Global species-energy relationship in forest plots: role of abundance, temperature and species climatic tolerances
Abstract
To evaluate the strength of evidence for hypotheses explaining the relationship between climate and species richness in forest plots. We focused on the effect of energy availability which has been hypothesized to influence species richness: (1) via the effect of productivity on the total number of individuals (the more individuals hypothesis, MIH); (2) through the effect of temperature on metabolic rate (metabolic theory of biodiversity, MTB); or (3) by imposing climatic limits on species distributions.
Across the world's forests there is no evidence to support the MIH, and a very limited evidence for a prominent role of productivity as a driver of species richness patterns. The role of temperature is much more important, although this effect is more complex than originally assumed by the MTB.
Variation in forest plot diversity appears to be mostly affected by variation in the minimum climatic values. This is consistent with the 'climatic tolerance hypothesis' that climatic extremes have acted as a strong constraint on species distribution and diversity.