Strong environmental forcings, from storms to fires and insect outbreaks to elephants, drive tree population dynamics in forests across the world. Despite the pervasiveness of these environmental drivers, most theoretical models of forest tree dynamics ignore them, focussing instead on neutral drift and niche stabilisation. What effect does environmental variance have on patterns of forest diversity? In our new paper, in press at Ecology, we show that a model with realistically strong environmental forcings can accurately reproduce both static and dynamic patterns of diversity in two tropical forest plots, one in Malaysia and one in Panama. This is superior to previous similar models that are unable to capture both types of diversity simultaneously—for example, neutral models are only able to realistically produce static patterns such as species-abundance distributions. Our work further underscores the need to include strong components of environmental variance in realistic models of tropical forest dynamics.

This work was led by Tak Fung, with Kassim Abd. Rahman and Christine Fletcher (Forest Research Institute Malaysia), and James O’Dwyer (Univ. of Illinois) as a collaborators.

Reproducing static and dynamic biodiversity patterns in tropical forests: the critical role of environmental variance. Tak Fung, James P. O’Dwyer, Kassim Abd. Rahman, Christine D. Fletcher and Ryan A. Chisholm, in press, Ecology.

Poulsenia armata, a tree that was formerly dominant in the canopy at the Panama plot but suffered 50% mortality during a 1980s drought (image credit: biogeodb.stri.si.edu).