Estimates of soil respiration and net primary production of three forests at different succession stages in South China

Abstract

Soil respiration (heterotropic and autotropic respiration, Rg) and aboveground litter fall carbon were measured at three forests at different succession (early, middle and advanced) stages in Dinghushan Biosphere Reserve, Southern China. It was found that the soil respiration increases exponentially with soil temperature at 5 cm depth (Ts) according to the relation Rg = a exp(bTs), and the more advanced forest community during succession has a higher value of a because of higher litter carbon input than the forests at early or middle succession stages. It was also found that the monthly soil respiration is linearly correlated with the aboveground litter carbon input of the previous month. Using measurements of aboveground litter and soil respiration, the net primary productions (NPPs) of three forests were estimated using nonlinear inversion. They are 475, 678 and 1148 g C m-2 yr-1 for the Masson pine forest (MPF), coniferous and broad-leaf mixed forest (MF) and subtropical monsoon evergreen broad-leaf forest (MEBF), respectively, in year 2003/2004, of which 54%, 37% and 62% are belowground NPP for those three respective forests if no change in live plant biomass is assumed. After taking account of the decrease in live plant biomass, we estimated the NPP of the subtropical MEBF is 970 g C m-2 yr-1 in year 2003/2004. Total amount of carbon allocated below ground for plant roots is 388 C m-2 yr-1 for the MPF, 504 g C m-2 yr-1 for the coniferous and broad-leaf MF and 1254 g C-2 yr-1 for the subtropical MEBF in 2003/2004. Our results support the hypothesis that the amount of carbon allocation belowground increases during forest succession. © 2006 Blackwell Publishing Ltd.