摘要
分析黄河源区景观格局的时空变化特征,为源区生态恢复和环境保护提供科学依据.基于近30年7期的土地利用数据,从类型水平和景观水平上分析黄河源区景观格局的时空变化特征并分析其驱动因素.结果表明:从类型水平指数上看,黄河源区耕地、水域和建设用地散布与并列指数大幅降低,各类型的形状逐渐复杂化;林地景观类型正处于被其他地类逐渐分割扩张的状态;草地是所有景观类型中优势度最高的类型,自然连通性最好.1990-2005年未利用地的形状指数(LSI)值最大,其景观整体形状较其他景观复杂.从景观水平指数上看,斑块密度、最大斑块指数、散布与并列指数和香农多样性指数总体呈现降低趋势,周长-面积比总体呈现增大趋势,斑块连通度指数基本保持不变,表明源区整体破碎化程度低,空间异质性减小.黄河源区景观格局变化主要受到社会经济因素和自然因素的共同影响,其中社会经济发展、人口增加和产业结构调整是景观格局变化的主要驱动因素;年均温、年均蒸发量和年均降水量等自然因素是影响景观格局变化的次要因素.
Abstract
The landscape pattern of the source region of the Yellow River has changed due to natural and anthropogenic factors,and the study of landscape dynamics is important for building regional ecological security.In this study,we analyzed the spatial and temporal changes of land use in the source region of Yellow River,and forces driving landscape dynamics were analyzed.The study was based on land use data collected each 5 years(1990,1995,2000,2005,2010,2015 and 2020)over a 30 year period.Land use designations included arable land,woodland,grass land,water,construction land,and un-used land.Results show that the interspersion and juxtaposition index(IJI)of arable land,water and construction land in the study area decreased significantly from the type level index,and the shapes of each type became more complex.Over the 30 year study period,the patch number(NP)of woodlands increased the most,indicating that woodlands were being gradually fragmented by other land use types.The patch landscape area density(PLAND)and cohesion of grasslands was the highest over the 30 years,with the highest dominance among landscape types and the best natural connectivity.During 1990-2005,the landscape shape index(LSI)of unused land was the highest,indi-cating that its overall landscape shape was more complex compared to other landscapes.In terms of landscape level indices,the patch density,maximum patch index,IJI and Shannon diversity index of the landscape displayed overall decreasing trends,while the perimeter-area ratio increased and the patch connectivity index changed little,indicating that overall fragmentation of the source area was low,and spatial heterogeneity decreased.Landscape pattern changes in the Yellow River source area were primarily influenced by socio-economic factors,among which economic development,popula-tion increase,and industrial restructuring were the main driving factors of land use change.Annual average temperature,annual average evaporation,and annual average precipitation were the primary natural factors affecting the landscape pattern.Our study provides a scientific basis for ecological res-toration,environmental protection and land use management in the Yellow River source area and is crucial for promoting ecologically sustainable development.
万方数据