TY - JOUR

T1 - Resource availability determines the importance of niche-based versus stochastic community assembly in grasslands

AU - Conradi, Timo

AU - Temperton, Victoria Martine

AU - Kollmann, Johannes

PY - 2017/8

Y1 - 2017/8

N2 - Niche-based selection and stochastic processes can operate simultaneously to generate spatial and temporal variation in species composition. Yet, the conditions under which ecological dynamics are dominated by niche-based versus stochastic processes are poorly understood. Using a field experiment in early-successional temperate grassland and null models of beta diversity, this study investigates the effects of soil nutrient supply on the relative importance of niche-based selection versus stochastic dynamics for variation in species composition among sites. Nutrient availability was manipulated experimentally,individual seed mixtures with 25 species were sown in each experimental plot, and then stochastic and deterministic niche-based assembly processes were allowed to happen. We found that compositional variation among grassland plots with low nutrient supply was driven by stochastic immigration and extinctions. In contrast, nutrient enrichment reduced the importance of stochasticity and imposed a deterministic environmental filter that homogenized communities through the selection of few species with greater competitive ability for light. This demonstrates that soil nutrient availability isa critical environmental feature that dictates the degree to which terrestrial plant communities are controlled by nichebased selection versus stochastic assembly processes. Our study shows further that alternative states of eutrophic grasslands emerge from initial stochastic variation in the composition of a particular functional group of species that can become dominant at high nutrient supply. We discuss potential mechanisms underlying the shift from stochastic to niche-driven dynamics along soil nutrient gradients.

AB - Niche-based selection and stochastic processes can operate simultaneously to generate spatial and temporal variation in species composition. Yet, the conditions under which ecological dynamics are dominated by niche-based versus stochastic processes are poorly understood. Using a field experiment in early-successional temperate grassland and null models of beta diversity, this study investigates the effects of soil nutrient supply on the relative importance of niche-based selection versus stochastic dynamics for variation in species composition among sites. Nutrient availability was manipulated experimentally,individual seed mixtures with 25 species were sown in each experimental plot, and then stochastic and deterministic niche-based assembly processes were allowed to happen. We found that compositional variation among grassland plots with low nutrient supply was driven by stochastic immigration and extinctions. In contrast, nutrient enrichment reduced the importance of stochasticity and imposed a deterministic environmental filter that homogenized communities through the selection of few species with greater competitive ability for light. This demonstrates that soil nutrient availability isa critical environmental feature that dictates the degree to which terrestrial plant communities are controlled by nichebased selection versus stochastic assembly processes. Our study shows further that alternative states of eutrophic grasslands emerge from initial stochastic variation in the composition of a particular functional group of species that can become dominant at high nutrient supply. We discuss potential mechanisms underlying the shift from stochastic to niche-driven dynamics along soil nutrient gradients.

KW - Biology

KW - Species Richness

KW - Plant diversity

KW - Beta-diversity

KW - Nitrogen deposition

KW - Relative role

KW - Biodiversity

KW - Coexistence

KW - competition

KW - Pools

KW - Colonization

KW - Sustainability Science

KW - Ecosystems Research

UR - http://www.scopus.com/inward/record.url?scp=85017339151&partnerID=8YFLogxK

U2 - 10.1111/oik.03969

DO - 10.1111/oik.03969

M3 - Journal articles

VL - 126

SP - 1134

EP - 1141

JO - Oikos

JF - Oikos

SN - 0030-1299

IS - 8

ER -