In this study, a field manipulative experiment was conducted with five simulated rain amount treatments (control, natural rain plus 25%, 50%, 75%, and 100% of multi-year mean precipitation) in a desert ecosystem in Northwest China, where the carbon cycle is extremely sensitive to the changes of rainfall amount and pattern. Photosynthesis and its temperature dependence in a desert shrub Nitraria tangutorum were investigated. The results are showed as follows. Rain addition treatments changed the magnitude of the photosynthetic acclimation to temperature in N.tangutorum. The apexes of the quadratic curves between photosynthesis rate and leaf surface air temperature shifted from about 29.31 ℃ in control plots to 28.87 ℃ and 28.57 ℃, in plots with 25% and 50% rain addition treatments, respectively. However, the apexes of the quadratic curves between photosynthesis rate and leaf surface air temperature shifted to 31.57 ℃ and 35.33 ℃ in plots with 75% and 100% rain addition treatments, respectively. The results will deepen our understanding of desert system carbon cycle.
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