1982-2009年东北多年冻土区植被净初级生产力动态及其对全球变化的响应

东北多年冻土区作为高纬度寒区之一,对全球变化较敏感.本文基于AVHRR和MODIS两种遥感数据源的归一化植被指数,应用CASA模型对1982-2009年东北多年冻土区植被净初级生产力(NPP)进行模拟.结果表明:1982-2009年,东北多年冻土区年均气温、年太阳辐射总量和年日照时数显著上升,年降水量显著下降,CO2浓度及其年增长率显著增大;植被年NPP呈显著的先增加后降低趋势,变化分异节点在1998年.研究期间,东北多年冻土区植被年均NPP总量为623 g C·m-2,植被年NPP空间分布差异明显.降水是该区生长季植被生长的主要影响因子,植被NPP对气候变化响应的空间异质性明显.土地利用变化通过改变土地覆被状况使植被NPP发生变化,影响了植被NPP的时空分布特征,植被NPP与CO2浓度呈显著正相关.多年冻土退化对植被NPP的影响随着各区域环境的不同而有所差异.多年冻土区植被NPP与年均地温呈显著正相关,与年最大冻土深度呈负相关.

Dynamic changes of vegetation net primary productivity in permafrost zone of Northeast China in 1982-2009 in response to global change

As one of the high-latitude cold regions, the permafrost zone of Northeast China (PZNC) is more sensitive to global change. Based on the AVHRR GIMMS NDVI and MODIS NDVI, and by using CASA model, this paper simulated the net primary productivity (NPP) in the PZNC from 1982 to 2009. In 1982-2009, the mean annual air temperature, annual solar radiation and sunshine duration, and atmospheric CO2 concentration and its annual increasing rate in the PZNC increased significantly while the annual precipitation had a significant decrease, and the annual NPP showed an up-and-down trend, with the turning point in 1998. The annual NPP had a high spatial heterogeneity, with an average of 623 g C X m(-2). Comparing with air temperature, the precipitation in growth season was the main factor affecting the NPP. Land use change altered land cover, and thus, the spatiotemporal characteristics of NPP. A significant positive correlation was observed between the NPP and atmospheric CO2 concentration. The impact of permafrost degradation on NPP differed with regional environment. The NPP had a significant positive correlation with the mean annual ground temperature, but a negative correlation with the annual maximum permafrost depth.