中文摘要：

以章古台沙地樟子松（10、22、32、42年生）人工林细根为对象，采用根钻法分析不同土层细根（直径≤2mm）根长密度和根面积指数的垂直分布特征，探讨其与土壤含水量的关系。结果表明：随着樟子松林龄增加，细根根长密度和根面积指数呈现出先升高后降低的趋势，在32a达到最大，显著高于其它林龄（P〈0．05）。樟子松林50％的细根长度和面积分布在0～37．6cm，32年生樟子松林细根分布削弱系数为0．981，大于其它林龄。10、42年生樟子松林细根根长密度和根面积指数与土壤含水量呈显著正相关（P〈0．05），而32年生樟子松林细根与土壤含水量不相关（P〉0．05）。以上结果说明，32年生樟子松林细根根长密度更高，面积更大，分布更深，但过度消耗了水资源。

英文摘要：

With different aged （10, 22, 32 and 42 years） Pinus sylvestris var. mongolica plantations on sandy land, an experi- ment was conducted to study the relationship of soil water content using soil coring, the fine root vertical distribution char- acters by measuring root length density and root area index of live fine root at different soil layers. The fine root length den- sity and root area index firstly rose, and then decreased with the increasing of age. 32 years old P. sylvestris var. mongoli- ca plantation was significantly higher than other aged stands （P〈0.05）. 50% of fine root length and area of P. sylvestris var. mongolica plantation was at 0-37.6 cm soil layers. The root extinction coefficient was 0. 981 for 32 years old P. syl- vestris var. mongolica plantation, higher than that of the other aged stands. There was significantly positive linear correla- tion between root length density and soil water content, and root area index and soil water content for 10 and 42 years old P. sylvestris var. mongolica plantations （P〈0. 05 ）, but the relationships were not significant for 32 years old （ P〉0.05 ）. These results indicated that the fine root length and area were higher, distributed deeper at 32 years old P. sylvestris var. mongolica plantation than those of other aged stands, but they excessively consumed the water.