【摘要】 本文利用挖掘法和渐近方程y=1 -βd( β为深度系数 ,d为土壤深度 (cm) ,y为地表到土层d的根面积比例 ( 0～ 1 )揭示半干旱毛乌素沙地不同生境中常绿灌木沙地柏根面积分布特征。结果表明 :( 1 )根面积指数(根面积 /地表面积 )随土壤水分可利用性降低而减小 ,这种格局有利于减缓植株地下部分对水分的竞争 ,从而经济、长时间地利用有限水分资源 ;( 2 )深度系数 ( β)、最大根系深度 (Rmax)、含 50 %总根面积的根系深度 (R50 )和含 90 %总根面积的根系深度 (R90 )均随水分可利用性降低而增大 ,这表明沙地柏可通过增大根系深度以补偿土壤水分的降低 ;( 3 )根面积分布特征既可能记载了生境中水分状况的变化 ,又可在一定程度上为群落动态提供证据更多还原

【Abstract】 To explore distribution characteristics of root area of the evergreen shrub, Sabina vulgaris growing in the contrasting habitats in semi\|arid Mu Us sandland,the methods of root excavation and asymptotic equation y=1-β d(β =depth coefficient, d= soil depth (cm), y= fraction of root area from soil surface to depth d )were used in this paper.The results showed as follows:(1)Root area index( RAI= root area/soil surface area,m 2/m 2)decreased with decreased soil water availability,which benefits to alleviate below-ground competition of the plants for water and to make better economical use of the limited water resource in the long run.(2)The values of β (depth coefficient)\, R max (maximum depth of root system)\, R 50 (depth of root system including 50% total root area)\, R 90 (depth of root system including 90% total root area)increased with decreasing soil water availability,which means that depth of root system of \%S.vulgaris\% has compensation effect for decreasing water content of soil through deepening its depth.(3)Distribution characteristics of root area might record the change of water regime in the habitats,could provide some evidence on community succession to some extent as well.更多还原