Selection of scale can reverse the importance of stochastic controls on community assembly |
| |
Authors: | Daehyun Kim |
| |
Institution: | Biogeomorphology Research and Analysis Group, Department of Geography, Institute for Korean Regional Studies, Seoul National University, Seoul, South Korea |
| |
Abstract: | Reconciling the long-standing debate on the importance of niche-related and neutral factors on community assembly, recent research suggests that both deterministic and stochastic processes operate simultaneously along a continuum in many biogeographical systems. In particular, stochastic processes seem to lose importance under stressful conditions, which results in the increasing influence of deterministic counterparts. In this paper, I show that, at local scales, this stochasticity–stress relationship can be reversed along the environmental stress gradients within a salt marsh: stochasticity manifested under harshness. Here, low-lying, more stressful sites contained all of the plant species of the local pool (i.e. a greater chance of ecological drift), whereas high-elevation, less stressful sites exhibited reduced species richness due to competitive exclusion (i.e. a lower chance of ecological drift). I conclude that determining whether the importance of stochasticity in shaping community structure is greater under benign or harsh conditions depends on the scale of interest. |
| |
Keywords: | β-diversity biological filtering environmental stress gradient niche versus neutral processes species richness |
|
|