石羊河中游河岸植被及其护岸能力研究

Types and soil conservation capacity of riparian vegetation at middle reach of Shiyang river

调查分析石羊河中游河岸植被及其保护河岸能力可为河岸管理与植被恢复提供参考。通过植被组成与结构以及河岸地貌调查,选用植被密度、覆盖度、根系主分布层深度计算河岸植被的保持土壤能力指数。结果表明:石羊河中游的植被可分为12个群丛。灌丛或灌丛+乔木群落成块状或条带状夹在其他植被类型之间,成为河岸植被的骨架。从河岸完整性以及群落保持土壤能力指数综合判断,沼泽化草甸以及盐化草甸+灌木的护岸能力较强,其次为灌丛,再次为灌丛+乔木。河岸植被保护石羊河中游两岸,使其形成限制性河床,不仅增加了河岸稳定性,而且提高了防治灾害能力。

Shiyang River basin is one of the inland river basins where the ecological environment is strongly disturbed by artificial action which leads to the degraded environment.It is signality to study the riparian vegetation of Shiyang River for management and protection of bank and returning to ecological environment.The element and structure of the riparian vegetation at middle reach of Shiyang River was investigated,and the density of plant,coverage ratio,the spreading depth of root density,vegetation type and biotype of dominant species were employed to comprehensively evaluate the riparian vegetation for protecting bank.The results are as follows： there are 11 associations.The shrubland or tree-shrub forest,which is the support of the riparian vegetation,thread amount others of vegetation.The number of coverage ratio and density of swamp-meadow are the biggest,but the depth of root is shallow and simple,so the meadow ＋ shrub with second of coverage ratio and density and more depth of root have the strong capacity to protect the bank.The shrubland that is constituted of by Tamarix ramosissima or Salix lineaisriputlaris is stronger to protect bank than that of tree-land with Populus gansuensis or Elaiagnus angustifolia,and it is easy that margin of bank breakdown with trees.The riparian vegetation not only makes up stable bank,but also prevents damage from flood.