关键词: 净初级生产力, CASA模型, 全球变化, 多年冻土退化, 东北多年冻土区

Abstract: 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·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.

Key words: NPP, CASA model, global change, permafrost degradation, permafrost zone of Northeast China.