DOI: 10.5061/dryad.06186q2
title: Data from: Grazing effect on grasslands escalated by abnormal precipitations in Inner Mongolia

description: 1. Grazing effects on arid and semi-arid grasslands can be constrained by
 aridity. Plant functional groups (PFGs) are the most basic component of
 community structure (CS) and biodiversity & ecosystem function
 (BEF). They have been suggested as identity-dependent in quantifying the
 responses to grazing intensity and drought severity. Here we examine how
 the relationships among PFGs, CS, BEF, and grazing intensity are driven by
 climatic drought. 2. We conducted a manipulative experiment with three
 grazing intensities in 2012 (non-drought year) and 2013 (drought year). We
 classified 62 herbaceous plants into four functional groups based on their
 life forms. We used the relative species abundance of PFGs to quantify the
 effects of grazing and drought, and to explore the mechanisms for the
 pathway correlations using structural equation models (SEM) among PFGs,
 CS, and BEF directly or indirectly. 3. Grazers consistently favored
 perennial forbs (e.g., palatable or nutritious plants), decreasing the
 plants’ relative abundance by 23% – 38%. Drought decreased the relative
 abundance of ephemeral plants by 42 ± 13%; and increased perennial forbs
 by 20 ± 7% and graminoids by 80 ± 31%. SEM confirmed that annuals and
 biennials had negative correlations with the other three PFGs, with
 perennial bunchgrasses facilitated by perennial rhizome grass. Moreover,
 the contributions of grazing to community structure (i.e., canopy height)
 were 1.6 – 6.1 times than those from drought, whereas drought effect on
 community species richness was 3.6 times of the grazing treatment. Lastly,
 the interactive effects of grazing and drought on BEF were greater than
 either alone; particularly, drought escalated grazing damage on primary
 production. 4. Synthesis. The responses of PFGs, CS, and BEF to grazing
 and drought were identity-dependent, suggesting that grazing and drought
 regulation of plant functional groups might be a way to shape ecosystem
 structure and function in grasslands.
description: The relative abundance
 of PFGsResults of Tukey's
 test of the relative abundance (Mean ± SD) of PFGs in different
 experimental treatments.Figure
 1.csvCommunity
 structureResults of Tukey's
 test of plant species richness, stand density, and canopy height in
 different experimental treatments (Mean ± SD).Figure
 2.csvBiodiversity and
 ecosystem functionResults of Tukey's
 test of plant species diversity, functional diversity, and aboveground
 biomass in different experimental treatments (Mean ±
 SD).Figure
 3.csvStructural equation
 modelingStructural equation
 modeling of grazing and drought to predict community structure and
 biodiversity & ecosystem function by regulating the plant functional
 groups.Figure
 4.csvTwo-way
 ANOVATwo-way ANOVA on the
 effects of grazing, drought and their interactive effects on relative
 abundance of plant functional groups (i.e., perennial bunchgrasses,
 perennial rhizome grass, perennial forbs, annuals and biennials),
 community structures (i.e., species richness, stand density, canopy
 height), and biodiversity and ecosystem functions (i.e., species
 diversity, functional diversity, and aboveground
 biomass).Table
 1.csv