Climatic extremes improve predictions of spatial patterns of tree species

Understanding niche evolution, dynamics, and the response of species to climate change requires knowledge of the determinants of the environmental niche and species range limits. Mean values of climatic variables are often used in such analyses. In contrast, the increasing frequency of climate extre...

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Published inProceedings of the National Academy of Sciences - PNAS Vol. 106; no. Supplement 2; pp. 19723 - 19728
Main Authors Zimmermann, Niklaus E, Yoccoz, Nigel G, Edwards, Thomas C. Jr, Meier, Eliane S, Thuiller, Wilfried, Guisan, Antoine, Schmatz, Dirk R, Pearman, Peter B
Format Journal Article
LanguageEnglish
Published United States National Academy of Sciences 17.11.2009
National Acad Sciences
SeriesColloquium Papers
Subjects
Biodiversity
Biogeography
Climate
Climate Change
Climate change adaptation
climate extremes
Climate models
climate variability
climatic factors
Colloquium Papers
Ecological modeling
Ecological niches
Evolution
Evolution & development
forest ecology
forest trees
Modeling
Models, Biological
niches
phytogeography
plant ecology
Plants
spatial distribution
Species
Species Specificity
Switzerland
Trees
Trees - physiology
Switzerland
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Summary:Understanding niche evolution, dynamics, and the response of species to climate change requires knowledge of the determinants of the environmental niche and species range limits. Mean values of climatic variables are often used in such analyses. In contrast, the increasing frequency of climate extremes suggests the importance of understanding their additional influence on range limits. Here, we assess how measures representing climate extremes (i.e., interannual variability in climate parameters) explain and predict spatial patterns of 11 tree species in Switzerland. We find clear, although comparably small, improvement (+20% in adjusted D², +8% and +3% in cross-validated True Skill Statistic and area under the receiver operating characteristics curve values) in models that use measures of extremes in addition to means. The primary effect of including information on climate extremes is a correction of local overprediction and underprediction. Our results demonstrate that measures of climate extremes are important for understanding the climatic limits of tree species and assessing species niche characteristics. The inclusion of climate variability likely will improve models of species range limits under future conditions, where changes in mean climate and increased variability are expected.
Bibliography:Author contributions: N.E.Z., N.G.Y., T.C.E., E.S.M., W.T., A.G., and P.B.P. designed research; N.E.Z., E.S.M., D.R.S., and P.B.P. performed research; N.E.Z., N.G.Y., E.S.M., D.R.S., and P.B.P. analyzed data; and N.E.Z., N.G.Y., T.C.E., E.S.M., W.T., A.G., D.R.S., and P.B.P. wrote the paper.
Edited by David D. Ackerly, University of California, Berkeley, CA, and accepted by the Editorial Board September 26, 2009
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0901643106