in response to summer precipitation between the months of the current and
18 19 20 21
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the previous growth year.
The occurrence of pointer years in time series of A. alba and F. sylvatica exhibited a
variable temporal pattern through time, with differences between stands and species. Thus, the expected increase of severe drought events may lead to more frequent occurrence of negative pointer years for F. sylvatica.
22
Finally, these results highlight that changes in rainfall patterns could have significant
23
impact on growth and species composition likely favoring more drought tolerant
24
species (i.e. Quercus spp.) in this area.
25
18
Page 18 of 40
1 2
References
3 Aussenac, G., 2002. Ecology and ecophysiology of circum-Mediterranean firs in
5
the context of climate change. Ann. For. Sci. 59, 823-832.
6
Battipaglia, G., Saurer, M., Cherubini, P., Siegwolf, R.T.W., Cotrufo, M.F., 2009.
7
Tree rings indicate different drought resistance of a native (Abies alba Mill) and
8
a non-native (Picea abies (L.) Karst) species co-occurring at a dry site in
9
Southern Italy. Forest Ecology and Management 257, 820-828.
an
us
cr
ip t
4
Biondi, F., Waikul, K., 2004. DENDROCLIM2002: AC++ program for statistical
11
calibration of climate signals in tree-ring chronologies. Computers and
12
Geosciences 30, 303-311.
13
Boden, S., Pyttel, P., Eastaugh, C.S., 2010. Impacts of climate change on the
14
establishment, distribution, growth and mortality of Swiss stone pine (Pinus
15
cembra L.). iForest - Biogeosciences and Forestry 3, 82-85.
16
Brunetti, M., Caloiero, T., Coscarelli, R., Gullà, G., Nanni, T., Simolo, C., 2012.
21
Ac ce p
te
d
M
10
22
Caloiero, T., Coscarelli, R., Ferrari, E., Mancini, M., 2011. Precipitation change
23
in Southern Italy linked to global scale oscillation indexes. Nat. Hazards Earth
24
Syst. Sci., 11, 1683-1694.
17 18 19 20
Precipitation variability and change in the Calabria region (Italy) from a high resolution daily dataset. International Journal of Climatology 32, 57-73. Cailleret, M., Davi, H., 2010. Effects of climate on diameter growth of cooccurring Fagus sylvatica and Abies alba along an altitudinal gradient. Trees 25 (2), 265-276.
19
Page 19 of 40
Carrer, M., Nola, P., Motta, R., Urbinati, C., 2010. Contrasting tree-ring growth
2
to climate responses of Abies alba toward the southern limit of its distribution
3
area. Oikos 119, 1515-1525.
4
Christensen, J.H., Hewitson, B., Busuioc, A., Chen, A., Gao, X., Held, I., Jones,
5
R., Kolli, R.K., Kwon, W.T., Laprise, R., Magaña Rueda, V., Mearns, L.,
6
Menéndez, C.G., Räisänen, J., Rinke, A., Sarr, A., Whetton, P., 2007. Regional
7
Climate Projections, in: Climate Change 2007: The Physical Science Basis.
8
Cambridge University Press, Cambridge, United Kingdom and New York, NY,
9
USA.
an
us
cr
ip t
1
Ciancio, O., Iovino, F., Menguzzato, G., Mirabella, A., 1985. L’abete (Abies alba
11
Mill.) in Calabria: possibilità e limiti di diffusione. Annali dell’Istituto
12
Sperimentale per la Selvicoltura 16, 1-249.
13
Cook, E.R., Briffa, K., Shiyatov, S., Mazepa, A., Jones P.D., 1990. Data analysis,
14
in: Cook, E.R., Kairiukstis, L.A., (Eds.), Methods of Dendrochronology:
15
Applications in the Environmental Sciences. Kluwer Academic Publishers,
16
Dordrecht, pp. 97–162.
21
Ac ce p
te
d
M
10
22
Corona, P., Ferrara, A., La Marca, O., 1989. Un sistema di misura delle
23
ampiezze anulari: il dendrocronografo “Smil 3”. L’Italia Forestale e Montana 5,
24
391-404.
17 18 19 20
Cook, E.R., Kairiukstis, L.A., 1990. Methods of Dendrochronology: Applications in the Environmental Science. Kluwer Academic Publisher, Dodrecht-BostonLondon.
Cook, E.R., Krusic, P.J., Holmes, R.H.; Peters, K,. 2007. Program ARSTAN Ver. 41d (/www.ldeo.columbia.edu/tree-ring-laboratory).
20
Page 20 of 40
Cufar, K., Prislan, P., de Luis, M., Gricar, J., 2008. Tree-ring variation, wood
2
formation and phenology of beech (Fagus sylvatica) from a representative site in
3
Slovenia, SE Central Europe. Trees 22, 749-758.
4
De Philippis, A., 1937. Classificazioni ed indici del clima in rapporto alla
5
vegetazione forestale italiana. Nuovo Giornale Botanico Italiano 44, 1-169.
6
Desplanque, C., 1997. Dendroécologie comparée du Sapin et de l'Epicéa dans les
7
Alpes internes Franco-Italiennes. Rôle des facteurs climatique et anthropique
8
sur leur répartition. Thèse de Docteur de l'Université Joseph Fourier,
9
Laboratoire Ecosystèmes Alpins, Grenoble, France.
an
us
cr
ip t
1
Desplanque, C., Rolland, C., Schweingruber, F.H., 1999. Influence of species and
11
abiotic factors on extreme tree ring modulation: Picea abies and Abies alba in
12
Tarentaise and Maurienne (French Alps). Trees 13, 218-227.
13
Di Filippo, A., Biondi, F., Cufar, K., de Luis, M., Grabner, M., Maugeri, M.,
14
Presutti Saba, E., Schirone, B., Piovesan, G., 2007. Bioclimatology of beech
15
(Fagus sylvatica L.) in the Eastern Alps: spatial and altitudinal climatic signals
16
identified through a tree-ring network. Journal of Biogeography 34 (11), 1873-
21
Ac ce p
te
d
M
10
22
(Fagus sylvatica L.) under different climatic and environmental conditions in
23
Europe - a dendroecological study. Forest Ecology and Management 173, 63-78.
17 18 19 20
1892.
Di Martino, P., 1988. Silver fir in tree forests of Molise, in: Salbitano, F., (Eds), Human influence on forest ecosystem development in Europe. ESF FERN CNR. Bologna, Pitagora Editrice, 335-338. Dittmar, C., Zech, W., Elling, W., 2003. Growth variations of common beech
21
Page 21 of 40
European Commission, 2003. Natura 2000 and Forests - Challenges and
2
opportunities - an Interpretation Guide. Luxembourg: Office for Official
3
Publications of the European Communities. Luxembourg.
4
Ferrari, G.A., Wolf, U., 1970. Considerazioni sui suoli e la rinnovazione naturale
5
dell’abete bianco (Abies alba Mill.) del bosco ‘‘Abeti Soprani’’ (Pescopennataro-
6
IS). Annali Accademia Italiana di Scienze Forestali 19, 423-439.
7
Freni, C., 1955. Andamento del ritmo vegetativo in Abies alba Mill.
8
dell’Aspromonte. Annali Accademia Italiana di Scienze Forestali 4, 135-154.
9
Fritts, H.C., 1976. Tree ring and climate. Academic Press, New York.
an
us
cr
ip t
1
Gallucci, V., Urbinati, C., 2009. Dinamismi di accrescimento e sensitività
11
climatica dell’abete bianco (Abies alba Mill.) nel SIC Alpe della Luna-Bocca
12
Trabaria (PU). Forest@ 6, 85-99.
13
Gao, X., Giorgi, F., 2008. Increased aridity in the Mediterranean region under
14
greenhouse gas forcing estimated from high resolution regional climate
15
projections. Global and Planetary Change 62, 195–209.
16
García-Plazaola, J.I., Becerril, J.M., 2000. Effects of drought on photoprotective
21
Ac ce p
te
d
M
10
22
measurements and modeling. Global Change Biology 15, 992-1014
23
Geßler, A., Keitel, C., Kreuzwieser, J., Matyssek, R., Seiler, W., Rennenberg, H.,
24
2007. Potential risks for European beech (Fagus sylvatica L.) in a changing
25
climate. Trees 21, 1-11.
17 18 19 20
mechanisms in European beech (Fagus sylvatica L.) seedlings from different provenances. Trees 4 (8), 485-490. Gaudinski, J.B., Torn, M.S., Riley, W.J., Swanston, C., Trumbore, S.E., Joslin, J.D., Majdi, H., Dawson, T.E., Hanson, P.J., 2009. Use of stored carbon reserves in growth of temperate tree roots and leaf buds: analyses using radiocarbon
22
Page 22 of 40
Gentilesca, T., Todaro, L., 2008. Crescita radiale e risposte climatiche dell’abete
2
bianco (Abies alba Mill.) in Basilicata. Forest@ 5, 47-56.
3
Gonzales, I.G., 2001. Weiser: a computer program to identify event and pointer
4
years in dendrochronological series. Dendrochronologia 19, 239-244.
5
Gricar, J., Cufar, K., 2008. Seasonal dynamics of phloem and xylem formation in
6
silver fir and Norway spruce as affected by drought. Russian Journal of Plant
7
Physiology 55, 538-543.
