DOI: 10.5061/dryad.p8cz8w9zz
title: Ungulate herbivores promote beta diversity and drive stochastic plant community assembly by selective defoliation and trampling: From a four-year simulation experiment

description: Ungulate herbivores shape grassland plant communities at multiple scales,
 ultimately affecting ecosystem function. However, ungulates have complex
 effects on grasslands, including defoliation, trampling, excreta return,
 and their interactions. Moreover, the effects of ungulate density on
 grasslands are regulated by these three mechanisms. Nevertheless, how
 these three mechanisms affect biodiversity at multiple scales and
 community assembly remains poorly understood. Here, we conducted a 4-year
 novel field experiment to disentangle the effects of defoliation,
 trampling, and excreta return by ungulates on plant community assembly in
 a temperate grassland in Inner Mongolia, China. This experiment set two
 different scenarios: moderate ungulate density (Moderate, characterised by
 selective defoliation and moderate trampling) and high ungulate density
 (Intense, characterised by non-selective defoliation and heavy trampling),
 including different combinations of defoliation, trampling, and excreta
 return in each scenario. We found that defoliation and trampling increased
 stochasticity in community assembly and promoted alpha and beta diversity
 under both scenarios. Specifically, defoliation promoted the coexistence
 of species with multiple resource acquisition strategies (higher
 functional trait diversity) by reducing interspecific competition;
 trampling tended to facilitate random species colonisation. Conversely,
 excreta return favoured grasses, promoting deterministic assembly and
 impacting species coexistence. Notably, selective defoliation in the
 moderate scenario led to a dominance of stochastic processes during
 community assembly, whereas non-selective defoliation still did not change
 the dominance of deterministic processes. Further, communities subject to
 selective defoliation were insensitive to changes in soil properties
 caused by trampling and excreta return, maintaining a high-level beta
 diversity and the stochastic of community assembly. Synthesis: Our study
 provides important insights into the mechanisms by which ungulate
 herbivores influence plant community assembly, suggesting that defoliation
 and trampling have the potential to drive stochastic processes, while
 excreta return plays the opposite role. Our study also suggests that
 selective foraging by ungulates acts as stronger stochastic forces during
 community assembly compared to non-selective defoliation. These results
 imply that considering ungulate feeding preferences and foraging behaviour
 in grassland management will help prevent biodiversity loss and biotic
 homogenisation.
description: # Ungulate herbivory promotes beta-diversity and drives stochastic plant
 community assembly by selective defoliation and trampling: from a
 four-year simulation experiment
 [https://doi.org/10.5061/dryad.p8cz8w9zz](https://doi.org/10.5061/dryad.p8cz8w9zz) In each of the 4 years, we determined the cover of plants in each plot in mid-August, and based on relative cover we calculated beta-diversity, beta-deviation, and species loss/gain rates for each treatment. We determined functional traits (including SLA, LDMC, LCC, LNC, and LPC) for each species at the same time as the vegetation surveys and calculated functional diversity. Following the vegetation survey, we obtained soil samples and measured soil properties including pH, bulk density, ammonium (NH4+-N) concentration, and nitrate (NO3--N) concentration. ## Description of the data and file structure The Excel file (20240610-Data-ungulate_herbivory.xls) contains 8 sheets: 1. Abbreviation: Meaning of abbreviations in the dataset. 2. group: Experimental design table. 3. beta.diversity: Data on beta-diversity, beta-deviation and soil heterogeneity. The unit of all variables in this sheet is one unit. 4. fd: Data on functional diversity. The unit of all variables in this sheet is one unit. 5. rela.coverage: Data on relative coverage. The unit of all variables in this sheet is one unit. The sum of relative coverage for all species in each plot is one. 6. soil: Data on four soil properties including pH, bulk density (g/cm3), ammonium (NH4+-N, mg/g dry soil) concentration, and nitrate (NO3--N, mg/g dry soil) concentration. 7. species: Species list and functional groups. 8. species.gain&loss: Data on plant species gain and loss rate.