气候变化背景下人类活动对承德接坝区植被净初级生产力的影响

承德接坝区位于农牧过渡区，对气候变化和人类活动极为敏感.以植被净初级生产力(NPP)作为评价指标，基于Thornthwaite Memorial模型计算潜在NPP和MODIS NPP遥感影像获取实际NPP数据，利用潜在NPP与实际NPP间的差值衡量人类活动作用下NPP的大小，运用Slope趋势和变异系数法分析实际NPP、潜在NPP和人类活动作用下NPP的变化趋势及稳定性分布，并采用相关系数法分析实际NPP与年降水量和年均气温间的相关性，最终量化气候变化和人类活动对该区域植被变化的影响.结果表明，潜在NPP自西北向东南递增，其变化趋势和稳定性均为自西向东递增.实际NPP与年降水量和年均气温呈正相关区域面积占比分别是99.87%和91.66%.该区域99.85%的植被得到改善且变化稳定，主要是由气候因素和人类活动共同主导(99.71%),而植被退化完全是由人为因素所导致(0.15%).

Impacts of Human Activities on the Net Primary Productivity of Vegetation in Chengde's Transitional Region from Plateau to Plain in the Context of Climate Change

Chengde''s transitional region from plateau to plain is located in the transition zone of agriculture and livestock and is extremely sensitive to climate change and human activities. This study used the net primary productivity(NPP) of vegetation as an evaluation index to quantify the degree impacts of climate change and human activities on vegetation change in the region. The Thornthwaite Memorial model was used to calculate the potential NPP, and the actual NPP was obtained based on MODIS NPP remote sensing images, using the difference between the actual and potential NPPs to express the amount of change in NPP owing to human activities. We used the slope trend and coefficient of variation method to analyze the trend and stability distribution of the actual NPP, potential NPP, and NPP influenced by human activities, and the correlation between actual NPP and annual precipitation and annual average temperature was analyzed using the correlation coefficient method. Finally, we quantified the impact of climate change and human activities on vegetation change in the region. The results showed that 99.87% of the vegetation in the region was improved and changed steadily, and the proportions of the areas showing positive correlation between actual NPP and annual precipitation and annual average temperature were 99.87% and 91.66%, respectively. The potential NPP showed an increasing trend from northwest to southeast, whereas the trend and stability of the potential NPP both showed an increasing trend from west to east. The area where climate change and human activities played a role in vegetation improvement accounted for 99.71%, and that affected by climate change accounted for 0.14%, with the proportion of human activities leading to vegetation degradation being 0.15%.