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苏联草原地区强度农业耕作的地方,表层土壤经常遭受风蚀.其风蚀程度决定于土壤的特性.例如,当风速为20—24米/秒时,典型重粘壤黑土的侵蚀每小时达到0.01—0.3吨/公顷,暗粟色和粟色壤土为0.3—14.5吨/公顷,而沙壤质和沙质黑土、粟色土的损失,达到62吨/公顷.为了使土壤免受风蚀,以提高农作物的产量,在草原地区设计和营造了防护林带体系.如果按照农业区域内风的状况,土壤对于风的抗性,以及其他风蚀因素来选择林带体系参数的话,那么林带的土壤防护效果将特别高.制约林带体系土壤改良效果的参数是:林带高度、林带结构、主林带走向、下垫面粗糙度,林带横断面的形状及林带之间的距离等.林带高度:在垂直的和水平的方向上影响着防风区域的长度,因而影响着林带之间的距离.林带高度依赖于林分的组成,乔木树种的年龄和配置、立地条件和营林技术.林带结构:和高度一样,是林带体系非常重要的空气动力学参数,决定着林带之间的距离.依据现有的分类,划分为三种主要的林带结构(表1).林带的结构依赖于林分的组成,林分的成层现象,林冠高度(这里和以后是指从地面到第一个活枝的距离),行数和乔灌木树种的配置.
Where intense agricultural practices in the Soviet steppe region, surface soils often suffer from wind erosion, the degree of wind erosion depends on soil properties, for example, erosion of typical heavy-loamy blacks reaches 0.01-0.3 per hour at wind speeds of 20-24 m / s Ton / ha, dark brown and millet loam 0.3-14.5 t / ha, while loss of sandy loam and sandy black and soils to 62 t / ha To help prevent soil erosion from wind erosion, Production and design of shelterbelt system in the grassland area, the soil protection effect of the forest belt will be particularly high if the forest system parameters are chosen according to the wind conditions within the agricultural area, the resistance of the soil to wind and other wind erosion factors. The parameters which control the soil improvement effect of forest belt system are: forest belt height, forest belt structure, main forest belt direction, underlying surface roughness, shape of forest belt cross section and distance between forest belt, etc. Height of forest belt: in vertical and horizontal direction Affecting the length of the windbreak and thus the distance between the shelters.The shelterbelt is highly dependent on the composition of the stands, the age and configuration of tree species, site conditions and silvicultural techniques. As with altitude, which is a very important aerodynamic parameter of the forest belt system, determines the distance between the forest belts and is divided into three main forest belt structures (Table 1) according to the current classification. The structure of the forest belt depends on the forest The composition of the points, the stratification of the stands, the height of the canopy (here and beyond refer to the distance from the ground to the first live branch), the number of rows and the configuration of the tree and shrub species.