三峡库区典型退耕还林模式水土保持功能研究

Soil and Water Conservation Functions of Typical Returning Farmland to Forest Mode of the Three-Gorge Reservoir Area

为评估退耕还林工程对流域水土流失的控制效应,选择三峡库区典型退耕还林模式(茶园、柑橘园、板栗林),以坡耕地为对照,观测和分析不同退耕模式下土壤物理性质及径流泥沙输出情况,结果表明:茶园、板栗林、柑橘园与坡耕地比较,年径流输出量平均减少了17.92%,大小关系为板栗林(110.71 m^3/hm^2)<柑橘园(164.16 m3/hm^2)<茶园(171.74 m3/hm^2)<坡耕地(181.38 m3/hm^2),板栗林径流量显著小于其他三种模式;年泥沙输出量大小关系同样为板栗林(141.92 kg/hm^2)<柑橘园(343.78 kg/hm^2)<茶园(394.79 kg/hm^2)<坡耕地(1 210.77 kg/hm^2),退耕模式相对于坡耕地泥沙输出量显著减少,平均减少了75.76%;退耕后土壤水分物理性质得到很大改善,退耕还林模式土壤容重降低,毛管孔隙度、非毛管孔隙度和总孔隙度增加,有利于水土保持功能的发挥。说明退耕还林后新形成的林地和园地具有较好的蓄水保土效益,对小流域的水土流失控制和土壤改良作用明显。

In order to evaluate the effect of returning farmland to forest works to the soil and water loss control of watersheds,the paper observed and analyzed the soil physical properties and runoff and sediment yield under the conditions of different modes of returning farmland to forest by taking slope farmland as contrast and selecting the typical mode of returning farmland to forest( tea garden,citrus orchard and Chinese chestnut forest) of the Three-Gorge Reservoir area. The outcomes show that a) comparing tea garden,Chinese chestnut forest and citrus orchard with slope farmland,the annual outflow of runoff has reduced 17.92 % in average and the order is as follows: Chinese chestnut forest( 110.71 m3/ hm^2) < citrus orchard( 164.16 m^3/ hm^2) < tea garden( 171.74 m^3/ hm^2) < slope farmland( 181.38 m^3/ hm^2). The runoff volume of Chinese chestnut forest is significantly smaller than that of the other three modes; b) the order of annual sediment yield is also the same rule as Chinese chestnut forest( 141.92 kg / hm^2) < citrus orchard( 343.78 kg/hm^2) <tea garden( 394.79 kg/hm^2) < slope farmland( 1 210.77 kg/hm^2). Comparing with the slope farmland,the sediment discharge of returning farmland to forest mode decreases significantly,averaging reduced by 75.76% and; c) after returning farmland to forest,the soil water physical properties have been improved greatly. Comparing with slope farmland,the soil bulk density of returning farmland to forest mode is reduced and capillary porosity,non-capillary porosity and total porosity are increased,being beneficial to the play of soil and water conservation function. It shows that the newly formed woodland and orchards have better benefits on soil and water conservation and have remarkable effects on soil and water loss control and soil improvement of small watersheds.