Experimental warming increases respiration and affects microbial communities of soil wetlands from different elevations of the Argentinean Puna

CHIAPPERO M. FERNANDA; VAIERETTI, MARÍA VICTORIA; GALLARDO, NORMA; IZQUIERDO, ANDREA E.

Soil Ecology Letters

Elsevier

Año: 2024

Global warming is expected to increase soil carbon (C) efflux through enhanced soil microbial processes, mainly in systems storing large quantities of soil organic C, like high elevation wetlands. Here, we assessed the impact of experimental warming on respiration and microbial communities of high Andean wetland soils of the Puna region located at three different elevations (3793, 3862, 4206 m a.s.l.). We incubated soils at 10 °C and 25 °C for 68 days and measured the soil respiration rate and its temperature sensitivity (Q10). Furthermore, we measured biomass and composition and enzymatic activity of soil microbial communities, and initial and final soil C content. Although warming increased soil respiration rates -with more pronounced effect in soils from 4206 m a.s.l-, Q10 did not differ between elevations. Soil C content was higher at the highest elevation wetland. Soil microbial biomass was lower at warming treatment but not enzymatic activity. However, the biomass-specific respiration and biomass-specific enzymatic activity was higher under warming, and in soil from the highest elevation wetland. In the short-term, warming could stimulate resource allocation to respiration rather than microbial growth, probably related to a reduction in the microbial carbon use efficiency. Simultaneously, soils with higher soil C concentrations could release more CO2, despite the similar Q10 between wetlands. Overall, the soil of these high Andean wetlands could become C sources instead of C sinks in view of forecasted increasing temperatures, with C-losses at regional scale.