8
Holmes, R.L., 1983. Computer-assisted quality control in tree-ring dating and
9
measurement. Tree Ring Bulletin 43, 69-78.
an
us
cr
ip t
1
Holmes, R.L., 1999. Dendrochronological Programm Library (DPL). Users
11
Manual. Laboratory of Tree-Ring Research, University of Arizona, Tucson.
12
(/www.ltrr.arizona.edu/pub/dpl/).
13
Intergovernmental Panel on Climate Change (IPCC), 2007. Climate Change
14
2007: The Physical Science Basis. Contribution of Working Group I to the
15
Fourth Assessment Report of the Intergovernmental Panel on Climate Change,
16
edited by S. Solomon et al., Cambridge Univ. Press, Cambridge, U. K.
21
Ac ce p
te
d
M
10
22
Lenoir, J., Gégout, J.C., Marquet, P.A., Ruffray, P.D., Brisse, H., 2008. A
23
significant upward shift in plant species optimum elevation during the 20th
24
century. Science 320, 1768-1771.
17 18 19 20
Jump, A.S., Hunt, J.M., Peñuelas, J., 2006. Rapid climate change-related growth decline at the southern range edge of Fagus sylvatica. Global Change Biology 12, 2163-2174.
Kern, Z., Popa, I., 2007. Climate-growth relationship of tree species from a mixed stand of Apuseni Mts., Romania. Dendrochronologia 24, 109-115.
23
Page 23 of 40
Linares, J.C., Covelo, F., Carreira, J.A., Merino, J.Á., 2012. Phenological and
2
water-use patterns underlying maximum growing season length at the highest
3
elevations: implications under climate change. Tree Physiology, 32b (2), 161-70.
4
Manetti, M.C., Cutini, A., 2006. Tree-ring growth of silver fir (Abies alba Mill.)
5
in two stands under different silvicultural systems in central Italy.
6
Dendrochronologia 23, 145-150.
7
Mátyás, C., Bozic, G., Gömöry, D., Ivankovic, M., Rasztovits, E., 2009. Juvenile
8
growth response of European beech (Fagus sylvatica L.) to sudden change of
9
climatic environment in SE European trials. IForest - Biogeosciences and
an
us
cr
ip t
1
Forestry 2, 213-220.
11
Nahm, M., Radoglou, K., Halyvopoulos, G., Geßler, A., Rennenberg, H., Fotelli,
12
M.N., 2006. Physiological performance of beech (Fagus sylvatica L.) at its
13
Southeastern distribution limit in Europe: seasonal changes in nitrogen, carbon
14
and water balance. Plant Biology 8, 52-63.
15
Pallardy, S.G., 2007. Physiology of Woody Plants, Third Edition. Academic
16
Press, San Diego.
21
Ac ce p
te
d
M
10
22
long-term tree ring beech chronology from a high-elevation old-growth forest of
23
Central Italy. Dendrochronologia 21 (1), 13-22.
17 18 19 20
Peguero-Pina, J.J., Camarero, J.J., Abadía, A., Martín, E., González-Cascón, R., Morales, F., Gil-Pelegrín, E., 2007. Physiological performance of silver-fir (Abies alba Mill.) populations under contrasting climates near the southwestern distribution limit of the species. Flora 202, 226-236. Piovesan, G., Bernabei, M., Di Filippo, A., Romagnoli, M., Schirone, B., 2003. A
24
Page 24 of 40
Piovesan, G., Biondi, F., Bernabei, M., Di Filippo, A., Schirone, B., 2005. Spatial
2
and altitudinal bioclimatic zones of the Italian peninsula identified from a beech
3
(Fagus sylavtica L.) tree-ring network. Acta Oecologica, 27 (3), 197-210.
4
Piovesan, G., Biondi, F., Di Filippo, A., Alessandrini, A., Maugeri, M., 2008.
5
Drought-driven growth reduction in old beech (Fagus sylvatica L.) forests of the
6
central Apennines, Italy. Global Change Biology 14 (6), 1265-1281.
7
Ripullone, F., Borghetti, M., Raddi, S., Vicinelli, E., Baraldi, R., Guerrieri, M.R.,
8
Nolè, A., Magnani, F., 2009. Physiological and structural changes in response to
9
altered precipitation regimes in a Mediterranean macchia ecosystem. Trees 23,
an
us
cr
ip t
1
823-834.
11
Rolland, C., 1993. Tree-ring and climate relationships for Abies alba in the
12
internal Alps. Tree-Ring Bulletin 53, 1-11.
13
Romagnoli, M., Schirone, B., 1992. Indagini dendroecologiche preliminari
14
sull’abete bianco del bosco Abeti Soprani (Pescopennataro-IS). Annali
15
dell’Accademia Italiana di Scienze Forestali 41, 3-30.
16
Rossi, S., Deslauriers, A., Anfodillo, T., Morin, H., Saracino, A., Motta, R.,
21
Ac ce p
te
d
M
10
22
Savidge, R.A., 2001. Intrinsic regulation of cambial growth. Journal of Plant
23
Growth Regulation, 20, 52-77.
17 18 19 20
Borghetti, M., 2006. Conifers in cold environments synchronize maximum growth rate of tree-ring formation with day length. New Phytologist 170, 301310.
Rovelli, E., 1995. La distribuzione dell'abete (Abies alba Mill.) sull'Appennino. Monti e Boschi 6, 5-13.
25
Page 25 of 40
Schweingruber, F.H., Kairiukstis, L., Shiyatov, S., 1990. Sample selection, in:
2
Cook, E.R., Kairiukstis, L.A., (Eds.). Methods of dendrochronology. Kluwer
3
Academic Publishers, Dordrecht, The Netherlands.
4
Schweingruber, F.H., Eckstein, D., Serre Bachet, F., Braker, O.U., 1990a.
5
Identification, presentation and interpretation of event years and pointer years
6
in dendrochronology. Dendrochronologia 8, 9-38.
7
Schweingruber, F.H., 1996. Tree Rings and Environment. Dendroecology. Paul
8
Haupt Verlag, Berne.
9
Serre-Bachet, F., 1982. The Mediterranean Area. Comment, in: Hughes, M.K.,
10
Kelly, P.M., Pilcher, J.R., Lamarche, V.C., 1982. Climate from tree-rings.
11
Cambridge Univ. Press, pp. 153-155.
12
Sitch, S., Huntingford, C., Gedney, N., Levy, P.E., Lomas, M., Piao, S.L., Betts,
13
R., Ciais, P., Cox, P., Friedlingstein, P., Jones, C.D., Prentice, I.C., Woodward,
14
F.I., 2008. Evaluation of the terrestrial carbon cycle, future plant geography and
15
climate-carbon cycle feedbacks using five Dynamic Global Vegetation Models
16
(DGVMs). Global Change Biology 14 (9), 2015-2039.
21
Ac ce p
te
d
M
an
us
cr
ip t
1
22
Tessier, L., 1982. Analyse dendroclimatologique compare de 6 populaions de
23
Pinus sylvestris (L.) dans la Drome. Ecologia Mediterranea 8 (3), 185-202.
24
Todaro, L., Andreu, L., D'alessandro, C.M., Gutierrez, E., Cherubini P.,
25
Saracino A., 2007. Response of Pinus leucodermis to climate and anthropogenic
17 18 19 20
Szabados, I., 2006. The effect of the precipitation on the tree ring width. Carpth. J. of Earth and Environmental Sciences 1 (2), 39-44. Tardif, J., Camarero, J. J., Ribas, M., Gutierrez, E., 2003. Spatiotemporal variability in tree growth in the central Pyrenees: Climatic and site influences, Ecol. Monogr. 73, 241–257.
26
Page 26 of 40
activity in the National Park of Pollino (Basilicata, Southern Italy). Biological
2
Conservation 137, 507-519.
3
Vitale, M., Mancini, M., Matteucci, G., Francesconi, F., Valenti, R., Attorre, F.,
4
2012. Model-based assessment of ecological adaptations of three forest tree
5
species growing in Italy and impact on carbon and water balance at national
6
scale under current and future climate scenarios. iForest - Biogeosciences and
7
Forestry 5, 235-246.
8
Vitasse, Y., Delzon, S., Dufrene, E., Pontailler, J.Y., Louvet, J.M., Kremer A.,
9
Michalet, R., 2009. Leaf phenology sensitivity to temperature in European trees:
10
do within-species populations exhibit similar responses? Agric. For. Meteorol.
11
149, 735-744.
12
Wigley, T.M.L., Briffa, K.R., Jones, P.D., 1984. On the Average Value of
13
Correlated
14
Hydrometeorology. Journal of Climate and Applied Meteorology 23, 201-213.
15
Yamaguchi, D.K., 1991. A simple method for cross-dating increment cores from
16
living
Series,
with
Applications
in
Dendroclimatology
and
Canadian
Ac ce p
trees.
te
d
Time
M
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us
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Journal
of
Forest
Research
21,
414-416.
27
Page 27 of 40
1 2
Acknowledgements
3 The International Ph.D program "BioEcoSystems and BioTechnology" at the
5
University of Basilicata supported A Rita.
