江西泰和县森林生态系统水源涵养功能评估

Assessment of Water Conservation Function of Forest Ecosystem in Taihe County,Jiangxi Province

森林生态系统综合水源涵养能力是林冠层、枯落物层和土壤层蓄水能力的总和。本文根据江西泰和县2003年森林资源二类调查,结合文献收集,从3个作用层评估了泰和县森林生态系统的水源涵养量及其空间分布格局,比较了不同森林类型、林龄、海拔、坡度下的林冠降雨截留能力,枯落物最大持水量和土壤蓄水能力。结果表明,林冠层平均截留率为16.31%,枯落物层持水率为2.14%,土壤层蓄水率为81.55%,3个层次总截留和蓄水量为1.41亿m3。各种森林类型水源涵养量由大到小依次为:杉木林>马尾松林>湿地松林>阔叶林>毛竹林>灌木林>混交林>经济林。幼林龄、中林龄、近熟林、成熟林和过熟林水源涵养贡献率分别为17.58%、65.39%、14.18%、2.48%和0.37%,涵养水源能力随林龄的增加而增加。空间上,泰和县森林生态系统的综合水源涵养力表现出从东西两侧向中部递减的分布。不同立地条件下林分的合理经营与管理对于整个森林生态系统水源涵养功能的发挥具有重要的作用。

Water conservation is an important function of forest ecosystem, which could weaken rainfall erosivity, slow down surface runoff and preserve soil and water. It is a comprehensive effect of three main hydrological processes, namely canopy interception, litter containment, and soil water storage. On the basis of the sixth inven- tory data of forest resources （2003） in Taihe County, Jiangxi Province and literature reviews, this paper estimat- ed the function of water conservation and its spatial distributions and variations. Also, we compared the water conservation capacity of forest ecosystem through three layers by forest types, age groups, elevations and slopes. The results showed that, the canopy layer could intercept approximately 16.31% of rainfall; the litter layer could hold 2.14% of water and the soil layer could store 81.55% of water. It can be seen that that soil layer is the main aquifer of forest ecosystem. The total amount of rainfall interception and water holding was 141 million cubic meters in Taihe. The amount of water conserved by different vegetation types in a descending order was Cun- ninghamia lanceolata forest 〉 Pinus massoniana forest 〉 Pinus elliottii forest 〉 Broad-leaved forest 〉 Phyllo- stachys pubescen forest 〉 Shrubby forest 〉Mixed forest 〉 Economic forest. The contribution rate of water con- servation of young stand, middle-aged stand, near-mature stand, mature stand and over-mature stand forests was 17.58%, 65.39%, 14.18%, 2.48% and 0.37%, respectively. The capacity of water containment increased with the increasing age of forest. The spatial distribution of water conservation capacity of forest ecosystem in Taihe tend- ed to decrease from eastern and westem to the central part. The damage of forest vegetation or soil could lead to water loss and soil erosion, and even natural disasters. Therefore, reasonable management of forest ecosystem under different conditions would play an essential role in the enhancement of water conservation function.