- Email: [email protected]
Peer review report 1 on What drives growth of Scots pine in continental Mediterranean climates: drought, low temperatures or both?
Agricultural and Forest Meteorology 201 (2015) 8–9
Contents lists available at ScienceDirect
Agricultural and Forest Meteorology journal homepage: www.elsevier.com/locate/agrformet
Peer Review Report
Peer review report 1 on What drives growth of Scots pine in continental Mediterranean climates: drought, low temperatures or both?
Original Submission Recommendation Minor Revision Comments to the author The authors of the manuscript “What drives growth of Scots pine in continental Mediterranean climates: drought, low temperatures or both?” apply a well vetted research approach (tree rings) at multiple spatial and temporal scales to identify the sensitivity of one tree species to climate at its southern range. This type of detailed understanding of climate sensitivity of species is essential for understanding future forest dynamics and vulnerabilities, and the presented study gives a clear narrative of scots pine sensitivity to drought stress at its warm range limit and cold temperature at its high elevation limit. While these patterns between climate and tree are not novel, Sanchez-Salguero provide quantitative relationships between climate factors (e.g. monthly temp and precip) and tree growth. Their approach and interpretation of results are sound, and the presentation of their manuscript is relatively clear and straightforward. The study makes a solid contributes to growing bodies of literature on scots pine (a major European species), influence of climate on tree growth, and impacts of climate change on forests. Furthermore, the results can be applied to managed and unmanaged ecosystems. The majority of my comments are fairly minor editorial suggestions (see list below). The more pervasive issues I had with the manuscript are: 1) Defining the larger network of sites as “country” scale reads strangely. Could the authors just refer to that network as a latitudinal gradient or regional study and when introducing the network of sites, give an extent compared to the local study (e.g. regional is 500+ km extent while local is <100 km extent) or just give the range of latitudes. That way the range of sites could be put in to context with other regions that may span “country” or not. 2) In several places in the manuscript it is hard to follow the reporting or interpretation of results because the authors do not give a direction to the latitude or elevation gradient. An example of this problem can be found throughout the paragraph starting on line 297. The first sentence ends with “along the latitudinal
DOI of published article: http://dx.doi.org/10.1016/j.agrformet.2015.03.004. 0168-1923/$ – see front matter http://dx.doi.org/10.1016/j.agrformet.2015.04.018
gradients studied” – are the trends with increasing latitude or decreasing? The reader can pick through the tables and figures to figure out the direction of the gradient, but it would make the reader’s job MUCH easier if the authors qualified the gradients as they write. 3) Based on Fig. 1, it seems that there is a consistent influence of previous august and September temp and water balance, but the authors seem to brush that aside and only focus on the Jan and June climate influences. Is there a reason?
More detailed comments: Abstract – the use of “frost” in the first line of the abstract is misleading because it suggests the research may address the impacts of frost on tree growth – but really the study just deals with minimum temperatures, often averaged over a month. Highlights – Line 81 – the second highlight is hard to follow. Could be “Impact of low summer rainfall negative at low elevations and high latitudes”. Also, the results really point at specific months, so maybe highlights generally should give months, rather than seasons to be more precise. Line 84 – while the paper brings in other research about local adaptation to climate by scots pine, the research presented does not really address this topic so maybe it should not be a highlight. Text – Line 93 – “Growth” should be qualified – “Tree growth” or “Plant growth”, “by” after “alternating” can be deleted. Line 95 – “constituted by” could be replaced with “of” Line 98 – comma after parenthesis Line 99 – in a sense, the answer to the question posed here is obvious – trees shut down in winter and don’t grow, so that’s a huge influence on growth. Perhaps the question could be more specific that acknowledges how changes in winter conditions could influence growth. Line 100 – “growing season” could be moved to before “drought” Line 117 – “In relation to recent climate trends” is awkward – could be edited. Line 126 – “determined” may be too strong, maybe “moderate” Line 131 – “The retrospective dendrochronological approach” is an abrupt transition, hard to follow. Line 145 – when “country scale” comes up, could be changed to a spatial extent, rather than an arbitrary political boundary whose scale is not universal. As suggested above, could be changed to “local” and “regional”.
