新疆喀什噶尔河岸植被对地下水埋深的退化响应

Degradation response of riverbank vegetation in Kashgar,Xinjiang to groundwater burial depth

地下水是干旱区重要的环境因子,影响着植被的生长分布。基于2018年新疆喀什噶尔河岸的监测井与植物样地监测数据,分析了研究区不同地下水埋深梯度的植物生长与群落分布情况,讨论地下水埋深对植被退化的影响,结果表明:1)研究区主要以乔木和灌木为主,其中胡杨出现频次最高,是研究区优势植被,其盖度和高度较小,长势受到地下水埋深制约。2)研究区地下水埋深低于5 m,植被盖度变化幅度在6%~40%。此地下水条件下,周边植被盖度大多小于10%,最高植被盖度达37.4%,高的物种多样性仍然分布在KS7、KS9、KS10这些地下水埋深在5~7 m的相对较浅的监测断面,植被呈现衰退趋势。3)随水埋深梯度增加,单位面积物种数、植被盖度呈现明显的下降趋势,其中单位面积物种数在埋深5~7 m最大,仅为0.18种/100 m^(2),植被已经出现明显的退化现象,退化现象随地下水埋深增加进一步加剧。4)灰色关联度表明,6个多样性指数与地下水埋深存在密切的关系,埋深增加导致多样性指数减小,物种丰富程度降低。其中,胡杨等干旱区的高丰度物种受水埋深变化影响较小,低丰度物种受影响较大。

Groundwater is an important environmental factor in arid areas,affecting the growth and distribution of vegetation.Based on the monitoring well and plant plot monitoring data on the banks of the Kashgar River in Xinjiang in 2018,the plant growth and community distribution of different groundwater burial depth gradients in the study area were analyzed,and the effects of groundwater burial depth on vegetation degradation were discussed,and the results showed that:1)The study area was mainly dominated by trees and shrubs,of which poplar had the highest frequency of occurrence,which was the dominant vegetation in the study area,its coverage and height were small,and its growth was restricted by groundwater burial depth.2)The groundwater burial depth in the study area is less than 5 m,and the variation of vegetation coverage is 6%to 40%.Under this groundwater condition,the coverage of surrounding vegetation is mostly less than 10%,the maximum vegetation coverage is 37.4%,and the high species diversity is still distributed in KS7,KS9,KS10,which are relatively shallow monitoring sections with groundwater burial depths of 5 to 7 m,and the vegetation shows a decline trend.3)With the decline of the depth of burial,the number of species per unit area and vegetation coverage showed a significant downward trend,of which the number of species per unit area was the largest at a burial depth of 5 to 7 m,only 0.18 species/100 m^(2),and the vegetation had obvious degradation phenomenon,and the degradation phenomenon was further aggravated with the decline of groundwater burial depth.4)The gray correlation degree shows that there is a close relationship between the six diversity indices and the burial depth of groundwater,and the decline in burial depth leads to a decrease in the diversity index and a decrease in species richness.Among them,high-abundance species in arid areas such as poplar are less affected by changes in burial depth,and low-abundance species are more affected.