东灵山林区不同森林植被水源涵养功能评价

森林植被发挥着涵养水源的作用,主要表现在以下几个方面:对降水的截留与再分配;调节河川径流,调节林内小气候,减小林内地表蒸发,改善土壤结构,减少地表侵蚀等. 通过对几种林分各层拦蓄降水和保土功能指标定性评价的基础上,用综合评定法对不同林分水源涵养和保土功能进行综合评价,选择出综合功能最好的林分,以期为北京山区的生态环境建设、植被恢复与保护提供一定的依据。在测定东灵山4种森林植被林冠层、枯枝落叶层和土壤层蓄水和土壤保持功能指标的基础上,采用综合评定法对4种森林植被水源涵养和土壤保持功能进行了评价。结果表明:各植被类型的林冠层截留各不相同,在雨季(6-9 月份) 辽东栎林的截留率最大,华北落叶松的最小;枯落物最大持水深以辽东栎林的最大,油松的最小;土壤水文特性各异,0-80 cm 土层平均容重以落叶阔叶林的最小,华北落叶松的最大;稳渗速率以落叶阔叶林的最大,油松的最小,初渗速率以辽东栎林的最大,油松的最小。不同林分水源涵养和土壤保持综合能力由大到小顺序为落叶阔叶混交林、辽东栎林、华北落叶松林、油松林。常绿阔叶灌丛水源涵养和土壤保持综合能力评价值(0.1039) 比其它植被类型少3个数量级,说明其水源涵养和土壤保持功能明显优于其它植被类型。由此可见,树种组成丰富、林下灌草盖度高、枯落物储量多的落叶阔叶混交林水源涵养和土壤保持能力最强,优于单一的阔叶林,而油松林最差。

Evaluation of soil and water conservation capacity of different forest types in Dongling Mountain

The forest ecosystem consists of gigantic canopy, thick forest litter, abundant roots and porous soil, and thus plays a critical role in soil and headwater conservation in mountain area. A forest ecosystem has different aspects of soil and water conservation functions in intercepting rainfall, adjusting river flow, reducingevapotranporation, amending forest microclimate, improving soil structure and reducing soil erosion, etc. One of the important goals of the ecological construction and vegetation recovery Beijing mountain are is to improve soil and water conservation capacity in this area. In order to offer better recommendations for soil and water conservation of forest ecosystems in Beijing metropolitan area, integreated evaluation of water and soil conservation capacity of the forest ecosystem is needed. Since 1990s, a number of water and soil conservation related criteria have been measured during growing season (May to October) at Beijing Forest Ecosystem Study Site. We collected and analyzed monitoring data of rainfall, forest canopy interception, water-holding capacity of forest litter, surface runoff, and soil loss during 2005-2008. The data collections were from four forest types: Liaodong oak (Quercus liaotungensis koidz), Huabei larch(Larix gmelinii var. principis-rupprechtii), Chinese pine (Pinus tabuliformis), and mixed deciduous broadleaf forest. Our results show that Liaodong oak forest had the highest canopy interception percentage (19.23%), followed by mixed deciduous broadleaf forest (18.33%), Chinese pine forest (13.29%) and Huabei larch forest (12.28%) during the rainy season. The water holding capacity of litter was highest in Liaodong oak forest (483.31%), and lowest in Chinese pine forest (362.63%); the water-holding capacity of soil was in order of mixed deciduous broadleaf forest (459.4mm), Liaodong oak (427.9mm), Chinese pine forest (418.8mm) and Huabei larch forest (407.5mm); the initial infiltration rate of the soil surface layer (0-80cm) ranged from 13.75 to 30.23 mm/min. The stable infiltration rate of soil water was mixed deciduous broadleaf forest (24.27mm/min) > Liaodong oak (20.19mm/min) > Huabei larch (10.55mm/min) > Chinese pine (8.36mm/min); the surface runoff of Chinese pine (4.37mm) was higher than other forest types, and the soil oss was the highest in Chinese pine forest as well. The integrated soil and water conservation capacity was in order of mixed deciduous broadleaf forest > Liaodong oak forest > Huabei larch forest > Chinese pine. The evaluation value (0.1039) of mixed deciduous broadleaf forest was much lower than other forest types. The deciduous broadleaf mixed forest had more abundant trees, more abundant underneath shrubs and grasses, and more forest litter; therefore its soil and water conservation capacity was the highest among the four forest types.