6
Authors acknowledge R Tognetti (Università del Molise) and G Milanese (Comunità
7
Montana Alto Molise) for support in sampling at Molise site and A Lapolla for
8
precious help in field work. We also acknowledge the financial support of the project
9
"A permanent natural laboratory in the Pollino National Park: a necessary prerequisite
10
for sustainable management" by the Parco Nazionale del Pollino, Rotonda, Italy. The
11
valuable comments by three anonymous referees greatly contributed to improve the
12
manuscript.
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1 2
Figure Legends
3 Figure 1: Walter and Leith climatic diagrams super-imposed on study sites location
5
map.
6
Figure 2: Climatic trends for Basilicata (full line) and Molise (dotted line) sites. Left
7
panel shows 20-years spline in mean temperatures and annual precipitation; right
8
panel indicates the last 30-years of summer trends (June-Sept) in temperature and
9
precipitation.
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Figure 3: Residual tree ring chronologies, from top to bottom: ABBas, FGBas,
11
ABMol, FGMol. Symbols indicate positive (filled) and negative (empty) pointer
12
years. Grey lines are the samples depth.
13
Figure 4: Climate-growth relationships between tree-ring residual chronologies and
14
monthly climatic variables (Tmax, Tmin, and P). Bars and lines indicate, respectively,
15
simple correlation coefficients (Pcorr), and response functions (RRFF). See methods
20
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21
and precipitation. Stars denote significant (p<0.05) correlations.
22
Figure 6: Superposed epoch analysis of species specific negative (grey bars) and
23
positive (white bars) pointer years and summer (June-August) precipitations for A.
24
alba (left panel) and F. sylvatica (right panel) over the common period 1925-2010.
16 17 18 19
for details.
Figure 5: Temporal changes in climate-growth relationships during the twentieth century. Thirty-year intervals lagged five years were evaluated from 1925 to 2010. The X and Y-axes represent, respectively the temporal element in years, and growth trend in bootstrapped correlations. Black and dotted lines are respectively temperature
29
Page 29 of 40
Basilicata site (A) and Molise site (B). The x-axis are years prior to and after an event
2
and on the y-axis are departures from the mean. Departure is the difference between
3
actual and bootstrap generated values of summer precipitations of the respective year;
4
dashed lines denote 95%, solid lines 99% confidence limit, stars indicate significant
5
departures.
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Page 30 of 40
1 2
Table Legends
3 Table 1: Study sites characteristics. Temperature and precipitation values are averages
5
from the period 1925-2010.
6
Table 2: Statistical properties of tree-ring detrended (Dt) and residuals (Rs)
7
chronologies. Mean sensitivity (MS), standard deviation (SD), first order
8
autocorrelation (AC1), signal-to-noise ratio (SNR), mean correlation between trees
9
(MC).
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Table 3: Inter- and intra-specific correlations between A. alba and F. sylvatica
11
residual chronologies. Statistically significant differences are indicated as *P < 0.01
12
and
M
10
<
0.001,
respectively.
Ac ce p
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**P
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1
ip t
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M
an
us
Latitude, N 39°56'32.57" 41° 51' 7.02" Longitude, W 16°14'6.45" 14° 17' 34.02" Altitude, (m) 1500 1490 Slope, (%) 12-25 10-15 Exposure N-NE NE Temperature, (°C)* 7.5 9.4 Precipitation, (mm y-1)* 1083 1030 _________________________________________________
cr
_________________________________________________ Characteristics Sites ______________________________ Basilicata Molise _________________________________________________
te
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
Table 1
Ac ce p
2
32
Page 32 of 40
Table 2 ___________________________________________________________________ Statistical properties Chronologies ____________________________________________
Chronology type
Dt
Rs
Dt
Rs
MS SD AC1 MC SNR
0.21 0.25 0.42 0.45 11.5
0.24 0.22 -0.10 0.52 15.1
0.18 0.20 0.35 0.35 8.13
0.19 0.17 -0.07 0.38 9.16
1794-2010 17/34 217 0.92
1825-2010 15/30 186 0.90
cr
1898-2010 17/34 113 0.93
us
1868-2010 16/32 143 0.96
Dt
Rs
Dt
Rs
0.18 0.30 0.38 0.28 6.02
0.21 0.29 -0.02 0.33 7.61
0.21 0.34 0.69 0.21 4.19
0.24 0.24 0.01 0.22 4.36
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Time span chronologies Number of trees/cores Number of years EPS (1920-2010)
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FGMol FGBas ABMol ABBas ___________________________________________________________________
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Table 3
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_________________________________ FGBas ABMol FGMol _________________________________ ABBas 0.182 0.242* 0.137 FGBas 0.131 0.546** ABMol 0.278*
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3 4 5 6 7 8 9
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S1125-7865(14)00031-9 http://dx.doi.org/doi:10.1016/j.dendro.2014.04.001 DENDRO 25277
To appear in: Received date: Revised date: Accepted date:
15-11-2012 4-2-2014 1-4-2014
Please cite this article as: Rita, A., Gentilesca, T., Ripullone, F., Todaro, L., Borghetti, M.,Differential climate-growth relationships in Abies alba Mill. and Fagus sylvatica L. in Mediterranean mountain forests, Dendrochronologia (2014), http://dx.doi.org/10.1016/j.dendro.2014.04.001 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Differential climate-growth relationships in Abies alba Mill. and Fagus sylvatica
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L. in Mediterranean mountain forests
3 Angelo Rita, Tiziana Gentilesca, Francesco Ripullone, Luigi Todaro, Marco Borghetti
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School of Agricultural, Forest, Food and Environmental Sciences, University of
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Basilicata
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Viale dell’Ateneo Lucano 10, 85100 Potenza (Italy)
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9 Corresponding author: Angelo Rita
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email address: [email protected]
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phone: 0039-3284737527; fax: 0039-0971-205378
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Keywords: Common beech, Dendrochronology, Mixed forests, Silver fir, Tree rings.
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1 2
Abstract
Pointer year analysis, simple correlations, and response functions were combined in a
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dendroecological study to evaluate climate-growth relationships over the last century
6
in two Abies alba Mill. and Fagus sylvatica L. mixed stands in Southern Italy
7
mountainous areas. Analyses revealed species-specific attributes at the two study
8
sites, i.e. Molise and Basilicata. Growth divergence between the two species emerged
9
based on three primary climatic drivers, including drought stress and spring warmer
10
temperatures during the current growing season for F. sylvatica, and water availability
11
in the previous growing season for A. alba. However, despite the microclimatic
12
differences between the two study sites, F. sylvatica showed similar climate-growth
13
patterns, while differences were indicated for A. alba, due to its minor susceptibility
14
to drought stress during the current growing season at the Basilicata site. Indeed, at
15
the southernmost geographic limits of A. alba drought avoidance mechanisms were
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confirmed, consistent with traits considered diagnostic for the species in the
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Mediterranean
region.
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1 2
Introduction
3 Changes in tree-growth response to temporal climatic variability have the potential to
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modify forest ecosystem equilibrium by altering plant phenological traits, ecological
6
species-specific amplitude and community composition dynamics.
7
The Mediterranean region is one of the most valuable ecological systems on earth,
8
rich in biodiversity, but also fragile, and therefore extremely vulnerable to the
9
consequences of climate change (Sitch et al., 2008). However, climate change will
10
indirectly contribute to an increase in drought events, consistent with a potential
11
decline of 4–27% of precipitation (Christensen et al., 2007; Ripullone et al., 2009)
12
primarily in summer (e.g. Gao and Giorgi 2008, Sitch et al. 2008). Furthermore, the
13
rise in average temperatures recorded during the last decades is expected to exhibit
14
further increases by 2.2-5.1 °C by 2100 (IPCC, 2007), with significant impacts on
15
forest ecosystems (Mátyás et al., 2009; Boden et al., 2010).
16
Therefore, deep concerns exist regarding the effects of climate change on the growth
21
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22
1996) constitutes a powerful tool to understand forest dynamics under uncertain
23
climate change scenarios. Species-specific studies performed in Mediterranean areas
24
demonstrated a decline in F. sylvatica vitality (Jump et al., 2006; Piovesan et al.,
25
2008). Results emphasized that even small increases in drought stress reduced F.
17 18 19 20
and distribution of species along altitudinal gradients (Lenoir et al., 2008), particularly in Mediterranean environments. One of the primary issue regarding Mediterranean forests is their southernmost distributional limit where these communities experienced increased sensitivity to summer drought stress. Detecting differential growth responses to climate (Fritts, 1976; Schweingruber,
3
Page 3 of 40
sylvatica growth, suggesting possible competitive replacement from other tree
2
species, e.g. Quercus petraea and Q. cerris (Vitale et al., 2012). Geßler et al. (2007)
3
showed that F. sylvatica might lose dominance towards more drought-tolerant tree
4
species largely on low water availability soils. However, Dittmar et al. (2003)
5
reported that F. sylvatica exhibits tolerance in dry areas. A. alba site specific studies
6
conducted at a regional scale confirmed the species sensitivity to decreased soil-water
7
availability (Aussenac, 2002). A decline in A. alba growth at its southern and lower
8
geographic range has been reported (Peguero-Pina et al., 2007; Battipaglia et al.,
9
2009; Cailleret and Davi, 2010). However, Rovelli (1995) indicated A. alba remains
10
in a few relicts stands along the Italian Apennine Mountains, probably due to climatic
11
and anthropogenic factors; and in some cases the species co-occurs with F. sylvatica.
