太行山区主要森林生态系统水源涵养能力

Water conservation capacity of forest ecosystems in Taihang Mountain

  • 摘要: 森林生态系统水源涵养功能是林冠层、枯落物层和土壤层对大气降水进行再分配的过程。本文通过文献收集整理太行山地区森林植被林冠一次降水截留量、枯落物层持水量和土壤层贮水量数据,分析该地区主要森林植被对降水的截留和贮蓄能力,采用综合蓄水能力法对森林植被的综合涵养水源能力进行评价,旨在为合理经营和管理森林生态系统提供依据。结果表明:1)土壤非毛管孔隙度与生态系统综合持水量呈正相关,且最大持水量占整个森林生态系统综合持水量的90%以上,表明土壤层作为森林生态系统水文效应最重要的一层,是整个森林系统水分循环的主要贮蓄库和调节器;2)针叶林中油松和侧柏的冠层一次降水截留量显著高于其他林型,其林冠结构更加适应该地区气象条件,林冠层降水再分配能力也优于其他林型;3)混交林郁闭度低,有利于林下灌、草丛的生长,其枯落物现存量比纯林和人工林更高,虽然林冠一次截留量低但林下具有丰富的枯落物层而更易涵养水源;4)天然林综合蓄水能力整体高于人工林,侧柏人工林和油松人工林综合蓄水能力仅次于刺槐、侧柏和油松天然林。综上可见,合理利用森林资源防止水土流失、天然林长期封育和合理控制优势树种密度及增加植被覆盖率对太行山地区植被恢复和生态建设具有重要意义。为提高该区综合水源涵养能力,可增加乡土树种油松和侧柏人工林的种植面积。

     

    Abstract: Water conservation is a comprehensive water resources regulatory function of forest ecosystems through various hydrological processes, including canopy interception, litter containment and soil retention. As a typical northern rocky mountain area, Taihang Mountain is characterized by low rainfall with uneven seasonal distribution, shallow soil, low soil water-holding capacity and fragile environment. In spite of this, Taihang Mountain is an important ecological security shelter for the water sources belt in the North China Plain. Water has become one of the key limiting factors for the protection and restoration of vegetation in the region. Therefore, comparative analysis of water conservation capacities of main forest vegetation types is needed for development of feasible measures for water conservation and sustainable water security in the region. In this paper, we selected 196 records of canopy interception, litter and soil water carrying capacity in the natural deciduous broad-leaved forest, artificial deciduous broad-leaved forest, mixed forest, natural coniferous forest, coniferous forest and shrubs in the mountain region. We integrated water storage capacity with canopy rainfall interception, litter and soil water-holding capacity and then analyze water carrying capacities of main forest vegetation types in the area. Forest integrated water conservation capacity was calculated using a water conservation function for forest ecosystems. The results showed that:1) soil non-capillary porosity had positive correlation with integrated water holding capacity of the ecosystem and the maximum soil water-holding capacity accounted for over 90% of the total water capacity of forest ecosystems in the region. It was revealed that soil layer, as the main water reservoir, was the most important layer for hydrological processes in the forests. 2) Coniferous forests such as Pinus tabuliformis and Platycladus orientalis were more suitable for regional meteorological conditions. Redistribution capacity of precipitation by coniferous forest is significantly higher than that of other forest types. 3) Low canopy density of mixed forest was beneficial to shrub growth and its litter holding was also higher than that of pure forest. 4) Although comprehensive water storage capacity of natural forest was higher than that of plantation forest, water storage capacity of P. orientalis plantation and P. tabuliformis plantation ranked inferior to that of natural forests of Robinia psendoacacia, P. orientalis and P. tabuliformis. In summary, it was important to take afforestation measures for soil erosion, long-term forest enclosure and appropriate stand density in order to fulfill the goals of ecosystem restoration and ecological reconstruction. In order to increase water conservation capacity, plantation forest with tree species such as P. tabuliformis and P. orientalis was recommended in afforestation. This study provided the basis for the evaluation of water conservation capacity of vegetation along with rational management of forest and water resources. It laid the foundation for environmental protection and disaster prevention and mitigation in Taihang Mountain.

     

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