扎龙湿地NPP时空格局及其对气候因子变化的响应

Spatio-temporal Evolution and Climate Effect of NPP in Zhalong Wetland

植被净初级生产力(NPP)是表征陆地生态系统对气候变化响应的重要指标,扎龙湿地是全球气候变化敏感区域湿地生态系统的典型代表,基于遥感资料和气候资料,借助GIS、RS技术和地理探测器方法,估算了2000-2017年扎龙湿地植被NPP时空分布特征,探索了植被NPP空间异质性及气候因素对其动态变化的影响,为研究气候变化背景下湿地碳循环的响应过程与驱动机制提供参考。结果表明,2000-2017年,扎龙湿地植被NPP年平均值为478.30 g·m^(-2)·a^(-1)(以C计,下同),其中有水草甸为483.33 g·m^(-2)·a^(-1),无水草甸为485.99 g·m^(-2)·a^(-1),农作物为448.70 g·m^(-2)·a^(-1),有水草甸和农作物的NPP年平均值均呈显著增加趋势。扎龙湿地核心区NPP年平均值最高,为513.75 g·m^(-2)·a^(-1);试验区NPP平均值最低,为422.80 g·m^(-2)·a^(-1)。水分因子对植被NPP的总体影响力大于温度因子,对水分的依赖程度由大到小排序依次为无水草甸、农作物、有水草甸,对温度的依赖程度由大到小排序依次为无水草甸、有水草甸、农作物。气候因子两两交互作用对自然植被NPP动态变化的总体影响显著大于农作物,其中4-10月EI和年平均气温的协同作用对无水草甸NPP动态变化的贡献率达37.85%,4-10月日较差和年平均气温的协同作用对有水草甸NPP动态变化的贡献率达31.14%,年平均气温和无霜期的协同作用对农作物NPP动态变化的贡献率达29.00%。

Net Primary Productivity(NPP)is an important indicator reflecting the response of terrestrial ecosystems to climate change.Zhalong Wetland is a typical representative of the wetland ecosystems which are sensitive to global climate change.So in this paper,Zhalong Wetland was chosen as the research area.And the analysis of its spatio-temporal pattern of NPP and response to the change of meteorological factors would provide references for studying the response process and driving mechanism of wetland carbon cycle under the background of climate change.Based on remote sensing and meteorological data,and by using Geo-Detector and platforms of GIS and RS,we estimated the spatio-temporal distribution characteristics of vegetation NPP and explored the spatial heterogeneity and the effect of meteorological factors on its dynamic evolution from 2000 to 2017.The results showed as follows.The annual average of vegetation NPP in Zhalong Wetland was 478.30 g·m^-2·a^-1(by C,the same below),which was 483.33 g·m^-2·a^-1 in watery meadow,485.99 g·m^-2·a^-1 in waterless meadow and 448.70 g·m^-2·a^-1 in crop.NPP of watery meadow and crop showed an increasing trend.The average value of NPP in the core area was the highest(513.75 g·m^-2·a^-1),and was the lowest in the test area(422.80 g·m^-2·a^-1).The whole influence of water factors on vegetation NPP was greater than that of temperature factors.The descending order of dependence on moisture was waterless meadow,crop and watery meadow,and that on temperature was waterless meadow,watery meadow and crop.The interaction effect of meteorological factors on dynamic change of natural vegetation NPP was significantly greater than that of crops.From April to October,the contribution rate of the synergistic effect of the EI and annual mean temperature on dynamic change of NPP in waterless meadow was 37.85%,while the contribution rate of diurnal temperature range and annual mean temperature on watery meadows was 31.14%and that of annual mean temperature and frost-free period on crop was 29.00%.