甘肃亚高山云杉人工林土壤特性及水源涵养功能对林分密度的响应特征

Effects of Stand Density on Soil Properties and Water Conservation Function of Picea asperata Plantation in the Subalpine Region of Gansu Province

定量分析不同密度云杉(Picea asperata)人工林的土壤特性及水源涵养功能,为人工林可持续经营提供理论依据。以28块7种不同密度梯度的云杉人工幼龄林为研究对象,采用样地调查及取样分析方法,测定土壤理化性质、枯落物持水量以及林地贮水性能等。结果表明:1)林分密度对云杉人工林的土壤容重、孔隙度、有机质含量、土壤持水量、枯落物蓄积量和持水量都具有显著影响,随着林分密度的增加,土壤孔隙度、土壤养分、枯落物蓄积量、枯落物持水量、土壤持水量表现为先增加后减小,而土壤容重则表现为先减小后增加。密度为1 550株/hm2时林分土壤容重最小(1.09 g/cm3),总孔隙度较大(58.99%),有机质含量最高(9.12%),枯落物总蓄积量最多(44.41 t/hm2),最大持水量较高(166.67 t/hm2),是密度为3 000株/hm2林分的4.49倍,土壤持水性能较好(3 898.93 t/hm2)。2)根据林地总贮水量评价的涵养水源功能依次为林分密度1 550株/hm2(4 068.36 t/hm2)>密度1 750株/hm2(3 945.32 t/hm2)>密度1 350株/hm2(3 698.39 t/hm2)>密度1 060株/hm2(3 484.10 t/hm2)>密度2 300株/hm2(3 157.60 t/hm2)>密度850株/hm2(2 915.03 t/hm2)>密度3 000株/hm2(2 820.81 t/hm2)。3)在该研究的林分密度范围内,密度为1 550株/hm2时林分的土壤特性及水源涵养功能最佳。

This paper aims to quantitatively analyze soil properties and water conservation function of Picea asperataa plantations with different stand densities and provide a theoretical basis for sustainable management of forests. Totally 28 plots with seven different densities in young Picea asperata plantation were investigated, and soil properties, water-holding capacities of litter and soil in these plots were measured. The results showed that： 1） Stand density has significant influence on soil bulk density, total porosity, organic matter content, soil water-holding capacity, litter accumulation, and litter water-holding capacity. With the increase of density, soil porosity, soil nutrient, litter accumulation, water-holding capacities of litter and soil all increase at first and then decrease, while bulk density decreases at first and then increases. The plantations with moderate density（1 550 trees/hm^2） have the lowest soil bulk density（1.08 g/cm^3）, the greatest total porosity（58.99%）, the highest organic matter contents（9.13%）, the most litter accumulation（44.41 t/hm^2）, good soil water-holding capacity（3 898.93 t/hm^2）, and the highest litter water-holding capacity which is 4.49 times of that of plantation with density of 3 000 trees/hm^2. 2） Based on the total water-holding capacity of litter and soil, water conservation function of the seven different stand densities in order are density of 1 550 trees/hm^2（4 068.36 t/hm^2）, density of 1 750 trees/hm^2（3 945.32 t/hm^2）, density of 1 350 trees/hm^2（3 698.39 t/hm^2）, density of 1 060 trees/hm^2（3 484.10 t/hm^2）, density of 2 300 trees/hm^2（3 157.60 t/hm^2）, density of 850 trees/hm^2（2 915.03 t/hm^2）, and density of 3 000 trees/hm^2（2 820.81 t/hm^2）. 3） According to this study, the forest with density about 1 550 trees/hm2 showed better soil properties and water conservation ability than other forests.