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Eucalypt plantations and climate change
Forest Ecology and Management 301 (2013) 28–34
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Eucalypt plantations and climate change q Trevor H. Booth ⇑ CSIRO Ecosystem Sciences and CSIRO Climate Adaptation Flagship, G.P.O. Box 1700, Canberra, ACT 2601, Australia
a r t i c l e
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Article history: Available online 19 May 2012 Keywords: Vulnerability Adaptation Carbon dioxide Simulation models Database
a b s t r a c t Eucalypts are grown in plantations in more than 90 countries, so it is important to assess their vulnerability to climate change. Global mean annual temperature over land has already increased by about 0.9 °C in the last century and many countries have agreed that urgent action should be taken to limit the increase in global mean temperature below 2 °C. Unfortunately, as emissions are currently tracking at higher levels than the worst case scenario envisaged by the Intergovernmental Panel on Climate Change it appears increasingly unlikely that temperature increase can be limited to 2 °C. This paper assesses the vulnerability of eucalypt plantations to climate change. Vulnerability is a function of potential impact, which is related to exposure and sensitivity, and adaptive capacity. Eucalypt plantations total more than 20 million hectares and are grown in many countries around the world, so have significant exposure to climate change. About 41% of more than 800 eucalypt taxa grow naturally in Australia within narrow climatic ranges of less than 2 °C, so are potentially sensitive to climatic change. Fortunately, the small number of commercially important species tend to have much wider climatic tolerances, but genetic selection to improve growth may well be reducing their climatic adaptability. Efforts have been made to simulate eucalypt growth under changing climatic and atmospheric conditions. If photosynthesis and water use efficiency are increased by increasing atmospheric carbon dioxide levels then some plantations may enjoy significant yield increases. However, recent results from eucalypts growing under elevated CO2 conditions in whole tree chambers suggest there is little if any ‘fertilisation effect’ on photosynthesis, though water use efficiency is increased. Consequently, productivity may increase in some plantations and decrease in others. Fortunately, the adaptive capacity of eucalypt plantations is high. Many eucalypts are grown on short rotations of less than ten years, so changing silvicultural practices and planting different genotypes to match changing climatic conditions is relatively easy. While the vulnerability of eucalypt plantations is only at a medium level it is concluded that sharing information about where particular eucalypt genotypes are grown, identifying potentially marginal climatic areas and recommending genotypes suitable for changing conditions would help to further reduce potential vulnerability. The development of a eucalypt database and mapping system is proposed as a major collaborative project to help to protect one of global forestry’s most valuable resources. Crown Copyright Ó 2012 Published by Elsevier B.V. All rights reserved.
1. Introduction Over 200 years eucalypts have moved from being a botanical novelty to their current status as a major source of biomass for paper pulp, fibreboard, industrial charcoal and fuelwood (Turnbull, 1999). There are now more than 20 million hectares of eucalypt plantations around the world with major centres in Brazil (4.2 m ha), India (3.9 m ha) and China (2.6 m ha) (GIT Consulting, 2009). More than 110 species of eucalypts have been introduced into more than 90 countries, and eucalypts are widely grown in
q Invited Paper for Special Issue on ‘‘Joining silvicultural and genetic strategies to minimize Eucalyptus environmental stresses: from research to practice’’, IUFRO WG 2.08.03, 14–18 November, 2011, Port Seguro, Bahia State, Brazil. Editor: Jean-Paul Laclau ([email protected]). ⇑ Tel.: +61 2 6246 4217, mobile: +0439 413816. E-mail address: [email protected]
the tropics and subtropics not only in plantations, but also in small woodlots, in windbreaks and other small scale plantings (Jacobs, 1981). Though many species were evaluated in many countries, a small number of species emerged which dominate global plantations. For example, in China more than 200 species were assessed, but only 10 species are now widely grown (McKenney et al., 1993; Turnbull, 2007). Current plantations around the world are dominated by the ‘big nine’ identified by Harwood (2011) as: Eucalyptus camaldulensis, Eucalyptus grandis, Eucalyptus tereticornis, Eucalyptus globulus, Eucalyptus nitens, Eucalyptus urophylla, Eucalyptus saligna, Eucalyptus dunnii, Eucalyptus pellita and their hybrids, which together account for more than 90% of the major eucalypt plantations. Great efforts have gone into tree improvement, at first focussing mainly on careful selection and breeding of first and second generations from collections from native stands (Eldridge et al., 1994). Later tree improvement methods included the use of hybrids and clones (Harwood, 2011).
0378-1127/$ - see front matter Crown Copyright Ó 2012 Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.foreco.2012.04.004
T.H. Booth / Forest Ecology and Management 301 (2013) 28–34
A couple of examples give some impression of how vital the continuing success of eucalypt plantations is to the economies of developing and transitioning countries. First, an economic analysis of a series of eucalypt tree improvement projects in China (van Bueren, 2004) suggested that a research investment had delivered benefits in excess of 1 billion dollars. Second, pulp producers in developing countries and countries with transitioning economies raised US$37.8 billion between 1990 and 2004 to develop pulp mills, many of which use plantation eucalypts for processing (Spek, 2005). For example, the Veracel pulp mill in Bahia province of Brazil, which cost around US$850 million, is supplied by 100,000 hectares of Eucalyptus plantation. With such large benefits and investments associated with the successful growth of eucalypts it is important to assess what potential threat, if any, climate change poses to eucalypt plantations around the world and what adaptations may be required to minimise any potential threats. 2. Climatic change Evidence continues to accumulate that global average temperatures are rising. The Berkeley Earth Project released draft papers describing its work in October 2011 (Berkeleyearth.org). They have analysed 1.6 billion temperature observations from more than 39,000 stations and confirmed global warming shown in previous work by the Hadley Centre, the National Oceanic and Atmospheric Administration (NOAA) and the National Aeronautics and Space Administration (NASA). The temperature increase has been about 0.9 °C over land over the past century and global temperature has increased by about 0.5 °C in the last 30 years (Foster and Rahmstorf, 2011). The global surface temperature for 2011 was the hottest ever observed during La Niña years (NOAA, 2012). The ‘Copenhagen Accord’ produced at the United Nations Framework Convention on Climate Change (UNFCCC) conference of parties (COP15) in December 2009 agreed that countries should take urgent action to limit the increase in global average temperatures to less than 2 °C (relative to pre-industrial levels) to avoid ‘dangerous interference with the climate system’. Some progress was made at the UNFCCC COP16 meeting at Cancun (December 2010) with 90 countries representing 80 per cent of global emissions making pledges to reduce carbon pollution. At COP17 in Durban (December 2011) parties to the UNFCCC agreed to negotiate by 2015 a new legally binding agreement to reduce emissions that would take effect from 2020. A recent study has shown that greenhouse gas emissions need to peak before 2020 to give the world a good chance of limiting average global temperature increases to 2 °C relative to pre-industrial levels (Rogelj et al., 2011). The need to limit emissions soon is because a significant proportion of CO2 stays in the atmosphere for a long time, so the temperature response will continue even when human-derived emissions return to zero. Unfortunately, a report on global emissions data for 2010 released in November 2011 by the US Department of Energy (Boden and Blasing, 2011) has shown that actual emissions are greater than even the worst case scenarios used in the Intergovernmental Panel on Climate Change Fourth Assessment report (IPCC, 2007). So, while limiting global temperature increase to 2 °C over preindustrial levels may still be possible, the world at present remains on track for a rise of about 4 °C or more by the end of the century. While increasing temperatures are the most certain effect of climate change, other factors important for tree growth will also change. For example, the South Eastern Australian Climate Initiative (CSIRO, 2010) found that the 13-year drought in the southern Murray–Darling Basin (MDB) and Victoria that ended in 2010–2011 was unprecedented compared with other recorded droughts since 1900 and could be related, in part at least, to climate change. Similarly, the Indian Ocean Climate Initiative (IOCI, 2009) has found a step decrease in total annual rainfall averaged across south west Western
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Australia of almost 10% since the mid-1970s. This rainfall decline is apparently associated with changes in the large scale atmospheric circulation that are most likely due to a combination of natural variability and the enhanced greenhouse effect (IOCI, 2011). Climate change is driven by rising levels of greenhouse gases, particularly carbon dioxide (IPCC, 2007). Increasing CO2 levels may affect tree growth not only through changes in temperature and rainfall, but also through increasing photosynthetic rates and increasing water use efficiency. However, the extent to which mature examples of individual species will be affected is far from clear, as much of the experimental evidence comes from small plants grown in controlled environments (see, Booth et al., 2010 for a short review of the impacts of enhanced CO2 on trees). Free air carbon dioxide enrichment (FACE) experiments with large trees should provide more reliable indications of the impacts on eucalypts (Raison et al., 2007). These release CO2 into the atmosphere around the experimental plants and provide more realistic growing conditions than growth chambers, but at a great financial cost. 3. How vulnerable are eucalypt plantations? A review of climate change risk and vulnerability in Australia (Allen Consulting Group, 2005) used an approach to vulnerability assessment adapted from a European study (Shroter and ATEAM consortium, 2004). This simply says that vulnerability is a function of potential impact and adaptive capacity, while potential impact is a function of exposure and sensitivity. Exposure relates to the influences that impact on a system, while sensitivity reflects the responsiveness of a system to climatic influences. Adaptive capacity reflects the ability of a system to change in a way that makes it better equipped to deal with external influences. In this paper some simple factors affecting exposure and sensitivity are first considered in isolation before a couple of examples of simulation models are used to illustrate how exposure and sensitivity combine to produce potential impacts. 3.1. Exposure Considering exposure factors for plantation forests in Australia the Allen Consulting Group (2005) identified reduced rainfall, increased fire hazard and pest infestations as factors that could adversely affect forestry. Studies carried out in Australia since this report was published have emphasised the importance of these three factors in forest management. For example, immature forests in Australia are particularly susceptible to drought, and reduced rainfall would be a particular concern for plantation managers (Battaglia et al., 2009). Interactions between climate change and increased fire hazard were reviewed in a submission to the 2009 Victorian Bushfires Royal Commission, which followed a tragic event which resulted in 173 deaths (Booth, 2009). While the fires affected largely native eucalypt forests, rather than plantations, many of the factors affecting exposure are similar. For instance, the fires took place in conditions of extremely high temperatures and prolonged drought, which while they may have been in part a result of natural variability were also consistent with expected trends in climate change. The impacts of a defoliating pest, Mycosphaerella leaf disease, on E. globulus plantation productivity in Australia under current and future climates have been studied using the CLIMEX and CABALA models (Pinkard et al., 2010). The results suggested that effects of defoliation could be significant and should not be ignored when considering future management under climate change. Most eucalypt plantations around the world potentially have exposure to some or all of these three factors. For example, drought may reduce eucalypt plantation yields by as much as one third
