毛乌素沙地沙柳人工林最优平茬周期的确定

摘要 针对毛乌素沙地沙柳人工林衰退问题，从防风固沙角度探讨沙柳林最佳平茬周期，为今后平茬作业提供理论依据。以毛乌素沙地丘间低地沙柳人工林为研究对象，测定平茬后不同林龄沙柳林林内粗糙度和风速廓线与林后沙丘迎风坡粗糙度，分析确定出兼顾沙柳特殊平茬生态学特性和防风固沙效益的最佳平茬周期。试验结果表明：沙柳在平茬后第4a，林内粗糙度呈现最大值，地表比较稳定，之后开始出现下降趋势；沙柳林林后沙丘迎风坡的粗糙度在平茬后初期，地表粗糙度低于起沙时粗糙度，易发生风蚀现象，之后随着沙柳的生长，平茬后第3a开始，林后7H（H为沙柳平均高度）内地表粗糙度均大于起沙时粗糙度，沙柳林对林后迎风坡防护效果较好，而4a后，沙柳林防风能力下降，地表粗糙度下降，地表抗风蚀能力减弱。研究得出沙柳林最优的平茬周期为4年。

Determination of optimum stump period of Salix psammophila plantation in Mu Us Sandy Land

Abstract] Aiming at the decline of Salix psammophila plantation in Mu Us Sand Land, the best stumping period of Salix psammophila forest was discussed from the perspective of wind and sand fixation, which provided a theoretical basis for the future operation. The research on the roughness length and wind speed profile of Salix psammophila forest and the windward slope of post-forest sand dune in the low forest area of Mu Us Sandy Land was carried out to determine the special characteristics of Salix psammophila special flat The beststumping period of ecological characteristics and wind and sand fixation benefits. The results showed that: in the 4a year after the sorghum, the roughness length of the forest showed the maximum, the surface was stable, and then began to decline. The roughness length of the windward slope of the sand dune after the sand willow forest was lower than that at the beginning of the flat ridge. The roughness length of sand is prone to wind erosion. After the growth of Salix psammophila, the surface roughness length of 7H (H is the average height of Salix psammophila) in the post-forest period is greater than that of sanding. Salix psammophila forest has a better protective effect on the windward slope after the forest, and after 4a, the sand-proof ability of Salix psammophila forest decreases, the surface roughness length decreases, and the surface wind erosion resistance decreases. The study concluded that the optimal stumping period of Salix psammophila forest is 4 years.