TY - JOUR

T1 - Microbial physiology and soil CO2 efflux after 9 years of soil warming in a temperate forest - no indications for thermal adaptations

AU - Schindlbacher, Andreas

AU - Schnecker, Jörg

AU - Takriti, Mounir

AU - Borken, Werner

AU - Wanek, Wolfgang

PY - 2015/11

Y1 - 2015/11

N2 - Thermal adaptations of soil microorganisms could mitigate or facilitate global warming effects on soil organic matter (SOM) decomposition and soil CO2 efflux. We incubated soil from warmed and control subplots of a forest soil warming experiment to assess if 9 years of soil warming affected the rates and the temperature sensitivity of the soil CO2 efflux, extracellular enzyme activities, microbial efficiency and gross N mineralization. Mineral soil (0-10 cm depth) was incubated at temperatures ranging from 3 - 23 °C. No adaptations to long-term warming were observed regarding the heterotrophic soil CO2 efflux (R10 warmed: 2.31 ± 0.15 μmol m(-2) s(-1) , control: 2.34 ± 0.29 μmol m(-2) s(-1) ; Q10 warmed: 2.45 ± 0.06, control: 2.45 ± 0.04). Potential enzyme activities increased with incubation temperature but the temperature sensitivity of the enzymes did not differ between the warmed and the control soil. The ratio of C:N acquiring enzyme activities was significantly higher in the warmed soil. Microbial biomass specific respiration rates increased with incubation temperature, but the rates and the temperature sensitivity (Q10 warmed: 2.54 ± 0.23, control 2.75 ±0.17) did not differ between warmed and control soil. Microbial substrate use efficiency (SUE) declined with increasing incubation temperature in both, warmed and control soil. SUE and its temperature sensitivity (Q10 warmed: 0.84 ± 0.03, control: 0.88 ± 0.01) did not differ between warmed and control soil either. Gross N mineralization was invariant to incubation temperature and was not affected by long-term soil warming. Our results indicate that thermal adaptations of the microbial decomposer community are unlikely to occur in C-rich calcareous temperate forest soils. This article is protected by copyright. All rights reserved.

AB - Thermal adaptations of soil microorganisms could mitigate or facilitate global warming effects on soil organic matter (SOM) decomposition and soil CO2 efflux. We incubated soil from warmed and control subplots of a forest soil warming experiment to assess if 9 years of soil warming affected the rates and the temperature sensitivity of the soil CO2 efflux, extracellular enzyme activities, microbial efficiency and gross N mineralization. Mineral soil (0-10 cm depth) was incubated at temperatures ranging from 3 - 23 °C. No adaptations to long-term warming were observed regarding the heterotrophic soil CO2 efflux (R10 warmed: 2.31 ± 0.15 μmol m(-2) s(-1) , control: 2.34 ± 0.29 μmol m(-2) s(-1) ; Q10 warmed: 2.45 ± 0.06, control: 2.45 ± 0.04). Potential enzyme activities increased with incubation temperature but the temperature sensitivity of the enzymes did not differ between the warmed and the control soil. The ratio of C:N acquiring enzyme activities was significantly higher in the warmed soil. Microbial biomass specific respiration rates increased with incubation temperature, but the rates and the temperature sensitivity (Q10 warmed: 2.54 ± 0.23, control 2.75 ±0.17) did not differ between warmed and control soil. Microbial substrate use efficiency (SUE) declined with increasing incubation temperature in both, warmed and control soil. SUE and its temperature sensitivity (Q10 warmed: 0.84 ± 0.03, control: 0.88 ± 0.01) did not differ between warmed and control soil either. Gross N mineralization was invariant to incubation temperature and was not affected by long-term soil warming. Our results indicate that thermal adaptations of the microbial decomposer community are unlikely to occur in C-rich calcareous temperate forest soils. This article is protected by copyright. All rights reserved.

KW - Enzyme activities

KW - Gross N mineralization

KW - Soil CO2 efflux

KW - Soil warming

KW - Substrate use efficiency

KW - Thermal adaptation

U2 - 10.1111/gcb.12996

DO - 10.1111/gcb.12996

M3 - Journal article

C2 - 26046333

VL - 21

SP - 4265

EP - 4277

JO - Global Change Biology

JF - Global Change Biology

SN - 1354-1013

IS - 11

ER -