委内瑞拉安第斯山脉云林的破坏对水分动态的影响  

Deforestation Impact on Water Dynamics in a Venezuelan Andean Cloud Forest

作　　者：MicheleAtaroff FermínRada 王胜 

机构地区：[1]安第斯大学(ULA)环境和生态科学研究所

出　　处：《AMBIO－人类环境杂志》2000年第7期440-444,共5页

摘　　要：安第斯山脉的云林在流域水文学和防止侵蚀方面起着重要作用。尽管大多数已被列入官方保护区,但仍有大量的云林正在被破坏,并被牧牛场所取代,牧牛场是委内瑞拉云林环境中最主要的土地利用方式。天然林水分动态以及牧场替代所产生的影响都不太被人了解。1996年以来,我们一直在进行一个研究项目,以研究云林水流量的一些情况和评估牧场替代所产生的水文学影响。研究地点位于委内瑞拉安第斯山脉,梅里达州的La Mucuy(海拨2300m,降雨量3124mm)。结果表明,在森林中,水分输入总量的91%来自降雨,9%来自云雾。叶截留总量为51%,对于热带山地森林来说,这是一个很高的值。水分输入总量中,大约有49%直达地面,其中枯落物截留6%,最后还有1.4%通过地表径流流失。因此,渗入量应约为42%。其中大约有16%的水分通过蒸腾散失,26%汇入流域。牧场研究结果表明,截留量为7%,而地表径流(2%)和蒸腾量(约66%)均高于森林。我们有关土地水分状况的结果初步表明,森林土壤(表层)湿度百分比明显高于牧场土壤。Andean cloud forests play an important role in watershed hydrology and protection against erosion. Even though most cloud forests fall under officially protected areas, a good deal of the cloud forests are being deforested and replaced by pastures for grazing cattle, which is the most important land use in Venezuelan cloud forest environments. The water dynamics of the natural forest as well as the impact of replacement by pastures are poorly understood. We have been conducting a research project since 1996, in order to study some of the water fluxes of the forest and to evaluate the hydrological impact of replacement by pasture. The study site is located at La Mucuy (2300 m with 3124 mm rainfall), Merida State, in the Venezuelan Andes. The results show that, in the forest, 91% of total incoming water was from rainfall and 9% was from cloudwater. Total foliage interception was 51%, which is a high value for a tropical montane forest. About 49% of the total incoming water reaches the ground as throughfall, whereas litter intercepts 6% of the water and a final 1.4% was lost by surface runoff. Therefore, infiltration must be about 42%. Approximately 16% was lost by transpiration leaving about 26% for drainage. Results from pastureland studies show 7% interception, while surface runoff (2%) and transpiration (about 66%) were higher than in the forest. Our first results on soil water status suggest that the forest soil (upper horizon) has a significantly higher % moisture than the pasture soil.

关 键 词：委内瑞拉 安第斯山脉 云林采伐 水文学 水分动态 

分 类 号：X143[环境科学与工程—环境科学] S715[农业科学—林学]