1990—2020年黄河源区林地面积与生态需水量的时空变化

Spatio-temporal changes of forest land area and ecological water requirement in the source region of the Yellow River from 1990 to 2020

【目的】探讨1990—2020年黄河源区林地面积与林地生态需水量的时空变化规律,为黄河源区林地生态需水量的合理调配提供依据。【方法】基于黄河源区1990—2020年的遥感影像数据和野外实测资料,通过目视解译确定黄河源区土地利用类型,通过计算得到林地面积和林地生态需水量数据;采用ArcGIS 10.8绘制林地面积与生态需水量的时空分布图,分别运用Canoco 5.0和SPSS 27作冗余分析和主成分分析。【结果】黄河源区1990—2020年的林地面积变化不大,林地主要分布于黄河源区中东部,以灌木林地为主;林地生态需水量的变化较小,总体上生态需水量表现为西多东少、北多南少。不同类型林地的生态需水量大小表现为灌木林地>有林地>疏林地>其他林地;影响源区生态需水量的最主要指标是斑块周长-面积比(mean perimeter-area ratio,PARA_MN),其次是斑块连通度指数(patch cohesion index,COHESION)。影响黄河源区生态需水量的主要因素为人口数量、经济水平、产业发展结构,自然环境因素的驱动力弱于社会环境因素。【结论】黄河源区1990—2020年林地面积呈小幅下降趋势,林地生态需水量变化不大;黄河源区景观水平多样性较低;黄河源区受人类活动的影响较大。

【Objective】Spatio-temporal changes of forest land area and ecological water requirement in the scource region of the Yellow River from 1990 to 2020 were investigated to provide a basis for the rationale deployment of ecological water supply and ecological protection in the area.【Method】Land use types in the source region of the Yellow River were classified based on visually interpretated remote sensing image data from the past 30 years combined with field measurements.Based on the calculated woodland area and its ecological water requirement,their spatial and temporal distribution maps were created using ArcGIS 10.8.Furthermore,redundancy analysis was performed using Canoco 5.0,and principal component analysis was conducted using SPSS 27.【Result】The source region of the Yellow River witnessed relatively steady variation in the woodland area over the past 30 years,mainly dominated by shrubland in the middle-eastern part of the headwater area.The ecological water requirement of the woodland showed less variability,with an overall uprising trend of being abundant in the north and west parts,and less in the south and east regions.The order of ecological water requirement for different types of forest land was as follows:shrub land>forested land>sparse woodland>other woodland types.Redundancy analysis on landscape pattern index and woodland ecological water requirement indicated that perimeter-area ratio PARA_MN was the primary index affecting the ecological water requirement in the source region,followed by plate connectivity index COHESION.Driving factor analysis indicated that the ecological water requirement of the Yellow River Basin was mainly influenced by population size,economic level and industrial development structure,and the driving force of social environment factors surpassed that of natural environment factors.【Conclusion】 In the past 30 years,the distribution of forest land area in the source region of the Yellow River has shown a slight downward trend,and the fluctuation of forest land ecological water requirement is relatively stable.Among them,the redundancy analysis of forest ecological water requirement shows that the landscape level diversity of the Yellow River source region is low,and the driving factor analysis shows that the Yellow River source region is greatly affected by human activities.