Shifting Species Interaction in Soil Microbial Community and Its Influence on Ecosystem Functions Modulating

Abstract

The supportive and negative evidence for the stress gradient hypothesis (SGH) led to an ongoing debate among ecologists and called for new empirical and theoretical work. In this study, we took various biological soil crust (BSCs) samples along a spatial gradient with four environmental stress levels to examine the fitness of SGH in microbial interactions and evaluate its influence on biodiversity-function relationships in BSCs. A new assessment method of species interactions within hard-cultured invisible soil community was employed, directly based on denaturing gradient gel electrophoresis fingerprint images. The results showed that biotic interactions in soil phototroph community dramatically shifted from facilitation to dominant competition with the improvement of microhabitats. It offered new evidence, which presented a different perspective on the hypothesis that the relative importance of facilitation and competition varies inversely along the gradient of abiotic stress. The path analysis indicated that influence of biotic interactions (r=0.19, p< 0.05) on ecosystem functions is lower than other community properties (r=0.62, p<0.001), including soil moisture, crust coverage, and biodiversity. Furthermore, the correlation between species interactions and community properties was non-significant with low negative influence (r=−0.27, p> 0.05). We demonstrate that the inversion of biotic interaction as a response to the gradient of abiotic stresses existed not only in the visible plant community but also in the soil microbial community.

Rhizosphere effect and salinity competing to shape microbial communities inPhragmites australis(Cav.) Trin. ex-Steud

“…In such extreme environments other variables could play a stronger role with respect to the biotic effect of rhizosphere in selecting the microbial communities. This hypothesis seems to be supported by similar findings of a smaller influence of biotic interactions than of abiotic stresses on ecosystem functions in biological soil crusts that have developed on desert soils (Li et al ., ). In our study we found that samples clustered according to the different values of salinity.…”

“…Although the effect of plant species and individuals on their rhizobacteria has been investigated extensively, especially as regards agricultural crops, very few studies have as yet investigated the microbial communities associated to roots of wild plants in hypersaline environments (e.g. Mapelli et al ., ). To the best of our knowledge there are no comparative studies focusing on the rhizobacterial communities associated with submerged plants in inland water sediments.…”

Differentiation of the characteristics of excreted extracellular polysaccharides reveals the heterogeneous primary succession of induced biological soil crusts

“…Moreover, it has to be stressed that the presence of environmental stressors (i.e., soil moisture, crust coverage, and species diversity) seems to be capable of differentiating the developmental level of IBSCs more than the biotic factors (Li et al 2013), with a consequent differentiation in the characteristics of the EPS matrix of the crusts hardly correlating with the age.…”

“…In general, microbial interactions are heavily influenced by environmental stress gradients (Bstress gradient hypothesis^(SGH)), which determine the relative frequency of facilitation and competition between the species. According to SGH, environmental constraints produce changes in the community, which are instrumental to fulfill the ecological functions of the BSCs (Li et al 2013).…”

Microbial secreted exopolysaccharides affect the hydrological behavior of induced biological soil crusts in desert sandy soils

“…Biofilms have been largely studied either for understanding their role in the environment (Davey and O'Toole, 2000;Battin et al, 2003;Romani et al, 2004) or for assessing their possible industrial applications (Singh et al, 2006;Colica et al, 2010;Sheng et al, 2010;De Philippis et al, 2011). In this frame, also a frontier study that combined applied and environmental aspects was carried out in Inner Mongolia (China) where, in order to promote the stabilization of desert soils in that area, EPS-producing cyanobacteria were inoculated in the soils for inducing the formation of biological soil crusts (BSCs) (Chen et al, 2006;Wang et al, 2009;Li et al, 2013b). In nature, BSCs are highly specialized communities constituted by cyanobacteria, green algae, fungi, mosses, lichens and other heterotrophs.…”