高寒沙区人工沙棘对风沙危害的生态响应

目的]沙棘(Hippophae rhamnoides)是高寒沙区典型的优良治沙物种,其风沙危害的抗逆性研究对沙棘生态适应性机理及高寒沙区生物治沙工作具有重大的探究与指导意义。方法]对不同类型沙丘不同林龄的人工沙棘林进行了样方调查和风沙活动监测。结果]沙棘群落特征与地表风蚀强度变化具有时空同步性。轻度风蚀与中轻度沙埋现象有助于沙棘的生长与群落的发展,固定与半固定沙丘人工沙棘的株高冠幅均为流动型沙丘沙棘的3~6倍;沙棘各生长指标与株下蚀积深度具有显著的二次函数拟合关系,8年生沙棘生长的最佳沙埋深度在30—40cm。2008—2016年,各沙丘沙棘群落特征与局地输沙率、粗糙度、蚀积深度等风沙活动特征分别表现出显著的指数递减、多函数递增和二次函数先增后加减的变化规律。结论]高寒沙区沙棘对风沙危害的响应特征反映了沙棘良好的风沙适应能力,也指示沙棘造林技术需要注重立地条件选取、造林结构改进与多物种配置,保障沙棘的稳定生长势态与良好的生态修复效益。

Ecological Responses of Hippophae Rhamnoides to Wind-sand Hazard in Alpine Sand Land

Objective] Hippophae rhamnoides is a typical species that controlling alpine desertification. Study on the responses of this artificial plant to wind-sand hazard is of great importance in exploring the vegetation adaptive mechanism and directing the sand-control work.Methods] The annual vegetation quadrat survey and the sand surface erosion monitoring.Results] The H. rhamnoides community features have been found changed temporally and spatially with the sand surface erosion intensity. Firstly, patterns of light wind erosion and medium sand accumulation contributed to the plant growth and community development of H. rhamnoides. Comparatively, the average vegetation height and canopy in fixed or semi-fixed sand dunes were 3~6 times larger than that in mobile sand dunes. Secondly, significant parabolic relationships were found between the community features and the erosion/deposition depth with the optimal sand deposition depth of 30-40 cm for eight-years-old H. rhamnoides forest. Thirdly, the H. rhamnoides community features changed with the sand transport rate, surface roughness and annual erosion depth as significant fitting curve of exponential decline, multiple functions increase and quadratic increase, respectively.Conclusion] H. rhamnoides showed a strong resistance to wind erosion and sand-burial. A number of influential factors, including afforesting sites, forest structure optimizations and enrichment of other vegetation species, should be taken into accounts in protecting community succession and ecology restoration.