DOI: 10.5061/dryad.p8t61
title: Data from: Soil biota suppress positive plant diversity effects on productivity at high but not low soil fertility

description: 1. Plant community productivity commonly increases with increasing plant
 diversity, which is explained by complementarity among plant species in
 resource utilization (complementarity effect), or by selection of
 particularly productive plant species in diverse plant communities
 (selection effect). Recent studies have also shown that soil biota can
 drive the positive plant diversity–productivity relationship by
 suppressing productivity more in low- than in high-diversity plant
 communities. However, much remains unknown about whether soil fertility
 plays a role in determining how soil biota affect plant
 diversity–productivity relationships. 2. We hypothesized that under high
 soil fertility conditions, negative soil biota effects dominate, which
 reduces plant monoculture biomass more than that of high-diversity plant
 communities. Conversely, under low soil fertility conditions, we
 hypothesized positive soil biota effects dominate, which facilitates plant
 resource partitioning and enhances community-level biomass in
 high-diversity plant communities. Hence we expected positive plant
 diversity–community productivity relationships under low and high soil
 fertility conditions but caused by different mechanisms. 3. We tested
 these hypotheses using woody seedlings and set up plant assemblages with
 four species richness levels (one, two, four and eight species), and grew
 them in sterilized and unsterilized (sterilized soil + living soil
 inoculum) soils at two nutrient levels (low vs. high fertility). 4. We
 found that at high fertility negative soil biota effects dominated and
 suppressed plant community biomass more in high-diversity plant
 communities than in monocultures, resulting in reduced complementarity
 effects of diverse plant communities and a non-significant plant species
 richness–community biomass relationship in unsterilized soil. Whereas at
 low fertility soil biota had net neutral to positive effects on plant
 community biomass but the beneficial effects did not increase with
 increasing plant species richness. Instead, soil biota neutrally affected
 the positive plant species richness–community biomass relationship,
 presumably due to non-specific effects of beneficial soil biota. 5.
 Synthesis. Soil biota and soil fertility interactively determine plant
 species richness–community biomass relationships. Moreover, soil biota
 modulate the complementary resource use among plant species. These
 findings suggest that environmental context plays an important role in
 determining whether and how soil biota generate the
 biodiversity–productivity relationship. Future studies would benefit from
 revealing the mechanisms underlying the interactive effects of soil biota,
 soil fertility, and plant diversity on ecosystem functioning.
description: Effects of soil biota on
 plant diversity effects'nutrient' has
 two treatments:fertilized vs. unfertilized. 'micro' has two
 treatments: sterilized vs. unsterilized soil. 'comp' means
 species composition. 'id'means species identity.
 'state' means whether the plant is alive or dead.
 'shoot'means shoot dry weight. 'root' means root dry
 weight.Shan
 Luo_JOE.csv