基于规划目标的京津风沙源治理区生态保护与修复效应

为改善和优化京津及周边地区生态环境状况,减轻风沙危害,2003年启动实施了京津风沙源治理工程。基于工程规划目标评估了京津风沙源治理区生态保护与修复效应,结果表明:(1)草地和林地作为京津风沙源治理区绿色生态屏障的主要组成,分别占治理区面积的57.3%和9.7%,而风沙策源地的耕地和沙地分别占17.2%和6.4%。(2)2003—2017年,京津风沙源治理区草地、耕地、沙地面积减少,而林地和其他类型面积增加。治理区植被覆盖度平均提高了2.3%,其中林地提高了4.3%,草地提高了2.4%。(3)沙尘天气发生的春季,治理区土壤风蚀量减少了54%。在防风固沙服务总量的贡献中,草地和沙地贡献了71%。因此,草地和沙地生态系统的植被恢复,对治理区生态系统防风固沙服务的提高发挥了最为重要的作用。(4)除治理区植被有所恢复外,由于气候整体变暖,近15年风场强度有所减弱,特别是沙尘天气易发生的春季风场强度减弱近45%,也是影响京津风沙源治理区风蚀量下降的一个重要原因。

The ecological effects of ecosystem conservation and restoration in Beijing-Tianjin sand source regions based on the planning objects

In order to improve and optimize the ecological environment in Beijing, Tianjin and surrounding areas, and mitigate the hazards of wind and sand, the Beijing-Tianjin Sand Sources Control Project (BTSSCP) was launched in 2003. The ecological effects of the BTSSCP were assessed according to the planning objects. The results showed that (1) the main parts of green ecological barrier in Beijing-Tianjin sand source regions were grassland and forest that accounted for 57.3% and 9.7% of the total area respectively, followed by cropland and sandy land that accounted for 17.2% and 6.4% of the total area respectively. (2) In 2003-2017, the area of grassland and cropland in the project region of first-stage BTSSCP decreased, while the area of forest and sand land increased. The area of the grassland, sand land and cropland in the project region of second-stage BTSSCP increased and the forest area decreased. In the past 15 years, the average vegetation coverage in the project region of BTSSCP increased by 2.3%, and the natural vegetation with increased coverage accounted for about 63% of the total area, of which the vegetation coverage of forest increased by 4.2% and the grassland increased by 2.4%. However, the average vegetation coverage in desert steppe did not increase. (3) From 2003 to 2017, the amount of soil wind erosion in the project region of BTSSCP reduced by 54%. In the total amount of soil erosion, the dust materials that can be transported remotely and directly had a direct impact on Beijing, Tianjin and Hebei were also reduced. (4) Among the factors that control soil wind erosion, the dominant grassland and sandy land contributed to 71%, which played an important role in improving the sand fixation service of the vegetation in sand source regions. In addition, the intensity of wind in spring reduced by 45% was also an important factor affecting the decrease of wind erosion in the project region of BTSSCP.