湘西北小流域不同植被类型枯落物层持水特性研究

Water-holding capacity and characteristics of litter layer of different vegetation types in small watershed of Northwest Hunan

利用野外观测与室内分析相结合的方法,对湘西北小流域4种植被类型的枯落物层持水特性进行了研究。结果表明:不同植被类型均以叶为主要积累凋落物方式,其次是枝条,碎屑最小,而坡耕地有别于各森林植被类型,坡耕地碎屑排第三,最小的是落果积累的方式。不同植被类型枯落物总厚度以枫樟混交林最大,坡耕地的最小;枯落物总储量马尾松林最大,为18. 75 t·hm^(-2);其次是枫樟混交林,为13. 59 t·hm^(-2);坡耕地的最小,仅为5. 81 t·hm^(-2);未分解层和半分解层枯落物储量均表现为马尾松林>枫樟混交林>杜仲林>坡耕地。4种植被类型枯落物最大持水量范围在5. 59～21. 05 t·hm^(-2)之间,枫樟混交林最大持水量最大,为21. 05 t·hm^(-2),其次为杜仲林、马尾松林,坡耕地的最大持水量最小,为5. 59 t·hm^(-2)。不同植被类型最大持水率均值表现为杜仲林>枫樟混交林>马尾松林>坡耕地;枯落物最大持水率中半分解层表现为杜仲林(249. 07%)>马尾松林(234. 29%)>枫樟混交林(203. 27%)>坡耕地(195. 92%),未分解层表现为杜仲林(301. 10%)>枫樟混交林(268. 01%>马尾松林(192. 56%)>坡耕地(102. 94%);不同植被类型最大持水率表现为半分解层(220. 64%)>未分解层(216. 15%),说明半分解层的枯落物持水能力大于未分解层。不同植被类型枯落物持水量与浸泡时间呈现明显的对数关系(R>0. 93),枯落物吸水速率与浸泡时间呈现明显的幂函数关系(R>0. 99)。

By using field investigation and experimental analysis,the water-holding capacity and characteristics of litter layer of different vegetation types of small watershed in Northwest Hunan were studied. The results showed that the main way to litter accumulation was leaf of different vegetation types,followed by branches,with the smallest detritus,while the sloping farmland was different from the forest vegetation types,and the debris of sloping farmland was in the third place. Moreover,the lowest was the way of fruit fall accumulation. The total thickness of litter in different vegetation types was the largest, and that of sloping farmland was the smallest. In addition,the total reserves of litter in Massoniana pine fores was the largest（18. 75t·hm^-2）,followed by the mixed forest of maple camphor with 13.59 t·hm^-2. Furthermore,the minimum was in sloping farmland with only 5. 81 t·hm^-2. The litter reserves of undecomposed layer and semi-decomposable layer were listed as follows：Massoniana pine forest〉Maple camphor mixed forest〉Eucommia ulmoides forest〉sloping farmland. The maximum water holding capacity of litter of four vegetation types was ranging from 5. 59 to 21.05 t·hm^-2 that the Maple camphor mixed forest was the maximum up to 21. 05 t·hm^-2,then the Massoniana pine forest. Moreover,sloping farmland was of the least water holding capacity that was 5. 59 t·hm^-2. The average values of displayed as follows： Eucommia ulmoides forest〉Maple camphor mixed forest〉Massoniana pine forest〉sloping farmland. Maximum water holding capacity of semi-decomposition layer of litter was sorted as follows：Eucommia ulmoides forest（249. 07%）〉Massoniana pine forest（234. 29%）〉Maple camphor mixed forest（203. 27%）〉sloping farmland（195. 92%）,while that of the undecomposed layer was Eucommia ulmoides forest 301. 10%）〉Maple camphor mixed forest（268. 01%）〉Massoniana pine forest（192. 56%）〉sloping farmland（102. 94%）. What＇s more,the maximum water holding capacity of different vegetation types was sorted as follows：semi-decomposition layer（220. 64%）compared to undecomposed layer（216. 15%）,indicating that the water holding capacity of semi-decomposition layer was better than undecomposed layer. There was a logarithmic relationship between litter retention capacity and soaking time of different vegetation types（R〉0. 93）. The water absorption rate of litter had a power function relationship with soaking time（R〉0. 99）.