Nitrifiers and denitrifiers respond rapidly to changed moisture and increasing temperature in a pristine forest soil

• Published in: FEMS microbiology ecology 2010-06, Vol.72 (3), p.395-406
• Main Authors: Szukics, Ute, Abell, Guy C.J, Hödl, Verania, Mitter, Birgit, Sessitsch, Angela, Hackl, Evelyn, Zechmeister-Boltenstern, Sophie
• Format: Article
• Language: English
• Subjects: Abundance; Ammonia; amoA; Anaerobic conditions; Animal, plant and microbial ecology; Archaea - genetics; Archaea - metabolism; Bacteria - genetics; Bacteria - metabolism; Biological and medical sciences; Climate change; Communities; Community structure; Denitrification; DNA, Archaeal - genetics; DNA, Bacterial - genetics; Ecology; Emissions; Extreme weather; Forest soils; Forestry; Forests; Fundamental and applied biological sciences. Psychology; General forest ecology; Generalities. Production, biomass. Quality of wood and forest products. General forest ecology; Microbial ecology; Microbiology; Microorganisms; Moisture content; N2O emission; nirK; NirK protein; Nitrates - analysis; Nitric Oxide - analysis; Nitrification; Nitrogen; Nitrogen - metabolism; Nitrous oxide; N₂O emission; Oxidizing agents; Polymorphism, Restriction Fragment Length; qPCR; Rainfall; Soil - analysis; Soil Microbiology; Soil moisture; Soil temperature; Soil water; Soils; Substrates; T-RFLP; Temperature; Temperature effects; Trees - microbiology; Water; Water content
• ISSN: 0168-6496; 1574-6941
• DOI: 10.1111/j.1574-6941.2010.00853.x

Complete cycling of mineral nitrogen (N) in soil requires the interplay of microorganisms performing nitrification and denitrification, whose activity is increasingly affected by extreme rainfall or heat brought about by climate change. In a pristine forest soil, a gradual increase in soil temperature from 5 to 25 °C in a range of water contents stimulated N turnover rates, and N gas emissions were determined by the soil water-filled pore space (WFPS). NO and N₂O emissions dominated at 30% WFPS and 55% WFPS, respectively, and the step-wise temperature increase resulted in a threefold increase in the NO₃⁻ concentrations and a decrease in the NH₄⁺ concentration. At 70% WFPS, NH₄⁺ accumulated while NO₃⁻ pools declined, indicating gaseous N loss. AmoA- and nirK-gene-based analysis revealed increasing abundance of bacterial ammonia oxidizers (AOB) with increasing soil temperature and a decrease in the abundance of archaeal ammonia oxidizers (AOA) in wet soil at 25 °C, suggesting the sensitivity of the latter to anaerobic conditions. Denitrifier (nirK) community structure was most affected by the water content and nirK gene abundance rapidly increased in response to wet conditions until the substrate (NO₃⁻) became limiting. Shifts in the community structure were most pronounced for nirK and most rapid for AOA, indicating dynamic populations, whereas distinct adaptation of the AOB communities required 5 weeks, suggesting higher stability.