The Bioclimate Envelope - Outdated and Simple?

Todays post will focus on the bioclimate envelope model and discuss whether they are useful in determining species migrationary response to climate change. The bioclimate envelope model has its roots in the ecological niche theory. The ecological niche is a conceptual space comprising all of the environmental variables in which a species can survive and grow. The bioclimate envelope can be defined as the climatic component of the ecological niche. Therefore it involves understanding the current species distribution, and how species physiologically will respond to climate change. It might enable us to make a redistribution of species over time using climate models.

The model is widely used in decision making on future climate change, however there are some criticisms. Pearson & Dawson (2003) express concern at how the model does not take into account how species interact with each other, rather how only they function alone. Since ecosystems are a complex web of interactions and feedbacks, taking into account only the species that is being studied could lead to erroneous model predictions. Another possible facet that is not included is evolutionary change. Studies by Thomas et al. (2001) and Woodward (1990) has studied rapid evolutionary change response to climate change of plant and insect species. This involves studying climate induced shifts in species, often excluding phenotypes that are poor dispersers or poorly adapted to local conditions.

Looking forward, the development of dynamic global species models would be a more accurate approach. There has been recent development of models on regional scales that break down ecosystems processes into key components and use that to spatially and temporally model species range shifts. However due to the complexity of these models, application to global scales have not yet been possible. This means that bioclimate envelope models are still perhaps the best available guide for policy making at the present time, though they must be viewed skeptically.