β Scribed by Jie Ma; Xin-Jun Zheng; Yan Li
No coin nor oath required. For personal study only.
As the substantial component of the ecosystem respiration, soil CO 2 flux is strongly influenced by infrequent and unpredictable precipitation in arid region. In the current study, we investigated the response of soil CO 2 flux to rain pulses at a saline desert in western China. Soil CO 2 flux was measured continuously during the whole growing season of 2009 at six sites. We found that there were remarkable changes in amplitude or diurnal patterns of soil CO 2 flux induced by rainfall events: from bimodal before rain to a single peak after that. Further analysis indicated that there is a significant linear relationship (P < 0.001) between soil CO 2 flux and soil temperature (T soil ). However, a hysteresis between the waveform of diurnal course of CO 2 flux and T soil was observed: with soil CO 2 flux always peaked earlier than T soil . Furthermore, a double exponential decay function was fitted to the soil CO 2 flux after rainfall, and total carbon (C) releases were estimated by numerical integration for rainfall events. The relative enhancement and total C release, in association with the rain pulses, was linearly related to the amount of precipitation. According to the size and frequency of rainfall events, the total amount of C release induced by rain pulses was computed as much as 7.88 g CΓm -2 in 2009, equivalent to 10.25% of gross primary production. These results indicated that rain pulses played a significant role in the carbon budget of this saline desert ecosystem, and the size of them was a good indicator of rain-induced flux enhancement.
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