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over a six to seven year rotation in locations near the Atlantic coast of Brazil (Almeida et al., 2010). While exposure to factors such as drought, fires and pests may reduce productivity, eucalypt plantations may benefit from exposure to raised atmospheric CO2 levels, through effects on photosynthesis and water use efficiency. How these effects combine to influence growth is considered in Section 3.3 which deals with simulation modelling. 3.2. Sensitivity With regard to sensitivity many eucalypts have narrow natural climatic ranges. In the early 1980s climatic interpolation surfaces were developed which enabled mean climatic conditions to be reliably assessed for any site (see, for example, Hutchinson et al., 1984) and a program called BIOCLIM (Busby, 1991) was the first to allow bioclimatic envelopes to be assessed for particular species. One of the first species to be analysed using BIOCLIM was Eucalyptus citriodora (Booth, 1985). This early version of BIOCLIM defined bioclimatic envelopes in terms of 12 factors, such as mean annual temperature and mean annual rainfall. Later, Hughes et al. (1996) used BIOCLIM to analyse more than 800 eucalypt taxa in terms of 35 bioclimatic factors. They found about 41% of the species evaluated had distributions with less than 2 °C variation in mean annual temperature. Only about 10% of the species evaluated had broad climatic ranges in their natural distributions (MAT range >9 °C). Bioclimatic analyses represent part of the multiple dimensions of the realised niche of each species (sensu Hutchinson, 1957, 1965) i.e. where it will grow when in competition with other species. It was quickly realised that eucalypt species elimination trials outside Australia provide a useful indication of the fundamental niche i.e. the range of conditions species will tolerate when competition with other species is minimised (see Booth et al., 1988). It’s interesting, though perhaps not surprising, that most of the nine species that dominate the global plantation eucalypt resource have extensive natural distributions (see Boland et al.. 1984) and broad fundamental climatic niches (mostly >9 °C) (see Table 1). E. dunnii is an interesting exception which has a ‘restricted’ natural occurrence, but has proved successful over a relatively wide range of climatic conditions. There have been enormous gains in productivity made through genetic improvement of eucalypts (Eldridge et al., 1994; Harwood, 2011), but little is known about how the increasing use of clones reduces climatic adaptability in comparison to planting seed collected from the wild or first or second generations of improved seed. 3.3. How will climate change impact growth? The previous sections provide some indication of the exposure and sensitivity of eucalypt plantations to climate change. Exposure Table 1 Approximate mean annual temperature requirements for the nine eucalypt species, which together with their hybrid combinations, dominate the world’s eucalypt plantations (Data from Booth and Pryor (1991), unless noted otherwise). Species
Approximate range of mean annual temperature (°C) in plantations
E. camaldulensis
18–28 13–22 14–22 9–18 14–25 9–18 20–27 14–23 17–27 18–28
E. E. E. E. E. E. E. E.
dunnii globulus grandis nitens pellita saligna tereticornis urophylla
(Northern provenances) (Southern provenances) (Jovanovic et al., 2000)
(Harwood, 2011) (Northern provenances)
and sensitivity combine to create potential impact. Computer simulation models are generally used to assess the likely impacts of climate change. For example, Almeida et al. (2009) analysed how climate change was likely to affect about 500,000 ha of E. grandis E. urophylla hybrid plantations growing within a 32 M ha region of eastern Brazil. They used the 3-PG model (Landsberg and Waring, 1997) to predict mean annual increment and water use efficiency. The model was modified to include the direct effects of increasing levels of atmospheric CO2 on photosynthesis and also stomatal conductance. Many experimental and theoretical studies suggest light saturated assimilation rate and light use efficiency will increase as atmospheric CO2 concentration increases, while maximum stomatal conductance is expected to decline (see, for example, Ainsworth and Rogers, 2007). These effects were incorporated into 3-PG through modifications of canopy quantum efficiency and canopy conductance through growth modifiers. The model was run for a 0.5° climatic grid using data for 1971– 2000 from the University of East Anglia Climate Research Unit (Mitchell et al., 2004). Projected data for 2030 and 2050 were based on the Intergovernmental Panel on Climate Change (IPCC, 2007) A1B scenario. These data represented a reduction of 2% and 3% in annual precipitation and an increase of 8% and 15% in vapour pressure deficit in 2030 and 2050 respectively relative to the standard ‘historical’ (1971–2000) period. As detailed soil data were not available a standard clay loam soil with 180 mm water holding capacity was used. The ‘historical’ scenario used an atmospheric CO2 level of 350 lg g 1 (i.e. 350 ppm), with 450 lg g 1 in 2030 and 520 lg g 1 in 2050. The results suggested that forest productivity may increase by about 6 m3 ha 1 year 1 by 2030, and 10 m3 ha 1 year 1 by 2050, corresponding to 17% and 26% increments compared with the historical period. Water use efficiency increased by an average of 1.0 g DM kg 1 H2O in 2030 and 1.7 g DM kg 1 H2O in 2050 compared with the historical scenario, which is equivalent to increases of 29% and 51% in WUE, respectively. 3.4. Incorporating uncertainties into growth predictions Almeida et al. (2009) used the best information available to assess the likely effects of increased atmospheric CO2 levels on tree growth. However, there are considerable uncertainties about how climatic and atmospheric changes will affect tree growth. Battaglia et al. (2009) analysed likely effects of climatic change on Australia’s plantation estate. They noted that ‘our knowledge of the effects of elevated CO2 on our plantation species is poor’ and ‘examples of species from the same genera and even clones of the same species differ markedly in their response to elevated CO2’. So, they dealt with uncertainties using Monte-Carlo analysis by identifying likely ranges of assumptions and then running the CABALA model (Battaglia et al., 2004) many times to consider many possible combinations of assumptions. For example, they simulated three different responses of photosynthesis to raised CO2: (a) No increase in photosynthesis, (b) partial increase (i.e. acclimation) and (c) full increase (i.e. no down-regulation). Simulations were run for present conditions as well as for projected conditions for 2030 and 2070. In total more than a million simulation runs were made for sites across Australia’s major plantation regions. Maps were produced showing projected regional changes in plantation productivity. As multiple assumptions were run for individual sites it was also possible to show where variations in predictions were relatively great or relatively small. An interesting feature of the analysis was that despite several uncertainties three main categories emerged for eucalypt plantations. Some regions were very likely to enjoy an increase in production with little increase in risk (e.g. E. globulus and E. nitens plantations in Tasmania), other areas were likely to increase in production with some in-
T.H. Booth / Forest Ecology and Management 301 (2013) 28–34
crease in risk (e.g. E. nitens and E. globulus in Victoria and the ‘Green Triangle’ area around the South Australian and Victoria border areas), while some regions were likely to suffer decreases in production with an increase in risk (e.g. eastern and northern extents of Western Australian E. globulus plantations). A similar analysis of the main plantation centres of the global eucalypt plantation resource defining areas of uncertainty and using multiple computer runs to identify areas where productivity is likely to increase and areas where it is likely to decrease would be very useful. In the absence of such a global analysis the general conclusion from such studies as those of Almeida et al. (2009) and Battaglia et al. (2009) is that impacts of climate change on eucalypt plantation productivity are likely to be highly site specific and will depend in part on the balance between the possibly detrimental effects of increased temperatures and rainfall declines in some areas, versus the potential productivity gains through elevated CO2. In places where species are already growing close to their optimal growing temperatures production gains may not eventuate. High temperatures and dry soils may also increase drought deaths. 3.5. Reducing uncertainties It’s clear from the previous section that one of the key uncertainties is how eucalypts will respond to changes in atmospheric CO2. Early work with eucalypt seedlings grown in open-topped chambers indicated that enhanced CO2 levels would increase net photosynthesis and growth. For example, Roden et al. (1999) reported 53% more stem growth in 8 months with Eucalyptus pauciflora seedlings grown at 2 ambient CO2. However, results from other tree species suggested that responses from seedlings may be different to those of more mature plants. The Hawkesbury Forest Experiment (near Sydney, Australia) was devised in order to grow eucalypts of up to 9 m in height under elevated CO2 without the expense of free air CO2 enrichment (FACE). Twelve whole tree chambers previously used for an elevated CO2 experiment in Sweden were shipped to Australia. Single E. saligna trees were grown from seedlings with six of the chambers being maintained at ambient CO2 conditions (390 lg g 1), while the other six were maintained at an enhanced level (630 lg g 1) for 2 years (Barton et al., 2010). Half of each set were subjected to periodic drought. The results showed little if any ‘fertilisation effect’ of elevated CO2. In other words there was strong down-regulation of photosynthesis. However, elevated CO2 increased water use efficiency and there was no acclimation of the stomatal response to CO2. While chambers are useful, there are obvious challenges in keeping conditions within a chamber comparable with those of the open air, so FACE experiments are also needed (Raison et al., 2007). A free-air CO2 enrichment trial (EUCFACE) was established in 2010 in native eucalypt woodland near the Hawkesbury site. FACE experiments would be particularly useful for each of the main nine globally important eucalypt plantation species. While enhanced CO2 trials have focussed mainly on effects on photosynthesis and water use efficiency there have been some surprising effects reported. For example, Barker et al. (2005) reported ten times as much frost damage on E. pauciflora (snow gum) seedlings when raised in open topped chambers at 2 ambient CO2 than when they were raised in similar chambers under ambient conditions.
