Soil Bacterial Community Response to Differences in Agricultural Management along with Seasonal Changes in a Mediterranean Region

Abstract

Land-use change is considered likely to be one of main drivers of biodiversity changes in grassland ecosystems. To gain insight into the impact of land use on the underlying soil bacterial communities, we aimed at determining the effects of agricultural management, along with seasonal variations, on soil bacterial community in a Mediterranean ecosystem where different land-use and plant cover types led to the creation of a soil and vegetation gradient. A set of soils subjected to different anthropogenic impact in a typical Mediterranean landscape, dominated by Quercus suber L., was examined in spring and autumn: a natural cork-oak forest, a pasture, a managed meadow, and two vineyards (ploughed and grass covered). Land uses affected the chemical and structural composition of the most stabilised fractions of soil organic matter and reduced soil C stocks and labile organic matter at both sampling season. A significant effect of land uses on bacterial community structure as well as an interaction effect between land uses and season was revealed by the EP index. Cluster analysis of culture-dependent DGGE patterns showed a different seasonal distribution of soil bacterial populations with subgroups associated to different land uses, in agreement with culture-independent T-RFLP results. Soils subjected to low human inputs (cork-oak forest and pasture) showed a more stable bacterial community than those with high human input (vineyards and managed meadow). Phylogenetic analysis revealed the predominance of Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes phyla with differences in class composition across the site, suggesting that the microbial composition changes in response to land uses. Taken altogether, our data suggest that soil bacterial communities were seasonally distinct and exhibited compositional shifts that tracked with changes in land use and soil management. These findings may contribute to future searches for bacterial bio-indicators of soil health and sustainable productivity.

Atmospheric Deposition-Carried Zn and Cd from a Zinc Smelter and Their Effects on Soil Microflora as Revealed by 16S rDNA

“…indicated that HM pollution could increase the number of some indigenous bacterial OTUs and taxa when the concentrations of the SOM fraction s was higher in the soil. The bacterial community in all five of the soil samples was dominated by Proteobacteria , while Acidobacteria and Actinobacteria were predominant among the other phyla with increasing distance and HM contamination5657.…”

Metagenomic analysis exploring taxonomic and functional diversity of soil microbial communities in Chilean vineyards and surrounding native forests

“…For instance, organically managed vineyards have higher soil microbial biomass and nematode densities than conventional vineyards (Coll et al, 2011). On the other hand, Bevivino et al (2014) report that undisturbed soils have more stable bacterial communities throughout the change of seasons than do vineyards. This suggests that natural habitats are more resilient to environmental or human perturbations.…”

“…There is abundant evidence confirming the important role played by soil microorganisms in several ecosystem services such as erosion control, soil formation, nutrient cycling, and plant health (Tiedje et al, 1999; Nannipieri et al, 2003; Garbeva, van Veen & van Elsas, 2004; Gardi et al, 2009). However, soil microbial communities are not static and can change across agricultural practices and environmental gradients (Bevivino et al, 2014; García-Orenes et al, 2013). For instance, the addition of organic matter to managed soils increases fungal abundance and causes the microbial community structure to resemble that of undisturbed forest soil (García-Orenes et al, 2013).…”

Detection of Clostridium perfringens in tsunami deposits after the Great East Japan Earthquake

“…Strong differences in class composition have reportedly been observed in soil sampled in different seasons: for instance, Bacilli and Actinobacteria dominate in spring (particularly, Bacilli in grass covered vineyards and cork‐oak forest, and Actinobacteria in managed meadow [MM] and hayland‐pasture rotation [PA]), whereas β ‐ Proteobacteria tend to dominate in autumn. Six of the seven identified classes ( β and γ ‐ Proteobacteria , Flavobacteria , Actinobacteria, and Bacilli ) have been recovered in both seasons, whereas Sphingobacteria have been recovered only in autumn . However, those researchers did not report increases/decreases in Colstridium numbers in that article.…”