The Case Against Climate Envelope Models of Species Range Shifts

In critiquing the "climate envelope" approach to predicting range shifts of forests in a warming world, which has been widely used by climate alarmists, authors Lo et al. (2010) write that "at landscape and stand scales (the most meaningful for forest planning), topography, geology, slope, aspect and soils will, among other ecosystem characteristics, modify the direct effects of regional climate on trees," citing the work of Pearson and Dawson (2003), while further noting that "additional non-climatic factors such as competition, seed production, invasibility and migration rates will be equally or more important, as well as factors only indirectly related to climate such as rate, type and intensity of disturbances," citing Bergeron et al. (2004).

Lo et al. illustrated their position by using the results of a dendroclimatological study of historical tree growth-climate relationships for three species of conifers distributed along an altitudinally-induced ecological gradient in the southern interior of British Columbia, Canada.

The three researchers proved their point by determining that the growth-climate relationships they documented differed "not only among species but also between ecological zones," which finding, in their words, "implies that the different combinations of tree species and site will react differently to the same change in climate." And, in a logical extension of what they observed, Lo et al. concluded that "predicted shifts in climatic zones are not a suitable proxy, on their own, for predicting shifts in species ranges at the landscape level."

Additional References
Bergeron, Y., Gauthier, S., Flannigan, M. and Kafka, V. 2004. Fire regimes at the transition between mixed-wood and Coniferous boreal forest in northwestern Quebec. Ecology 85: 1916-1932.

Pearson, R.G. and Dawson, T.P. 2003. Predicting the impacts of climate change on the distribution of species: are bioclimate envelope models useful? Global Ecology and Biogeography 12: 361-371.