Subordinate plants sustain the complexity and stability of soil micro-food webs in natural bamboo forest ecosystems.
Subordinate plants have a significant impact on soil organisms in primary successional floodplains and grassland ecosystems, but their role in subtropical forest ecosystems remains unclear. An experiment was conducted in a subtropical forest to test the hypothesis that removal of shrubs or subordinate arbour tree species would reduce the complexity and stability of the soil micro-food web. Principal response curves (PRCs) were performed to assess the responses of soil microbial and nematode communities to plant removal compared with a control through time. The effect of plant removal on complexity and stability in the soil micro-food web was assessed using a suite of indices including ratio of omnivorouspredatory to herbivorous nematode abundance (OP:H ratio), nematode diversity, resistance and resilience. Furthermore, increments of bamboo productivity among treatments were estimated. Soil microbial community structure changed in response to plant removal in 2009, but recovered in 2010, and the only change observed was increased soil fungal biomass. In contrast, plant removal had greater impact on soil nematode community composition in 2010 than 2009. Subordinate arbour tree species removal (with or without shrubs) decreased the values of nematode richness, evenness, diversity, ratio of microbial-feeding to herbivorous nematode abundance (M:H ratios), OP:H ratios and resistance indices in 2010, but only decreased OP:H ratios in 2009 and increased the values of nematode dominance in 2010. Although increments in bamboo productivity were statistically similar among treatments, there was a trend decreasing progressively from control to shrub removal+selective-cutting of subordinate arbour tree species, shrub removal, and selective-cutting of subordinate arbour tree species treatments. Synthesis and applications. Subordinate plants help sustain the complexity and stability of soil micro-food webs in subtropical bamboo forest ecosystems. Therefore, protection of subordinate plants and maintaining high plant diversity are important parts of a responsible management strategy in subtropical bamboo forests.