Precipitation frequency controls interannual variation of soil respiration by affecting soil moisture in a subtropical forest plantation

Abstract

Despite the significance of interannual variation of soil respiration (R S ) for understanding long-term soil carbon dynamics, factors that control the interannual variation of R S have not been sufficiently investigated. Interannual variation of R S was studied using a 6-year data set collected in a subtropical plantation dominated by an exotic species, slash pine (Pinus elliottii Engelm.), in China. The results showed that seasonal variation of R S was significantly affected by soil temperature and soil water content (SWC). R S in the dry season (July–October) was constrained by seasonal drought. Mean annual R S was estimated to be 736 ± 30 g C·m –2 ·year –1 , with a range of 706–790 g C·m –2 ·year –1 . Although this forest was characterized by a humid climate with high precipitation (1469 mm·year –1 ), the interannual variation of R S was attributed to the changes of annual mean SWC (R 2 = 0.66, P = 0.03), which was affected by annual rainfall frequency (R 2 = 0.80, P < 0.01) and not rainfall amount (P = 0.84). Consequently, precipitation pattern indirectly controlled the interannual variation of R S by affecting soil moisture in this subtropical forest. In the context of climate change, interannual variation of R S in subtropical ecosystems is expected to increase because of the predicted changes of precipitation regime.