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duce vulnerability if potential impacts can be reduced. In other words, adaptive capacity is the ability of a system to change in a way that makes it better equipped to deal with external influences. Booth et al. (2010) reviewed adaptation options for dealing with projected climate change. Though this summary focussed on Australian plantations, the general categories would be similar for global eucalypt plantations. The following are some examples of adaptive options: (a) Genotypes – There is great potential for managers of eucalypt plantations to respond to climate change if necessary by planting different genetic material. Many eucalypt plantations are grown on relatively short rotations of 6–10 years for pulp and paper production, so the opportunity to adapt occurs much more frequently than for species that may be grown for 50 or more years for sawlogs. The small number of species that dominate global plantations should allow improved information on the climatic requirements of particular genotypes to be collected relatively easily. In May 2011 E. grandis became the second tree species to have its entire genome sequenced (web site: eucalyptusdb. bi.up.ac.za). CSIRO scientists are using genomic techniques to identify genes associated with drought tolerance in different provenances of E. camaldulensis and several other eucalypt species (S. Southerton pers. comm.). Improved knowledge about the role of particular genes should help develop new genotypes with improved characteristics, such as drought tolerance. Already the first genetically modified eucalypts are being developed with improved frost tolerance, as well as improved growth and processing characteristics (Arborgen, 2010; Bassa et al., 2011). (b) Stand management – There are excellent opportunities to manipulate spacing and thinning to respond to changing conditions. For example, a simple adaptation to match planting densities to mean annual rainfall in E. globulus plantations in Western Australia is described below. (c) Site selection – It would be desirable to restrict new plantations to currently suitable environments if rainfall decreases, but slower growth rates associated with drier environments may become more acceptable if payments for carbon sequestration become available (see Polglase et al., 2011). In other words, site selection adaptations need to consider both changing environmental and economic conditions. (d) Fire management – Protective measures (e.g. widening of firebreaks) could be relatively easily increased if risks of fire increase as a result of hotter and drier conditions. (e) Pests, diseases and weeds – Climate change will change the distributions of potential pests, diseases and weeds, so new challenges must be faced by forest managers. However, forest managers have adapted successfully to new problems before climate change was an issue. For example, eucalypt plantations in Brazil introduced resistant genotypes when guava rust (Puccinia psidii) became a problem (Glen et al., 2007; Alfenas et al., 2011). (f) Establishment strategies – It may be necessary to adjust planting times as conditions change and to make use of improved seasonal forecasting. (g) Climatic risks – Increasing reliance should be placed on recent climatic records as conditions change. For example, it may be advisable to consider frost risks on the basis of data from the last 25 years rather than the last 100 years.
3.6. Adaptive capacity We have considered the exposure and sensitivity of eucalypt plantations and how exposure and sensitivity can be combined in models to estimate potential impacts. Adaptive capacity can re-
Adaptations need not be complex. A simple adaptation recommendation for E. globulus plantings in the south-west of Western Australia provides a good example. There has been a decline in rainfall in this region that as mentioned earlier is believed in part
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at least be related to climate change (IOCI, 2009, 2011). Blue gum plantations used to be planted at 1250 stems per hectare, but some drought deaths were experienced. A simple adaptation has been recommended to minimise drought deaths, which is to plant one seedling per ha per mm of rainfall (White, D. pers. comm. cited in Booth 2010). So, in regions with 900 mm of annual rainfall 900 sph would be planted and in regions with 1000 mm of rainfall 1000 should be planted. IUFRO has prepared a detailed report considering adaptation options for both native and plantation forests (Seppälä et al., 2009). It includes an appendix with about 15 pages of potential adaptations based on a paper by Ogden and Innes (2007). For example, two simple recommendations relevant to eucalypt plantations are to design trials to test improved genotypes over diverse climatic environments and to avoid use of clonal material selected purely on basis of past growth rates.
cies. FAO’s ‘Eucalypts for Planting’ (Jacobs, 1981) describes experiences with the introduction of about 110 eucalypt species in more than 90 countries around the world. Some remarkable books and reports describe the introduction of eucalypts into particular regions. Probably none is more detailed that Poynton’s (1979) 882 page ‘Tree Planting in Southern Africa Volume 2 The Eucalypts’ which describes trials of 88 species at 271 sites. A major limitation of the Poynton book was that reliable temperature data were not available for 208 of the sites. The development of interpolation surfaces for many countries allowed climatic conditions to be estimated for sites that were distant from the nearest meteorological station (Booth, 1996). CAB International’s (2005) Forestry Compendium CD brought together information for many species including eucalypts in computer searchable form.
3.7. Vulnerability Having considered how exposure and sensitivity combine to produce impact and how adaptive capacity can reduce impact, how should vulnerability of eucalypt plantations to climate change be rated? Exposure should probably be rated as high. Eucalypts are widely planted around the world. Reduced rainfall, drought, increased fire hazard and pest infestations could adversely affect productivity and recently established plantations are particularly susceptible to drought. Pest, diseases and weeds are likely to benefit from disturbances associated with climate change. Sensitivity should probably be rated as medium. It reflects the responsiveness of a system to climatic influences. Many eucalypt species show limited climatic adaptability in their natural environments. In contrast, the small number of very successful plantation species show great climatic adaptability, but it’s likely that increasing selection to produce improved productivity is reducing genetic variability and may well be reducing climatic adaptability. Potential impact as assessed by simulation models is probably medium. Many plantations may well benefit from increased atmospheric CO2 levels, but more information is needed to be confident of how widespread and prolonged benefits may be. Some plantations may experience reduced productivity particularly as a result of reduced rainfall. Fortunately there is very good adaptive potential in eucalypt plantations. Many plantations are grown on short rotations and this provides regular opportunities to adjust both genotypes planted and their management. Only a small number of species dominate global plantations, so there is the opportunity to study each species intensively. While potential impact of climate change on plantations is medium their adaptive capacity is high, so overall their vulnerability is only medium. Given the considerable uncertainties about the climatic adaptability of individual genotypes it would be inappropriate to assess vulnerability as less than medium. There are probably positive benefits for eucalypt plantation forestry from adaptation through use of appropriate genotypes and management adjustments that take account of changing conditions. The main impediment to minimising the vulnerability of eucalypt plantations to climate change is lack of knowledge.
Eucalypt plantations provide billions of dollars of benefits in three of the world’s most dynamic economies (Brazil, China and India) as well as in many other countries. While many eucalypt plantations are likely to benefit to some extent from increasing atmospheric CO2, changing temperatures and rainfall will cause problems at some sites. We need to know where future climate change conditions are likely to place particular genotypes outside their suitable conditions, so we can develop appropriate adaptations. A eucalypt database and climatic mapping system should be developed to fulfil this need. Major plantation genotypes of the ‘big nine’ (Harwood, 2011) would be a priority for such a system. However, it would also collect and map information relevant to lesser-known species, which are important in particular regions, especially in developing countries. The system would also collect information from species elimination trials for any eucalypt species, as such information is vital in assessing the vulnerability of their native stands to climate change. For example, E. nitens grows well at many sites in South Africa, but doesn’t flower and hence doesn’t produce seed as conditions are warmer than those within its natural distribution (T. Swain, pers. comm.). Previous databases have concentrated largely on providing summary data at the species level. For example, the CAB International (2005) database describes the range of climatic conditions suitable for particular species. So, it provides ranges of climatic conditions for important factors such as mean annual temperature, mean annual rainfall, mean maximum temperature of the hottest month and mean minimum temperature of the coldest month. What is now needed to deal with changing climatic conditions is information on the particular sites where particular genotypes are grown. It would then be possible to assess for each site whether the genotype is growing under unusually extreme conditions and if future climate change may place the site beyond the suitable conditions for that particular genotype. The locational database would be complemented by climate change scenario data and mapping capabilities. So, regions suitable for growing particular genotypes under current and future climatic conditions could be mapped. A basic system would just consider key climatic factors for particular genotypes (similar to Booth, 1996), but a more sophisticated system could include growth simulation (similar to Battaglia et al., 2009) as well as pest and disease risk assessment models (similar to Pinkard et al., 2010).
