Increasing tree diversity reduces spatial heterogeneity of soil organic carbon and promotes carbon storage in subtropical forests

Plant diversity’s effect on ecosystem functioning is well-established, but its effect on the spatial heterogeneity of soil carbon (C) stocks and microbial responses with increasing diversity is still unclear. Here we propose that increasing tree diversity (TD) would reduce the spatial heterogeneity of soil C stocks while increasing soil C storage, but with inconsistent effect on soil microbial distribution. We test these hypotheses in a subtropical forest comprising three plots each of a monoculture, 10-species, and 30-species plantations. Spatially explicit analysis along distance matrices was conducted on measured soil C fractions and microbial distribution using geostatistical modeling. We show that increasing TD, especially with 30 species reduced the sill value and spatial heterogeneity of soil organic C (SOC) (nugget ratio (NR): >75%) and dissolved organic C (DOC) (NR: 25–75%). Increasing TD reduced the standard deviation in SOC, total dissolved C (TDC), and dissolved inorganic C (DIC) values, while significantly (p