Land-use and forest floor explain prokaryotic metacommunity structuring and spatial turnover in Amazonian forest-to-pasture conversion areas

Abstract

Advancing extensive cattle production shifts the forest landscape and is considered one of the main drivers against biodiversity conservation in the Brazilian Amazonia. Considering soil as an ecosystem it becomes vital to identify the effects of land-use changes on soil microbial communities, structure, as well as its ecological functions and services. Herein, we explored relationships between land-use, soil types and forest floor (i.e., association between litter, root layer and bulk soil) on the prokaryotic metacommunity structuring in the Western Amazonia. Sites under high anthropogenic pressure were evaluated along a gradient of ± 800 km. Prokaryotic metacommunity are synergistically affected by soil types and land-use systems. Especially, the gradient of soil fertility and land-use shapes the structuring of the metacommunity and determines its composition. Forest-to-pasture conversion increases alpha, beta, and gamma diversities when considering only the prokaryotes from the bulk soil. Beta diversity was significantly higher in all forests when the litter and root layer were taken into account with the bulk soil. Our argumentation is that the forest floor harbors a prokaryotic metacommunity that adds at the regional scale of diversity a spatial turnover hitherto underestimated. Our findings highlight the risks of biodiversity loss and, consequently, the soil microbial diversity maintenance in tropical forests.

Biogeographic responses and niche occupancy of microbial communities following long-term land-use change

“…1) and consequent loss in pairwise beta diversities (Fig. 2), which is indicative of biotic homogenization (Rodrigues et al 2013;Maaß et al 2014;Rocha et al 2021). These results corroborate our previous study, in which we evaluated, through metagenomics, the patterns of microbial alpha and beta diversities in two out of six counties evaluated here (Goss-Souza et al 2017).…”

“…While generalists follow the Baas Becking theory of "everything is everywhere" (De Wit and Bouvier 2006), habitat specialists are the microorganisms that have restricted occupancy, as represented by their low occurrence across environmental and geographical gradients (Meyer et al 2018;Gao et al 2019;Ceola et al 2021). The competitive/cooperative interactions among microbial populations in a local community (Li et al 2018) and sets of metapopulations in metacommunity (Hovatter et al 2011;Rocha et al 2021) are very intricate (Leibold et al 2004) and land-use change can greatly alter the role of these interactions in microbial community assembly (Creamer et al 2016;Brinkmann et al 2019;Goss-Souza et al 2020). Some authors have found land-use change and management intensification in tropical soils, as selective abiotic filters, by increasing the competition among species for habitat and limiting resources, according to niche (Mendes et al 2014;Goss-Souza et al 2019).…”