黄土高原不同林地类型水土保持效益分析

Different Types of Vegetation Cover and Water Conservation Benefits

研究黄土高原北部水蚀风蚀交错区——陕西吴起县退耕还林以来各林地的水土保持效益,对油松沙棘混交林(Pinus tabuliformis+Hippophae rhamnoides)、沙棘林地(Hippophae rhamnoides)、油松林地(Pinus tabuliformis)、达呼里胡枝子+赖草地(Lespedeza davurica+Leymus secalinus)径流小区的产流产沙情况、土壤物理性质(土壤孔隙度和容重)、土壤抗冲性、土壤水分状况进行分析。得出以下结论:(1)不同植被类型的林地土壤抗冲性有明显的差异,相同植被类型的林地抗冲性随坡度的增大而降低;林草植被措施具有极强的提高土壤抗冲性的能力;(2)达呼里胡枝子+赖草地、油松林地的径流量最大,油松沙棘混交林的径流量次之,沙棘林地径流量最小;植被类型相同但坡度不同的林地,坡度大的林地地表径流量高;每种林地的径流量随着降雨强度的增大而增大;(3)侵蚀模数按从小到大的林地顺序是:沙棘纯林、沙棘油松混交林、达呼里胡枝子+赖草、油松林地;在植被类型相同、坡度不同的小区,地表径流量和侵蚀模数随坡度增大而增大。从5个径流小区水土保持效益分析结果看,试验小区保水保土效益油松林地最低,其中沙棘纯林水土保持效益最为显著,说明退耕还林后,林草植被的恢复及土壤物理性质的改良,减少了风力、水力等外营力的破坏,能有效地控制水土流失。

The northern Loess Plateau wind erosion crisscross region of the forest since Wuqi county Shaanxi province soil and water conservation forest efficiency.Pinus tabuliformis＋Hippophae rhamnoides、Hippophae rhamnoides、Pinus tabuliformis,of calling depends on where Lespedeza davurica＋Leymus secalinus runoff and sediment runoff conditions,soil physical properties（soil porosity and bulk density）,soil erosion resistance,soil moisture were analysised.Could draw the following conclusions：（1）Of different vegetation types of soil erosion significantly different,the same type of forest vegetation in erosion resistance decreased with increasing slope;vegetation measures soil erosion was extremely sexuality.（2）Of calling in Lespedeza davurica＋Leymus secalinus,Pinus tabuliformis to the maximum runoff,followed by Pinus tabuliformis＋Hippophae rhamnoides runoff,runoff Hippophae rhamnoides minimum;vegetation types in the same forest but different slope,a large forest of high surface runoff;each forest runoff increased with rainfall intensity runoff increasing.（3）The erosion of forest land from small to large number of the order was： Hippophae rhamnoides、Pinus tabuliformis＋Hippophae rhamnoides、Lespedeza davurica＋Leymus secalinus、Pinus tabuliformis;in the same vegetation type,slope different cell,surface runoff and erosion modulus increased with the slope.Soil runoff from the 5-benefit results of analysising,the experimental plot water and soil conservation benefited to the lowest Pinus tabuliformis,and water conservation benefited of Hippophae rhamnoides which the most significant,indicating that after returning farmland to forests,with the restoration of vegetation and soil improvement of the physical structure,reducing the wind,water loaded with forces,but the damage,could effectively control soil erosion.