甘肃省土地荒漠化时空演变及驱动力分析

Analysis of Spatiotemporal Evolution and Driving Forces of Land Desertification in Gansu Province

[目的]对甘肃省的荒漠化状况及驱动因素进行分析,为该地区荒漠化综合防治及“三北”防护林等生态工程的推进提供科学依据。[方法]基于植被指数及地表反照率构建了荒漠化差值指数,使用趋势分析、空间自相关分析等方法分析了甘肃省2000—2022年23 a间的荒漠化时空分布特征,并利用地理时空加权回归法对其影响因素进行了分析。[结果]①甘肃省荒漠化整体呈现出“西北荒东南绿”的特点,西北区域同时受风蚀荒漠化和盐渍化影响,荒漠化最严重,向东南方向荒漠化程度逐渐减轻,中部地区受水土流失影响荒漠化程度较严重,南部区域荒漠化程度较轻;时间上,23 a间,甘肃省荒漠化程度逐渐改善,且南部区域改善程度强于北部区域;②从空间自相关看,甘肃省荒漠化主要表现出聚集特性,即荒漠化程度表现出明显的空间正相关性;③降雨对缓解荒漠化最有益处,且对西北的影响大于东南,风速和人口会加剧荒漠化的发生,西南部气温升高荒漠化程度会加重,其余区域则相反。[结论]2000—2022年甘肃省荒漠化整体呈改善趋势,西北部荒漠化仍较严重,甘肃省荒漠化的驱动因素存在较明显的时空异质性,最主要的因素为降雨。

[Objective]The desertification status and its driving factors in Gansu Province were analyzed in order to provide a scientific basis for the comprehensive prevention and control of desertification and the promotion of ecological projects such as the“Three Norths”shelterbelt program.[Methods]Trend analysis and spatial autocorrelation analysis were used to characterize the spatial and temporal distribution of desertification in Gansu Province from 2000 to 2022,and geographically and temporally weighted regression was used to analyze the influencing factors.[Results]①The overall desertification in Gansu Province was characterized as“desertification in the northwest and green in the southeast”.The northwest region was affected by both wind erosion and salinization,and exhibited the most serious desertification,which gradually decreased towards the southeast.The central region was affected by soil and water loss,and had a serious degree of desertification,while the south region had a less serious degree of desertification.The degree of desertification in Gansu Province gradually decreased during the 23-year study period,and the amount of decrease was greater in the southern region than in the northern region.②In terms of spatial autocorrelation,desertification in Gansu Province was mainly characterized by aggregation,i.e.,the degree of desertification showed obvious positive spatial correlation.③Increased precipitation was most beneficial in mitigating desertification and had a greater impact in the northwest than in the southeast,while wind speed and population exacerbated desertification.Desertification was exacerbated by warmer temperatures in the southwest and vice versa in the rest of the region.[Conclusion]From 2000 to 2022,desertification in Gansu Province showed an improving trend,while desertification in the northwestern part of the province was still serious.There was obvious spatial and temporal heterogeneity in the drivers of desertification in Gansu Province,and the most important factor affecting desertification was precipitation.