4. Sharing information
5. Conclusions
Sharing information on eucalypts and their climatic requirements was an important part of creating successful plantations. For more than 40 years CSIRO’s Australian Tree Seed Centre has collected and distributed seed for trials, as well as providing information on the characteristics and potential uses of particular spe-
The Berkeley Earth Project has provided more evidence that the global climate is changing. It appears likely that the rise in mean global temperature above pre-industrial levels will be greater than 2 °C (Rogelj et al., 2011). There is already atmospheric as well as climatic change. The increasing level of CO2 may affect photosynthetic
4.1. A eucalypt database and climatic mapping system
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rates and also water use efficiency. There is a need for more experimental work, particularly FACE experiments, to reduce this uncertainty and to determine the effects particularly for the ‘big nine’ plantation eucalypt species. There are considerable uncertainties about how eucalypt species will respond and responses may vary between and within species. However, early simulation studies suggest that there may be more winners than losers in terms of productivity changes. Given the considerable uncertainties a global analysis similar to that carried out for Australian plantations by Battaglia et al. (2009) would be useful for the whole world. This would help to identify the regions where we can be reasonably confident that eucalypt plantation productivity may increase, as well as the regions where we can be reasonably sure it will decline. Though many plantations may well benefit from increasing CO2 levels, uncertainties are too great to rate the potential impact as less than medium. For example, the simulated increases in productivity in Brazilian plantations under raised CO2 levels reported by Almeida et al. (2009) may be too optimistic and should be treated with caution. The changes to the 3-PG model to incorporate raised CO2 effects were based largely on results from trials with noneucalypts, as these were the only data available at the time. The work is interesting as 3-PG is one of the most widely used forest growth models, but further refinements are needed as results from elevated CO2 experiments with eucalypts become available (Barton et al., 2010, 2012). Though the potential impact is medium, eucalypt plantations have high adaptive capacity, so overall vulnerability is probably medium. The key to reducing vulnerability is to reduce uncertainties. There is an important role for experimental research in clarifying the photosynthesis and water use efficiency responses of major plantation eucalypts under climatic and atmospheric change. These results should then be incorporated into simulation models to help identify genotypes and locations at particular risk. As improved models and impact predictions are developed the information will need to be communicated. A recent series of reports on climate change and Australian forests provides a possible structure for such reports (ABARES, 2011). This set of reports includes both a national synthesis and six regional reports. The regional reports include regional climate change projections, tree growth projections, sensitivity analyses, socio-economic effects, regional community impacts and adaptation measures. There was only limited information available on the direct effects on eucalypts of increases in atmospheric CO2 when the team began this large project, so they chose not to include these effects in their 3-PG modelling. However, they recognise that these effects may ‘partially or fully offset modelled declines in tree growth’. A particularly useful feature of this study is the one page plain English summaries of key points in both the national and regional reports. As well as improved tree growth simulation models there is also a need for a eucalypt database and mapping system to identify genotypes and locations that may be particularly vulnerable. Such a system would help to identify genotypes growing under extreme conditions. Occasional low-cost monitoring of genotypes growing under extreme conditions, often using data already collected, would provide early warning of particular problems that would complement experimental and simulation studies. Adaptation may not require complex or expensive changes. Useful adaptations that are quick, simple and cheap to apply are already being developed. The recommendation to change spacing when establishing E. globulus plantations in Western Australia to reflect different rainfall levels is a good example of a straightforward response to changing climatic conditions. Sharing information about climatic requirements helped to establish eucalypts as one of the most important components of the global forest plantation resource. Sharing information can help to protect eucalypt plantations from future climatic change. There
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is a need to develop a eucalypt plantation database and climatic analysis system. In some ways this would be similar to the Atlas of Living Australia (www.ala.org.au). This includes location information for particular species in Australia and provides tools to analyse climatic conditions at these sites and to map climatically suitable areas. Instead of information on natural locations the proposed eucalypt database would provide information on where particular genotypes of eucalypts are grown in plantations around the world. It would provide tools to analyse the climatic conditions at these sites under current and future conditions and also the ability to map where suitable climatic conditions occur for particular genotypes around the world both now and in the future. Acknowledgements I am grateful to the organisers of the IUFRO conference on ‘Improvement and Culture of Eucalypts’ for inviting me to give a presentation on this topic at their conference at Porto Seguro, Brazil in November 2011. I’m also grateful to the anonymous reviewers for their helpful suggestions. References ABARES, 2011. Potential effects of climate change on forests and forestry in Australia – National Synthesis, Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra. Available from: (accessed 17.3.12). Ainsworth, E.A., Rogers, A., 2007. The response of photosynthesis and stomatal conductance to rising CO2: mechanisms and environmental interactions. Plant, Cell Environ. 30, 258–270. Alfenas, A.C., Guimaraes, L.M.S., Graca, R.N., Alfenas, A.F., Zaperlon, T.G., Rosado, C.C.G., Zauza, E.A.V., Mafia, R.G., Coutinho, M.M., 2011. Minimising disease risks in eucalypt plantations. In: Goncalves, J.L.M. (Ed.), IUFRO Conference on Improvement and Culture of Eucalypts Proceedings. ESALQ, Piracicaba, pp. 51–53. Allen Consulting Group 2005. Climate Change Risk and Vulnerability. Report to the Australian Greenhouse Office, Department of the Environment and Heritage, Canberra. Almeida, A.C., Sands, P.J., Bruce, J., Siggins, A.W., Leriche, A., Battaglia, M., Batista, T.R., 2009. Use of a spatial process-based model to quantify forest plantation productivity and water use efficiency under climate change scenarios. In: 1st World IMACS/MODSIM Congress, Cairns, Australia, 13–17 July, 2009. Available from: (accessed 17.3.12). Almeida, A.C., Siggins, A., Batista, T.R., Beadle, C., Fonseca, S., Loos, R., 2010. Mapping the effect of spatial and temporal variation in climate and soils on Eucalyptus plantation production with 3-PG, a process-based growth model. For. Ecol. Manage. 259, 1730–1740. ArborGen, 2010. Freeze tolerant eucalyptus. Available from: (accessed 17.3.12). Barker, D.H., Loveys, B.R., Egerton, J.J.G., Gorton, H., Williams, W.E., Ball, M.C., 2005. CO2 enrichment predisposes foliage of a eucalypt to freezing injury and reduces spring growth. Plant, Cell Environ. 28, 1506–1515. Barton, C.V.M., Ellsworth, D.S., Medlyn, B.E., Duursma, R.A., Tissue, D.T., Adams, M.A., Eamus, D.A., Conroy, J.P., McMurtrie, R.E., Parsby, J., Linder, S., 2010. Whole-tree chambers for elevated atmospheric CO2 experimentation and tree scale flux measurements in south-eastern Australia: the Hawkesbury forest experiment. Agric. For. Meteorol. 150, 941–951. Barton, C.V.M., Duursma, R.A., Medlyn, B.E., Ellsworth, D.S., Eamus, D., Tissue, D.T., Adams, M.A., Conroy, J.P., Crous, K.Y., Liberloo, M., Löw, M., Linder, S., McMurtrie, R.E., 2012. Effects of elevated CO2 on instantaneous transpiration efficiency at leaf and canopy scales in Eucalyptus saligna. Glob. Change Biol. 18, 585–595. Bassa, A.G., Hinchee, M., Rottman, W., Kwan, B., Cunningham, M., 2011. Transgenic technologies of Eucalyptus. In: Goncalves, J.L.M. (Ed.), IUFRO Conference on Improvement and Culture of Eucalypts Proceedings. ESALQ, Piracicaba, p. 82. Battaglia, M., Sands, P., White, D., Mummery, D., 2004. CABALA: a linked carbon, water and nitrogen model of forest growth for silvicultural decision support. For. Ecol. Manage. 193, 251–282. Battaglia, M., Bruce, J., Brack, C., Baker, T., 2009. Climate change and Australia’s plantation estate: analysis of vulnerability and preliminary investigation of adaptation options. Forest and Wood Products Australia. Project Report PNC068-0708. 125 p. Available from: (accessed 17.3.12). Boden, T., Blasing, T., 2011. Record high 2010 global carbon dioxide emissions from fossil–fuel combustion and cement manufacture. US Department of Energy (ORNL), Carbon Dioxide Information Analysis Center (CDIAC). 3 November, 2011. Available from: (accessed 17.3.12).
