title: Effects of warming and drought on potential N2O emissions and denitrifying bacteria abundance in grasslands with different land-use.
abstract: Increased warming in spring and prolonged summer drought may alter soil microbial denitrification. We measured potential denitrification activity and denitrifier marker gene abundances (nirK, nirS, nosZ) in grasslands soils in three geographic regions characterized by site-specific land-use indices (LUI) after warming in spring, at an intermediate sampling and after summer drought. Potential denitrification was significantly increased by warming, but did not persist over the intermediate sampling. At the intermediate sampling, the relevance of grassland land-use intensity was reflected by increased potential N2O production at sites with higher LUI. Abundances of total bacteria did not respond to experimental warming or drought treatments, displaying resilience to minor and short-term effects of climate change. In contrast, nirS- and nirK-type denitrifiers were more influenced by drought in combination with LUI and pH, while the nosZ abundance responded to the summer drought manipulation. Land-use was a strong driver for potential denitrification as grasslands with higher LUI also had greater potentials for N2O emissions. We conclude that both warming and drought affected the denitrifying communities and the potential denitrification in grassland soils. However, these effects are overruled by regional and site-specific differences in soil chemical and physical properties which are also related to grassland land-use intensity.
authors.affiliation: Institute of Soil Science and Land Evaluation, Soil Biology Section, University of Hohenheim, 70599 Stuttgart, Germany daniel_keil@gmx.net.
authors.forename: Daniel
authors.initials: D
authors.lastname: Keil
authors.affiliation: Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
authors.forename: Pascal A
authors.initials: PA
authors.lastname: Niklaus
authors.affiliation: Computational Landscape Ecology, Helmholtz-Centre for Environmental Research, Permoser Str. 15, 04318 Leipzig, Germany Department of Biometry and Environmental System Analysis, University of Freiburg, 79106 Freiburg, Germany.
authors.forename: Lars R
authors.initials: LR
authors.lastname: von Riedmatten
authors.affiliation: Institute of Soil Science and Land Evaluation, Soil Biology Section, University of Hohenheim, 70599 Stuttgart, Germany.
authors.forename: Runa S
authors.initials: RS
authors.lastname: Boeddinghaus
authors.affiliation: Department of Biometry and Environmental System Analysis, University of Freiburg, 79106 Freiburg, Germany.
authors.forename: Carsten F
authors.initials: CF
authors.lastname: Dormann
authors.affiliation: Faculty of Biology/Geobotany, University of Freiburg, 79106 Freiburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Scherer-Lorenzen
authors.affiliation: Institute of Soil Science and Land Evaluation, Soil Biology Section, University of Hohenheim, 70599 Stuttgart, Germany.
authors.forename: Ellen
authors.initials: E
authors.lastname: Kandeler
authors.affiliation: Institute of Soil Science and Land Evaluation, Soil Biology Section, University of Hohenheim, 70599 Stuttgart, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Marhan
mesh_terms: D001419:Bacteria / Q000235:genetics; D057231:Climate Change; D058440:Denitrification / Q000235:genetics; D055864:Droughts; D005798:Genes, Bacterial; D065948:Grassland; D059013:Microbial Consortia / Q000502:physiology*; D009569:Nitric Oxide / Q000096:biosynthesis; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology
chemical_list: D012336:RNA, Ribosomal, 16S; D012987:Soil; D009569:Nitric Oxide
keywords: Biodiversity Exploratories; climate change; denitrification; grassland; land-use index; microbial community; potential N2O emissions