Tropical pasture and forest soil (15cm depth) before an after incubation - 16S rRNA Targeted loci environmental
Article title: Adaptation and resistance of soil prokaryotic communities to drought intensification in old-growth forests and pastures of southwestern Amazonia. Climate change is predicted to intensify droughts in tropical regions. However, the extent to which drought intensification and the subsequent changes in root exudate (RE) composition alters the structure of the soil prokaryotic community (SPC) remains poorly understood. We conducted a 69-day incubation experiment to determine the effects of severe drought and RE application on the SPC activity and structure in soils under primary forests and pastures from southwestern Amazonia. At the beginning of each cycle, half of the incubation units received artificial RE solution (+RE), while the other half received sterile water (+H2O). After each drying period, half of the units were kept at 30% water holding capacity (WHC) for 18 days, representing the regional WHC in the dry season (RD+RE and RD+H2O) in the study area. The other half were kept at 5% WHC, simulating severe drought (SD+RE and SD+H2O). At the end of the incubation, both, soil desiccation and RE availability modified the SPC composition and activity, while land-use exerted a secondary role. The lowest prokaryotic diversity values were observed in SD+RE at both land-uses. After wetting, higher SPC activity was observed in +RE treatments than in +H2O treatments due to the utilization of the supplemented RE. We concluded that the SPCs of both land-uses were well adapted to the regional drought. However, after severe droughts the SPCs significantly shifted towards being dominated by a few drought-resistant families, highlighting the vulnerability of tropical soils to changes in the precipitation patterns and their potential impact on ecosystem stability and soil functions.