LAUSR

The positive effects of spatial heterogeneity in soil nutrients on plant performance have been well documented, but whether such effects depend on the presence of soil biota or the substrate type in which the heterogeneity is manipulated remains largely unknown. In a greenhouse experiment, we grew the rhizomatous clonal grass Leymus chinensis in three different substrates (i.e., field soil, potting soil, and mixtures of ceramsite and quartz) that were subjected to two different soil nutrient treatments (i.e., a homogeneous treatment and a heterogeneous treatment consisting of low- and high-nutrient soil patches) and inoculated with either live or sterilized soil biota. In the presence of the live soil biota, L. chinensis produced more biomass in the homogeneous than in the heterogeneous treatment, independent of the substrate type. With the sterilized soil biota, however, L. chinensis produced more biomass in the heterogeneous than in the homogeneous treatment. In the heterogeneous treatment consisting of the field soil and the potting soil, L. chinensis produced more biomass in the high-nutrient patches than in the low-nutrient patches. In contrast, it produced more biomass in the low-nutrient patches than in the high-nutrient patches in the heterogeneous treatment consisting of the field soil and the mixture of quartz and ceramsite. Both soil biota and soil substrates can influence the responses of clonal plants to soil nutrient heterogeneity. Our results highlight the vital importance of including soil biota and soil physical properties in studies designed to examine the effects of soil nutrient heterogeneity on plant performance, population dynamics, species coexistence and ecosystem functioning.