京津风沙源区防风固沙功能对植被覆盖度变化的时空响应研究

Response of the sand-fixing service on vegetation cover change in the Beijing-Tianjin sandstorm source area

防风固沙功能受气象、土壤、植被、土地利用等多种因素的影响,监测评估区域防风固沙功能对不同影响因子的响应状况可为生态保护工程的布局实施提供重要依据。以京津风沙源治理工程区为例,基于NDVI指数和RWEQ模型,构建了植被覆盖度与防风固沙功能的同步变化指数模型,评估分析了工程区防风固沙功能对植被覆盖度变化的响应水平及时空差异。结果表明:(1)2000—2015年京津风沙源区防风固沙功能与植被覆盖度的同步变化指数(SI)波动增加,多年平均值达到0.85,说明区域防风固沙功能对植被覆盖度变化存在显著响应且整体表现出增强趋势;(2)评估期内工程区83%的地区防风固沙功能与植被覆盖度变化高度同步(SI>0.8),17%地区表现出较高程度的同步变化(0.6<SI≤0.8);(3)正蓝旗、巴林右旗、翁牛特旗等地区防风固沙功能对植被覆盖度变化的响应水平相对较高,而商都县、兴和县、乌兰察布等地区相对较低。因此,京津风沙源区防风固沙功能与植被覆盖度变化呈现为强同步性,植被覆盖度可作为防风固沙效益的直接监测指标,同时,对于同步变化指数(SI)相对较低的区域应注重综合采用植被恢复措施以外的工程或化学材料等沙障措施提升防风固沙功能。

Identifying and assessing the effectiveness of vegetation control for sand-fixing is an important basis for planning and layout ecological management projects.However,there is little research on the spatial-temporal response between vegetation cover changes and sand-fixing service.Taking the Beijing-Tianjin sandstorm control engineering area as an example,this paper constructs a synchronous change index model of vegetation coverage and sand-fixing capability,to quantitatively evaluates the spatial and temporal differences between vegetation cover change and sand-fixing capability changes from 2000 to 2015,and reveals the trend and potential areas of sand-fixing capability caused by vegetation changes.The results show that,the synchronization change index of vegetation cover and sand-fixing capacity in the study area fluctuate increased from 2000 to 2015,and the multi-year average value reach 0.85,which shows that the sand-fixing service strongly responded with the vegetation coverage change and the response level gradually enhanced.Among them, 83% of the engineering areas present high synchronicity between vegetation coverage and sand-fixing capacity, and 17% has higher synchronicity. From the perspective of administrative district, such areas as Zhenglan Banner, Balinyou and Wengniute Banner show relative high synchronization of vegetation cover change and sand-fixing service, but Xilinhot, Abaqi Banner, Xianghuang Banner, and so on are relative low in the synchronous index. Therefore, the sand-fixing service in the Beijing-Tianjin sandstorm control engineering area strongly responded with the vegetation coverage change, and the vegetation coverage can serve as the surrogate variable of sand-fixing service, and those areas with relative lower synchronous index should be adopted comprehensive sand barrier measures in addition to vegetation restoration.