陕西省生态系统水源涵养功能评估分析

以陕西省为研究对象,基于水量平衡法并结合GIS空间分析与线性回归法,对2000—2014年区域生态系统水源涵养功能动态变化进行科学评估和重要性评价,并以此为方向探讨区域生态红线规划。结果表明:(1)陕西省水源涵养能力南北高,中间低,空间差异显著,单元水源涵养量为0～800.90 mm;近15年水源涵养功能增加区域面积占研究区总面积的86.71%,总水源涵养量呈"整体上升,局部下降"特征。(2)气候要素与水源涵养量相关性较强,植被类型也影响着水源涵养的空间特性。植被类型中,森林是生态系统水源涵养的主体,其中,水源涵养能力为:常绿阔叶林常绿针叶林落叶阔叶林落叶针叶林。(3)研究区内水源涵养量200 mm的区域占总面积的65.12%,整体水源涵养生态价值不高;综合划定水源涵养生态保护红线面积约77 593.31 km~2,占总面积的37.70%,主要分布在秦岭中西部高山区、汉水谷地以南以及延河流域以北,生态系统类型以林地为主。

Evaluation of Ecosystem Water Conservation Function of Shaanxi Province

Using water balance method combined with GIS spatial analysis and linear regression method,this paper evaluated the water conservation functions of various ecosystems,basing on which the definition of the ecological protection red line was discussed. Results showed that: (1) Water conservation capacity was higher in the southern Shaanxi,followed by that in the north and central Shaanxi. Annual water conservation per square kilometer fluctuated between 0~800.90 mm,with significant spatial difference. From 2000 to 2014,the total water conservation capacity increased significantly and the area with increasing water conservation rose to 86.71% of the total area,and the total water conservation capacity characterized by "overall rise and partial decline". (2) Strong relationships were detected among climatic elements and water conservation. Meanwhile,the vegetation types also played certain roles in affecting the spatial patterns of water conservation. Among vegetation types,forest was the major contributor to the water conservation function in this region. The order of water conservation capacity in terms of forest ecosystems was evergreen broad-leaved forest > evergreen coniferous forest > deciduous broad-leaved forest > deciduous coniferous forest. (3) In the study area,the area with unit water conservation less than 200 mm accounts for 65.12% of the total area,indicating insignificant overall water conservation value. The red line areas of water conservation and ecological protection is comprehensively delimited to approximately 77 593.31 km²,37.70% of the total area,which was mainly distributed in the mountainous areas of the central and western Qinling Mountains,southern Hanshui Valley and northern Yanhe River Basin.