A Significant Upward Shift in Plant Species Optimum Elevation During the 20th Century
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J. M. Moisselin, M. Schneider, C. Canellas, O. Mestre, Meteorologie38, 45 (2002).
Materials and methods are available as supporting material on Science Online.
The impact of the symmetry assumption in Gaussian logistic regressions (GLR) on our results was tested by using a more flexible curve-fitting tool namely generalized additive models (GAM) which allows for asymmetry in hump-shaped curves ( 23 ). We also found a statistically highly significant shift of 27 m per decade (mean difference in optimum elevation 59.4 m 95% CI = 16.5 102.4; n = 171; Student's paired-sample t test t = 2.73; df = 170; P < 10 –2 ).
The ecological amplitude is a proxy for the size of the species altitudinal range around the optimum elevation ( 23 ). We found no significant differences between 1905–1985 and 1986–2005 (mean difference in ecological amplitude 2.3 m 95% CI = –11.9 16.6; n = 171; Student's paired-sample t test t = 0.32; df = 170; P = 0.75).
E. Dambrineet al., in Forest Decline and Atmospheric Deposition Effects in the French Mountains, G. Landmann, M. Bonneau, Eds. (Springer Verlag, Berlin, 1994), pp. 177–200.
We thank the thousand of recorders who contributed to the building of EcoPlant and Sophy databases; J.-D. Bontemps J.-C. Pierrat and C. Coudun for their much-appreciated statistical advice; J.-L. Dupouey for stimulating discussion; and three anonymous reviewers for helpful comments on previous versions of this manuscript that strongly improved the quality of our analyses. EcoPlant is a phytoecological database financed by the French Environment and Energy Management Agency (ADEME) and the Office National des Forêts (ONF). Part of this work was conducted while P.A.M. was a Sabbatical Fellow at the National Center for Ecological Analysis and Synthesis a center funded by NSF (grant DEB-0072909) the University of California and the Santa Barbara campus. P.A.M. acknowledges support from a Guggenheim Fellowship and grants FONDAP-FONDECYT 1501-0001 and ICM P05-02 PFB-23 CONICYT. J.C.G. acknowledges support from FONDECYT 11060313 and FONDECYT Cooperacion Internacional 7070147. J.L. was found by a Ph.D. grant from the French National Institute for Agricultural Research (INRA).