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Boland, D.J., Brooker, M.I.H., Chippendale, G.M., Hall, N., Hyland, B.P.M., Johnston, R.D., Kleinig, D.A., Turner, J.D., 1984. Forest Trees of Australia. Thomas Nelson, Australia, CSIRO, Melbourne. Booth, T.H., 1985. A new method for assisting species selection. Commonw. For. Rev. 64, 241–250. Booth, T.H. (Ed.), 1996. Matching Trees and Sites. Proceedings of an international workshop held in Bangkok, 27–30 March 1995. ACIAR Proceedings No. 63. 126 p. Booth, T.H. (Ed.) 2009. Climate Change and the 2009 Bushfires. CSIRO Submission 09/345 prepared for the 2009 Victorian Bushfires Royal Commission. Available from: (accessed 17.3.12 under ‘CSIRO’). Booth, T.H., Kirschbaum, M.U.F., Battaglia, M., 2010. Forestry. In: Stokes, C., Howden, M. (Eds.), Adapting Agriculture to Climate Change. CSIRO Publishing, Melbourne, pp. 137–152. Booth, T.H., Nix, H.A., Hutchinson, M.F., Jovanovic, T., 1988. Niche analysis and tree species introduction. For. Ecol. Manage. 23, 47–59. Booth, T.H., Pryor, L.D., 1991. Climatic requirements of some commercially important eucalypt species. For. Ecol. Manage. 43, 47–60. Busby, J.R., 1991. BIOCLIM – a bioclimatic analysis and prediction system. In: Margules, C.R., Austin, M.P. (Eds.), Nature Conservation: Cost Effective Biological Surveys and Data Analysis. CSIRO, East Melbourne, pp. 64–68. CAB International, 2005. Forestry Compendium CD. CABI, Wallingford, England. CSIRO, 2010. Climate variability and change in south-eastern Australia: a synthesis of findings from Phase 1 of the South Eastern Australian Climate Initiative (SEACI). CSIRO, Canberra. 36 pp. Available from: (accessed 17.3.12). Eldridge, K., Davidson, J., Harwood, C., van Wyk, G., 1994. Eucalypt Domestication and Breeding. Cambridge University Press, Cambridge. Foster, G., Rahmstorf, S., 2011. Global temperature evolution 1979–2010. Environ. Res. Lett. 6, 1–9. GIT Consulting 2009. Eucalyptus Universalis – cultivated eucalypt forests global map 2008. GIT forest consulting. Available from: (accessed 17.3.12). Glen, M., Alfenas, A.C., Zauza, E.A.V., Wingfield, M.J., Mohammed, C., 2007. Puccinia psidii: a threat to the Australian environment and economy a review. Australas. Plant Path. 36, 1–16. Harwood, C., 2011. Introductions: doing it right. In: Walker, J. (Ed.), Developing a Eucalypt Resource. Learning from Australia and Elsewhere. Wood Technology Research Centre, University of Canterbury, New Zealand, pp. 43–54. Hughes, L., Cawsey, E.M., Westoby, M., 1996. Climatic range sizes of Eucalyptus species in relation to future climate change. Glob. Ecol. Biogeogr. Lett. 5, 23–29. Hutchinson, G.E., 1957. Concluding remarks. Cold Spring Harbour Symp. Quant. Biol. 22, 415–427. Hutchinson, G.E., 1965. The niche: an abstractly inhabited hypervolume. In: Hutchinson, G.E. (Ed.), The Ecological Theatre and the Evolutionary Play. Yale University Press, New Haven, CT, pp. 26–78. Hutchinson, M.F., Booth, T.H., McMahon, J.P., Nix, H.A., 1984. Estimating monthly mean values of daily solar radiation for Australia. Sol. Energy 32, 277–290. IOCI, 2009. How our climate has changed. Indian Ocean Climate Initiative, Perth. 4 pp. Available from: (accessed 17 Mar 2012). IOCI, 2011. The Indian Ocean climate initiative: stage 3. Report of the 2010 symposium. Department of Environment and Conservation, Western Australia. 64 pp.
IPCC, 2007. Climate change 2007: the physical science basis. In: Contribution of Working Group 1 to the Fourth Assessment Report of the Intergovernmental Panel on Climate change. Cambridge University Press, Cambridge. Jacobs, M.R., 1981. Eucalypts for Planting, second ed. FAO, Rome. Jovanovic, T., Arnold, R., Booth, T.H., 2000. Determining the climatic suitability of Eucalyptus dunnii for plantations in Australia, China and Central and South America. New Forest. 19, 215–226. Landsberg, J.J., Waring, R.H., 1997. A generalised model of forest productivity using simplified concepts of radiation-use efficiency, carbon balance and partitioning. For. Ecol. Manage. 95, 209–228. McKenney, D.W., Davis, J.S., Turnbull, J.W., Searle, S.D., 1993. Impact of Australian tree species selection research in China: an economic perspective. For. Ecol. Manage. 60, 59–76. Mitchell, T.D., Carter, T.R., Jones, P.D., Hulme, M., New, M., 2004. A comprehensive set of climate scenarios for Europe and the globe: the observed record (1900– 2000) and 16 scenarios (2000–2100). University of East Anglia, Norwich. NOAA, 2012. State of the climate – global analysis 2011. National Oceanic and Atmospheric Administration, National Climate Data Center. Available from:
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Eucalypt plantations and climate change q Trevor H. Booth ⇑ CSIRO Ecosystem Sciences and CSIRO Climate Adaptation Flagship, G.P.O. Box 1700, Canberra, ACT 2601, Australia
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Article history: Available online 19 May 2012 Keywords: Vulnerability Adaptation Carbon dioxide Simulation models Database
a b s t r a c t Eucalypts are grown in plantations in more than 90 countries, so it is important to assess their vulnerability to climate change. Global mean annual temperature over land has already increased by about 0.9 °C in the last century and many countries have agreed that urgent action should be taken to limit the increase in global mean temperature below 2 °C. Unfortunately, as emissions are currently tracking at higher levels than the worst case scenario envisaged by the Intergovernmental Panel on Climate Change it appears increasingly unlikely that temperature increase can be limited to 2 °C. This paper assesses the vulnerability of eucalypt plantations to climate change. Vulnerability is a function of potential impact, which is related to exposure and sensitivity, and adaptive capacity. Eucalypt plantations total more than 20 million hectares and are grown in many countries around the world, so have significant exposure to climate change. About 41% of more than 800 eucalypt taxa grow naturally in Australia within narrow climatic ranges of less than 2 °C, so are potentially sensitive to climatic change. Fortunately, the small number of commercially important species tend to have much wider climatic tolerances, but genetic selection to improve growth may well be reducing their climatic adaptability. Efforts have been made to simulate eucalypt growth under changing climatic and atmospheric conditions. If photosynthesis and water use efficiency are increased by increasing atmospheric carbon dioxide levels then some plantations may enjoy significant yield increases. However, recent results from eucalypts growing under elevated CO2 conditions in whole tree chambers suggest there is little if any ‘fertilisation effect’ on photosynthesis, though water use efficiency is increased. Consequently, productivity may increase in some plantations and decrease in others. Fortunately, the adaptive capacity of eucalypt plantations is high. Many eucalypts are grown on short rotations of less than ten years, so changing silvicultural practices and planting different genotypes to match changing climatic conditions is relatively easy. While the vulnerability of eucalypt plantations is only at a medium level it is concluded that sharing information about where particular eucalypt genotypes are grown, identifying potentially marginal climatic areas and recommending genotypes suitable for changing conditions would help to further reduce potential vulnerability. The development of a eucalypt database and mapping system is proposed as a major collaborative project to help to protect one of global forestry’s most valuable resources. Crown Copyright Ó 2012 Published by Elsevier B.V. All rights reserved.
1. Introduction Over 200 years eucalypts have moved from being a botanical novelty to their current status as a major source of biomass for paper pulp, fibreboard, industrial charcoal and fuelwood (Turnbull, 1999). There are now more than 20 million hectares of eucalypt plantations around the world with major centres in Brazil (4.2 m ha), India (3.9 m ha) and China (2.6 m ha) (GIT Consulting, 2009). More than 110 species of eucalypts have been introduced into more than 90 countries, and eucalypts are widely grown in
q Invited Paper for Special Issue on ‘‘Joining silvicultural and genetic strategies to minimize Eucalyptus environmental stresses: from research to practice’’, IUFRO WG 2.08.03, 14–18 November, 2011, Port Seguro, Bahia State, Brazil. Editor: Jean-Paul Laclau ([email protected]). ⇑ Tel.: +61 2 6246 4217, mobile: +0439 413816. E-mail address: [email protected]
the tropics and subtropics not only in plantations, but also in small woodlots, in windbreaks and other small scale plantings (Jacobs, 1981). Though many species were evaluated in many countries, a small number of species emerged which dominate global plantations. For example, in China more than 200 species were assessed, but only 10 species are now widely grown (McKenney et al., 1993; Turnbull, 2007). Current plantations around the world are dominated by the ‘big nine’ identified by Harwood (2011) as: Eucalyptus camaldulensis, Eucalyptus grandis, Eucalyptus tereticornis, Eucalyptus globulus, Eucalyptus nitens, Eucalyptus urophylla, Eucalyptus saligna, Eucalyptus dunnii, Eucalyptus pellita and their hybrids, which together account for more than 90% of the major eucalypt plantations. Great efforts have gone into tree improvement, at first focussing mainly on careful selection and breeding of first and second generations from collections from native stands (Eldridge et al., 1994). Later tree improvement methods included the use of hybrids and clones (Harwood, 2011).
