京津冀地区水源涵养价值流动分析及生态补偿额度

科学测算生态补偿额度是推进生态补偿落实、实现区际经济与生态保护协调发展的重要基础。以京津冀为研究区，应用InVEST模型及影子工程法定量测算2005年、2010年和2018年的区域水源涵养服务价值量，利用生态系统服务供需比识别水源涵养价值输出区，运用断裂点公式和场强模型分析价值流动的时空特征，并基于价值转移量和地理探测器探测的主导因子构建水源涵养生态补偿模型，计算了京津冀各县（区）的水源涵养服务补偿额度。结果表明：（1）2005年、2010年和2018年京津冀地区水源涵养服务价值分别为19.4×10⁸元、40.2×10⁸元和47.8×10⁸元，林地对水源涵养价值增加起着至关重要的作用。（2）各流域内水源涵养服务价值输出区主要分布在太行山脉、燕山山脉和坝上高原地区，且输出区数量呈增加态势。（3）2005年、2010年和2018年各流域水源涵养流入到消费区的价值的高值区变化较大，主要发生在滦河山区、北三河山区、大清河山区和永定河册田水库至三家店区4个流域内，低值区的分布则变化较小；但受森林覆盖率、水系以及地形的影响，水源涵养服务价值转移量总体呈增加趋势。（4）基于水源涵养生态补偿模型，得到京、津、冀三地支付金额比例为2.04：1.61：1，各县（区）需支付补偿金额在0-340.95万元；而京、津、冀三地受偿金额比例为1：0：1.87，各输出区的受偿金额则在0-545.75万元之间。

Assessing payment for ecosystem services based on water retention value flow in Beijing-Tianjin-Hebei region

Scientific measurement of the payment for ecosystem services was an important basis for promoting the implementation of payment for ecosystem services and realizing the coordinated development between regional economy and ecological conservation. The values of water retention services in 2005, 2010 and 2018 were estimated by the InVEST model and shadow project approach in Beijing-Tianjin-Hebei region. Given the differences in value, the output area of water retention value was determined by using the ratio method of ecosystem services supply and demand. The temporal and spatial characteristics of value flow were also analyzed by the breakpoint formula and field strength model. Based on the value transfer amount and the dominant factors defined by the geographical detectors, the payment for ecosystem services model for water retention was constructed to calculate the payment of water retention services in each county of this area. The results showed that:(1) the value of water retention services in 2005, 2010 and 2018 in Beijing-Tianjin-Hebei region was 1.94, 4.02, and 4.78 billion yuan (RMB), respectively, in which forest ecosystem played a key role. (2) The output areas for water retention value in each basin were mainly distributed in the Taihang Mountains, Yanshan Mountains and Bashang Plateau, and the number of the output areas showed an increasing trend. (3) The values flowing into the consumption area were different in 2005, 2010 and 2018 in each basin. It can be seen that changes in high-value areas were significant, especially in Luanhe Mountains Basin, Beisanhe Mountains Basin, Daqinghe Mountains Basin and Yongdinghe Cetian Reservoir-Sanjiadian Basin, while the distribution changes in the low-value areas were inapparent. In addition, the amount of value transfer under the influence of forest coverage, river systems and topography also showed an increasing trend on the whole. (4) Based on the results calculated by the payment for ecosystem services model, the ratio of payment for water retention services of Beijing, Tianjin and Hebei was 2.04:1.61:1, and the payment amount of each county (district) was between 0 and 3.41 million yuan, while the ratio of accepting compensation was 1:0:1.87, and the amount of accepting compensation for each county (district) was between 0 and 5.46 million yuan.