近50年气候变化对七星河湿地生态系统自然植被第一性净生产力的影响

Impact of Climate Change on Natural Vegetation Net Primary Productivity in Qixing River Wetland Ecosystem from 1961-2008

自然植被第一性净生产力(Net primary productivity,NPP)可能是对气候变化反应最为敏感的生态环境因素之一,研究气候变化对NPP的影响可为湿地资源的恢复与保护及可持续发展提供理论依据。本研究利用1961—2008年网格插值的七星河湿地逐日气温、降水量资料,采用Miam(iR)模型计算植被NPP(NPP地上与NPP总),并分析气温、降水量、植被干燥指数等对湿地自然植被NPP的影响。结果表明,七星河湿地NPP总与NPP地上的平均值分别为110.36和29.05DMt/(hm2·a),近50年来湿地NPP总与NPP地上总体上呈增长趋势,年平均上升幅度分别为0.1291和0.0340DMt/(hm2·a)。湿地自然植被NPP与年平均气温、年生长季平均气温呈较显著正相关,与年降水量、生长季降水量呈极显著负相关,与生长季植被干燥指数呈极显著正相关;当湿地生长季平均气温每升高1℃、湿地年降水量每增加1mm、湿地植被生长季的干燥指数每增加1℃/mm,NPP总和NPP地上分别增加了1.5220和0.4006DMt/(hm2·a)。在水资源较充足的七星河湿地,气温适度升高、降水量略呈减少、气候相对较干燥(水热条件配合较好)的气候条件有利于形成季节性积水的沼泽化湿地,提高植被光合作用率,促进七星河湿地自然植被NPP的增加。近50年的七星河湿地年平均自然植被NPP总约为2.2072×106t;年平均固碳量为0.8829×106t。在未来IPCC2000年排放方案SRES-B2(较低排放)情景下,未来七星河湿地自然植被NPP总和固碳量呈下降趋势,与近50年平均值相比,2020、2050和2100年下降幅度分别为5.37%、9.91%和13.59%。

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/（hm 2 ·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/（hm 2 ·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/（hm 2 ·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 2.2072×10 6 t, the yearly carbon absorbed was 0.8829×10 6 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.