12
The climatic factors influencing F. sylvatica (Dittmar et al., 2003; Piovesan et al.,
13
2003, 2005) and A. alba (Rolland, 1993; Manetti and Cutini, 2006; Gentilesca and
14
Todaro, 2008) growth have been reported, but very few studies have been conducted
15
in stands where the two species grow sympatrically (Kern and Popa, 2007; Cailleret
16
and Davi, 2010).
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Therefore, the objectives of our study were to identify the primary climatic factors
influencing radial growth in A. alba and F. sylvatica mixed stands, and to ascertain the presence or absence of species-specific responses to climatic variation during the
last century. Two mixed stands of A. alba and F. sylvatica along the Italian Apennines
Mountains were evaluated. Dendroclimatic analysis was conducted by developing 90-
22
year climate-growth relationships for tree-ring chronologies and species-specific
23
responses between the two sites. In addition to correlation and response function
24
analyses, we performed a pointer year analysis to detect years with extreme growth
25
deviations.
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1 2 3
Materials and methods
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4 Site characteristics
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One study site is located at Bosco Pantano (1500 m a.s.l.) (Fig. 1) within Pollino
7
National Park in the municipality of Terranova del Pollino (Basilicata Region,
8
Southern Italy). Mesozoic limestone and dolomite formations constitute the
9
orographic relief structure. The lower Calabro-Lucanian massif slopes are
10
characterized by Eocene flysch formations comprised of sandstone and limestone; the
11
soils are a slightly leached calcareous matrix.
12
The study site was classified according to Mayr-Pavari (De Philippis, 1937) in the
13
cold Fagetum phytoclimatic zone. F. sylvatica dominates the mesic forest in this
14
altitudinal belt, primarily forming pure stands, or mixed with A. alba and other tree
15
species, including Ulmus minor Mill., Acer pseudoplatanus L. and Taxus baccata L.
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Sampling was performed in a plot (about 0.5 ha) where A. alba accounts for 41% of
21
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A. alba prevails (Ferrari and Wolf, 1970). The entire region is included in the
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Fagetum phytoclimatic zone, which is further supported by the understory species
24
composition. Field work was carried out in a plot (about 0.5 ha), where A. alba is the
25
dominant tree species, accounting for 50% of the total growing stock (Lombardi et al.,
17 18 19 20
the total growing stock (Guarino et al. unpublished), and is easily observed within the
dense F. sylvatica canopy cover in the form of majestic specimens.
The second study site, Abeti Soprani (1490 m a.s.l.) (Fig. 1) is located in the
Pescopennataro municipality (Molise Region, Central Italy). The pedology is
characterized by Rendzina, Miocenic-clay soils, and Cretacic white limestone, where
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2011), mixed with F. sylvatica, and occasionally other species, including Pyrus
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communis L., T. baccata L., Fraxinus ornus L., A. pseudo-platanus L., A. campestre
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L., Carpinus betulus L., and Sorbus torminalis Crantz. This community is considered
4
a relict, representative of past A. alba Apennine stands, surviving only in small glacial
5
refugia in the Italian peninsula (Ciancio et al., 1985).
6
Selected sites exhibited fairly similar characteristics (Table 1). Both localities are
7
included in Natura 2000 sites, where A. alba is an endangered species included in a
8
priority habitat (code 9220*) (European Commission, 2003). The natural forest
9
structure was historically disturbed by anthropogenic activities; in particular, forest
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management during the twentieth century was based on A. alba timber exploitation
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through selective felling, particularly during World War II (Di Martino 1988; Todaro
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et al. 2007).
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Tree-ring samples were collected for each stand in 2010, following standard
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dendrochronological procedures (Schweingruber et al., 1990). Two cores per
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dominant tree were collected at breast height (1.3 m) in opposite directions, perpendicular to slope, from each of 33 F. sylvatica trees [17 trees from Basilicata
(FGBas) and 16 trees from Molise (FGMol)], and 32 A. alba trees [15 trees from Basilicata (ABBas) and 17 trees from Molise (ABMol)], respectively. Each core was dried, mounted on wooden slats, and polished with progressively finer sandpaper.
22
Ring width samples, previously visually cross-dated (Yamaguchi, 1991), were
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measured using the incremental measuring table SMIL3 (Corona et al., 1989), with
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0.01 mm accuracy. Measured tree-ring width series were statistically verified using
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COFECHA software (Holmes, 1983), and the two tree-ring series from every tree
2
were averaged.
3
Age-related growth trends were removed by standardizing the raw chronologies in
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detrended (Dt) using ARSTAN software (Cook et al., 2007) with a cubic spline curve
5
function, with 50% frequency cut-off, to amplify the climatic (high frequency), and
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remove the non-climatic (low frequency) signals. Approximately two-thirds of the
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mean length of time span was applied to estimate the function (Cook and Kairiukstis,
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1990): 70-years cubic smoothing spline for ABBas, ABMol, and FGMol, and a 32-
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years cubic smoothing spline for FGBas chronologies.
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Each final residual tree-ring series (Rs) was modeled through an autoregressive
11
process, where the individual series order was selected by searching the first
12
minimum of the Akaike Information Criterion (AIC). A biweight robust mean was
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calculated to reduce the influence of outliers (Cook and Briffa, 1990). Residual tree-
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ring width chronologies for each species were used to evaluate relationships between
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radial growth and climate (Cook and Briffa, 1990). The following statistical
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parameters commonly used in dendrochronology were computed from the tree-ring
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series: the mean sensitivity (MS), as a measure of the degree of relative interannual variation in ring width (Fritts, 1976); first-order autocorrelation (AC1) (Fritts, 1976), which reflects the influence of the previous ring on the current year's growth; the
signal-to-noise ratio (SNR ratio) as an expression of the common signal strength among trees; and the expressed population signal (EPS), which quantifies the site-
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specific common variability among tree-ring series, based on a threshold value of 0.85
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(Wigley et al., 1984). Spatial similarity between series and climatic areas was
24
evaluated by the Pearson correlation coefficient using SPSS software (IBM Corp.).
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Page 7 of 40
1 Climatic data
3
We used monthly precipitation (P), minimum (Tmin) and maximum (Tmax)
4
temperatures recorded from climatic reference stations; the dataset was acquired from
5
the Annual Hydrological Bulletin (Servizio Idrografico e Mareografico Italiano).
6
Bosco Pantano (Bas): temperature (T) series was recorded at Castrovillari (343 m
7
a.s.l.) from 1924 to 2010, and precipitation (P) was recorded at Terranova di Pollino
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(1232 m a.s.l) from 1923 to 2010. Missing P values were estimated by linear
9
regression (R2 = 0.75), with a series recorded at San Lorenzo Bellizzi meteorological
10
station (851 m a.s.l.). Annual T and P patterns showed high summer temperatures, and
11
irregular precipitation distribution throughout the year. Mean annual precipitation was
12
1083 mm, distributed as follows: 39.5% in winter, 23.7% in spring, 29.2% in autumn,
13
and 7.6% in summer; snow cover typically persists from November to the end of
14
May, with the highest persistence values between January and February.
15
Abeti Soprani (Mol): T and P were recorded at Pescopennataro (1290 m a.s.l.) from
16
1924 to 2010 and 1918 to 2010, respectively. Missing T and P values were estimated
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by linear regression with a series recorded at Agnone (for T) (806 m a.s.l.) and
Capracotta (for P) (1004 m a.s.l.), the nearest meteorological stations (R2 = 0.99, R2 = 0.98, R2 = 0.68, respectively for Tmax, Tmin, and P). The area is characterized by
respective mean annual temperature and precipitation of 9.4 °C and 1030 mm. January was recorded as the coldest month (mean 1.5 °C), and August the warmest
22
(mean 23.1 °C). Temperature values for the two study sites were estimated by
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applying a reduction coefficient of 0.7 °C for every 100 m of altitude.
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The climatic data showed a general tendency for increased temperatures, most evident
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in the last 30 years (Fig. 2), particularly in minimum autumn-winter season values
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(Brunetti et al. 2012). Annual precipitation exhibited a non-significant decreased
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tendency during the last century at both sites (Caloiero et al. 2011; Brunetti et al.
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2012), while a general increase in summer precipitation was observed after 1980 (Fig.
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2).
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5 Climate-growth relationships
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Climate-growth relationships were assessed using DENDROCLIM2002 software
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(Biondi and Waikul, 2004), applying bootstrapped confidence intervals to estimate the
9
significance of both correlation and response function coefficients. Correlation
10
(Pcorr) and response functions (RRFF) for P < 0.05 were evaluated by concurrent
11
temperature (T) and precipitation (P) iterations. Ring width indices (Rs) and
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meteorological parameters (monthly P, Tmin, and Tmax) were analyzed for the 1925 to
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2010 period; the time window considered for climate correlations was set from
14
previous year July to current years October as reported as reported in Serre-Bachet
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(1982) and Savidge (2001) for Mediterranean areas.
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Temporal variability in growth-climate relationships was tested by calculating
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correlation functions from 1920 to 2010 in moving time windows of 30 years, in
consecutive shifts of five years.
Pointer year analysis
Pointer year analysis was performed to determine whether climatic factors were
22
responsible for conspicuously smaller or larger tree-ring increments as described by
23
Schweingruber et al. (1990a).
