Abstract:

Utilizing MODIS NPP and meteorological station data from 2001 to 2021, this study calculated the net ecosystem productivity (NEP) in the Hulunbuir region and analyzed the spatial and temporal distribution of NEP and its relationships with temperature and precipitation. The results show that the annual average NEP in the Hulunbuir is 249.4 gC·m^-2·a^-1, decreasing from the central and southern forests of the Greater Khingan Range to its flanks, with the western Hulunbuir grasslands having the lowest NEP and the highest coefficient of variation, indicating a relatively fragile ecological environment. The NEP in the Hulunbuir region has increased at an average rate of 4.5 gC·m^-2·a^-1, with rapid increases observed in the forest-agriculture transition zone east of the Greater Khingan Range and slower increases in the northern part of the Greater Khingan Range and southeastern Hulunbuir grasslands. The Hurst index analysis suggests that future trends in NEP across most of Hulunbuir will exhibit anti-persistence, which is not conducive to enhancing the region′s carbon sequestration capacity. The NEP in Hulunbuir′s grasslands, croplands, and forests at the southeastern foothills of the Greater Khingan Range shows a significant or highly significant positive correlation with precipitation during the growing season. The NEP in the grassland areas has a significant or highly significant negative correlation with temperatures during the growing season, while the post-fire areas in the Greater Khingan Range show a significant or highly significant positive correlation with temperatures during the growing season.

Key words: Carbon sequestration, Hurst index, Precipitation during the growing season, Temperature during the growing season