中国主要森林生态系统水文功能的比较研究(英文)

 基于中国不同区域生态站的观测资料，着重从降雨截留（林冠截留、枯枝落叶层截持和土壤蓄水）、调节径流和蒸散等3个方面对我国主要森林生态系统的水文生态功能进行了比较研究。各生态系统林冠年截留量在134～626 mm间变动，由大到小排列为：热带山地雨林，亚热带西部山地常绿针叶林，热带半落叶季雨林，温带山地落叶与常绿针叶林，寒温带、温带山地常绿针叶林，亚热带竹林，亚热带、热带东部山地常绿针叶林，寒温带、温带山地落叶针叶林，温带、亚热带落叶阔叶林，亚热带山区常绿阔叶林，亚热带、热带西南山地常绿针叶林，南亚热带常绿阔叶林，亚热带山地常绿阔叶林。枯落物持水量可以达到自身干重的2～5倍，但也因林型而异。土壤非毛管持水量变动在36～142 mm之间，平均89 mm。常绿阔叶林的非毛管持水量通常高于100 mm，而寒温带/温带落叶阔叶林和常绿针叶林通常低于100 mm. 土壤的非毛管持水量通常占生态系统中截持水量的90%，其次是枯落物和林冠层。这说明，森林土壤在调节降雨截留中占有重要地位，其水文功能的大小取决于土壤结构和空隙度，而这些恰恰又受枯落物和森林植被特征的影响。森林皆伐后，一般地表径流会显著地增加，而适当抚育措施则对地表径流影响不大。流域径流受诸多因素的影响，包括植被、土壤、气候、地形、地貌以及人类影响导致的流域景观变化，比较研究表明森林变化对流域径流的影响尚未得到一致的规律性的结果。通过对比研究不同森林的蒸散变化，发现随降雨量的增加，森林蒸散量略有增加，而相对蒸散率却在下降，相对蒸散率在40%～90%间变动。

COMPARATIVE ANALYSIS OF HYDROLOGICAL FUNCTIONS OF MAJOR FOREST ECOSYSTEMS IN CHINA

Based on case studies from nearly 20 forest ecological stations in different bioregions of China, the characteristics of eco_hydrological functions of forest ecosystems were studied in terms of canopy interception, soil_water storage and holding capacity. Annual canopy rainfall interception ranged from 134 to 626 mm, and was ranked in the descending order as follows : tropical mountain rain forest, subtropical western mountain evergreen coniferous forest, tropical semi_deciduous monsoon forest, temperate mountain deciduous/evergreen coniferous forest, cold_temperate/temperate mountain evergreen coniferous forest, subtropical bamboo forest, subtropical/tropical eastern mountain evergreen coniferous forest, cold_temperate/temperate mountain deciduous coniferous forest, temperate/subtropical deciduous broadleaf forest, subtropical mountain evergreen broadleaf forest, subtropical/tropical south_west mountain evergreen coniferous forest, south subtropical evergreen broadleaf forest, and subtropical mountain evergreen/broadleaf forest. The moisture holding capacity of litter was about two_to_five times its dry_weight, but varied with forest type. The soil non_capillary moisture capacity of forests ranged from 36 to 142 mm with an average of 89 mm. Non_capillary capacity of evergreen broadleaf forests was more than 100 mm, but was less than 100 mm in the cold_temperate/temperate deciduous broadleaf and evergreen coniferous forests. From an ecosystem point of view, the soil non_capillary holding capacity counted for more than 90% of the total, followed by forest litter, which ranged from 3 to 10 mm, and canopy interception only occupied a small proportion (less than 2 mm). This indicates that forest soils play a significant role in regulating rainfall interception. The hydrological role of forest soil depends on its structure and porosity, which is further affected by litter_fall and forest vegetation on sites. There was no consistent result with respect to the relationship between forest cover and annual runoff based on paired comparison of forest watersheds or direct measurements of the same forest watershed with a change of forest cover over time. Soil surface runoff was found to increase remarkably after forest logging, in particular, after clear_cut on a large scale irrespective of forest types or regions. An appropriate thinning or tending practices, however, could reduce soil surface runoff to a certain degree in forest watersheds. With increasing precipitation, forest evapo_transpiration increased slightly, while the Relative Evapo_transpiration Ratio (RER) decreased with the RER variation ranging from 40% to 90%.