Effects of soil water content, temperature and experimental nitrogen deposition on nitric oxide (NO) efflux from semiarid shrubland soil

Southern Californian urban shrublands are exposed to high nitrogen (N) deposition, which can potentially enhance soil nitric oxide (NO) efflux; however, environmental controls on NO emission are still uncertain. We conducted a laboratory experiment to evaluate the NO efflux response of chaparral soi...

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Bibliographic Details
Published in:Journal of arid environments 2015-06, Vol.117, p.67-74
Main Authors: Vourlitis, George L., DeFotis, Catherine, Kristan, William
Format: Article
Language:English
Subjects:
Anthropogenic nitrogen deposition
Arrhenius equation
Chaparral
Deposition
Efflux
Global change
Moisture
Moisture content
Nitric oxide
Nitrogen cycle
Semi-arid ecosystems
Soil (material)
Soil moisture
Southern California
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Summary:Southern Californian urban shrublands are exposed to high nitrogen (N) deposition, which can potentially enhance soil nitric oxide (NO) efflux; however, environmental controls on NO emission are still uncertain. We conducted a laboratory experiment to evaluate the NO efflux response of chaparral soil to variations in N availability, temperature and moisture. We hypothesized that NO efflux would increase with N addition, have an optimum response to soil moisture, and increase exponentially with temperature. Our results supported our hypotheses. Nitrogen addition caused a linear increase in NO efflux, primarily because of an increase in NH4+. NO efflux reached a peak at intermediate soil moisture (25% water-filled pore space (WFPS)), and the temperature response of NO flux was well-described by the Arrhenius model. However, there were statistically significant interactions between N, temperature and soil water content, making the NO response complex. Our results suggest that southern California urban shrublands may be important sources of NO, and that chronic, high levels of anthropogenic N deposition will enhance NO efflux from these ecosystems. •NO efflux from chaparral soils increases with experimental N addition.•NO efflux from chaparral soils reaches a maximum in intermediate soil moistures.•NO efflux from chaparral soils increases exponentially as a function of temperature.•Interactions between N input and soil moisture and temperature on NO efflux are complex.•Chaparral ecosystems exposed to high levels of N deposition are important sources of NO.
ISSN:0140-1963
1095-922X
DOI:10.1016/j.jaridenv.2015.02.011