0378-1127/$ - see front matter Crown Copyright Ó 2012 Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.foreco.2012.04.004
T.H. Booth / Forest Ecology and Management 301 (2013) 28–34
A couple of examples give some impression of how vital the continuing success of eucalypt plantations is to the economies of developing and transitioning countries. First, an economic analysis of a series of eucalypt tree improvement projects in China (van Bueren, 2004) suggested that a research investment had delivered benefits in excess of 1 billion dollars. Second, pulp producers in developing countries and countries with transitioning economies raised US$37.8 billion between 1990 and 2004 to develop pulp mills, many of which use plantation eucalypts for processing (Spek, 2005). For example, the Veracel pulp mill in Bahia province of Brazil, which cost around US$850 million, is supplied by 100,000 hectares of Eucalyptus plantation. With such large benefits and investments associated with the successful growth of eucalypts it is important to assess what potential threat, if any, climate change poses to eucalypt plantations around the world and what adaptations may be required to minimise any potential threats. 2. Climatic change Evidence continues to accumulate that global average temperatures are rising. The Berkeley Earth Project released draft papers describing its work in October 2011 (Berkeleyearth.org). They have analysed 1.6 billion temperature observations from more than 39,000 stations and confirmed global warming shown in previous work by the Hadley Centre, the National Oceanic and Atmospheric Administration (NOAA) and the National Aeronautics and Space Administration (NASA). The temperature increase has been about 0.9 °C over land over the past century and global temperature has increased by about 0.5 °C in the last 30 years (Foster and Rahmstorf, 2011). The global surface temperature for 2011 was the hottest ever observed during La Niña years (NOAA, 2012). The ‘Copenhagen Accord’ produced at the United Nations Framework Convention on Climate Change (UNFCCC) conference of parties (COP15) in December 2009 agreed that countries should take urgent action to limit the increase in global average temperatures to less than 2 °C (relative to pre-industrial levels) to avoid ‘dangerous interference with the climate system’. Some progress was made at the UNFCCC COP16 meeting at Cancun (December 2010) with 90 countries representing 80 per cent of global emissions making pledges to reduce carbon pollution. At COP17 in Durban (December 2011) parties to the UNFCCC agreed to negotiate by 2015 a new legally binding agreement to reduce emissions that would take effect from 2020. A recent study has shown that greenhouse gas emissions need to peak before 2020 to give the world a good chance of limiting average global temperature increases to 2 °C relative to pre-industrial levels (Rogelj et al., 2011). The need to limit emissions soon is because a significant proportion of CO2 stays in the atmosphere for a long time, so the temperature response will continue even when human-derived emissions return to zero. Unfortunately, a report on global emissions data for 2010 released in November 2011 by the US Department of Energy (Boden and Blasing, 2011) has shown that actual emissions are greater than even the worst case scenarios used in the Intergovernmental Panel on Climate Change Fourth Assessment report (IPCC, 2007). So, while limiting global temperature increase to 2 °C over preindustrial levels may still be possible, the world at present remains on track for a rise of about 4 °C or more by the end of the century. While increasing temperatures are the most certain effect of climate change, other factors important for tree growth will also change. For example, the South Eastern Australian Climate Initiative (CSIRO, 2010) found that the 13-year drought in the southern Murray–Darling Basin (MDB) and Victoria that ended in 2010–2011 was unprecedented compared with other recorded droughts since 1900 and could be related, in part at least, to climate change. Similarly, the Indian Ocean Climate Initiative (IOCI, 2009) has found a step decrease in total annual rainfall averaged across south west Western
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Australia of almost 10% since the mid-1970s. This rainfall decline is apparently associated with changes in the large scale atmospheric circulation that are most likely due to a combination of natural variability and the enhanced greenhouse effect (IOCI, 2011). Climate change is driven by rising levels of greenhouse gases, particularly carbon dioxide (IPCC, 2007). Increasing CO2 levels may affect tree growth not only through changes in temperature and rainfall, but also through increasing photosynthetic rates and increasing water use efficiency. However, the extent to which mature examples of individual species will be affected is far from clear, as much of the experimental evidence comes from small plants grown in controlled environments (see, Booth et al., 2010 for a short review of the impacts of enhanced CO2 on trees). Free air carbon dioxide enrichment (FACE) experiments with large trees should provide more reliable indications of the impacts on eucalypts (Raison et al., 2007). These release CO2 into the atmosphere around the experimental plants and provide more realistic growing conditions than growth chambers, but at a great financial cost. 3. How vulnerable are eucalypt plantations? A review of climate change risk and vulnerability in Australia (Allen Consulting Group, 2005) used an approach to vulnerability assessment adapted from a European study (Shroter and ATEAM consortium, 2004). This simply says that vulnerability is a function of potential impact and adaptive capacity, while potential impact is a function of exposure and sensitivity. Exposure relates to the influences that impact on a system, while sensitivity reflects the responsiveness of a system to climatic influences. Adaptive capacity reflects the ability of a system to change in a way that makes it better equipped to deal with external influences. In this paper some simple factors affecting exposure and sensitivity are first considered in isolation before a couple of examples of simulation models are used to illustrate how exposure and sensitivity combine to produce potential impacts. 3.1. Exposure Considering exposure factors for plantation forests in Australia the Allen Consulting Group (2005) identified reduced rainfall, increased fire hazard and pest infestations as factors that could adversely affect forestry. Studies carried out in Australia since this report was published have emphasised the importance of these three factors in forest management. For example, immature forests in Australia are particularly susceptible to drought, and reduced rainfall would be a particular concern for plantation managers (Battaglia et al., 2009). Interactions between climate change and increased fire hazard were reviewed in a submission to the 2009 Victorian Bushfires Royal Commission, which followed a tragic event which resulted in 173 deaths (Booth, 2009). While the fires affected largely native eucalypt forests, rather than plantations, many of the factors affecting exposure are similar. For instance, the fires took place in conditions of extremely high temperatures and prolonged drought, which while they may have been in part a result of natural variability were also consistent with expected trends in climate change. The impacts of a defoliating pest, Mycosphaerella leaf disease, on E. globulus plantation productivity in Australia under current and future climates have been studied using the CLIMEX and CABALA models (Pinkard et al., 2010). The results suggested that effects of defoliation could be significant and should not be ignored when considering future management under climate change. Most eucalypt plantations around the world potentially have exposure to some or all of these three factors. For example, drought may reduce eucalypt plantation yields by as much as one third
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over a six to seven year rotation in locations near the Atlantic coast of Brazil (Almeida et al., 2010). While exposure to factors such as drought, fires and pests may reduce productivity, eucalypt plantations may benefit from exposure to raised atmospheric CO2 levels, through effects on photosynthesis and water use efficiency. How these effects combine to influence growth is considered in Section 3.3 which deals with simulation modelling. 3.2. Sensitivity With regard to sensitivity many eucalypts have narrow natural climatic ranges. In the early 1980s climatic interpolation surfaces were developed which enabled mean climatic conditions to be reliably assessed for any site (see, for example, Hutchinson et al., 1984) and a program called BIOCLIM (Busby, 1991) was the first to allow bioclimatic envelopes to be assessed for particular species. One of the first species to be analysed using BIOCLIM was Eucalyptus citriodora (Booth, 1985). This early version of BIOCLIM defined bioclimatic envelopes in terms of 12 factors, such as mean annual temperature and mean annual rainfall. Later, Hughes et al. (1996) used BIOCLIM to analyse more than 800 eucalypt taxa in terms of 35 bioclimatic factors. They found about 41% of the species evaluated had distributions with less than 2 °C variation in mean annual temperature. Only about 10% of the species evaluated had broad climatic ranges in their natural distributions (MAT range >9 °C). Bioclimatic analyses represent part of the multiple dimensions of the realised niche of each species (sensu Hutchinson, 1957, 1965) i.e. where it will grow when in competition with other species. It was quickly realised that eucalypt species elimination trials outside Australia provide a useful indication of the fundamental niche i.e. the range of conditions species will tolerate when competition with other species is minimised (see Booth et al., 1988). It’s interesting, though perhaps not surprising, that most of the nine species that dominate the global plantation eucalypt resource have extensive natural distributions (see Boland et al.. 1984) and broad fundamental climatic niches (mostly >9 °C) (see Table 1). E. dunnii is an interesting exception which has a ‘restricted’ natural occurrence, but has proved successful over a relatively wide range of climatic conditions. There have been enormous gains in productivity made through genetic improvement of eucalypts (Eldridge et al., 1994; Harwood, 2011), but little is known about how the increasing use of clones reduces climatic adaptability in comparison to planting seed collected from the wild or first or second generations of improved seed. 3.3. How will climate change impact growth? The previous sections provide some indication of the exposure and sensitivity of eucalypt plantations to climate change. Exposure Table 1 Approximate mean annual temperature requirements for the nine eucalypt species, which together with their hybrid combinations, dominate the world’s eucalypt plantations (Data from Booth and Pryor (1991), unless noted otherwise). Species
