新疆博尔塔拉河表土孢粉组合与植被关系研究

博尔塔拉河流域位于中哈边境,其植被和土壤具有十分明显的垂直分布和区域性差异,根据该流域一条自西向东沿着海拔高度从210 m 到3 235 m 长约200多km的样带上所采集的人为干扰较少的49 个表土花粉样品的孢粉组合图式和现代植被样方调查资料,探讨了博尔塔拉河流域植被与表土花粉之间的关系。该区孢粉谱从上至下可划分为6个带,分别对应高山草甸带、亚高山草甸草原带、森林灌丛带、灌丛草原带、荒漠草原带、荒漠植被带。值得注意的是第6个孢粉带因含有具湿地特征的隐域性植被类型花粉组分,故又分成2个亚带,即荒漠植被亚带Ⅵ₁和荒漠植被亚带Ⅵ₂。森林灌丛植被带上限的云杉花粉含量明显比该带下限的含量高,表明云杉花粉的传播在沟谷地区受山谷风的影响较大。与此同时,将孢粉数据与气象数据相结合,分析结果得出比较有代表性的云杉属(Picea)、桦属(Betula)、藜科(Chenopodiaceae)、麻黄属(Ephedra)等花粉,与降水量和温度的关系较为密切。

Surface Pollen Assemblages and Vegetation Relationships in the Bortala River Basin of Xinjiang,China

The Bortala River Basin is a distinct vertical gradient distribution area of vegetation and soil types at the arid region of the northwest China. According to the data of vegetation plots and pollen assemblages of 49 modern pollen samples,which were collected along an altitudinal gradient from 210 to 3 235 m belonging to the Bortala River Basin (Xinjiang, China), we analyzed the relationship between vegetation and surface pollen assemblages. The 49 surface samples were divided into six pollen zones (alpine meadow zone, subalpine meadow and steppe zone, forest-shrub zone, shrub steppe zone, desert steppe zone, desert vegetation zone) based on modern vegetation data and characteristics of the surface pollen spectra. Desert vegetation zone was separated into two subzones (desert vegetation subzone and desert with intrazonal vegetation subzone). The valley wind might help to improve the pollen transportation, but the percentages of Picea pollen in the upper limit of the forest-shrub zone were higher than those detected in the lower limit, suggesting that the upslope wind had a stronger impact on the transportation of Picea pollen than the downslope wind. Moreover, there was a good relationship between elevation, the climatic factors (temperature and precipitation) and the typical pollen taxa (Picea, Betula, Chenopodiaceae and Ephedra).