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Species and site specific pointer years were calculated on residual (Rs) series using
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the software Weiser (Gonzales, 2001), by applying a 7-year time window and ±1.0σ
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Page 9 of 40
as local threshold. A given year was considered as pointer year when it was depicted
2
by more than eight trees (> 75%) per species and site.
3
To evaluate the impact of summer water availability on the occurrence of pointer
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years, averaged monthly precipitation (from June to August) versus pointer years
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were processed in superposed epoch analysis (SEA), over the common period 1925-
6
2010, by using EVENT Version 6.02P program (Holmes, 1999). An 11-year interval
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(5 years before to 5 years after each event) was used as the time window. In this
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analysis, windows for each event are superimposed and averaged, and the average
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patterns emerging examined for statistically significant differences through 1000
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random simulations that provide 95% bootstrap confidence intervals.
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Tree-ring series (Fig. 3) were successfully cross-dated in both species and sites.
17 18 19 20 21
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Statistical parameters associated with tree-ring residual (Rs), detrended (Dt), were in
considerable agreement with those reported in other studies (Gentilesca and Todaro, 2008; Gallucci and Urbinati, 2009; Carrer et al., 2010). Summary results are as follows: 1) FGBas MS values were lower than other studies for Mediterranean species (Serre-Bachet, 1982; Tessier, 1982); 2) ABBas exhibited
22
the highest AC1 (Dt) value compared to the other chronologies; 3) F. sylvatica
23
chronologies showed a higher SNR compared to A. alba, and the signals were
24
strongest for the Molise site; 4) in all chronologies the EPS values (Table 2) were
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higher than the threshold level (≥ 0.85, Wigley et al. (1984)) for the climate analysis
2
time span.
3
The correlation between residual chronologies (Table 3) showed species-specific
4
variation at the Basilicata site. FGMol-FGBas Rs chronologies showed high
5
significant correlations, despite the clear geographic disjunction between the sites.
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The dendroclimatic output (Fig. 4) showed negative response functions (RRFF) in
9
ABBas for T(max) in August(t-1), and August(t), and positive RRFF for December(t-1). A
10
positive correlation (Pcorr) for T(min) was found during the winter season (Dec(t-1),
11
Feb(t)). A positive (Pcorr and RRFF) and negative (Pcorr) correlation were
12
respectively depicted for precipitation in August(t-1) and in January(t).
13
No correlation was detected for T(max) in FGBas. However, a positive correlation
14
(Pcorr) for T(min) in May(t) was observed. Further, a positive Pcorr and RRFF in June(t)
15
and Aug(t-1) were identified for precipitation.
16
ABMol showed a positive Pcorr for T(max) in May(t), and a negative Pcorr and RRFF
18 19 20 21 22
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for Sep(t-1). Negative Pcorr for T(min) in Sept(t-1), Oct(t-1 ), Jul(t), and Aug(t), and negative
RRFF for Sept(t-1) were detected. Precipitation showed positive Pcorr for Sept(t-1), June(t), July(t), August(t), and a negative RRFF in Jan(t).
FGMol exhibited a positive Pcorr for T(max) in May(t), and a negative Pcorr in Aug(t). Positive Pcorr for T(min) in May(t), and positive Pcorr for precipitation in June(t) and July(t) were also observed.
23 24
Temporal changes in climate-growth relationships
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Calculation of moving correlation functions between residual chronologies and
2
climate parameters revealed temporal trends (Fig. 5) in August and September of the
3
previous year (year(t-1)), and in summer months of the current year (year(t)), i.e. June,
4
July, August, and September.
5
Results showed temporal variation, particularly interesting in A. alba at both study
6
sites. Growth of ABBas appeared strongly and stable influenced by precipitation (P)
7
in August(t-1) from 1940 on. For the recent decades 1980-2010 also temperature (T) in
8
August(t-1) showed significant but negative correlations with ABBas growth.
9
In ABMol, an increased P influence on radial growth was observed for year(t-1), which
10
was more pronounced in September; however, a decreasing trend was indicated in the
11
final decades of the last century, particularly during summer (year(t)), e.g. June, July,
12
and August. In addition, influence of June T on growth of ABMol changed from a
13
significant negative correlation during the first half of the last century to a significant
14
positive correlation from 1960 on.
15
During the entire period analyzed, the temporal variability in climate-growth
16
relationships resolved for F. sylvatica was consistent with the long-term correlations
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depicted in Figure 5; temporal variation between study sites was not evident.
Pointer years analysis
Generally, for all chronologies, negative pointer years were more frequent than positive. In detail, F. sylvatica chronologies showed the highest number of pointer
22
years (19 for FGBas and 22 for FGMol). Compared to Fagus, a minor number of
23
pointer years were detected for Abies. In fact, ABMol showed a total of 13 pointer
24
years, while few pointer years were detected for the ABBas chronology (3 positives
25
and 6 negatives), and most occurred during the last 30 years, including 1967, 1981,
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Page 12 of 40
1986, and 2008, which were identified as narrow rings, and 1930 and 1990 as wide
2
rings.
3
Concurrence between species in the extreme growth deviations was found in 1930 and
4
1981 at the Basilicata site, and in 1931, 1974 and 1994 at the Molise site (Fig. 3).
5
Superposed epoch analysis (SEA) revealed significant influence (p < 0.05) of drought
6
on the occurrence of pointer years for all chronologies, excepted ABBas (Fig. 6A). In
7
particular, specie-specific correspondence in negative departures for FGBas and
8
FGMol was found, while site-specific correspondence in negative departures was
9
found at the Molise site (Fig. 6B).
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Long-term climate-growth relationships
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In our study, a high correlation between residual F. sylvatica chronologies from two
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different sites suggested a common climatic influence along the Mediterranean
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Apennine (Piovesan et al. 2003). However, similar evidence was not revealed following a comparison of A. alba chronologies. The positive FGMol growth response to May temperatures (Fig. 4) during the current
growth year was supported by previous studies (Dittmar et al., 2003; Di Filippo et al., 2007). In general, at this elevation a warmer May is associated with a positive
22
influence on metabolic activity and biochemical reactions at the onset of vegetative
23
activity (Cufar et al., 2008). Higher temperatures in spring might allow trees to limit
24
physiological damage by late frosts, inducing positive growth influences (Di Filippo
25
et al. 2007). Instead June precipitation showed a positive influence on growth at both
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sites, congruent with previous reports from the Apennine Mountains (Piovesan et al.,
2
2003; Di Filippo et al., 2007), and other European sites (Dittmar et al., 2003;
3
Szabados, 2006).
4
Late summer temperatures (Aug(t)) negatively influenced tree ring growth in FGMol,
5
likely due to increased water stress. On the other hand, FGBas showed heightened
6
resistance to drought stress, probably influenced by the previous year’s precipitation
7
(Aug(t-1)), consistent with other Mediterranean stand studies (Dittmar et al., 2003;
8
Nahm et al., 2006), and attributed to more efficient internal stomatal regulation
9
mechanisms (García-Plazaola et al., 2000).
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Milder winter temperatures favored A. alba (Fig. 4), which was particularly evident at
11
ABBas. Several dendroecological investigations (Desplanque, 1997; Manetti and
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Cutini, 2006; Kern and Popa, 2007) concomitantly demonstrated the importance of
13
above-average winter temperatures for growth of A. alba. Moreover, mild winters
14
might cause a two-fold effect on thermal amplitude reduction and photosynthetic
15
capacity (Aussenac, 2002), in addition to limiting winter frost damage (Desplanque et
16
al., 1999).
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Consistent with reports by Romagnoli and Schirone (1992), our results suggested ABMol was more susceptible, compared to ABBas, to drought stress during the
current growing season, indicated by positive relationships with June(t)-July(t)August(t) precipitation, and negative relationships with minimum July(t)-August(t) temperatures. Furthermore, our results suggested benefits to June precipitation, as the
22
cambium is fully active (Gricar and Kufar, 2008), and the number of tracheids has
23
quadupled (Freni, 1955; Rossi et al., 2006). September(t-1) showed a marked affect on
24
ABMol growth; in fact, precipitation exhibited positive and temperature negative
25
effects.
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The marked effect of September(t-1) on ABMol growth suggested that climatic
2
conditions of the previous year strongly influenced growth during the following
3
growing season (Pallardy, 2007). Gaudinski et al. (2009) showed that one-third of the
4
carbon employed in new root tissue formation was derived from the photosynthate
5
fixed prior to the start of the current growing season. The precipitation effects from
6
the previous year are often more pronounced than the effects of the current year.
7
These results were confirmed by other findings on the same species growing in the
8
Pyrenees (Tardif et al., 2003; Marcias et al., 2006) and Alps (Rolland, 1993; Cailleret
9
et al., 2010).
an
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Our results showed that water balance from the previous summer exerted more
11
influence on ABBas. In fact, the absence of factors indicating drought stress in the
12
current year was explained as a result of an efficient stress avoidance strategy
13
(Aussenac, 2002; Pallardy, 2007; Carrer et al., 2010). Linares et al. (2012) observed
14
that drought avoidance mechanisms in A. pinsapo (Boiss.) might prevent functional
15
damage; however, the tradeoff was a substantial compromise in tree growth, which
16
might result in an influence on species strength competition.
