TY - JOUR

T1 - Long-term warming of a forest soil reduces microbial biomass and its carbon and nitrogen use efficiencies

AU - Tian, Ye

AU - Schindlbacher, Andreas

AU - Malo, Carolina Urbina

AU - Shi, Chupei

AU - Heinzle, Jakob

AU - Kwatcho Kengdo, Steve

AU - Inselsbacher, Erich

AU - Borken, Werner

AU - Wanek, Wolfgang

N1 - Funding Information: This study was funded by the Austrian Science Fund - FWF (project I 3745). We sincerely thank Christian Holtermann for field site maintenance, Margarete Watzka, Sabine Maringer, Sabrina Pober, and Ludwig Seidl for technical and material support, Shasha Zhang for experimental guidance, Tania L. Maxwell for her guidance in the data analysis, and Marilena Heitger for laboratory assistance. Moreover, we acknowledge the inspirational communications and warm support from people in the Terrestrial Ecosystem Research laboratories, University of Vienna.

PY - 2023/9

Y1 - 2023/9

N2 - Global warming impacts biogeochemical cycles in terrestrial ecosystems, but it is still unclear how the simultaneous cycling of carbon (C) and nitrogen (N) in soils could be affected in the longer-term. Here, we evaluated how 14 years of soil warming (+4 °C) affected the soil C and N cycle across different soil depths and seasons in a temperate mountain forest. We used H218O incorporation into DNA and 15N isotope pool dilution techniques to determine gross rates of C and N transformation processes. Our data showed different warming effects on soil C and N cycling, and these were consistent across soil depths and seasons. Warming decreased microbial biomass C (−22%), but at the same time increased microbial biomass-specific growth (+25%) and respiration (+39%), the potential activity of β-glucosidase (+31%), and microbial turnover (+14%). Warming reduced gross rates of protein depolymerization (−19%), but stimulated gross N mineralization (+63%) and the potential activities of N-acetylglucosaminidase (+106%) and leucine-aminopeptidase (+46%), and had no impact on gross nitrification (+1%). Microbial C and N use efficiencies were both lower in the warming treatment (−15% and −17%, respectively). Overall, our results suggest that long-term warming drives soil microbes to incorporate less C and N into their biomass (and necromass), and to release more inorganic C and N to the environment, causing lower soil C and N storage in this forest, as indicated by lower soil C and total N contents. The decreases in microbial CUE and NUE were likely triggered by increasing microbial P constraints in warmed soils, limiting anabolic processes and microbial growth and promoting pervasive losses of C and N from the soil.

AB - Global warming impacts biogeochemical cycles in terrestrial ecosystems, but it is still unclear how the simultaneous cycling of carbon (C) and nitrogen (N) in soils could be affected in the longer-term. Here, we evaluated how 14 years of soil warming (+4 °C) affected the soil C and N cycle across different soil depths and seasons in a temperate mountain forest. We used H218O incorporation into DNA and 15N isotope pool dilution techniques to determine gross rates of C and N transformation processes. Our data showed different warming effects on soil C and N cycling, and these were consistent across soil depths and seasons. Warming decreased microbial biomass C (−22%), but at the same time increased microbial biomass-specific growth (+25%) and respiration (+39%), the potential activity of β-glucosidase (+31%), and microbial turnover (+14%). Warming reduced gross rates of protein depolymerization (−19%), but stimulated gross N mineralization (+63%) and the potential activities of N-acetylglucosaminidase (+106%) and leucine-aminopeptidase (+46%), and had no impact on gross nitrification (+1%). Microbial C and N use efficiencies were both lower in the warming treatment (−15% and −17%, respectively). Overall, our results suggest that long-term warming drives soil microbes to incorporate less C and N into their biomass (and necromass), and to release more inorganic C and N to the environment, causing lower soil C and N storage in this forest, as indicated by lower soil C and total N contents. The decreases in microbial CUE and NUE were likely triggered by increasing microbial P constraints in warmed soils, limiting anabolic processes and microbial growth and promoting pervasive losses of C and N from the soil.

KW - isotope pool dilution

KW - microbial carbon use efficiency (CUE)

KW - microbial nitrogen use efficiency (NUE)

KW - soil carbon (C) cycling

KW - soil nitrogen (N) cycling

KW - Soil warming

UR - http://www.scopus.com/inward/record.url?scp=85163923656&partnerID=8YFLogxK

U2 - 10.1016/j.soilbio.2023.109109

DO - 10.1016/j.soilbio.2023.109109

M3 - Article

AN - SCOPUS:85163923656

VL - 184

JO - Soil Biology and Biochemistry

JF - Soil Biology and Biochemistry

SN - 0038-0717

M1 - 109109

ER -