DOI: 10.5061/dryad.r5m20
title: Data from: Grazing-induced shifts in community functional composition and soil nutrient availability in Tibetan alpine meadows

description: The functional structure of plant communities can be altered by grazing
 through two main mechanisms: species turnover (i.e. changes in species
 occurrence and relative abundance) and intraspecific trait variability
 (ITV), which is driven by phenotypic responses of individual plants and
 shifts in the relative abundance of genotypic variants within species.
 Studies of grassland ecosystem function under grazing often focus on
 community changes induced by species turnover, which ignores the effects
 of ITV on biomass productivity, soil carbon or nutrient availability. By
 quantifying the relative contribution of both effects on shifts in
 community-wide traits, we highlight the role of ITV in community
 functional response to grazing and its implications for ecosystem function
 in Tibetan alpine meadows. We measured three chemical traits (LC: leaf
 carbon, LN: leaf nitrogen and LP: leaf phosphorus concentrations) and two
 morphological traits (SLA: specific leaf area, LDMC: leaf dry matter
 content) that are critical components of plant production and forage
 quality in grazed and ungrazed plots. Using variance decomposition of
 community-weighted means (CWM) for these foliar traits, we distinguished
 the relative importance of ITV vs. change in species occurrence and
 abundance in response to grazing and the associated changes in soil carbon
 and nutrient availability. The CWM for foliar nutrients and SLACWM
 increased in response to grazing together with decreases in soil carbon
 and nutrient stores, especially LPCWM enrichment and loss of available
 soil P. The LPCWM was strongly negatively correlated with LDMCCWM, which
 was significantly higher in ungrazed plots. These community-wide trait
 responses to grazing were generally best captured by ITV and not changes
 in species occurrence and abundance, although ITV was consistently
 correlated with species turnover for all traits. Synthesis and
 applications. In response to continuous grazing, plants in Tibetan alpine
 meadows increase specific leaf area and foliar nutrients but tend to have
 lower leaf dry matter content, a response consistent with faster growth
 and regrowth under grazing. This intraspecific trait variability response
 drives a shift in community function from conservative, slow-growing
 resource use in ungrazed meadows to exploitative resource use under
 grazing. This community-wide functional response enhances forage quality,
 in turn favouring the secondary productivity of small herbivorous mammal
 communities, but also contributes to accelerated depletion of soil
 available phosphorus. We discuss the implications of these results for
 biodiversity conservation, ecosystem function and rangeland sustainability
 in the Qinghai–Tibetan Plateau, especially with regard to managing grazing
 rotation to strike a balance between favouring secondary productivity of
 domesticated stock vs. small herbivorous mammals.
description: Niu ,He&
 Lechowiczl_Data_JAECollected in the field;
 Site abbreviation: AZ=AaZi, WLK=WaLaKa,HY=HongYuan,QH=QingHai,
 NQ=NaQu