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山西北部地区处于毛乌素沙漠前沿,是暖温带落叶阔叶林向温带干旱草原的过渡带。20世纪50-60年代当地营造了大面积的小叶杨(Populus simonii)人工林,形成了以林网为主体的农田防护林体系,对防治农田土壤风蚀起到了重要的作用。近年来,在旧林带更新改造中,对林带结构、树种配置缺乏技术,表现出在营造林带中有较大盲目性。为了对防护林今后的发展提供科学依据和方法,1996-2001年作者在山西北部的朔州、大同等地设置了定位调查观测点,使用轻便式风速风向仪、通风干湿球温度计、地温计、玻璃皿对小叶杨不同结构林带的防风功能进行了调查研究。提出了农田防护林的设计应以树木展叶期的防风能力为指标,以疏透结构为最佳配置,初植株行距为2 m3 m,4-6行配置,5年后可形成疏透结构林带。表4参13。
The northern part of Shanxi Province is at the forefront of the Muusu Desert and is the transition zone between warm temperate deciduous broad-leaved forests and temperate arid steppe. In the 1950s and 1960s, a large area of populus simonii plantation was built locally, forming a farmland shelter forest system with forest net as the main body, which played an important role in preventing wind erosion of farmland soil. In recent years, in the renovation and transformation of the old forest belts, there is a lack of technology for the structure of the forest belt and the allocation of tree species, which shows that there is a greater blindness in the construction of forest belts. In order to provide a scientific basis and method for the future development of shelterbelt, the author set up the survey and observation points in Shuozhou and Datong in the north of Shanxi Province from 1996 to 2001, using the portable anemometer, ventilation dry and wet bulb thermometer, Glass dish of Populus simon different structure of the windbreak function were investigated. It is proposed that the design of farmland shelterbelt should be based on the windbreaking ability of trees during the leaf-setting stage and the structure of dredging should be the best configuration. The initial plant spacing is 2 m3 m and 4-6 rows. After 5 years, . Table 4 Reference 13.