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作 者 ：周士威 程致力 尹洁芬

期 刊 ：林业科学 1987年 23卷 1期 页码：11-23

关键词：防风；

摘 要 ：本实验采用野外模式林带的观测与风洞模拟实验相结合的方法,探讨了三种结构林带的防风性能和机制:林带垂直和水平影响范围分别达到4H和50H左右(测试仪器NLF2型四道电子风速仪,精度±0.5m/sec),透风系数为0.35的疏透结构林带减低风速20%的有效防护距离(L₍₂₀₎)为18.5H;林带影响下的风速与湍流度的大小呈密切的负相关(r=-0.94)。同时提出了一个评价林带防风效应的新指标——隙高比(X_i),并阐明了如何应用隙高比值与林带的行距、行数的关系,来规划设计防风林带以及判断现有林带的防风性能。文中按有效防护距离(L₍₂₀₎)给出了1—8行通风结构林带各行的最佳隙高比值。

Abstract:This paper, based on a way experimented in the open and windtunnel, puts forward a new index, X_i (a ratio of the average gap between the crown of one tree and the other to average height of the belts), which can evaluate the effect of shelterbelts. Research has shown that X_i is useful for planning and designing shelterbelts and can also judge the sheltering effect of belts growing in the fields. The protected character and mechanism of three types of belts are also studied in the paper. The results are briefly summarized as follows:1. The influence range of different types of belts extends about 4H in the vertical range and 50H in the horizontal range. The distance where wind speed reductions are still at least 20 per cent occurs 18.5H behind belts with a permeability of 35 per cent. The value of wind speed in the lee of belts is closely related with turbulence (r=-0.94).2. X_i is a important index for expressing the effect of the belts on air flow as well as permeability. The optimum X_i for each row in the belts having 1-row to 8-rows was given in the paper.

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