To quantitatively investigate the water conservation function of the natural spruce forest at the watershed scale in the central Tianshan Mountains,the Urumqi River Basin was chosen as a study area.The InVEST model was used to investigate the capacity for water conservation of the spruce forest and other land use types,as well as quantitatively analyze water conservation changes of the spruce forest under the conditions of different distribution areas and terrain factors.The results showed that:(1) The InVEST model could adequately assess water conservation at the watershed scale.The InVEST model simulation showed that the total water conservation of the spruce forest in the Urumqi River Basin was 4.93 × 106 m3,which accounted for 20.46％ of the total water conservation in the study area (2.41 × 107 m3).In addition,the average water conservation depth of forest area was 54.25 mm.(2) The contribution rate of water conservation in the slope,aspect,and elevation was consistent with the spatial distribution pattern of the spruce forest.At first,per hectare water conservation increased with altitude and then decreased,and it decreased with an increase in slope.The water conservation ability in the shade slope was greatest.(3) The spruce forest showed the greatest capacity,which reached 544.78 m3/hm2.The total,average depth and unit area of water conservation exhibited an increasing trend with increasing spruce forest coverage.(4) The contribution rate of water conservation in the spruce forest was closely related to forest area.Total water conservation in study area and spruce area increased to 0.437 × 106 m3 and 0.522 × 106 m3 with a 1％ increase of spruce forest area,respectively.Therefore,the forest plays a vital role in maintaining sustainable and stable water conservation and ecological service functions,which necessitate effective measures to strengthen the protection and management of spruce forests.%为定量分析天山中部流域尺度云杉天然林水源涵养功能,以乌鲁木齐河流域为研究区,使用InVEST模型,研究云杉林及其它主要地类水源涵养量的大小,并对云杉林在不同分布面积、不同地形因子条件下的水源涵养量变化进行定量分析.结果表明:①InVEST模型可较好的确定研究区流域尺度水源涵养量.基于InVEST模型的模拟,乌鲁木齐河流域云杉林区水源涵养总量为4.93× 106 m3,占研究区水源涵养总量(2.41×107 m3)的20.46％,林区平均水源涵养深度为54.25 mm;②云杉林区水源涵养量的大小在海拔、坡度、坡向上的变化与云杉林空间分布格局一致,每公顷水源涵养量随海拔升高先增大后降低、随坡度增大而降低;阴坡水源涵养能力最强;③研究区各地类中以林地水源涵养量最大(水源涵养量544.78 m3/hm2),随着云杉林覆盖率的不断增加,水源涵养总量、平均水源涵养深度及单位面积涵养量均呈增加趋势;④研究区水源涵养量的贡献率与森林面积密切相关,云杉林面积每增加1％,研究区与云杉林区水源涵养总量分别增加0.437× 106m3、0.522× 106m3;加强对研究区云杉林的保护与抚育管理,才能使森林发挥持续稳定的水源涵养生态服务功能.
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