大兴安岭南段典型天然林枯枝落叶层及土壤层持水特性研究

Water holding capacits of litters and soils in typical natural forests in south of Da Xing’an Mountains

本研究选择大兴安岭南段西辽河上游重要水源涵养地典型天然林-山杨(Populus davidiana)林和白桦(Betula platyphylla)林为研究对象,采用野外长期定位观测法、土壤剖面调查法、浸泡试验、土壤物理性质测定等实验方法,探讨了该地区枯枝落叶层及土壤层持水特性。结果表明:山杨林和白桦林枯枝落叶层储量分别为7.83(t·hm-2)和7.99(t·hm-2),最大持水量分别达28.38t·hm-2和26.32 t·hm-2,达自身重量3.78倍和3.29倍,有效拦蓄量分别为24.13(t·hm-2)和22.37(t·hm-2);两种林分枯枝落叶层及其各组分持水量与持水时间呈显著对数关系(R2>0.96)。两种林分枯枝落叶层持水速率与时间的幂函数关系最为显著(R2=0.999);两种林分土壤容重均随土层厚度加深而增大,而总孔隙度和最大持水量变化与之相反,当土壤层0-20cm时总孔隙度为最大,山杨林为64.49%,白桦林为71.96%。山杨林土壤层最大持水量小于白桦林,分别为4775.80(t·hm-2)和5228.60(t·hm-2)。枯枝落叶层和土壤层对森林生态系统水土保持和水源涵养起至关重要的作用。

Populus davidiana and Betula platyphylla forests in the southern section of the Da Xing’an Mountains were selected as the research object.Field long-term positioning observation,soil profile investigation,immersion test and soil physical property measurement were used to research the water holding characteristics of litter layer and soil layer in this area.The results showed that the litter reserves of poplar and Betula platyphylla forests were 7.83(t·hm-2)and 7.99(t·hm-2),respectively,and the maximum water holding capacities were 28.38 t·hm-2 and 26.32 t·hm-2,respectively.Both of the litter reserves and maximum water holding were significantly larger than the undecomposed layer.The effective storage capacities were 24.13(t·hm-2)and 22.37(t·hm-2),respectively.The water holding capacity of each component showed a significant logarithmic relationship with the water holding time(R2>0.96),and the water holding rate was a power function with time(R2=0.999)in two litter layers.The soil bulk density of both forests increased with the thickness of the soil layer,while the total porosity and maximum water holding capacity were in contrast.The total porosity of the 0-20 cm soil layer was the largest,the poplar forest was 64.49%,and the birch forest was 71.96%.The maximum water holding capacity of the soil layer in poplar forest was lower than that in Betula platyphylla forest,which was 4775.80(t·hm-2)and 5228.60(t·hm-2),respectively,while the water holding capacity in poplar forest was higher than that in Betula platyphylla forest,which was 3663.58(t·hm-2)and 3785.18(t·hm-2).The litter layer and soil layer played important roles in soil conservation and water conservation of forest ecosystems.