京津风沙源区生态保护与建设工程对防风固沙服务功能的影响

目的] 评价京津风沙源生态保护与建设工程自2000年启动实施近20 a以来的防风固沙效应，以指导工程二期的实施。方法] 选取植被覆盖度、风蚀量和防风固沙服务功能保有率等指标进行分析。结果] 京津风沙源区以草地为主，其次为林地和农田；工程实施以来，多年平均土壤风蚀量为7.87×10⁸ t，以微度和轻度侵蚀为主；一期工程实施期间的土壤风蚀量总体呈逐年减小趋势，二期工程实施以来，风沙源区遭受风蚀危害又逐渐加重，尤其是沙化草原亚区，该区风蚀模数变化趋势达到了8.96 t/（hm²·a）；就防风固沙服务功能保有率而言，整个风沙源区均值达到了0.82，低值区主要分布于沙化草原亚区（0.743）和晋北山地丘陵亚区（0.752）；二期工程实施以来，大部分区域保有率均显著提升，这与二期工程实施期间全年及冬春季的植被覆盖度变化情况一致。结论] 京津风沙源的风蚀防治区重点在保有率下降区域和以草地和沙地为主的沙化草原亚区、浑善达克沙地亚区和科尔沁沙地亚区。

Effects of Ecological Protection and Construction Project on Windbreak and Sand Fixation Service Function in Beijing-Tianjin Area

Objective] Beijing-Tianjin sand control projects have been implemented for 20 years. This study intend to provide further guidance for the implementation of the second phase of the project by evaluating the effects of wind and sand fixation under the influence of the project implementation.Methods] The vegetation coverage and wind erosion, retention rate of wind, and sand fixation service function were calculated by using a revised wind erosion equation model.Results] The Beijing-Tianjin aeolian sand source area was dominated by grasslands, followed by forest and farmland. Since the implementation of the project, the average annual amount of soil wind erosion has been 7.87×10⁸ tons, mainly with mired and mild erosion. The amount of soil wind erosion during the implementation of the first phase of the project generally decreased year by year. Since the implementation of the second phase of the project, wind erosion hazards gradually increased, especially in subregions of desertified grasslands, where the change trend of the wind erosion modulus reached 8.96 t/(hm²·a). The average retention rate of the wind and sand fixation service function of the entire sandstorm source area reached 0.82, and the low-value areas were mainly distributed in the desertified grassland subregion (0.743) and the hilly and mountainous area of Northern Shanxi Province (0.752). Since the implementation of the second phase of the project, the retention rate in most areas increased significantly, which was consistent with the changes in vegetation coverage throughout the year as well as in winter and spring.Conclusion] The focus of wind erosion prevention and control is on areas with a decrease in the retention rate and the desertified grassland subregions, Hunshandake sandy subregion, and Horqin sandy subregion.