18 19 20 21
d
te
Ac ce p
17
M
10
Temporal changes in climate-growth relationships Moving correlation functions provided a dynamic view on the evolution of tree growth response to climate. F. sylvatica exhibited relatively similar temporal trends (Fig. 5) at both sites, reinforcing the results obtained by long-term climate-growth
22
relationships (Fig. 4), and confirming the previous summer water availability
23
requirements for FGBas.
24
A. alba exhibited a clear divergence in growth-climate relationships among sites. In
25
particular, June(t) response in ABMol showed a peculiar reversal trend between
15
Page 15 of 40
temperature and precipitation. Precipitation strongly and positively influenced tree
2
growth since 1920, while it was no longer a limiting growth factor from 1950 to 2010.
3
Conversely, during the same month, temperature correlations exhibited an inverse
4
trend compared with precipitation, and positively influenced tree growth during the
5
second half of the twentieth century, having had a negative impact on tree growth
6
during the first half. This decreasing influence of precipitation on growth in July(t) and
7
Aug(t) is probably due to the observed increasing trend in summer precipitation,
8
recently demonstrated by Brunetti et al. (2012). Alternatively, the significant
9
influence of September(t-1) precipitation on growth of ABMol could be considered as a
10
driver for growth pattern change, noted from 1970-2010, showing an adaptive
11
response to changing climatic conditions.
12
Indeed, by dividing the summer months of the current year into two time periods, it
13
might be possible to differentiate ABMol (Fig. 5) into a first period (1923-1960),
14
where an accentuated precipitation influence was evident, and a second time period
15
(1961-2008), where precipitation progressively decreased in significance, in contrast
16
to temperatures. Therefore, increasing temperatures could play an important future
18 19 20 21
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17
ip t
1
role with the effects of enhancing drought conditions or leading to changes in growing
season length as recently demonstrated for A. alba (Vitasse et al., 2009), and A.
pinsapo (Linares et al., 2012) in Mediterranean areas.
Pointer years evidence
22
The pointer years analysis provides complementary information regarding response to
23
climate over the last century. Pointer years were more frequent in F. sylvatica than in
24
A. alba chronologies, both for Basilicata and Molise sites. SEA analysis suggests that
25
the relative abundance of summer precipitations led to positive pointer years for
16
Page 16 of 40
ABMol and FGMol (Fig. 6B). On the contrary, low precipitation in summer caused
2
negative pointer years exclusively for F. sylvatica, at both sites. This is in accordance
3
to Dittmar and Elling (2003), who explain the most of the strong negative growth
4
deviations in F. sylvatica forests with dry conditions.
5
Accordingly, the narrow tree rings coincided with the some of the driest summer in
6
the Mediterranean region (e.g. 1931, 1939, 1946, and 1988). In particular, the year
7
1931 was one of the driest years in the last century, characterized by a summer
8
precipitation deficit of 95% compared to the long-term average.
9
Moreover, the occurrence of positive pointer years reflected the site-specific
10
precipitation regime: most of the positive pointer years at Molise site were associated
11
with exceptionally high summer precipitation (e.g. 1940, 1959, 1964, and 1976).
12
Finally, pointer years had a variable temporal pattern throughout time. Our results,
13
calculated over a 10-year time window (data not shown), indicated a slight increase in
14
the number of pointer years in all chronologies, likely attributable to the increasing in
15
extreme precipitation events (IPCC, 2007) during the last decades. This is in
16
accordance to Piovesan et al. (2003) who observed an increasing frequency of
18 19 20 21
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17
ip t
1
negative pointer years during the last decades for high elevation F. sylvatica chronologies.
Conclusions
22 23
The influence of climate on A. alba and F. sylvatica radial growth was investigated
24
using chronologies developed from two mixed stands of the abovementioned species
25
from the Southern Apennines mountains growing under fairly similar conditions.
17
Page 17 of 40
Dendroecological approaches revealed differential climate-growth responses. These
2
differences are obviously site and specie-dependent, and mostly related to the water
3
availability.
4
Overall, growth patterns were highly responsive to summer water stress, with the
5
exception of ABBas, where growth was strongly influenced by climatic conditions
6
during the previous growing season, suggesting substantial investment from nutrient
7
reserves formed during the actual year of ring formation.
8
At Molise, current summer water stress exhibited control on Fagus and Abies growth.
9
Basilicata favored both species growth due to decreased temperature amplitude in
10
spring, and a reported upward summer precipitation trend, which slightly alleviated
11
drought stress. Furthermore, A. alba at its southernmost distribution confirmed these
12
drought avoidance mechanisms.
13
Analysis of temporal changes in climate-growth relationships emphasized the
14
increasing influence of precipitation levels from the previous year on growth in both
15
species at the Basilicata site. A. alba at the Molise site demonstrated a reverse growth
16
tendency in response to summer precipitation between the months of the current and
18 19 20 21
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d
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17
ip t
1
the previous growth year.
The occurrence of pointer years in time series of A. alba and F. sylvatica exhibited a
variable temporal pattern through time, with differences between stands and species. Thus, the expected increase of severe drought events may lead to more frequent occurrence of negative pointer years for F. sylvatica.
22
Finally, these results highlight that changes in rainfall patterns could have significant
23
impact on growth and species composition likely favoring more drought tolerant
24
species (i.e. Quercus spp.) in this area.
25
18
Page 18 of 40
1 2
References
3 Aussenac, G., 2002. Ecology and ecophysiology of circum-Mediterranean firs in
5
the context of climate change. Ann. For. Sci. 59, 823-832.
6
Battipaglia, G., Saurer, M., Cherubini, P., Siegwolf, R.T.W., Cotrufo, M.F., 2009.
7
Tree rings indicate different drought resistance of a native (Abies alba Mill) and
8
a non-native (Picea abies (L.) Karst) species co-occurring at a dry site in
9
Southern Italy. Forest Ecology and Management 257, 820-828.
an
us
cr
ip t
4
Biondi, F., Waikul, K., 2004. DENDROCLIM2002: AC++ program for statistical
11
calibration of climate signals in tree-ring chronologies. Computers and
12
Geosciences 30, 303-311.
13
Boden, S., Pyttel, P., Eastaugh, C.S., 2010. Impacts of climate change on the
14
establishment, distribution, growth and mortality of Swiss stone pine (Pinus
15
cembra L.). iForest - Biogeosciences and Forestry 3, 82-85.
16
Brunetti, M., Caloiero, T., Coscarelli, R., Gullà, G., Nanni, T., Simolo, C., 2012.
21
Ac ce p
te
d
M
10
22
Caloiero, T., Coscarelli, R., Ferrari, E., Mancini, M., 2011. Precipitation change
23
in Southern Italy linked to global scale oscillation indexes. Nat. Hazards Earth
24
Syst. Sci., 11, 1683-1694.
17 18 19 20
Precipitation variability and change in the Calabria region (Italy) from a high resolution daily dataset. International Journal of Climatology 32, 57-73. Cailleret, M., Davi, H., 2010. Effects of climate on diameter growth of cooccurring Fagus sylvatica and Abies alba along an altitudinal gradient. Trees 25 (2), 265-276.
19
Page 19 of 40
Carrer, M., Nola, P., Motta, R., Urbinati, C., 2010. Contrasting tree-ring growth
2
to climate responses of Abies alba toward the southern limit of its distribution
3
area. Oikos 119, 1515-1525.
4
Christensen, J.H., Hewitson, B., Busuioc, A., Chen, A., Gao, X., Held, I., Jones,
5
R., Kolli, R.K., Kwon, W.T., Laprise, R., Magaña Rueda, V., Mearns, L.,
6
Menéndez, C.G., Räisänen, J., Rinke, A., Sarr, A., Whetton, P., 2007. Regional
7
Climate Projections, in: Climate Change 2007: The Physical Science Basis.
8
Cambridge University Press, Cambridge, United Kingdom and New York, NY,
9
USA.
an
us
cr
ip t
1
Ciancio, O., Iovino, F., Menguzzato, G., Mirabella, A., 1985. L’abete (Abies alba
11
Mill.) in Calabria: possibilità e limiti di diffusione. Annali dell’Istituto
12
Sperimentale per la Selvicoltura 16, 1-249.
13
Cook, E.R., Briffa, K., Shiyatov, S., Mazepa, A., Jones P.D., 1990. Data analysis,
14
in: Cook, E.R., Kairiukstis, L.A., (Eds.), Methods of Dendrochronology:
15
Applications in the Environmental Sciences. Kluwer Academic Publishers,
16
Dordrecht, pp. 97–162.
21
Ac ce p
te
d
M
10
22
Corona, P., Ferrara, A., La Marca, O., 1989. Un sistema di misura delle
23
ampiezze anulari: il dendrocronografo “Smil 3”. L’Italia Forestale e Montana 5,
24
391-404.
17 18 19 20
Cook, E.R., Kairiukstis, L.A., 1990. Methods of Dendrochronology: Applications in the Environmental Science. Kluwer Academic Publisher, Dodrecht-BostonLondon.
Cook, E.R., Krusic, P.J., Holmes, R.H.; Peters, K,. 2007. Program ARSTAN Ver. 41d (/www.ldeo.columbia.edu/tree-ring-laboratory).
20
Page 20 of 40
Cufar, K., Prislan, P., de Luis, M., Gricar, J., 2008. Tree-ring variation, wood
2
formation and phenology of beech (Fagus sylvatica) from a representative site in
3
Slovenia, SE Central Europe. Trees 22, 749-758.
