中文摘要：

选择华南海岸典型沙地, 采用全挖法, 对4种典型沙生植物木麻黄（Casuarina equisetifolia）、厚藤（Ipomoea pes-caprae）、老鼠艻（Spinifex littoreus）和狗牙根（Cynodon dactylon）的根系构型进行了研究。结果表明： 1）狗牙根和老鼠艻的根系总体分支率显著高于木麻黄, 厚藤最小, 说明大部分草本植物在生长过程中通过增加根系分支率, 提高物质传输效率, 除木麻黄外, 其他3个物种枝系均平卧伸展, 易于受到沙埋生出不定根, 进一步提高其物质传输效率; 2） 4种沙生植物根系平均连接长度最大的为木麻黄, 平均连接长度为19.25 cm, 且相对其他3个物种传导根所占的比例最大, 说明木麻黄通过增加平均连接长度以减少根系内部对土壤资源的竞争, 并提高传导根的比例, 以增加资源传输效率; 3） 4种沙生植物根系构型均倾向于叉状分支, 其中草本植物的根系构型更为接近, 说明草本植物受到的资源胁迫相对较小, 有利于在海岸沙地恢复中快速定居; 与内陆地区沙生植物相比, 海岸沙生植物在土壤资源的获取及空间拓展方面表现出显著的差异, 反映出不同生境条件下物种对生境胁迫的适应策略。因此, 海岸沙地前缘植被恢复应以草本植物为主, 尤其是具有不定根的物种, 乔木则不适合。

英文摘要：

Aims Roots are an important part of plants; they not only facilitate the utilization of soil water and nutrients, but also successively anchor the plants against wind and water wave erosion. This study was conducted to determine the adaptive strategy of root architectural characteristics in different plant life forms, in order to assist the selection of most suitable plant species for the coastal dune restoration. Methods After a detailed field investigation of sand dunes in South China, four species were sampled on a damaged coastal sand dune, including Casuarina equisetifolia, Ipomoea pes-caprae, Spinifex littoreus and Cynodon dactylon, and roots were excavated for analyzing their architectural characteristics such as root bifurcation ratio, root link length, root topological index and root-shoot ratio. Important findings There were great differences as well as similarities in the root architectural characteristics among the four plant species. The total root bifurcation ratios in Spinifex littoreus and Cynodon dactylon were apparently higher than in other two species, and was lowest in Ipomoea pes-caprae, indicating that herbaceous plants are more competitive for soil resources by having a higher root bifurcation ratio. With except of Casuarina equisetifolia, all other three species were easily sand buried due to their flatten and extended shoots, which might further improve the transportation efficiency of soil resources. The average root link lengths of the four species were smaller in coastal sandy dunes than which in inland areas; Casuarina equisetifolia had the greatest average root link length of 19.25 cm among the four species studied, and greater proportion of transportation roots than other three species. This demonstrated that an increase in average root link length and proportion of transportation roots would favor the reduction of root competition for soil resources and high efficiency of resources transportation. Ipomoea pes-caprae had a smaller proportion of the assimilation roots, but the adve