Fig. 1

Conceptual figures showing the three hypothesis. a The number of colonizing plant species was expected to decrease with increasing plant diversity of resident species. b Plant biomass production, soil basal respiration, and microbial biomass increases were expected to increase with increasing plant diversity (dashed line) in weeded subplots, while those variables will become similar across all initial experimental plant diversity levels after plant colonization in non-weeded subplots (solid line). The reader should note that the conceptual figures are graphically and qualitatively depicting the hypotheses. For simplicity, we depicted linear relationships between the variables. However, these lines are not based on empirical data, and we did not necessarily expect linear relationships between variables