长江上游地区主要森林植被类型蓄水能力的初步研究

Water retention capacity evaluation of main forest vegetation types in the upper Yangtze basin

论文在收集长江上游各类森林林冠层、枯落物层和土壤层等3个水文生态功能作用层资料的基础上,根据山地气候带和群落生活型将长江上游森林归并为14个植被类型,对其降水截留规律和蓄水能力进行了综合评价。在森林综合蓄水能力中,土壤层和枯落物层持水量占了绝大部分比例,土壤非毛管孔隙度对森林蓄水能力具有决定作用,可以利用凋落物现存量和土壤非毛管孔隙度来评价和估算枯落物和土壤蓄水的综合能力。在长江上游各类森林植被中,常绿阔叶林、常绿落叶阔叶混交林、铁杉、槭、桦林、云杉林、冷杉林和硬叶常绿阔叶林具有较强的持水能力,这些植被在长江上游高山峡谷区山地垂直带中广泛分布,对整个流域水源涵养和水土保持具有重要作用。因此,在长江上游实施天然林保护和退耕还林工程等生态建设具有重要意义。

The upper Yangtze basin,with abundant forest resources, is an important water sources area,which functions as water tower for the territory of eastern China.Evaluation of water retention capacity of forest ecosystems can provide important references for ecosystem function assessment and ecological construction.We collected data of water retention information of forest canopy,litter and soil function layers to evaluate rainfall interception and comprehensive capacity of water retention by 14 forest vegetation types according to mountain climate zones and growth form classification of forest.Among comprehensive water retention capacity,water retentions in soil and litter layer account for the most proportion.Soil non-capillary porosity plays the key role in the determination of water retention capacity of ecosystem.The water retention capacity of litter and whole ecosystem can be evaluated by phytomass of litter and soil non-capillary por-osity.Subtropical evergreen broad-leaved forest,evergreen and deciduous mixed broad-leaved fore-st,hemlock,maple and birch mixed forest,spruce and fir forest and sclcrophyllous evergreen broad-leaved forest have more water retention capacities among the forest ecosystems in the upper Yangtze River and have wide distribution in the high mountain and dissected gorge area. These ecosystems are important for water retention and soil conservation throughout the basin. Therefore,it is of great significance to implement ecological engineering programs such as natural forest protection and convertsion of farmland to forest in the upper Yangtze basin.