Warming-induced enhancement of soil N sub(2)O efflux linked to distinct response times of genes driving N sub(2)O production and consumption

• Published in: Biogeochemistry 2014-06, Vol.119 (1-3), p.371-386
• Main Authors: Billings, SA, Tiemann, L K
• Format: Article
• Language: English
• ISSN: 0168-2563; 1573-515X
• DOI: 10.1007/s10533-014-9973-2

Temperature responses of denitrifying microbes likely play a governing role in the production and consumption of N sub(2)O. We investigated temperature effects on denitrifier communities and their potential to produce N sub(2)O and N sub(2) by incubating grassland soils collected in multiple seasons at four temperatures with super(15)N-enriched NO sub(3) super(-) for ~24 h. We quantified [N sub(2)O] concentration across time, estimated its production and reduction to N sub(2), and quantified relative abundance of genes responsible for N sub(2)O production (cnorB) and reduction (nosZ). In all seasons, net N sub(2)O production was positively linked to incubation temperature, with highest estimates of net and gross N sub(2)O production in late spring soils. N sub(2)O dynamics were tightly coupled to changes in denitrifier community structure, which occurred on both seasonal and incubation time scales. We observed increases in nosZ abundance with increasing incubation temperature after 24 h, and relatively larger increases in cnorB abundance from winter to late June. The difference between incubation and in situ temperature was a robust predictor of cnorB:nosZ. These data provide convincing evidence that short-term increases in temperature can induce remarkably rapid changes in community structure that increase the potential for reduction of N sub(2)O to N sub(2), and that seasonal adaptation of denitrifying communities is linked to seasonal changes in potential N sub(2)O production, with warmer seasons linked to large increases in N sub(2)O production potential. This work helps explain observations of high spatial and temporal variation in N sub(2)O effluxes, and highlights the importance of temperature as an influence on denitrification enzyme kinetics, denitrifier physiology and community adaptations, and associated N sub(2)O efflux and reduction.