4
De Philippis, A., 1937. Classificazioni ed indici del clima in rapporto alla
5
vegetazione forestale italiana. Nuovo Giornale Botanico Italiano 44, 1-169.
6
Desplanque, C., 1997. Dendroécologie comparée du Sapin et de l'Epicéa dans les
7
Alpes internes Franco-Italiennes. Rôle des facteurs climatique et anthropique
8
sur leur répartition. Thèse de Docteur de l'Université Joseph Fourier,
9
Laboratoire Ecosystèmes Alpins, Grenoble, France.
an
us
cr
ip t
1
Desplanque, C., Rolland, C., Schweingruber, F.H., 1999. Influence of species and
11
abiotic factors on extreme tree ring modulation: Picea abies and Abies alba in
12
Tarentaise and Maurienne (French Alps). Trees 13, 218-227.
13
Di Filippo, A., Biondi, F., Cufar, K., de Luis, M., Grabner, M., Maugeri, M.,
14
Presutti Saba, E., Schirone, B., Piovesan, G., 2007. Bioclimatology of beech
15
(Fagus sylvatica L.) in the Eastern Alps: spatial and altitudinal climatic signals
16
identified through a tree-ring network. Journal of Biogeography 34 (11), 1873-
21
Ac ce p
te
d
M
10
22
(Fagus sylvatica L.) under different climatic and environmental conditions in
23
Europe - a dendroecological study. Forest Ecology and Management 173, 63-78.
17 18 19 20
1892.
Di Martino, P., 1988. Silver fir in tree forests of Molise, in: Salbitano, F., (Eds), Human influence on forest ecosystem development in Europe. ESF FERN CNR. Bologna, Pitagora Editrice, 335-338. Dittmar, C., Zech, W., Elling, W., 2003. Growth variations of common beech
21
Page 21 of 40
European Commission, 2003. Natura 2000 and Forests - Challenges and
2
opportunities - an Interpretation Guide. Luxembourg: Office for Official
3
Publications of the European Communities. Luxembourg.
4
Ferrari, G.A., Wolf, U., 1970. Considerazioni sui suoli e la rinnovazione naturale
5
dell’abete bianco (Abies alba Mill.) del bosco ‘‘Abeti Soprani’’ (Pescopennataro-
6
IS). Annali Accademia Italiana di Scienze Forestali 19, 423-439.
7
Freni, C., 1955. Andamento del ritmo vegetativo in Abies alba Mill.
8
dell’Aspromonte. Annali Accademia Italiana di Scienze Forestali 4, 135-154.
9
Fritts, H.C., 1976. Tree ring and climate. Academic Press, New York.
an
us
cr
ip t
1
Gallucci, V., Urbinati, C., 2009. Dinamismi di accrescimento e sensitività
11
climatica dell’abete bianco (Abies alba Mill.) nel SIC Alpe della Luna-Bocca
12
Trabaria (PU). Forest@ 6, 85-99.
13
Gao, X., Giorgi, F., 2008. Increased aridity in the Mediterranean region under
14
greenhouse gas forcing estimated from high resolution regional climate
15
projections. Global and Planetary Change 62, 195–209.
16
García-Plazaola, J.I., Becerril, J.M., 2000. Effects of drought on photoprotective
21
Ac ce p
te
d
M
10
22
measurements and modeling. Global Change Biology 15, 992-1014
23
Geßler, A., Keitel, C., Kreuzwieser, J., Matyssek, R., Seiler, W., Rennenberg, H.,
24
2007. Potential risks for European beech (Fagus sylvatica L.) in a changing
25
climate. Trees 21, 1-11.
17 18 19 20
mechanisms in European beech (Fagus sylvatica L.) seedlings from different provenances. Trees 4 (8), 485-490. Gaudinski, J.B., Torn, M.S., Riley, W.J., Swanston, C., Trumbore, S.E., Joslin, J.D., Majdi, H., Dawson, T.E., Hanson, P.J., 2009. Use of stored carbon reserves in growth of temperate tree roots and leaf buds: analyses using radiocarbon
22
Page 22 of 40
Gentilesca, T., Todaro, L., 2008. Crescita radiale e risposte climatiche dell’abete
2
bianco (Abies alba Mill.) in Basilicata. Forest@ 5, 47-56.
3
Gonzales, I.G., 2001. Weiser: a computer program to identify event and pointer
4
years in dendrochronological series. Dendrochronologia 19, 239-244.
5
Gricar, J., Cufar, K., 2008. Seasonal dynamics of phloem and xylem formation in
6
silver fir and Norway spruce as affected by drought. Russian Journal of Plant
7
Physiology 55, 538-543.
8
Holmes, R.L., 1983. Computer-assisted quality control in tree-ring dating and
9
measurement. Tree Ring Bulletin 43, 69-78.
an
us
cr
ip t
1
Holmes, R.L., 1999. Dendrochronological Programm Library (DPL). Users
11
Manual. Laboratory of Tree-Ring Research, University of Arizona, Tucson.
12
(/www.ltrr.arizona.edu/pub/dpl/).
13
Intergovernmental Panel on Climate Change (IPCC), 2007. Climate Change
14
2007: The Physical Science Basis. Contribution of Working Group I to the
15
Fourth Assessment Report of the Intergovernmental Panel on Climate Change,
16
edited by S. Solomon et al., Cambridge Univ. Press, Cambridge, U. K.
21
Ac ce p
te
d
M
10
22
Lenoir, J., Gégout, J.C., Marquet, P.A., Ruffray, P.D., Brisse, H., 2008. A
23
significant upward shift in plant species optimum elevation during the 20th
24
century. Science 320, 1768-1771.
17 18 19 20
Jump, A.S., Hunt, J.M., Peñuelas, J., 2006. Rapid climate change-related growth decline at the southern range edge of Fagus sylvatica. Global Change Biology 12, 2163-2174.
Kern, Z., Popa, I., 2007. Climate-growth relationship of tree species from a mixed stand of Apuseni Mts., Romania. Dendrochronologia 24, 109-115.
23
Page 23 of 40
Linares, J.C., Covelo, F., Carreira, J.A., Merino, J.Á., 2012. Phenological and
2
water-use patterns underlying maximum growing season length at the highest
3
elevations: implications under climate change. Tree Physiology, 32b (2), 161-70.
4
Manetti, M.C., Cutini, A., 2006. Tree-ring growth of silver fir (Abies alba Mill.)
5
in two stands under different silvicultural systems in central Italy.
6
Dendrochronologia 23, 145-150.
7
Mátyás, C., Bozic, G., Gömöry, D., Ivankovic, M., Rasztovits, E., 2009. Juvenile
8
growth response of European beech (Fagus sylvatica L.) to sudden change of
9
climatic environment in SE European trials. IForest - Biogeosciences and
an
us
cr
ip t
1
Forestry 2, 213-220.
11
Nahm, M., Radoglou, K., Halyvopoulos, G., Geßler, A., Rennenberg, H., Fotelli,
12
M.N., 2006. Physiological performance of beech (Fagus sylvatica L.) at its
13
Southeastern distribution limit in Europe: seasonal changes in nitrogen, carbon
14
and water balance. Plant Biology 8, 52-63.
15
Pallardy, S.G., 2007. Physiology of Woody Plants, Third Edition. Academic
16
Press, San Diego.
21
Ac ce p
te
d
M
10
22
long-term tree ring beech chronology from a high-elevation old-growth forest of
23
Central Italy. Dendrochronologia 21 (1), 13-22.
17 18 19 20
Peguero-Pina, J.J., Camarero, J.J., Abadía, A., Martín, E., González-Cascón, R., Morales, F., Gil-Pelegrín, E., 2007. Physiological performance of silver-fir (Abies alba Mill.) populations under contrasting climates near the southwestern distribution limit of the species. Flora 202, 226-236. Piovesan, G., Bernabei, M., Di Filippo, A., Romagnoli, M., Schirone, B., 2003. A
24
Page 24 of 40
Piovesan, G., Biondi, F., Bernabei, M., Di Filippo, A., Schirone, B., 2005. Spatial
2
and altitudinal bioclimatic zones of the Italian peninsula identified from a beech
3
(Fagus sylavtica L.) tree-ring network. Acta Oecologica, 27 (3), 197-210.
4
Piovesan, G., Biondi, F., Di Filippo, A., Alessandrini, A., Maugeri, M., 2008.
5
Drought-driven growth reduction in old beech (Fagus sylvatica L.) forests of the
6
central Apennines, Italy. Global Change Biology 14 (6), 1265-1281.
7
Ripullone, F., Borghetti, M., Raddi, S., Vicinelli, E., Baraldi, R., Guerrieri, M.R.,
8
Nolè, A., Magnani, F., 2009. Physiological and structural changes in response to
9
altered precipitation regimes in a Mediterranean macchia ecosystem. Trees 23,
an
us
cr
ip t
1
823-834.
11
Rolland, C., 1993. Tree-ring and climate relationships for Abies alba in the
12
internal Alps. Tree-Ring Bulletin 53, 1-11.
13
Romagnoli, M., Schirone, B., 1992. Indagini dendroecologiche preliminari
14
sull’abete bianco del bosco Abeti Soprani (Pescopennataro-IS). Annali
15
dell’Accademia Italiana di Scienze Forestali 41, 3-30.
