Plant interaction modifies effects of soil heterogeneity on seed germination, plant growth, and biomass of plant communities.

Soil heterogeneity significantly impacts the structure and function of plant communities. However, most of the previous studies only focussed on the effects of soil heterogeneity on plant populations, while the joint effects of plant interaction and soil heterogeneity on plant communities remain unclear. Thus, a manipulation experiment was done to explore the effects of soil heterogeneity and species combination on the seed germination, plant height and plant biomass, where three soil heterogeneity levels were created by varying patch sizes (small, medium, and large), and 10 species combinations were generated by growing four typical forages on the Qinghai-Tibetan Plateau (Elymus nutans, Festuca sinensis, Poa pratensis, and Vicia unijuga) either in monocultures or in mixtures. Data were analysed at three scales (at the pot scale, at the monoculture, and at the mixture scale). Results showed that with decreasing patch size, (i) at the pot scale, the seed germination and plant height in both monocultures and mixtures decreased, while the plant biomass in mixtures first decreased and then increased, and the plant biomass in monocultures decreased; and (ii) at the monoculture scale and the mixture scale, the plant height of E. nutans in the monoculture first decreased and then increased, while the plant height of the other monocultures decreased. Furthermore, the plant biomass of E. nutans in the monoculture first decreased and then increased, while the plant biomass of the rest species combination decreased. This study provides insight into the future restoration of degraded grassland in alpine meadows and the healthy management of artificial grasslands.