Approximate range of mean annual temperature (°C) in plantations
E. camaldulensis
18–28 13–22 14–22 9–18 14–25 9–18 20–27 14–23 17–27 18–28
E. E. E. E. E. E. E. E.
dunnii globulus grandis nitens pellita saligna tereticornis urophylla
(Northern provenances) (Southern provenances) (Jovanovic et al., 2000)
(Harwood, 2011) (Northern provenances)
and sensitivity combine to create potential impact. Computer simulation models are generally used to assess the likely impacts of climate change. For example, Almeida et al. (2009) analysed how climate change was likely to affect about 500,000 ha of E. grandis E. urophylla hybrid plantations growing within a 32 M ha region of eastern Brazil. They used the 3-PG model (Landsberg and Waring, 1997) to predict mean annual increment and water use efficiency. The model was modified to include the direct effects of increasing levels of atmospheric CO2 on photosynthesis and also stomatal conductance. Many experimental and theoretical studies suggest light saturated assimilation rate and light use efficiency will increase as atmospheric CO2 concentration increases, while maximum stomatal conductance is expected to decline (see, for example, Ainsworth and Rogers, 2007). These effects were incorporated into 3-PG through modifications of canopy quantum efficiency and canopy conductance through growth modifiers. The model was run for a 0.5° climatic grid using data for 1971– 2000 from the University of East Anglia Climate Research Unit (Mitchell et al., 2004). Projected data for 2030 and 2050 were based on the Intergovernmental Panel on Climate Change (IPCC, 2007) A1B scenario. These data represented a reduction of 2% and 3% in annual precipitation and an increase of 8% and 15% in vapour pressure deficit in 2030 and 2050 respectively relative to the standard ‘historical’ (1971–2000) period. As detailed soil data were not available a standard clay loam soil with 180 mm water holding capacity was used. The ‘historical’ scenario used an atmospheric CO2 level of 350 lg g 1 (i.e. 350 ppm), with 450 lg g 1 in 2030 and 520 lg g 1 in 2050. The results suggested that forest productivity may increase by about 6 m3 ha 1 year 1 by 2030, and 10 m3 ha 1 year 1 by 2050, corresponding to 17% and 26% increments compared with the historical period. Water use efficiency increased by an average of 1.0 g DM kg 1 H2O in 2030 and 1.7 g DM kg 1 H2O in 2050 compared with the historical scenario, which is equivalent to increases of 29% and 51% in WUE, respectively. 3.4. Incorporating uncertainties into growth predictions Almeida et al. (2009) used the best information available to assess the likely effects of increased atmospheric CO2 levels on tree growth. However, there are considerable uncertainties about how climatic and atmospheric changes will affect tree growth. Battaglia et al. (2009) analysed likely effects of climatic change on Australia’s plantation estate. They noted that ‘our knowledge of the effects of elevated CO2 on our plantation species is poor’ and ‘examples of species from the same genera and even clones of the same species differ markedly in their response to elevated CO2’. So, they dealt with uncertainties using Monte-Carlo analysis by identifying likely ranges of assumptions and then running the CABALA model (Battaglia et al., 2004) many times to consider many possible combinations of assumptions. For example, they simulated three different responses of photosynthesis to raised CO2: (a) No increase in photosynthesis, (b) partial increase (i.e. acclimation) and (c) full increase (i.e. no down-regulation). Simulations were run for present conditions as well as for projected conditions for 2030 and 2070. In total more than a million simulation runs were made for sites across Australia’s major plantation regions. Maps were produced showing projected regional changes in plantation productivity. As multiple assumptions were run for individual sites it was also possible to show where variations in predictions were relatively great or relatively small. An interesting feature of the analysis was that despite several uncertainties three main categories emerged for eucalypt plantations. Some regions were very likely to enjoy an increase in production with little increase in risk (e.g. E. globulus and E. nitens plantations in Tasmania), other areas were likely to increase in production with some in-
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crease in risk (e.g. E. nitens and E. globulus in Victoria and the ‘Green Triangle’ area around the South Australian and Victoria border areas), while some regions were likely to suffer decreases in production with an increase in risk (e.g. eastern and northern extents of Western Australian E. globulus plantations). A similar analysis of the main plantation centres of the global eucalypt plantation resource defining areas of uncertainty and using multiple computer runs to identify areas where productivity is likely to increase and areas where it is likely to decrease would be very useful. In the absence of such a global analysis the general conclusion from such studies as those of Almeida et al. (2009) and Battaglia et al. (2009) is that impacts of climate change on eucalypt plantation productivity are likely to be highly site specific and will depend in part on the balance between the possibly detrimental effects of increased temperatures and rainfall declines in some areas, versus the potential productivity gains through elevated CO2. In places where species are already growing close to their optimal growing temperatures production gains may not eventuate. High temperatures and dry soils may also increase drought deaths. 3.5. Reducing uncertainties It’s clear from the previous section that one of the key uncertainties is how eucalypts will respond to changes in atmospheric CO2. Early work with eucalypt seedlings grown in open-topped chambers indicated that enhanced CO2 levels would increase net photosynthesis and growth. For example, Roden et al. (1999) reported 53% more stem growth in 8 months with Eucalyptus pauciflora seedlings grown at 2 ambient CO2. However, results from other tree species suggested that responses from seedlings may be different to those of more mature plants. The Hawkesbury Forest Experiment (near Sydney, Australia) was devised in order to grow eucalypts of up to 9 m in height under elevated CO2 without the expense of free air CO2 enrichment (FACE). Twelve whole tree chambers previously used for an elevated CO2 experiment in Sweden were shipped to Australia. Single E. saligna trees were grown from seedlings with six of the chambers being maintained at ambient CO2 conditions (390 lg g 1), while the other six were maintained at an enhanced level (630 lg g 1) for 2 years (Barton et al., 2010). Half of each set were subjected to periodic drought. The results showed little if any ‘fertilisation effect’ of elevated CO2. In other words there was strong down-regulation of photosynthesis. However, elevated CO2 increased water use efficiency and there was no acclimation of the stomatal response to CO2. While chambers are useful, there are obvious challenges in keeping conditions within a chamber comparable with those of the open air, so FACE experiments are also needed (Raison et al., 2007). A free-air CO2 enrichment trial (EUCFACE) was established in 2010 in native eucalypt woodland near the Hawkesbury site. FACE experiments would be particularly useful for each of the main nine globally important eucalypt plantation species. While enhanced CO2 trials have focussed mainly on effects on photosynthesis and water use efficiency there have been some surprising effects reported. For example, Barker et al. (2005) reported ten times as much frost damage on E. pauciflora (snow gum) seedlings when raised in open topped chambers at 2 ambient CO2 than when they were raised in similar chambers under ambient conditions.
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duce vulnerability if potential impacts can be reduced. In other words, adaptive capacity is the ability of a system to change in a way that makes it better equipped to deal with external influences. Booth et al. (2010) reviewed adaptation options for dealing with projected climate change. Though this summary focussed on Australian plantations, the general categories would be similar for global eucalypt plantations. The following are some examples of adaptive options: (a) Genotypes – There is great potential for managers of eucalypt plantations to respond to climate change if necessary by planting different genetic material. Many eucalypt plantations are grown on relatively short rotations of 6–10 years for pulp and paper production, so the opportunity to adapt occurs much more frequently than for species that may be grown for 50 or more years for sawlogs. The small number of species that dominate global plantations should allow improved information on the climatic requirements of particular genotypes to be collected relatively easily. In May 2011 E. grandis became the second tree species to have its entire genome sequenced (web site: eucalyptusdb. bi.up.ac.za). CSIRO scientists are using genomic techniques to identify genes associated with drought tolerance in different provenances of E. camaldulensis and several other eucalypt species (S. Southerton pers. comm.). Improved knowledge about the role of particular genes should help develop new genotypes with improved characteristics, such as drought tolerance. Already the first genetically modified eucalypts are being developed with improved frost tolerance, as well as improved growth and processing characteristics (Arborgen, 2010; Bassa et al., 2011). (b) Stand management – There are excellent opportunities to manipulate spacing and thinning to respond to changing conditions. For example, a simple adaptation to match planting densities to mean annual rainfall in E. globulus plantations in Western Australia is described below. (c) Site selection – It would be desirable to restrict new plantations to currently suitable environments if rainfall decreases, but slower growth rates associated with drier environments may become more acceptable if payments for carbon sequestration become available (see Polglase et al., 2011). In other words, site selection adaptations need to consider both changing environmental and economic conditions. (d) Fire management – Protective measures (e.g. widening of firebreaks) could be relatively easily increased if risks of fire increase as a result of hotter and drier conditions. (e) Pests, diseases and weeds – Climate change will change the distributions of potential pests, diseases and weeds, so new challenges must be faced by forest managers. However, forest managers have adapted successfully to new problems before climate change was an issue. For example, eucalypt plantations in Brazil introduced resistant genotypes when guava rust (Puccinia psidii) became a problem (Glen et al., 2007; Alfenas et al., 2011). (f) Establishment strategies – It may be necessary to adjust planting times as conditions change and to make use of improved seasonal forecasting. (g) Climatic risks – Increasing reliance should be placed on recent climatic records as conditions change. For example, it may be advisable to consider frost risks on the basis of data from the last 25 years rather than the last 100 years.
3.6. Adaptive capacity We have considered the exposure and sensitivity of eucalypt plantations and how exposure and sensitivity can be combined in models to estimate potential impacts. Adaptive capacity can re-
Adaptations need not be complex. A simple adaptation recommendation for E. globulus plantings in the south-west of Western Australia provides a good example. There has been a decline in rainfall in this region that as mentioned earlier is believed in part
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at least be related to climate change (IOCI, 2009, 2011). Blue gum plantations used to be planted at 1250 stems per hectare, but some drought deaths were experienced. A simple adaptation has been recommended to minimise drought deaths, which is to plant one seedling per ha per mm of rainfall (White, D. pers. comm. cited in Booth 2010). So, in regions with 900 mm of annual rainfall 900 sph would be planted and in regions with 1000 mm of rainfall 1000 should be planted. IUFRO has prepared a detailed report considering adaptation options for both native and plantation forests (Seppälä et al., 2009). It includes an appendix with about 15 pages of potential adaptations based on a paper by Ogden and Innes (2007). For example, two simple recommendations relevant to eucalypt plantations are to design trials to test improved genotypes over diverse climatic environments and to avoid use of clonal material selected purely on basis of past growth rates.
cies. FAO’s ‘Eucalypts for Planting’ (Jacobs, 1981) describes experiences with the introduction of about 110 eucalypt species in more than 90 countries around the world. Some remarkable books and reports describe the introduction of eucalypts into particular regions. Probably none is more detailed that Poynton’s (1979) 882 page ‘Tree Planting in Southern Africa Volume 2 The Eucalypts’ which describes trials of 88 species at 271 sites. A major limitation of the Poynton book was that reliable temperature data were not available for 208 of the sites. The development of interpolation surfaces for many countries allowed climatic conditions to be estimated for sites that were distant from the nearest meteorological station (Booth, 1996). CAB International’s (2005) Forestry Compendium CD brought together information for many species including eucalypts in computer searchable form.