16
Rossi, S., Deslauriers, A., Anfodillo, T., Morin, H., Saracino, A., Motta, R.,
21
Ac ce p
te
d
M
10
22
Savidge, R.A., 2001. Intrinsic regulation of cambial growth. Journal of Plant
23
Growth Regulation, 20, 52-77.
17 18 19 20
Borghetti, M., 2006. Conifers in cold environments synchronize maximum growth rate of tree-ring formation with day length. New Phytologist 170, 301310.
Rovelli, E., 1995. La distribuzione dell'abete (Abies alba Mill.) sull'Appennino. Monti e Boschi 6, 5-13.
25
Page 25 of 40
Schweingruber, F.H., Kairiukstis, L., Shiyatov, S., 1990. Sample selection, in:
2
Cook, E.R., Kairiukstis, L.A., (Eds.). Methods of dendrochronology. Kluwer
3
Academic Publishers, Dordrecht, The Netherlands.
4
Schweingruber, F.H., Eckstein, D., Serre Bachet, F., Braker, O.U., 1990a.
5
Identification, presentation and interpretation of event years and pointer years
6
in dendrochronology. Dendrochronologia 8, 9-38.
7
Schweingruber, F.H., 1996. Tree Rings and Environment. Dendroecology. Paul
8
Haupt Verlag, Berne.
9
Serre-Bachet, F., 1982. The Mediterranean Area. Comment, in: Hughes, M.K.,
10
Kelly, P.M., Pilcher, J.R., Lamarche, V.C., 1982. Climate from tree-rings.
11
Cambridge Univ. Press, pp. 153-155.
12
Sitch, S., Huntingford, C., Gedney, N., Levy, P.E., Lomas, M., Piao, S.L., Betts,
13
R., Ciais, P., Cox, P., Friedlingstein, P., Jones, C.D., Prentice, I.C., Woodward,
14
F.I., 2008. Evaluation of the terrestrial carbon cycle, future plant geography and
15
climate-carbon cycle feedbacks using five Dynamic Global Vegetation Models
16
(DGVMs). Global Change Biology 14 (9), 2015-2039.
21
Ac ce p
te
d
M
an
us
cr
ip t
1
22
Tessier, L., 1982. Analyse dendroclimatologique compare de 6 populaions de
23
Pinus sylvestris (L.) dans la Drome. Ecologia Mediterranea 8 (3), 185-202.
24
Todaro, L., Andreu, L., D'alessandro, C.M., Gutierrez, E., Cherubini P.,
25
Saracino A., 2007. Response of Pinus leucodermis to climate and anthropogenic
17 18 19 20
Szabados, I., 2006. The effect of the precipitation on the tree ring width. Carpth. J. of Earth and Environmental Sciences 1 (2), 39-44. Tardif, J., Camarero, J. J., Ribas, M., Gutierrez, E., 2003. Spatiotemporal variability in tree growth in the central Pyrenees: Climatic and site influences, Ecol. Monogr. 73, 241–257.
26
Page 26 of 40
activity in the National Park of Pollino (Basilicata, Southern Italy). Biological
2
Conservation 137, 507-519.
3
Vitale, M., Mancini, M., Matteucci, G., Francesconi, F., Valenti, R., Attorre, F.,
4
2012. Model-based assessment of ecological adaptations of three forest tree
5
species growing in Italy and impact on carbon and water balance at national
6
scale under current and future climate scenarios. iForest - Biogeosciences and
7
Forestry 5, 235-246.
8
Vitasse, Y., Delzon, S., Dufrene, E., Pontailler, J.Y., Louvet, J.M., Kremer A.,
9
Michalet, R., 2009. Leaf phenology sensitivity to temperature in European trees:
10
do within-species populations exhibit similar responses? Agric. For. Meteorol.
11
149, 735-744.
12
Wigley, T.M.L., Briffa, K.R., Jones, P.D., 1984. On the Average Value of
13
Correlated
14
Hydrometeorology. Journal of Climate and Applied Meteorology 23, 201-213.
15
Yamaguchi, D.K., 1991. A simple method for cross-dating increment cores from
16
living
Series,
with
Applications
in
Dendroclimatology
and
Canadian
Ac ce p
trees.
te
d
Time
M
an
us
cr
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1
Journal
of
Forest
Research
21,
414-416.
27
Page 27 of 40
1 2
Acknowledgements
3 The International Ph.D program "BioEcoSystems and BioTechnology" at the
5
University of Basilicata supported A Rita.
6
Authors acknowledge R Tognetti (Università del Molise) and G Milanese (Comunità
7
Montana Alto Molise) for support in sampling at Molise site and A Lapolla for
8
precious help in field work. We also acknowledge the financial support of the project
9
"A permanent natural laboratory in the Pollino National Park: a necessary prerequisite
10
for sustainable management" by the Parco Nazionale del Pollino, Rotonda, Italy. The
11
valuable comments by three anonymous referees greatly contributed to improve the
12
manuscript.
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1 2
Figure Legends
3 Figure 1: Walter and Leith climatic diagrams super-imposed on study sites location
5
map.
6
Figure 2: Climatic trends for Basilicata (full line) and Molise (dotted line) sites. Left
7
panel shows 20-years spline in mean temperatures and annual precipitation; right
8
panel indicates the last 30-years of summer trends (June-Sept) in temperature and
9
precipitation.
an
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4
Figure 3: Residual tree ring chronologies, from top to bottom: ABBas, FGBas,
11
ABMol, FGMol. Symbols indicate positive (filled) and negative (empty) pointer
12
years. Grey lines are the samples depth.
13
Figure 4: Climate-growth relationships between tree-ring residual chronologies and
14
monthly climatic variables (Tmax, Tmin, and P). Bars and lines indicate, respectively,
15
simple correlation coefficients (Pcorr), and response functions (RRFF). See methods
20
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21
and precipitation. Stars denote significant (p<0.05) correlations.
22
Figure 6: Superposed epoch analysis of species specific negative (grey bars) and
23
positive (white bars) pointer years and summer (June-August) precipitations for A.
24
alba (left panel) and F. sylvatica (right panel) over the common period 1925-2010.
16 17 18 19
for details.
Figure 5: Temporal changes in climate-growth relationships during the twentieth century. Thirty-year intervals lagged five years were evaluated from 1925 to 2010. The X and Y-axes represent, respectively the temporal element in years, and growth trend in bootstrapped correlations. Black and dotted lines are respectively temperature
29
Page 29 of 40
Basilicata site (A) and Molise site (B). The x-axis are years prior to and after an event
2
and on the y-axis are departures from the mean. Departure is the difference between
3
actual and bootstrap generated values of summer precipitations of the respective year;
4
dashed lines denote 95%, solid lines 99% confidence limit, stars indicate significant
5
departures.
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1 2
Table Legends
3 Table 1: Study sites characteristics. Temperature and precipitation values are averages
5
from the period 1925-2010.
6
Table 2: Statistical properties of tree-ring detrended (Dt) and residuals (Rs)
7
chronologies. Mean sensitivity (MS), standard deviation (SD), first order
8
autocorrelation (AC1), signal-to-noise ratio (SNR), mean correlation between trees
9
(MC).
an
us
cr
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4
Table 3: Inter- and intra-specific correlations between A. alba and F. sylvatica
11
residual chronologies. Statistically significant differences are indicated as *P < 0.01
12
and
M
10
<
0.001,
respectively.
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ip t
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Latitude, N 39°56'32.57" 41° 51' 7.02" Longitude, W 16°14'6.45" 14° 17' 34.02" Altitude, (m) 1500 1490 Slope, (%) 12-25 10-15 Exposure N-NE NE Temperature, (°C)* 7.5 9.4 Precipitation, (mm y-1)* 1083 1030 _________________________________________________
cr
_________________________________________________ Characteristics Sites ______________________________ Basilicata Molise _________________________________________________
te
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
Table 1
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Table 2 ___________________________________________________________________ Statistical properties Chronologies ____________________________________________
Chronology type
Dt
Rs
Dt
Rs
MS SD AC1 MC SNR
0.21 0.25 0.42 0.45 11.5
0.24 0.22 -0.10 0.52 15.1
0.18 0.20 0.35 0.35 8.13
0.19 0.17 -0.07 0.38 9.16
1794-2010 17/34 217 0.92
1825-2010 15/30 186 0.90
cr
1898-2010 17/34 113 0.93
us
1868-2010 16/32 143 0.96
Dt
Rs
Dt
Rs
0.18 0.30 0.38 0.28 6.02
0.21 0.29 -0.02 0.33 7.61
0.21 0.34 0.69 0.21 4.19
0.24 0.24 0.01 0.22 4.36
an
Time span chronologies Number of trees/cores Number of years EPS (1920-2010)
ip t
FGMol FGBas ABMol ABBas ___________________________________________________________________
d
M
_________________________________________________________________________
te
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
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1 2
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Table 3
2
ip t
_________________________________ FGBas ABMol FGMol _________________________________ ABBas 0.182 0.242* 0.137 FGBas 0.131 0.546** ABMol 0.278*
cr
3 4 5 6 7 8 9
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Figure_1
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Figure_2
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Figure_3
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Figure_4
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Figure_5
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Figure_6
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