Soil Bacterial Community Responds to Land-Use Change in Riparian Ecosystems

Abstract

Riparian forests were frequently cleared and converted to agricultural pastures, but in recent times these pastures are often revegetated in an effort to return riparian forest structure and function. We tested if there is a change in the soil bacterial taxonomy and function in areas of riparian forest cleared for agricultural pasture then revegetated, and if soil bacterial taxonomy and function is related to vegetation and soil physicochemical properties. The study was conducted in six riparian areas in south-eastern Australia, each comprising of three land-use types: remnant riparian forest, cleared forest converted to pasture, and revegetated pastures. We surveyed three strata of vegetation and sampled surface soil and subsoil to characterize physicochemical properties. Taxonomic and functional composition of soil bacterial communities were assessed using 16S rRNA gene sequences and community level physiological profiles, respectively. Few soil physiochemical properties differed with land use despite distinct vegetation in pasture relative to remnant and revegetated areas. Overall bacterial taxonomic and functional composition of remnant forest and revegetated soils were distinct from pasture soil. Land-use differences were not consistent for all bacterial phyla, as Acidobacteria were more abundant in remnant soils; conversely, Actinobacteria were more abundant in pasture soils. Overall, bacterial metabolic activity and soil carbon and nitrogen content decreased with soil depth, while bacterial metabolic diversity and evenness increased with soil depth. Soil bacterial taxonomic composition was related to soil texture and soil fertility, but functional composition was only related to soil texture. Our results suggest that the conversion of riparian forests to pasture is associated with significant changes in the soil bacterial community, and that revegetation contributes to reversing such changes. Nevertheless, the observed changes in bacterial community composition (taxonomic and functional) were not directly related to changes in vegetation but were more closely related to soil attributes.

Riparian fungal communities respond to land-use mediated changes in soil properties and vegetation structure

“…Dimensions for variables with eigenvalues ≥ 1 that cumulatively explained 80% or more of the variation were used in the RDA that was used to assess the relationship between environmental properties and soil fungal taxonomic and functional composition. This approach was used by Waymouth et al (2021) where variables included in the RDA are dimensions from the PCA and were fitted using the envfit function in vegan package (Oksanen 2015). Vegetation factors were duplicated for both soil depths.…”

“…Vegetation surveys were conducted as described in Waymouth et al (2021). Briefly, one 25 m × 25 m quadrat (625 m 2 ) was located within each land-use type, at each of the six study sites for sampling of vegetation and soils.…”

“…Soils were sampled from within each quadrat according to protocols established by the Biomes of Australian Soil Environments (BASE; Bissett et al 2016). Soil was sampled as per Waymouth et al (2021). Briefly, each soil sample was a composite of 27 cores, taken from nine locations (3 cores per location) that were evenly spaced along two diagonal transects that dissected each quadrat.…”

“…Pasture had significantly different vegetation properties relative to restored and remnant land-use types (PERMANOVA P < 0.01; Online Resource 6). More details about differences with land use in both vegetation and soil physicochemical properties can be found in Waymouth et al (2021).…”

Alteração da biodiversidade microbiana do solo devido ao cultivo agrícola: uma revisão

“…Outros fatores importantes são a abundância, a composição e a atividade da comunidade bacteriana pois podem ser fundamentais na melhoria das propriedades do solo e aumentar o das plantas após a mudança no uso da terra. Conhecer essa relação entra as bactérias presentes no solo e a cultura implantada no solo durante a conversão de terras nativas em agrícolas é essencial para aumentar o sucesso e a relação custo-benefício da produção ou na conversão de terras agrícolas em terras nativas no sucesso da revegetação (Waymouth et. al., 2021).…”