实施禁牧前后宁夏草地防风固沙的时空变化特征

Spatiotemporal patterns of windbreak and sand fixation before and after grazing prohibition in Ningxia

为了给宁夏进一步制定草地生态恢复的综合决策提供参考,实现草地生态系统的可持续发展,基于气象、遥感等数据,利用修正风蚀方程模型(RWEQ)对宁夏禁牧前后31年草地防风固沙服务功能的时空变化及趋势进行定量评估。结果表明:1)禁牧前(1988-2003年)土壤风蚀模数平均值为5.59 kg·m^(−2);禁牧后(2003-2018年)平均值为1.45 kg·m^(−2)。土壤风蚀强度(共6级)为轻度侵蚀和微度侵蚀的区域面积在禁牧后增加了14281 km,比例增至73.52%,土壤风蚀强度降低。2)禁牧前防风固沙量平均值为25.49 kg·m^(−2);禁牧后平均值为14.3 kg·m^(−2)。禁牧后草地防风固沙量级别以“中”为主,面积增大了7382 km^(2),比例增至23.65%。3)1998-2018年宁夏草地防风固沙保有率呈增加态势,在73.2%~96.7%变化。禁牧前防风固沙功能保有率平均值为81.24%;禁牧后平均值为91.9%。禁牧后宁夏草地防风固沙服务能力明显提升,生态建设工程成效显著。因此,未来应加强分区治理,实施差异化方案。

In Ningxia,China,information is required to formulate comprehensive plans for ecological restoration and to realize the sustainable development of grassland ecosystems.As such,this study was based on meteorology and remote sensing data related to the grassland ecosystem in Ningxia.We applied the Revised Wind Erosion Equation(RWEQ)to quantitatively evaluate the spatiotemporal variations in soil conservation service functions over a 31-year period before and after grazing prohibition in Ningxia.Our results are as follows:1)Before(1988 to 2003)and after(2003 to 2018)grazing prohibition,the average soil wind erosion modulus was 5.59 and 1.45 kg·m^(−2),respectively.After grazing prohibition,the area of intense soil wind erosion(six levels in total)slightly decreased to 14281 km^(2),the proportion of which increased to 73.52%;wind erosion intensity decreased.2)Before and after grazing prohibition,the average sand-fixing function was 25.49 and 14.30 kg·m^(−2),respectively After grazing prohibition,the levels of wind prevention and sand fixation function were mainly classified as medium,covering an area of 8765 km^(2),the proportion of which had increased to 23.65%.3)From 1998 to 2018,the retention rate of windbreak and sand fixation in Ningxia grassland showed an increasing trend,ranging from 73.2%to 96.7%.Before and after grazing prohibition,the average retention rate of windbreak and sand fixation function was 81.24%and 91.9%,respectively.This finding shows the contribution of grassland to wind prevention and sand fixation in Ningxia was gradually increasing,and the ecological construction project had achieved remarkable results.Therefore,regional governance should be strengthened and differentiated schemes should be implemented in the future.