Peer Review Report / Agricultural and Forest Meteorology 201 (2015) 8–9
Line 147 – this last sentence is hard to follow. A suggested rewrite: We hypothesize that at the global limit to scots pine distribution, the lowest sites and southernmost sites will be responsive to drought, whereas. . .. . . Line 165 – monthly climatic data are referred to here, but it seems that daily data are used with the 5, 10, 15 day windows analysis. Are these data described or am I misunderstanding the analyses? Line 168 – “came” can be removed Line 171 – no s needed at the end of “temperature” Line 172 – “study sites were estimate” is not clear – what does that mean? Data from the three climate stations were used to approximate climate at the three sites? Line 204 – calculating residuals by division can cause outermost growth to be both inflated (due to dividing by smaller and small numbers) and variance increased – is there a chance that increased strength of correlation coefficients in Fig 3 is a residual of how you treated the chronologies? Line 236 – it seems like daily temps and precip were used – was the data source described? Line 253 – add comma after “elevation” Line 256 – “along” could be “across” Line 261 – “August to December” – the correlation was mostly with August and September Line 262 – “cumulate” should be “accumulate” Line 266 – “On a monthly scale” could be deleted Line 268 – “In contrast” could be deleted. Also, it may be helpful to spell out the relationship between water balance and radial growth since the statistical relationship is counter intuitive (but ecological one is intuitive). Line 292 – no “s” needed after “precipitation” Line 297 – here’s the section with confusion about the direction of the gradients and trends of precip and temp. E.g. line 308
9
“decrease with latitude” – does that mean latitude is decreasing too? Line 339 – The first sentence is hard to understand – what are the authors trying to get at here. Reading this sentence my first response is to wonder why phenotypic plasticity is mentioned, but not genetic variability and ecotypes. These topics are nicely discussed in later paragraphs, but this sentence is misdirecting. Lone 360 – could the analysis of climate influence on tree growth at 5, 10, 15 day and month inform this discussion of drought duration and tree stress? Line 380 – “which” should be “that” Line 386 – “effects” does not need an s Line 398 – “Further” should be “Furthermore” Line 424 – “Of” can be deleted Line 427 – could infection by mistletoe influences some of the patterns – are there regional or local patterns of infection? Line 441 – not sure, but I think “populations” could be deleted. Line 448 – should be “situated nearby” Fig 4 – making the boundaries around the circles in the maps darker/thicker would help visibility when viewed in black and white Table A1 – I don’t understand the trend category. Is this explained in the methods? Margot Kaye, PhD Assistant Professor The Pennsylvania State University School of Forest Resources 303 Forest Resources Bldg University Park, PA 16803 United States Tel.: +1 814 865 4841 Fax: +1 814 865 3725
Contents lists available at ScienceDirect
Agricultural and Forest Meteorology journal homepage: www.elsevier.com/locate/agrformet
Peer Review Report
Peer review report 1 on What drives growth of Scots pine in continental Mediterranean climates: drought, low temperatures or both?
Original Submission Recommendation Minor Revision Comments to the author The authors of the manuscript “What drives growth of Scots pine in continental Mediterranean climates: drought, low temperatures or both?” apply a well vetted research approach (tree rings) at multiple spatial and temporal scales to identify the sensitivity of one tree species to climate at its southern range. This type of detailed understanding of climate sensitivity of species is essential for understanding future forest dynamics and vulnerabilities, and the presented study gives a clear narrative of scots pine sensitivity to drought stress at its warm range limit and cold temperature at its high elevation limit. While these patterns between climate and tree are not novel, Sanchez-Salguero provide quantitative relationships between climate factors (e.g. monthly temp and precip) and tree growth. Their approach and interpretation of results are sound, and the presentation of their manuscript is relatively clear and straightforward. The study makes a solid contributes to growing bodies of literature on scots pine (a major European species), influence of climate on tree growth, and impacts of climate change on forests. Furthermore, the results can be applied to managed and unmanaged ecosystems. The majority of my comments are fairly minor editorial suggestions (see list below). The more pervasive issues I had with the manuscript are: 1) Defining the larger network of sites as “country” scale reads strangely. Could the authors just refer to that network as a latitudinal gradient or regional study and when introducing the network of sites, give an extent compared to the local study (e.g. regional is 500+ km extent while local is <100 km extent) or just give the range of latitudes. That way the range of sites could be put in to context with other regions that may span “country” or not. 2) In several places in the manuscript it is hard to follow the reporting or interpretation of results because the authors do not give a direction to the latitude or elevation gradient. An example of this problem can be found throughout the paragraph starting on line 297. The first sentence ends with “along the latitudinal
DOI of published article: http://dx.doi.org/10.1016/j.agrformet.2015.03.004. 0168-1923/$ – see front matter http://dx.doi.org/10.1016/j.agrformet.2015.04.018
gradients studied” – are the trends with increasing latitude or decreasing? The reader can pick through the tables and figures to figure out the direction of the gradient, but it would make the reader’s job MUCH easier if the authors qualified the gradients as they write. 3) Based on Fig. 1, it seems that there is a consistent influence of previous august and September temp and water balance, but the authors seem to brush that aside and only focus on the Jan and June climate influences. Is there a reason?
