Publication Date:
2014-09-05
Description:
Soil CO 2 flux is strongly influenced by precipitation in many ecosystem types, yet knowledge of the effects of precipitation on soil CO 2 flux in semi-arid desert ecosystems remains insufficient, particularly for sandy soils. To address this, we investigated the response of sandy soil CO 2 flux to rainfall pulses in a desert ecosystem in northern China during August–September, 2011. Significant changes ( P 〈 0.05) were found in diel patterns of soil CO 2 flux induced by small (2.1 mm), moderate (12.4 mm) and large (19.7 mm) precipitation events. Further analysis indicated that rainfall pulses modified the response of soil CO 2 flux to soil temperature, including hysteresis between soil CO 2 flux and soil temperature, with F s higher when T s was increasing than when T s was decreasing, and the linear relationship between them. Moreover, our results showed that rainfall could result in absorption of atmospheric CO 2 by soil, possibly owing to mass flow of CO 2 induced by a gradient of gas pressure between atmosphere and soil. After each precipitation event, soil CO 2 flux recovered exponentially to pre-rainfall levels with time, with the recovery times exhibiting a positive correlation with precipitation amount. Based on the amounts of precipitation that occurred at our site during the measurement period (August–September), the accumulated rain-induced carbon absorption evaluated for rainy days was 1.068 g C m -2 ; this corresponds approximately to 0.5–2.1% of the net primary production of a typical desert ecosystem. Thus, our results suggest that rainfall pulses can strongly influence carbon fluxes in desert ecosystems. This article is protected by copyright. All rights reserved.
Print ISSN:
0885-6087
Electronic ISSN:
1099-1085
Topics:
Architecture, Civil Engineering, Surveying
,
Geography
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