Article ID Journal Published Year Pages File Type
4392860 Journal of Arid Environments 2015 8 Pages PDF
Abstract

•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.

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.

Related Topics
Physical Sciences and Engineering Earth and Planetary Sciences Earth-Surface Processes
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