More detailed comments: Abstract – the use of “frost” in the first line of the abstract is misleading because it suggests the research may address the impacts of frost on tree growth – but really the study just deals with minimum temperatures, often averaged over a month. Highlights – Line 81 – the second highlight is hard to follow. Could be “Impact of low summer rainfall negative at low elevations and high latitudes”. Also, the results really point at specific months, so maybe highlights generally should give months, rather than seasons to be more precise. Line 84 – while the paper brings in other research about local adaptation to climate by scots pine, the research presented does not really address this topic so maybe it should not be a highlight. Text – Line 93 – “Growth” should be qualified – “Tree growth” or “Plant growth”, “by” after “alternating” can be deleted. Line 95 – “constituted by” could be replaced with “of” Line 98 – comma after parenthesis Line 99 – in a sense, the answer to the question posed here is obvious – trees shut down in winter and don’t grow, so that’s a huge influence on growth. Perhaps the question could be more specific that acknowledges how changes in winter conditions could influence growth. Line 100 – “growing season” could be moved to before “drought” Line 117 – “In relation to recent climate trends” is awkward – could be edited. Line 126 – “determined” may be too strong, maybe “moderate” Line 131 – “The retrospective dendrochronological approach” is an abrupt transition, hard to follow. Line 145 – when “country scale” comes up, could be changed to a spatial extent, rather than an arbitrary political boundary whose scale is not universal. As suggested above, could be changed to “local” and “regional”.
Peer Review Report / Agricultural and Forest Meteorology 201 (2015) 8–9
Line 147 – this last sentence is hard to follow. A suggested rewrite: We hypothesize that at the global limit to scots pine distribution, the lowest sites and southernmost sites will be responsive to drought, whereas. . .. . . Line 165 – monthly climatic data are referred to here, but it seems that daily data are used with the 5, 10, 15 day windows analysis. Are these data described or am I misunderstanding the analyses? Line 168 – “came” can be removed Line 171 – no s needed at the end of “temperature” Line 172 – “study sites were estimate” is not clear – what does that mean? Data from the three climate stations were used to approximate climate at the three sites? Line 204 – calculating residuals by division can cause outermost growth to be both inflated (due to dividing by smaller and small numbers) and variance increased – is there a chance that increased strength of correlation coefficients in Fig 3 is a residual of how you treated the chronologies? Line 236 – it seems like daily temps and precip were used – was the data source described? Line 253 – add comma after “elevation” Line 256 – “along” could be “across” Line 261 – “August to December” – the correlation was mostly with August and September Line 262 – “cumulate” should be “accumulate” Line 266 – “On a monthly scale” could be deleted Line 268 – “In contrast” could be deleted. Also, it may be helpful to spell out the relationship between water balance and radial growth since the statistical relationship is counter intuitive (but ecological one is intuitive). Line 292 – no “s” needed after “precipitation” Line 297 – here’s the section with confusion about the direction of the gradients and trends of precip and temp. E.g. line 308
9
“decrease with latitude” – does that mean latitude is decreasing too? Line 339 – The first sentence is hard to understand – what are the authors trying to get at here. Reading this sentence my first response is to wonder why phenotypic plasticity is mentioned, but not genetic variability and ecotypes. These topics are nicely discussed in later paragraphs, but this sentence is misdirecting. Lone 360 – could the analysis of climate influence on tree growth at 5, 10, 15 day and month inform this discussion of drought duration and tree stress? Line 380 – “which” should be “that” Line 386 – “effects” does not need an s Line 398 – “Further” should be “Furthermore” Line 424 – “Of” can be deleted Line 427 – could infection by mistletoe influences some of the patterns – are there regional or local patterns of infection? Line 441 – not sure, but I think “populations” could be deleted. Line 448 – should be “situated nearby” Fig 4 – making the boundaries around the circles in the maps darker/thicker would help visibility when viewed in black and white Table A1 – I don’t understand the trend category. Is this explained in the methods? Margot Kaye, PhD Assistant Professor The Pennsylvania State University School of Forest Resources 303 Forest Resources Bldg University Park, PA 16803 United States Tel.: +1 814 865 4841 Fax: +1 814 865 3725