DOI: 10.5061/dryad.n2z34tmvd
title: Data from: Mycorrhizal suppression and phosphorus addition influence the stability of plant community composition and function in a temperate steppe

description: Nutrient enrichment can reduce ecosystem stability, typically measured as
 the temporal stability of productivity that has multiple underlying
 mechanism including species resistance and resilience to nutrient pulses
 and the resulting compositional change. Moreover, nutrient enrichment can
 alter plant-soil interactions (e.g. mycorrhizal symbiosis) that determine
 plant productivity and diversity. Thus, it is likely that nutrient
 enrichment and interactions between plants and their soil communities
 co-determine the stability in plant community composition and
 productivity. Yet our understanding as to how nutrient enrichment affects
 the multiple facets of ecological stability and the role of
 above-belowground interactions are still lacking. We tested how
 mycorrhizal suppression and phosphorus (P) addition influenced functional
 and compositional stability of plant community in a three-year field
 study. Here functional stability is the temporal community variance in
 primary productivity; compositional stability is represented by
 compositional resistance, turnover, species extinction and invasion.
 Compared with mycorrhizal suppression, the intact AM fungal communities
 reduced community variance in primary productivity by reducing species
 synchrony at high levels of P addition. Species synchrony and population
 variance were linearly associated with community variance when mycorrhiza
 were not suppressed, while these relationships were decoupled or weakened
 by mycorrhizal suppression. The intact AM fungal communities promoted the
 compositional resistance of plant communities by reducing compositional
 turnover, but this effect was suppressed by P addition. P addition
 increased the number of species extinctions and thus promoted
 compositional turnover. Our study shows P addition and AM fungal
 communities can jointly and independently modify the various components of
 ecosystem stability in terms of plant community productivity and
 composition.
description: We used a
 two-factor randomized block design containing all combinations of two
 levels of fungicide treatment (natural and fungicide treatment) and 6
 levels of P addition (0, 2.4, 4.7, 9.4, 19.0 and 37.8 g
 P<sub>2</sub>O<sub>5</sub>
 m<sup>-2</sup>·year<sup>-1</sup>), for a total of
 12 treatments. In May 2010, we established 10 blocks and all treatments
 were randomly assigned to 12 plots (2 × 2 m) in each block. Block
 arrangement took into account the slope at the study sites. There were 2-m
 gaps between each plot and block to reduce potential effects of treatments
 on each other.  Above-ground biomass, cover and
 species richness were measured at the peak of plant biomass production in
 the middle of August from 2010 to 2012. Species richness and cover was
 measured non-destructively in a permanent quadrat (1 × 1 m) in each plot
 (where no other sampling took place), established in May 2010. One subplot
 (0.5 × 1 m) was used to estimate above-ground biomass in each plot every
 year, with a new subplot selected every year for this purpose. Shoots of
 each species were cut at the soil surface and oven dried at 65°C for 72
 hours, before being weighed. We recorded shoot dry weight of each species
 separately. Net biomass production (productivity) was calculated as the
 sum of shoot dry weights of all plant species in each subplot and
 expressed as g m<sup>-2</sup>.