乌兰布和沙漠东北缘人工梭梭林防风效能分析

目的]测定乌兰布和沙漠东北缘不同林龄各坡位的风速,揭示梭梭林防风效能随林龄的变化规律以及与梭梭空间构型的关系。方法]以乌兰布和沙漠东北缘种植3,5和8a的人工梭梭林为研究对象,通过测定林内及CK不同坡位距地表10,20,50,100,200cm高度处风速,对比不同年限梭梭林的防风效能。结果]随着林龄的增加,梭梭林对近地表风速减弱作用增强;同一坡位下,3a梭梭林防风效能主要作用在0—100cm高度内,防风效能为48.19%,100—200cm高度内风速迅速恢复。5,8a梭梭林对0—200cm高度范围均有很好的防护作用,防风效能分别为69.72%,71.93%,二者间减弱效果差异不明显。相关分析显示梭梭林空间构型与防风效能显著相关,梭梭盖度、高度、冠幅与防风效能的相关性分别达到0.935,0.930,0.942。结论]3a梭梭林迎风坡底、背风坡的防风效能优于迎风坡中、迎风坡顶,5,8a梭梭林与之相反。

Windbreak Effectiveness of Haloxylon Ammodendron on Northeast Edge of Ulan Buh Desert

Objective] Wind speeds at different slope positions of Haloxylon Ammodendron forest were investigated on the northeast edge of Ulan Buh desert, in order to reveal the variation of windbreak effectiveness of Haloxylon ammodendron with plantation age and spatial pattern.Methods] Forests of H. ammodendron at 3 a, 5 a and 8 a plantation ages were selected as research objects. The wind speeds at 10 cm, 20 cm, 50 cm, 100 cm, 200 cm heights above ground were measured respectively in the bottom, middle and top of windward slope and bottom of leeward slope for windbreak effectiveness analyzing.Results] The wind speed near ground surface declined with the increase of plantation ages. Windbreak effectiveness of 3 years'' shrub was mainly found in 0-100 cm height, the averaged value was 48.19%. At 100-200 cm height, wind speed rebounded to the CK value quickly. Good windbreak effect were found both in 5 years and 8 years forests at height 0-200 cm, and their windbreak efficiency were 69.72% and 71.93% respectively. Correlation analysis showed that there existed a significant correlation between plantation pattern and windbreak effect. The correlation coefficients between windbreak effect and forest coverage, height and crown width were 0.935, 0.930, 0.942 respectively.Conclusion] Windbreak effects in the bottom of windward slope and leeward slope were better than those in the middle and top of windward slope of 3 years forest. It was contrary for the forests having 5 years and 8 years plantation ages.