紫鹊界梯田区植被凋落物水资源调配特性

Water Resources Reallocation Properties of Vegetation Litters in Ziquejie Terrace

通过野外调查和室内实验,分别对紫鹊界梯田区植被凋落物的蓄水与泄水等水资源调配特性进行探讨。结果表明,梯田区各群落凋落物的储量分别为杉林1.82t/hm2,竹杉林1.46t/hm2,竹林1.23t/hm2,板栗林0.95t/hm2和荒草0.73t/hm2。凋落物的蓄水表现为吸水过程,各凋落物浸泡8h后,吸水基本饱和,浸泡24h时最大持水率依次为竹杉林420%,竹林310%,荒草283%,杉林252%和板栗林226%。凋落物泄水的实质为释水,在释水24h后,各凋落物并未达到稳定状态,此时杉林、竹林、板栗林、荒草及竹杉林凋落物的释水率依次为188%,161%,148%,126%和124%。凋落物持水率与浸泡时间之间、释水率与释水时间之间存在对数函数关系,吸水速率与浸泡时间之间、释水速率与释水时间之间满足幂函数关系。凋落物蓄水能力的大小与其泄水能力的强弱并不一致,且蓄水远快于泄水。最后,建立了凋落物水资源调配能力计算式,并用于紫鹊界梯田区,计算结果表明,该区域5种植被凋落物水资源调配能力遵循竹杉林>杉林>竹林>荒草>板栗林的顺序。

By means of field investigation and indoor experiment,the water resources reallocation properties of vegetation litters including water-storing and water-releasing were studied.The results indicated that the litter reserves for different vegetation communities in Ziquejie terrace changed and followed the order of spruce forest(1.82t/hm2)>spruce-bamboo mixed forest(1.46t/hm2)>bamboo forest(1.23t/hm2)> chestnut forest(0.95t/hm2)>wild grass ground(0.73t/hm2).The water-storing process was presented as water-adsorption.When immersed in water for over 8hthe litters could be considered approximately saturated.The maximum water-holding rate for spruce-bamboo mixed forest,bamboo forest,wild grass ground,spruce forest and chestnut forest was 420%,310%,283%,252%and 226%,respectively when immersed in water for 24h.Releasing water in conditions of 20 ℃ and 24% humidity for 24h,the releasing process did not reach stabilization,and the releasing ratio of litters for spruce forest,bamboo forest,chestnut forest,wild grass ground and spruce-bamboo mixed forest was 188%,161%,148%,126% and 124%,respectively.According to regression analysis,there was a logarithmic function relationship between water-holding rate and water-immersed time,as well as between water-releasing ratio and releasing time.A power function relationship existed between water adsorption rate and immersed time,as well as between water releasing rate and releasing time.The water-storing capability of litters was not proportional to its water-releasing ability,and the former was much stronger than the latter.At last,a formula for calculating the water resources reallocation ability of litters was proposed.It was calculated that the water resources reallocation capability for different litters was distinct and was subject to the following order of spruce-bamboo mixed forest>spruce forest>bamboo forest>wild grass ground>chestnut forest.