Predicting the direction and magnitude of small mammal disturbance effects on plant diversity across scales

Meredith Root-Bernstein

doi:10.21425/f5fbg15278

Abstract

Despite years of research on small mammal disturbance effects on plant diversity, predicting the direction and magnitude of these effects remains elusive. Models such as the intermediate distur- bance hypothesis, the perturbation hypothesis, or the ecosystem engineering hypothesis of small mam- mal disturbance, show considerable overlap but fail to account for key variable interactions and thus provide mainly post hoc explanations. Recent re views have emphasized the importance of small mam- mals to basic and applied ecology. Re-examining the mechanisms underlying their disturbance effects is thus timely. Here I present the Slope-Hump Model, which integrates previous models and insights from the literature, and which is capable of predicting the direction and relative magnitude of disturbance effects on plant diversity. These predictions qualitatively match the results of recent meta-analyses. The model also suggests new patterns and predictions that can stimulate both pure and applied ecology re- search.

Highlights

The effects of small mammal disturbances on bio‐ diversity, especially of plants, is a recurrent topic of interest to community ecology research (Kelt 2011, Root‐Bernstein and Ebensperger 2012, Davidson et al 2012)
I propose a simple novel model, which I designate by the original name the Slope‐ Hump model of disturbance
Note an in‐ congruency: while in the IDH competition controls the response only on the left side of the hump and disturbance that degrades biomass controls the right side, here nutrient availability controls the competition response on both sides of the hump

Summary

Introduction

The effects of small mammal disturbances on bio‐ diversity, especially of plants, is a recurrent topic of interest to community ecology research (Kelt 2011, Root‐Bernstein and Ebensperger 2012, Davidson et al 2012). Note an in‐ congruency: while in the IDH competition controls the response only on the left side of the hump (and is an implied variable not shown as its own axis in the graphical model) and disturbance that degrades biomass controls the right side, here nutrient availability controls the competition response on both sides of the hump It is not clear why the role of nutrient avail‐ ability would be specific to ‘endogenous’ trophic effects. The ecosystem engineering hypothe‐ sis (EEH) as applied to small mammal disturbances (Wright and Jones 2004) predicts that small mam‐ mals can directly modify productivity (defined as the rate of conversion of abiotic inputs to bio‐ mass), including indirect measures such as soil nutrient availability This may occur, for example, by species making changes to physical qualities of the soil or nutrient cycling rates. The effects of any particular disturbance on species richness are contingent on the species pool

The model

Comparison of models

Model predictions