DOI: 10.5061/dryad.8sf7m0cz7
title: Water limitation drives species loss in grassland communities after nitrogen addition and warming

description: Nutrient addition, particularly nitrogen, often increases plant
 aboveground biomass but causes species loss. Asymmetric competition for
 light is frequently assumed to explain the biomass-driven species loss.
 It, however, remains unclear whether other factors such as water can also
 play a role. Increased aboveground leaf area following nitrogen addition
 and warming may increase transpiration and lead to water limitation,
 leading to a decline in diversity. To test this, we conducted field
 measurements from a grassland community exposed to nitrogen and water
 addition, and warming. We found that warming and/or nitrogen addition
 significantly increased aboveground biomass but reduced species richness.
 Water addition prevented species loss in either nitrogen-enriched or
 warmed treatments, while it partially mitigated species loss in the
 treatment exposed to increases in both temperature and nitrogen. These
 findings thus strongly suggest that water limitation can be an important
 driver of species loss as biomass increases after nitrogen addition and
 warming when soil moisture is limiting. This result is further supported
 by a meta-analysis of published studies across grasslands worldwide. Our
 study indicates that loss of grassland species richness in the future may
 be greatest under a scenario of increasing temperature and nitrogen
 deposition, but decreasing precipitation.
description: The field measurements from a grassland community exposed to
 increased nitrogen, water availability and warming. A
 meta-analysis of published studies across grasslands worldwide
description: ### field-data.csv field-data dataset is experimental data * Treatment is
 different treatments,  * AGB is aboveground biomass, unit: g/m² * SR is
 species richness, unit: m² * Treatment abbreviations: Ambient (AMB), Water
 (W), nitrogen (N), temperature (T), water and nitrogen (WN),  water
 and temperature (WT), nitrogen and temperature (NT), water, nitrogen
 and temperature (WNT). ### meta-AGB.csv meta-AGB is the abovementide
 biomass data set used for meta-analysis. * latitude  is latitude, unit: °
 * longitude is longitude,unit: ° * quantile is different treatment, * CM
 is the average value of the control group, unit: g/m² * CSD is the
 standard error of the control group, unit: g/m² * TM is the average value
 of the experimental group, unit: g/m² * TSD is the standard error of the
 experimental group, unit: g/m² * null is missing values. These are due to
 the absence of reported latitude and longitude in the collected
 literature. ### meta-SR.csv The meta-SR is the species richness data used
 in the meta-analysis, and other indicators are consistent with aboveground
 biomass.  Variables are the same as meta-AGB.csv. The unit for CM, CSD,
 TM, and TSD is m². ### Species\_frequency.csv * Treatment is different
 treatments, * species is the species name, * Frequency is the occurrence
 frequency of the species, unit: unitless * Treatment abbreviations:
 Ambient (AMB), Water (W), nitrogen (N), temperature (T), water
 and nitrogen (WN),  water and temperature (WT), nitrogen and temperature
 (NT), water, nitrogen and temperature (WNT).