沙蒿与油蒿灌丛的防风阻沙作用

Wind prevention and sand resistance effects of Artemisia sphaerocephala and Aordosica

沙蒿与油蒿广泛分布于我国沙漠地区,是沙地植被的重要建群种和优势种。在腾格里沙漠南缘半流动沙地,实测了两种典型固沙植物沙蒿与油蒿的防风阻沙作用,从灌丛空间构型对比分析了其防风阻沙机制。结果表明,沙蒿与油蒿灌丛均具有明显的降低风速作用,但油蒿灌丛较沙蒿灌丛具有更显著的防风作用,而且对灌丛后不同位置、近地面不同高度层风速的降低程度明显不同。在灌丛后6倍株高范围内,沙蒿灌丛对50cm高度风速降低程度显著大于20cm,而油蒿灌丛对近地面20cm高度层风速降低程度显著大于50cm。在相同风速下,油蒿灌丛后20cm高度平均风速是沙蒿灌丛的1/2,而50cm高度平均风速与沙蒿灌丛相近。同时,沙蒿灌丛阻沙作用弱,而油蒿灌丛具有明显的阻沙作用,单株积沙体积达到45.2±16.1dm3,积沙重量达到72.1±25.7kg,油蒿灌丛积沙量大小与灌丛结构间存在显著的正相关。研究表明,紧密型结构的油蒿灌丛是较松散型结构沙蒿灌丛更为理想的防风固沙植物,其灌丛分枝数多、分枝角度小、生物量大且多分布在近地面层是具有显著防风阻沙作用的根本原因,该结论可为干旱区防风固沙植被建设物种选择提供依据。

Artemisia sphaerocephala and A.ordosica are the two typical desert Artemisia species widely distributing in desert areas,and also,the important dominant species in sand-binding vegetation.In this study,a field survey was conducted on the wind prevention and sand resistance effects of A.sphaerocephala and A.ordosica at the southern edge of the Tengger Desert,with the related mechanisms analyzed.Both A.sphaerocephala and A.ordosica were effective in reducing wind speed,and A.sphaerocephala was more effective than A.ordosica.The reduction degree of the wind speed at different positions at the back of the plants and at different heights above ground surface had distinct difference.At the positions from zero to six times plant height at the back of the plants,the wind speed reduction degree of A.sphaerocephala at the height of 50 cm above ground surface was obviously bigger than that at the height of 20 cm,but the wind speed reduction degree of A.ordosica at the height of 20 cm above ground surface was obviously bigger than that at the height of 50 cm.At the same wind speeds,the mean wind speed at the height of 20 cm at the back of A.ordosica was half of that of A.sphaerocephala,but the mean wind speed at the height of 50 cm of A.ordosica was near to that of A.sphaerocephala.A.sphaerocephala was weak whereas A.ordosica was stronger in sand resistance.The sand accumulation volume of A.ordosica reached 45.2±16.1 dm3,and its sand accumulation weight was 72.1±25.7 kg.There was a significant positive correlation between single plant sand accumulation volume and spatial structure of A.ordosica.A.ordosica（with compact architecture） was considered better than A.sphaerocephala（with loose architecture） in wind prevention and sand resistance.A.ordosica was characterized by more primary branches,small branching angle,and large biomass distributing at near-surface layer,which contributed to the strong effect of the plant in wind prevention and sand resistance.This conclusion provided an important basis for the species selection of sand-binding vegetation construction in arid areas.