桂西南净生态系统生产力时空变化及其影响因素

Temporal and Spatial Variation of Net Ecosystem Productivity and Its Influencing Factors in Southwest Guangxi

净生态系统生产力(NEP)是估算生态系统碳源/汇的重要指标,分析NEP时空变化特征及其对气候因子之间的响应,对科学评估区域生态系统的固碳能力及应对气候变化具有重要意义。以桂西南作为研究对象,基于遥感数据、土地利用数据、气象数据、DEM数据等数据,运用趋势分析、相关分析和残差分析等方法研究了桂西南地区NEP时空分布特征,并探讨了不同气候因子对NEP的影响。结果表明:(1)2000-2018年研究区NEP的均值变化趋势均呈增长趋势,NEP年增长率为2.0384 g·m^(-2)·a^(-1),非喀斯特地区的NEP增长速率为2.7428 g·m^(-2)·a^(-1),而喀斯特地区NEP增长速率为0.6817 g·m^(-2)·a^(-1)。(2)19年来研究区NEP总体在空间呈现西北高,东南低的分布格局。NEP呈极显著增加的区域(15.39%)大于呈极显著减少区域(8.13%),说明研究区整体上生态系统的碳汇能力呈现出增强趋势。(3)研究区NEP与气温和降水均呈现出正相关关系,但NEP与降水的相关系数(0.0904)强于与气温的相关系数(0.0455)。(4)研究区内人类活动对NEP正负影响的贡献率分别是50.24%和49.76%。

Net ecosystem productivity(NEP)is an important index to estimate ecosystem carbon source/sink.Analyzing the spatial and temporal variation characteristics of NEP and its response to climate factors is of great significance to scientifically evaluate the carbon sequestration capacity of regional ecosystem and deal with climate change.Based on remote sensing data,land use data,meteorological data and DEM data,this paper studied the temporal and spatial distribution characteristics of NEP in Southwest Guangxi by using the methods of trend analysis,correlation analysis and residual analysis,and discussed the impact of different climate factors on NEP.The results showed that:(1)The mean value of NEP in the study area had been increasing from 2000 to 2018,with an annual growth rate of 2.0384 g·m^(-2)·a^(-1) in southwest Guangxi,2.7428 g·m^(-2)·a^(-1) in non-karst areas,and 0.6817 g·m^(-2)·a^(-1) in karst areas.(2)In the past 19 years,NEP in the study area had a spatial distribution pattern of high in the northwest and low in the southeast.The area with a very significant increase in NEP(15.39%)was greater than the area with a significant decrease(8.13%),indicating that the carbon sink capacity of the ecosystem in the study area as a whole showed an increasing trend.(3)There was a positive correlation between NEP and temperature and precipitation in study area,but the correlation coefficient between NEP and precipitation(0.0904)was stronger than that with temperature(0.0455).(4)The contribution rates of human activities to the positive and negative effects of NEP in the study area were 50.24%and 49.76%respectively.