Vegetation net primary productivity （NPP） is an important variable reflecting the growth status of vegetation and an important indicator characterizing the carbon sequestration capacity of vegetation. Based on multi-source data such as MODIS NPP and climatic topography from 2002 to 2020， the spatial and temporal variations of vegetation carbon sequestration capacity in the Beijing-Tianjin-Hebei Region and its influencing factors were investigated at the county scale and image metric scale by using the methods of trend analysis， spatial analysis， Hurst index， optimal parameter geodetector， and bias correlation. The results showed that： ① The vegetation carbon sequestration capacity in the Beijing-Tianjin-Hebei Region showed a fluctuating increasing trend from 2002 to 2020， with an average annual increase of 4.316 6 g·（m2·a）-1. A total of 64.77% of the highly significant increasing areas were located in the northwestern and northeastern parts of the region （Zhangjiakou City and Chengde City）， while 3.61% of the decreasing areas were sporadically located in Qian'an， Fengnan， Caofeidian， Changli， Huanghua， Wuan， Yongnian， Daming， and other counties and districts. ② Spatially， the vegetation carbon sequestration capacity showed a stepwise distribution pattern of "low-high-low" from northwest to southeast， with a high mean value in the northeast， low mean values in the northwest and southeast， and large spatial differences. The overall spatial distribution of the Hurst index showed a decreasing trend from the southeast to the northwest， which indicates that the development of the vegetation carbon sequestration capacity of the southeast of the Beijing-Tianjin-Hebei Region was more stable than that of the northwest in the future， and the study area was more stable than in the northwest. This indicates that the future development of vegetation carbon sequestration capacity in the southeast of the Beijing-Tianjin-Hebei Region is more stable than that in the northwest， and that the future vegetation carbon sequestration capacity in the study area is generally on a slow increase. ③ Mean annual temperature， landform type， and rock type were the main factors influencing the changes of vegetation carbon sequestration capacity， and there was an interactive enhancement effect on the changes of vegetation carbon sequestration capacity among different influencing factors. Both mean annual air temperature and evapotranspiration （ET） contributed to the C sequestration capacity of vegetation， but the response of C sequestration capacity of vegetation to air temperature and ET varied significantly in different regions. The results of this study can help to improve the characteristics of vegetation C sequestration capacity and its driving mechanism in the Beijing-Tianjin-Hebei Region and can also provide a reference for the formulation of C sequestration and emission reduction policies in the region.
Keywords: Beijing-Tianjin-Hebei; influencing factors; net primary productivity （NPP）; optimal parameter geodetector （OPGD）; spatial and temporal variability; vegetation carbon sequestration.