Asociación entre la productividad primaria y la diferenciación de la composición microbiana del suelo entre bosques naturales y campos ganaderos a escala regional.

RIBERO, MARTIN NICOLÁS; LAMMEL, DANIEL; SCHIAFFINO, MARÍA ROMINA; RILLIG, MATTHIAS; FILLOY, JULIETA

Quilmes

Congreso; ISMElat 2023; 2023

International society of microbial ecology/Universidad de Quilmes

The Earth surface presents markedly modified landscapes, where patches of natural environments coexist immersed in a mosaic of human-influenced environments. The adjacency of structurally contrasting environments in the same landscape leads to biological communities that are close in space, but taxonomically distant.The composition of soil microbial communities is related to ecosystem characteristics, particularly plant diversity. Thus, in the agricultural-livestock frontier, we expect the taxonomic dissimilarity of soil bacterial communities between forests and cattle-fields to be greater when the reference forest has a higher plant diversity. Here we evaluated whether ecosystem diversity determines the dissimilarity of soil bacterial communities between natural forests and contiguous cattle-pastures.To conduct the study, we compiled databases of genomic analyses of soil bacterial communities (amplicon sequencing of the 16S rRNA gene) comparing South American native forest sites and extensive cattle ranching sites. Studies were obtained in eight landscapes, covering the Amazon (4 studies), Cerrado (1), Caatinga (2) and Pampa (1) regions. The regional actual evapotranspiration (AET) was taken as a proxy of net primary productivity (NPP), which is positively associated with plant diversity at large scales. In each region, taxonomic dissimilarity was calculated based on sequence variants (ASV) between forests and pastures (three replicas each). To evaluate the influence of AET on dissimilarity, a selection of linear models was made based on the Akaike criterion. The model with AET in second degree polynomial form proved to be the most informative. The model identified the Amazon region (warm-humid) and the Caatinga (warm-arid) as the regions where forests and pastures differ the most. The level of community differentiation between native and anthropogenic environments seems to be mediated by the NPP of the reference ecosystems. But, contrary to what we expected, dissimilarity reached its maximum in both high- and low- productive ecosystems. Therefore, our prediction is only true up to a threshold where, in arid ecosystems, the trend reverses, probably due to anthropogenic activities to subsidize the agroecosystem. In conclusion, the coexistence of natural and human-influenced environments leads to taxonomically distinct soil bacterial communities, with their dissimilarity influenced by ecosystem productivity, except in arid ecosystems where other factors may disrupt this relationship.