Heterotroph removal alters the difference in plant biomass among plant species compositions in systems with different N availability

Abstract

ABSTRACT We studied the effects of heterotroph removal on the relationship between species composition and plant biomass in systems with different N availability. Two understory herb species (Ophiopogon bodinieri and Lophatherum gracile) were grown in monocultures and mixture, and heterotroph removal treatments (control, insecticide, fungicide, and fungicide-insecticide combination) were performed on each plant species composition in systems without or with N addition. Results showed that (1) in systems without N addition, the plant biomass of O. bodinieri monoculture was higher than that of the mixture under insecticide and fungicide-insecticide treatments, but this difference disappeared in systems with N addition. (2) In systems without N addition, fungicide and insecticide application increased leaf area but decreased root length and root tips of O. bodinieri monocultures. In systems with N addition, fungicide and insecticide application increased root tips of O. bodinieri monocultures and root diameter of mixtures. (3) In systems without N addition, fungicide and insecticide application increased the soil pH of O. bodinieri monocultures. In systems with N addition, fungicide application decreased the soil K concentration of O. bodinieri monocultures. Our findings suggest that heterotroph removal alters the difference in plant biomass among plant species compositions in systems with different N availability.