珠穆朗玛峰绒布沟西藏沙棘生境类型及海拔梯度下表型变异

Habitat Types and Phenotypic Variation of Hippophae tibetana along an Altitudinal Gradient in the Rongbu Valley of Mt. Everest, Tibet, China

西藏沙棘(Hippophae tibetana)是沙棘属中最进化的种类,也是青藏高原上分布较广的沙棘种类.但是目前几乎未见关于西藏沙棘的基础生态学研究报道.根据珠穆朗玛峰绒布沟沿海拔梯度进行的西藏沙棘群落样方调查,采用二元指示种分析(TWINSPAN)法和去势对应分析(DCA)法,研究了海拔梯度下西藏沙棘的生境类型、影响其分布的环境主导因子和表型变异规律.结果表明,珠峰绒布沟西藏沙棘生境可以分为5个类型:河边砾石滩地、河谷灌丛草地、沙石滩地、草甸和柳树林缘.DCA排序结果反映其群落的分布和生长主要受海拔和土壤湿度两种环境主导因子的影响.通过有关数据的回归分析发现,西藏沙棘植株的叶宽、基径、高度和盖度都随海拔的升高呈显著减小的趋势,但叶片长度与海拔不显著相关.西藏沙棘的盖度随样方与河水实际距离的增大而减小.

Hippophae tibetana is the most advanced species in its genus and also a widely distributed species in the Qinghai- Tibetan Plateau, China. But, so far no ecological study on this plant has been undertaken. This paper aims to investigate the habitat types, environmental factors and phenotypic variation of H. tibetana along an altitudinal gradient in the Rongbu Valley in the area of Mt. Everest. Based on the survey of plots,TWINSPAN and DCA were performed to classify the habitat types and find main environmental factors. The regression analysis was performed to know how the altitude affected the leaf width, leaf length, base diameter, height and coverage of H. tibetana. At the same time, the relationship between coverage of H. tibetana and its location distance from riverside was also detected. The results of TWINSPAN and DCA showed that the habitat of H. tibetana could be classified into five types, gravel riverside, shrub grasslands, sandy riverside, meadow and Salix forest. DCA results also indicated that both altitude and soil moisture were the main environmental factors affecting the distribution and growth of H. tibetana. Linear regression analysis showed that the leaf width, base diameter, height and coverage of H. tibetana significantly decreased with increasing of altitude. However, there was no significant relationship between altitude and leaf length. The coverage of H. tibetana significantly decreased with increasing of its location distance from riverside. Fig 3, Tab 2, Ref 31