Soil aggregate-mediated microbial responses to long-term warming
Abstract
Soil microbial carbon use efficiency (CUE) is a combination of growth and respiration, which may respond differently to climate change depending on physical protection of soil carbon (C) and its availability to microbes. In a mid-latitude hardwood forest in central Massachusetts, 27 years of soil warming (+5 °C) has resulted in C loss and altered soil organic matter (SOM) quality, yet the underlying mechanisms remain unclear. Here, we hypothesized that long-term warming reduces physical aggregate protection of SOM, microbial CUE, and its temperature sensitivity. Soil was separated into macroaggregate (250–2000 μm) and microaggregate (<250 μm) fractions, and CUE was measured with 18O enriched water (H218O) in samples incubated at 15 and 25 °C for 24 h. We found that long-term warming reduced soil C and nitrogen concentrations and extracellular enzyme activity in macroaggregates, but did not affect physical protection of SOM. Long-term warming showed little effect on CUE or microbial biomass turnover time because it reduced both growth and respiration. However, CUE was less temperature sensitive in macroaggregates from the warmed compared to the control plots. Our findings suggest that microbial thermal responses to long-term warming occur mostly in soil compartments where SOM is less physically protected and thus more vulnerable to microbial degradation.
Department
Soil Biogeochemistry and Microbial Ecology
Publication Date
11-11-2020
Journal Title
Soil Biology and Biochemistry
Publisher
Elsevier
Digital Object Identifier (DOI)
Document Type
Article
Recommended Citation
Xiao Jun Allen Liu, Grace Pold, Luiz A. Domeignoz-Horta, Kevin M. Geyer, Hannah Caris, Hannah Nicolson, Kenneth M. Kemner, Serita D. Frey, Jerry M. Melillo, Kristen M. DeAngelis, Soil aggregate-mediated microbial responses to long-term warming, Soil Biology and Biochemistry, Volume 152, 2021, 108055, ISSN 0038-0717, https://doi.org/10.1016/j.soilbio.2020.108055.