近40 a榆林市土地利用空间格局变化及影响因素分析

Spatial pattern changes and influencing factors of land use in Yulin City in the past 40 years

土地利用空间格局变化反映土地利用合理性和生态环境情况。以位于农牧业交错带的生态环境脆弱区陕北榆林市为研究区,运用核密度分析法表达土地利用空间格局变化,采用土地利用动态度、土地利用综合动态度、土地利用变化强度、土地利用转移矩阵指数分析榆林市近40 a的土地利用变化速度、强度、结构及其影响因素。结果表明:榆林市近40 a土地利用变化以耕地面积减少、建设用地大幅度增加和未利用地减少为主。东南部耕地密度等级降低,西南部呈现相反的变化趋势;林地呈“多核心增长”;草地高密度核心位于北部,等级升高;建设用地高密度核心位于西北部6个县区,增长幅度大。未利用地高密度核心为西北部毛乌素沙漠,斑块破碎化,沙地治理效果显著。政策因素、社会经济因素和人口因素的综合作用是影响土地利用空间格局变化的主要原因。退耕还林还草使得人地矛盾得到改善,减缓了水土流失;毛乌素沙地治理成效显著。未来发展需注重生态格局安全,以生态保护为前提,实现科学、绿色、可持续的高质量发展。

Yulin City is located in the northern agro-pastoral zone of China and has a fragile ecological environment.It is an important barrier to ecological security.Land use patterns are affected by the allocation structure and management of the ecological environment.In this study,the land use patterns of Yulin from 1980 to 2018 were analyzed to identify the relationship between spatiotemporal changes and influencing factors.The primary data source was land use data at a 30-m resolution.The normalized difference vegetation index was used to represent vegetation.Data were taken from three industries to represent economic factors.Demographic data were used to reflect demographic changes.Kernel density analysis was used to calculate the density of data points with land use attributes.Different indices were used to analyze the speed,intensity,and structure of changes in land use patterns.The results showed that changes in land use patterns were mainly due to a decrease in cultivated land,substantial increase in construction,and decrease in unused land.Cultivated land decreased in the southeastern area but increased in the southwest.Forestland showed“multicore growth”.The grassland was most dense in the north and increased over time.Construction was most dense in six counties in the northwest and showed a large increase over time.Most unused land was in the northwest,which included the Mu Us Desert,and was significantly affected by land management.The spatial changes in land use patterns were attributed to the combined effects of policy,socioeconomic,and demographic factors.The results indicate that the waste of cultivated land should be prevented.Additionally,the relationship between policy implementation,cultivated land quality,and ecological protection should be coordinated,and traditional practices of agriculture and animal husbandry should be optimized.Man-made construction and development in desert areas should be reduced.The interweaving effects of human activities and changes in the ecological environment should be considered to promote ecological protection.We advocate the concept of ecological civilization,which can be defined as the mutual symbiosis between man,nature,and the geographical environment.