白桦次生林4个林龄0～30cm土层水源涵养功能比较

以小兴安岭地区白桦次生林4个林龄为研究对象,对其凋落物持水量、土壤贮水性能、土壤特性等进行研究.试验表明：4个林龄凋落物的蓄积量和最大持水量是70 a为最低,40 a为最大;土壤非毛管孔隙度在各林龄间变化呈波动性,30 a白桦次生林0～30 cm土层非毛管孔隙最小,不利于水分下渗,40 a白桦次生林0～ 30 cm土层非毛管孔隙最大,有利于降水的下渗,土壤水源涵养功能大小排序为40 a（3 276.820 t·hm-2）＜30 a（3 434.626 t·hm-2）＜50 a（3 525.015 t·hm-2）＜70 a（3 629.445 t·hm-2）.

Comparison of Water Conservation Function in 0-30cm Soil Layer of Betula Platyphylla Secondary Forest at Four Stages

Four stages of betula platyphylla secondary forest in the Xiaoxing＇anling Mountains were investigated and the water holding capacity of litter, water storage performance of soil, soil characteristics and other indices were studied. Results showed that both of the litter volume and water holding capacity of litter were the lowest in the 70 - year-old betula platyphylla secondary forest and the 40 - year-old forest had the maximum values among the four stages of forest. The non-capillary soil porosity varied among the four stages of forest. It was not beneficial for rainfall infiltration through the 0 - 30cm soil layer of the 30 year-old of betula platyphylla sec- ondary forest, since the non-capillary soil porosity was the minimum, while the 40 year-old forest with very large non-capillary porosity was beneficial to rainfall infiltration. The orders of the soil water conservation function of the four stages of betula platyphylla secondary forest were： 40a （3276.82t.hm-2） 〈 30a （3434.626t.hm-2） 〈 50a （3525.015t.hm-2） 〈70a （3629.445t.hm-2）.