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Abstract Ecosystem functional responses such as soil CO2emissions are constrained by microclimate, available carbon (C) substrates and their effects upon microbial activity. In tropical forests, phosphorus (P) is often considered as a limiting factor for plant growth, but it is still not clear whether P constrains microbial CO2emissions from soils. In this study, we incubated seven tropical forest soils from Brazil and Puerto Rico with different nutrient addition treatments (no addition, Control; C, nitrogen (N) or P addition only; and combined C, N and P addition (CNP)). Cumulative soil CO2emissions were fit with a Gompertz model to estimate potential maximum cumulative soil CO2emission (Cm) and the rate of change of soil C decomposition (k). Quantitative polymerase chain reaction (qPCR) was conducted to quantify microbial biomass as bacteria and fungi. Results showed that P addition alone or in combination with C and N enhancedCm, whereas N addition usually reducedCm, and neither N nor P affected microbial biomass. Additions of CNP enhancedk, increased microbial abundances and altered fungal to bacterial ratios towards higher fungal abundance. Additions of CNP, however, tended to reduceCmfor most soils when compared to C additions alone, suggesting that microbial growth associated with nutrient additions may have occurred at the expense of C decomposition. Overall, this study demonstrates that soil CO2emission is more limited by P than N in tropical forest soils and those effects were stronger in soils low in P. HighlightsA laboratory incubation study was conducted with nitrogen, phosphorus or carbon addition to tropical forest soils. Soil CO2emission was fitted with a Gompertz model and soil microbial abundance was quantified using qPCR. Phosphorus addition increased model parametersCmand soil CO2emission, particularly in the Puerto Rico soils. Soil CO2emission was more limited by phosphorus than nitrogen in tropical forest soils.
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Leafcutter ants enhance microbial drought resilience in tropical forest soil
Abstract We conducted a research campaign in a neotropical rainforest in Costa Rica throughout the drought phase of an El‐Nino Southern Oscillation event to determine microbial community dynamics and soil C fluxes. Our study included nests of the leafcutter antAtta cephalotes, as soil disturbances made by these ecosystem engineers may influence microbial drought response. Drought decreased the diversity of microbes and the abundance of core microbiome taxa, including Verrucomicrobial bacteria and Sordariomycete fungi. Despite initial responses of decreasing diversity and altered composition, 6 months post‐drought the microbiomes were similar to pre‐drought conditions, demonstrating the resilience of soil microbial communities to drought events.A. cephalotesnests altered fungal composition in the surrounding soil, and reduced both fungal mortality and growth of Acidobacteria post‐drought. Drought increased CH4consumption in soils due to lower soil moisture, andA. cephalotesnests decrease the variability of CH4emissions in some soil types. CH4emissions were tracked by the abundance of methanotrophic bacteria and fungal composition. These results characterize the microbiome of tropical soils across both time and space during drought and provide evidence for the importance of leafcutter ant nests in shaping soil microbiomes and enhancing microbial resilience during climatic perturbations.
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- Award ID(s):
- 2012878
- PAR ID:
- 10509141
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Environmental Microbiology Reports
- Volume:
- 16
- Issue:
- 3
- ISSN:
- 1758-2229
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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