Changes in Plant Species Richness Induce Functional Shifts in Soil Nematode Communities in Experimental Grassland

Abstract

BackgroundChanges in plant diversity may induce distinct changes in soil food web structure and accompanying soil feedbacks to plants. However, knowledge of the long-term consequences of plant community simplification for soil animal food webs and functioning is scarce. Nematodes, the most abundant and diverse soil Metazoa, represent the complexity of soil food webs as they comprise all major trophic groups and allow calculation of a number of functional indices.Methodology/Principal FindingsWe studied the functional composition of nematode communities three and five years after establishment of a grassland plant diversity experiment (Jena Experiment). In response to plant community simplification common nematode species disappeared and pronounced functional shifts in community structure occurred. The relevance of the fungal energy channel was higher in spring 2007 than in autumn 2005, particularly in species-rich plant assemblages. This resulted in a significant positive relationship between plant species richness and the ratio of fungal-to-bacterial feeders. Moreover, the density of predators increased significantly with plant diversity after five years, pointing to increased soil food web complexity in species-rich plant assemblages. Remarkably, in complex plant communities the nematode community shifted in favour of microbivores and predators, thereby reducing the relative abundance of plant feeders after five years.Conclusions/SignificanceThe results suggest that species-poor plant assemblages may suffer from nematode communities detrimental to plants, whereas species-rich plant assemblages support a higher proportion of microbivorous nematodes stimulating nutrient cycling and hence plant performance; i.e. effects of nematodes on plants may switch from negative to positive. Overall, food web complexity is likely to decrease in response to plant community simplification and results of this study suggest that this results mainly from the loss of common species which likely alter plant – nematode interactions.

Root biomass and exudates link plant diversity with soil bacterial and fungal biomass

“…Consistent with field experiments2632, soil microbial biomass increased with plant diversity, and soil microbial communities shifted along the plant diversity gradient towards more fungal-dominated communities633. While our results confirm previous experiments that reported plant biomass-mediated effects of plant diversity on soil microbial biomass32, the present study provides one of the first empirical evidences that this plant diversity effect could be driven –at least in part– by changes in plant root exudation.…”

“…Thus, the measures of root exudate amount and diversity should be regarded as proxies representing relative differences among experimental treatments rather than absolute measures. Despite those caveats, the present study provides empirical evidence for the significant role of root exudates in linking above- and belowground communities and the diversity of plant communities with the functional composition of soil microbial communities1222 stimulating future work on the mechanisms of rhizosphere interactions262833.…”

Plant species richness does not attenuate responses of soil microbial and nematode communities to a flood event

“…In line with the results of Eisenhauer et al (2011), overall nematode density increased significantly with increasing plant diversity (after the flood), but that coincided with significant changes in nematode community composition.…”

The isolation and functional identification on producing cellulase ofPseudomonas mendocina

“…Through the SDS-PAGE analysis of protein standard achieved the standard curve (Fig. 5), the cellulase was figure out by measuring the relative mobility 10 and the cellulase molecular weight were 42.4 k D and 20.4 k D .…”

“…9 As a main soil animal, Nematodes are widely distributed in various habitats as the function soil animal species, which play an important role in soil ecosystem. 10 The response of soil microbes to nematodes is mainly reflected in the changes of biomass, microbial activity and microbial community structure. 11 The researchers found that nematodes could change the genetic structure of microbial communities with denaturing gradient gel electrophoresis (DGGE) through investigating 4 kinds of bacterivorous nematodes using microbial community culture system.…”