Journal
SOIL BIOLOGY & BIOCHEMISTRY
Volume 135, Issue -, Pages 184-193Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.soilbio.2019.04.020
Keywords
Microbial biomass C; Soil enzymes; Nematodes; Carbon cycle; Nitrogen cycle; Phosphorus cycle
Categories
Funding
- German Research Foundation (DFG) [TH 2307/1-1]
- German Centre for Integrative Biodiversity Research Halle-Jena-Leipzig - German Research Foundation [FZT 118]
- NSF Long-Term Ecological Research grants [DEB-0620652, DEB-1234162]
- Long-Term Research in Environmental Biology grant [DEB-1242531]
- Ecosystem Sciences grant [DEB-1120064]
- U.S. Department of Energy Programs for Ecosystem Research grant [DE-FG02-96ER62291]
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Ecological communities are increasingly confronted with multiple global change factors, which can have wide-ranging consequences for ecosystem structure and functions. Yet, we lack studies on the interacting effects of multiple global change factors on ecological communities - particularly long-term studies in field settings. Here, using a grassland field experiment in temperate North America, we report the interactive effects of four of the most common and pressing global change factors of the Anthropocene (elevated CO2, elevated nitrogen, warming, and summer drought) on soil microbial and free-living soil nematode communities, which together form an extensive share of terrestrial biodiversity. In addition, we measured microbial mass-specific soil enzyme activities related to carbon, nitrogen, and phosphorus cycles. Our results showed that mass-specific soil enzyme activities and their stoichiometry were strongly affected by higher-order interactions among the global change factors. In particular, the three-way interaction among elevated CO2, reduced precipitation, and warming decreased the ratio of carbon-to phosphorus-acquiring enzymes as well as nitrogen-to phosphorus-acquiring enzymes in the soil, indicating a relative increase in the breakdown of organic phosphorus in the soil. We also found that the three-way interaction among elevated CO2, reduced precipitation, and warming altered the predominant decomposition pathway in the soil (towards a bacterial-dominated energy channel in future environments), indicated by the Channel Index of nematode communities. Further, the three-way interaction among nitrogen fertilization, reduced precipitation, and warming enhanced acid phosphatase (related to the P cycle). Nematode density increased at elevated nitrogen and ambient CO2 as well as at ambient nitrogen and elevated CO2, whereas it did not differ from controls at elevated nitrogen and elevated CO2. Changes in microbial biomass were mainly driven by the additive effects of elevated CO2 and temperature. Our results reveal various ways in which global change factors affect (both additively and interactively) soil biotic responses mainly via altering nutrient demands of soil microorganisms and changing soil community structure and energy channels.
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