DOI: 10.5061/dryad.mq56q
title: Data from: Herbivory and eutrophication mediate grassland plant nutrient responses across a global climatic gradient

description: Plant stoichiometry, the relative concentration of elements, is a key
 regulator of ecosystem functioning and is also being altered by human
 activities. In this paper we sought to understand the global drivers of
 plant stoichiometry and compare the relative contribution of climatic vs.
 anthropogenic effects. We addressed this goal by measuring plant elemental
 (C, N, P and K) responses to eutrophication and vertebrate herbivore
 exclusion at eighteen sites on six continents. Across sites, climate and
 atmospheric N deposition emerged as strong predictors of plot‐level tissue
 nutrients, mediated by biomass and plant chemistry. Within sites,
 fertilization increased total plant nutrient pools, but results were
 contingent on soil fertility and the proportion of grass biomass relative
 to other functional types. Total plant nutrient pools diverged strongly in
 response to herbivore exclusion when fertilized; responses were largest in
 ungrazed plots at low rainfall, whereas herbivore grazing dampened the
 plant community nutrient responses to fertilization. Our study highlights
 (1) the importance of climate in determining plant nutrient concentrations
 mediated through effects on plant biomass, (2) that eutrophication affects
 grassland nutrient pools via both soil and atmospheric pathways and (3)
 that interactions among soils, herbivores and eutrophication drive plant
 nutrient responses at small scales, especially at water‐limited sites.
description: Anderson.et.al.Ecology.model1.LRR.scriptR script to execute the analysis of covariance on the log response ratio of total plant nutrients in fertilized and unfertilized treatments across 20 grassland sites (model 1).Anderson.et.al.Ecology.model2.SEM.scriptR script to execute the hierarchical structural equation model (model 2) using a piece-wise approach. The model analyzes direct and indirect effects of climate, herbivory and nutrient supply on total plant nutrient responses (the sum of N, P and K) at multiple spatial scales by combining site- and plot-level predictors in a multi-level structural equation model.Model1.LRR.dataData file required to run model 1. Data included in the file are the site ID, the treatment (fenced or unfenced), mean annual precipitation in mm yr-1 (MAP), average annual temperature in oC (MAT), solar insolation in KWh m-2 day-1 (SOLAR.INS), total soil %N (SOIL.PCT.N), and the log ratio of the total nutrient content in fertilized/total nutrient content in control for carbon (LRR.C), nitrogen (LRR.N), phosphorus (LRR.P) and potassium (LRR.K).Model2.SEM.plot.dataData file required to run model 2 at the plot level. Data included in the file are a row number, site ID, the treatment (2 x 2 NPK fertilizer by fencing), an indicator variable for fence (FENCE), an indicator variable for fertilization (NPK.ADDED), mean annual precipitation in mm yr-1 (MAP), average annual temperature in oC (MAT), solar insolation in KWh m-2 day-1 (SOLAR.INS), atmospheric nitrogen deposition in kg ha-1 yr-1(N.DEPOSITION), a grazing index, total soil %N (SOIL.PCT.N), total aboveground plant biomass in g m-2 (TOTAL.AG.BIOMASS), the percent of biomass that is grass (PERCENT.GRASS.BIOMASS) and the concentration of NPK (plant.NPK), nitrogen (plant.N), phosphorus (plant.P) and potassium (plant.K) in plant tissue.Model2.SEM.site.dataData file required to run model 2 at the site level. Data included in the file are the site ID, average annual temperature in oC (MAT), mean annual precipitation in mm yr-1 (MAP), solar insolation in KWh m-2 day-1 (SOLAR.INS), atmospheric nitrogen deposition in kg ha-1 yr-1(N.DEPOSITION), a grazing index and the percent of biomass that is grass (PERCENT.GRASS.BIOMASS).