3.7. Vulnerability Having considered how exposure and sensitivity combine to produce impact and how adaptive capacity can reduce impact, how should vulnerability of eucalypt plantations to climate change be rated? Exposure should probably be rated as high. Eucalypts are widely planted around the world. Reduced rainfall, drought, increased fire hazard and pest infestations could adversely affect productivity and recently established plantations are particularly susceptible to drought. Pest, diseases and weeds are likely to benefit from disturbances associated with climate change. Sensitivity should probably be rated as medium. It reflects the responsiveness of a system to climatic influences. Many eucalypt species show limited climatic adaptability in their natural environments. In contrast, the small number of very successful plantation species show great climatic adaptability, but it’s likely that increasing selection to produce improved productivity is reducing genetic variability and may well be reducing climatic adaptability. Potential impact as assessed by simulation models is probably medium. Many plantations may well benefit from increased atmospheric CO2 levels, but more information is needed to be confident of how widespread and prolonged benefits may be. Some plantations may experience reduced productivity particularly as a result of reduced rainfall. Fortunately there is very good adaptive potential in eucalypt plantations. Many plantations are grown on short rotations and this provides regular opportunities to adjust both genotypes planted and their management. Only a small number of species dominate global plantations, so there is the opportunity to study each species intensively. While potential impact of climate change on plantations is medium their adaptive capacity is high, so overall their vulnerability is only medium. Given the considerable uncertainties about the climatic adaptability of individual genotypes it would be inappropriate to assess vulnerability as less than medium. There are probably positive benefits for eucalypt plantation forestry from adaptation through use of appropriate genotypes and management adjustments that take account of changing conditions. The main impediment to minimising the vulnerability of eucalypt plantations to climate change is lack of knowledge.
Eucalypt plantations provide billions of dollars of benefits in three of the world’s most dynamic economies (Brazil, China and India) as well as in many other countries. While many eucalypt plantations are likely to benefit to some extent from increasing atmospheric CO2, changing temperatures and rainfall will cause problems at some sites. We need to know where future climate change conditions are likely to place particular genotypes outside their suitable conditions, so we can develop appropriate adaptations. A eucalypt database and climatic mapping system should be developed to fulfil this need. Major plantation genotypes of the ‘big nine’ (Harwood, 2011) would be a priority for such a system. However, it would also collect and map information relevant to lesser-known species, which are important in particular regions, especially in developing countries. The system would also collect information from species elimination trials for any eucalypt species, as such information is vital in assessing the vulnerability of their native stands to climate change. For example, E. nitens grows well at many sites in South Africa, but doesn’t flower and hence doesn’t produce seed as conditions are warmer than those within its natural distribution (T. Swain, pers. comm.). Previous databases have concentrated largely on providing summary data at the species level. For example, the CAB International (2005) database describes the range of climatic conditions suitable for particular species. So, it provides ranges of climatic conditions for important factors such as mean annual temperature, mean annual rainfall, mean maximum temperature of the hottest month and mean minimum temperature of the coldest month. What is now needed to deal with changing climatic conditions is information on the particular sites where particular genotypes are grown. It would then be possible to assess for each site whether the genotype is growing under unusually extreme conditions and if future climate change may place the site beyond the suitable conditions for that particular genotype. The locational database would be complemented by climate change scenario data and mapping capabilities. So, regions suitable for growing particular genotypes under current and future climatic conditions could be mapped. A basic system would just consider key climatic factors for particular genotypes (similar to Booth, 1996), but a more sophisticated system could include growth simulation (similar to Battaglia et al., 2009) as well as pest and disease risk assessment models (similar to Pinkard et al., 2010).
4. Sharing information
5. Conclusions
Sharing information on eucalypts and their climatic requirements was an important part of creating successful plantations. For more than 40 years CSIRO’s Australian Tree Seed Centre has collected and distributed seed for trials, as well as providing information on the characteristics and potential uses of particular spe-
The Berkeley Earth Project has provided more evidence that the global climate is changing. It appears likely that the rise in mean global temperature above pre-industrial levels will be greater than 2 °C (Rogelj et al., 2011). There is already atmospheric as well as climatic change. The increasing level of CO2 may affect photosynthetic
4.1. A eucalypt database and climatic mapping system
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rates and also water use efficiency. There is a need for more experimental work, particularly FACE experiments, to reduce this uncertainty and to determine the effects particularly for the ‘big nine’ plantation eucalypt species. There are considerable uncertainties about how eucalypt species will respond and responses may vary between and within species. However, early simulation studies suggest that there may be more winners than losers in terms of productivity changes. Given the considerable uncertainties a global analysis similar to that carried out for Australian plantations by Battaglia et al. (2009) would be useful for the whole world. This would help to identify the regions where we can be reasonably confident that eucalypt plantation productivity may increase, as well as the regions where we can be reasonably sure it will decline. Though many plantations may well benefit from increasing CO2 levels, uncertainties are too great to rate the potential impact as less than medium. For example, the simulated increases in productivity in Brazilian plantations under raised CO2 levels reported by Almeida et al. (2009) may be too optimistic and should be treated with caution. The changes to the 3-PG model to incorporate raised CO2 effects were based largely on results from trials with noneucalypts, as these were the only data available at the time. The work is interesting as 3-PG is one of the most widely used forest growth models, but further refinements are needed as results from elevated CO2 experiments with eucalypts become available (Barton et al., 2010, 2012). Though the potential impact is medium, eucalypt plantations have high adaptive capacity, so overall vulnerability is probably medium. The key to reducing vulnerability is to reduce uncertainties. There is an important role for experimental research in clarifying the photosynthesis and water use efficiency responses of major plantation eucalypts under climatic and atmospheric change. These results should then be incorporated into simulation models to help identify genotypes and locations at particular risk. As improved models and impact predictions are developed the information will need to be communicated. A recent series of reports on climate change and Australian forests provides a possible structure for such reports (ABARES, 2011). This set of reports includes both a national synthesis and six regional reports. The regional reports include regional climate change projections, tree growth projections, sensitivity analyses, socio-economic effects, regional community impacts and adaptation measures. There was only limited information available on the direct effects on eucalypts of increases in atmospheric CO2 when the team began this large project, so they chose not to include these effects in their 3-PG modelling. However, they recognise that these effects may ‘partially or fully offset modelled declines in tree growth’. A particularly useful feature of this study is the one page plain English summaries of key points in both the national and regional reports. As well as improved tree growth simulation models there is also a need for a eucalypt database and mapping system to identify genotypes and locations that may be particularly vulnerable. Such a system would help to identify genotypes growing under extreme conditions. Occasional low-cost monitoring of genotypes growing under extreme conditions, often using data already collected, would provide early warning of particular problems that would complement experimental and simulation studies. Adaptation may not require complex or expensive changes. Useful adaptations that are quick, simple and cheap to apply are already being developed. The recommendation to change spacing when establishing E. globulus plantations in Western Australia to reflect different rainfall levels is a good example of a straightforward response to changing climatic conditions. Sharing information about climatic requirements helped to establish eucalypts as one of the most important components of the global forest plantation resource. Sharing information can help to protect eucalypt plantations from future climatic change. There
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is a need to develop a eucalypt plantation database and climatic analysis system. In some ways this would be similar to the Atlas of Living Australia (www.ala.org.au). This includes location information for particular species in Australia and provides tools to analyse climatic conditions at these sites and to map climatically suitable areas. Instead of information on natural locations the proposed eucalypt database would provide information on where particular genotypes of eucalypts are grown in plantations around the world. It would provide tools to analyse the climatic conditions at these sites under current and future conditions and also the ability to map where suitable climatic conditions occur for particular genotypes around the world both now and in the future. Acknowledgements I am grateful to the organisers of the IUFRO conference on ‘Improvement and Culture of Eucalypts’ for inviting me to give a presentation on this topic at their conference at Porto Seguro, Brazil in November 2011. I’m also grateful to the anonymous reviewers for their helpful suggestions. References ABARES, 2011. Potential effects of climate change on forests and forestry in Australia – National Synthesis, Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra. Available from:
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Boland, D.J., Brooker, M.I.H., Chippendale, G.M., Hall, N., Hyland, B.P.M., Johnston, R.D., Kleinig, D.A., Turner, J.D., 1984. Forest Trees of Australia. Thomas Nelson, Australia, CSIRO, Melbourne. Booth, T.H., 1985. A new method for assisting species selection. Commonw. For. Rev. 64, 241–250. Booth, T.H. (Ed.), 1996. Matching Trees and Sites. Proceedings of an international workshop held in Bangkok, 27–30 March 1995. ACIAR Proceedings No. 63. 126 p. Booth, T.H. (Ed.) 2009. Climate Change and the 2009 Bushfires. CSIRO Submission 09/345 prepared for the 2009 Victorian Bushfires Royal Commission. Available from:
IPCC, 2007. Climate change 2007: the physical science basis. In: Contribution of Working Group 1 to the Fourth Assessment Report of the Intergovernmental Panel on Climate change. Cambridge University Press, Cambridge. Jacobs, M.R., 1981. Eucalypts for Planting, second ed. FAO, Rome. Jovanovic, T., Arnold, R., Booth, T.H., 2000. Determining the climatic suitability of Eucalyptus dunnii for plantations in Australia, China and Central and South America. New Forest. 19, 215–226. Landsberg, J.J., Waring, R.H., 1997. A generalised model of forest productivity using simplified concepts of radiation-use efficiency, carbon balance and partitioning. For. Ecol. Manage. 95, 209–228. McKenney, D.W., Davis, J.S., Turnbull, J.W., Searle, S.D., 1993. Impact of Australian tree species selection research in China: an economic perspective. For. Ecol. Manage. 60, 59–76. Mitchell, T.D., Carter, T.R., Jones, P.D., Hulme, M., New, M., 2004. A comprehensive set of climate scenarios for Europe and the globe: the observed record (1900– 2000) and 16 scenarios (2000–2100). University of East Anglia, Norwich. NOAA, 2012. State of the climate – global analysis 2011. National Oceanic and Atmospheric Administration, National Climate Data Center. Available from: