Abstract:

Natural vegetation net primary productivity（NPP） may be one of the most sensitive ecological environment factors for climate change reaction, the study of climate change impact on NPP can provide theoretical basis for recovery, protection and sustainable development of the wetland. With daily meteorological data such as air temperature and rainfall received by grid interpolation method in Qixing river wetland from 1961 to 2008, based on Miami(R) model and mathematical analysis of climate change, the impacts of climate change on NPP of wetland natural vegetation were analyzed, the factors of climate change include air temperature, rainfall and the vegetation dry index, NPP include NPP地上and NPP总. The results showed that the average values of NPP总 and NPP地上were respectively 110.36 and 29.05 DMt/(hm2?a) and the NPP总 and NPP地上 were increasing in Qixing river wetland from 1961 to 2008, the average increasing rates were respectively 0.1291 and 0.0340 DMt/(hm2?a). The NPP of wetland natural vegetation was better positive correlative with the average yearly air temperature and the one during growing season, the best negative correlative with the yearly rainfall and the one during growing season, and the best positive correlative with the vegetation dry index during growing season. The NPP总 and NPP地上 of the wetland increased respectively 1.5220 and 0.4006 DMt/(hm2?a) when the average air temperature during growing season increased 1 ℃, the yearly rainfall increased 1 mm, and the vegetation dry index during growing season increased 1 ℃/mm. Because water resource was relatively adequate in Qixing river wetland, the NPP of Qixing river wetland natural vegetation increased under good climate conditions which included air temperature increased moderately, rainfall decreased slightly, and climate was relative dry, which were beneficial to form the seasonal waterlogged swamping wetland which could increase efficiency of vegetation photosynthesis. The average yearly value of the NPP总 was about 2.2072×106 t, the yearly carbon absorbed was 0.8829×106 t in Qixing river wetland from 1961 to 2008. Under the future condition of IPCC2000 discharge plan SRES-B2, which the carbin dioxide by the discharge is lower. The yearly NPP总 and carbon absorbed will be decreasing in the future, the decreased extents will be respectively 5.37%, 9.91% and 13.59% in 2020, 2050 and 2100 compared with the average values from 1961 to 2008.