民勤黏土沙障-人工梭梭林物种多样性及土壤水分变化特征

Species diversity in Minqin clay sand barrier-artificial Haloxylon ammodendron plantations and the characteristics of soil moisture changes

以民勤荒漠区6种不同布设年限(1 a、5 a、10 a、20 a、40 a、60 a)黏土沙障-人工梭梭林样地和流动沙地(对照)为研究对象,对其物种构成、重要值、优势种群特征、物种多样性和土壤水分含量进行调查,探究长时间尺度黏土沙障-人工梭梭林构建对区域植物群落结构、物种多样性和土壤水分的影响。结果表明:民勤荒漠区黏土沙障-人工梭梭林调查样地共记录到植物6科12属12种,以藜科、蒺藜科为主。人工防沙体系的构建能够显著提升区域植物物种数量(从4种增加到5~8种),且随着布设年限的延长,优势种由沙米(Agriophyllum squarrosum)、梭梭(Haloxylon ammodendron)逐步向雾冰藜(Grubovia dasyphylla)、猪毛菜(Kali collinum)、黄花矶松(Limonium aureum)、梭梭(Haloxylon ammodendron)优势种演变,生活型也从以一年生草本为主的单一型向一年生草本+多年生草本+灌木的复合型发生演变。物种丰富度指数、Shannon-Wiener指数、Simpson指数、Pielou指数和Alatalo指数总体呈现出单峰型变化趋势,以布设20 a时物种数最多,物种分布最均匀,对照沙地物种数最少,物种分布均匀度最差。不同样地植物群落的Jaccard指数表现为:对照沙地与布设1 a样地>布设20 a与布设40 a样地>布设1 a与布设5 a样地>布设10 a与布设20 a样地>布设40 a与布设60 a样地>布设5 a与布设10 a样地,相异性指数与Cody指数则表现相反。区域土壤含水率波动态势与植物群落演替趋势保持一致,且相较于较深层土壤(40~60 cm),浅层土壤(10~30 cm)对区域植物自然演替进程所起到的作用更为明显。

In the present study,clay sand barrier-artificial Haloxylon ammodendron plantations and a mobile sand site(control) in the Minqin desert area were used to investigate the plant species composition,species importance value,dominant species characteristics,species diversity,and soil moisture content.This study explored the long term effects of clay sand barrier-artificial Haloxylon ammodendron plantation construction on regional plant community structure,species diversity,and soil moisture.In total,12 species belonging to 12 genera and 6 families were recorded in the clay sand barrier-artificial Haloxylon ammodendron plantations in the Minqin desert area,with Chenopodiaceae and Zygophyllaceae being the dominant families.The construction of the artificial sand control system significantly increased the number of plant species in the region(from 4 species to 5-8 species).With an increase in the installation period,the vegetation structure gradually evolved from Agriophyllum squarrosum and Haloxylon ammodendrine(dominant species) to Grubovia dasyphylla,Kali collinum,Limonium aureum,and Haloxylon ammodendrine(dominant species).The life forms also shifted from a single type dominated by annual herbaceous plants to a composite type consisting of annual herbaceous plants,perennial herbaceous plants,and shrubs.Regarding alpha diversity,species richness index,Shannon-Wiener index,Simpson index,Pielou index,and Alatalo index showed an overall unimodal trend,with the highest species number and most even species distribution observed in the 20-year installation site and the lowest species number and most uneven species distribution observed in the control sand site.The Jaccard index of plant community similarity between neighboring sites with various installation periods showed the following order:control sand site > 1-year installation site >20-year and 40-year installation sites > 1-year and 5-year installation sites > 10-year and 20-year installation sites > 40-year and 60-year installation sites > 5-year and 10-year installation sites.The dissimilarity index and Cody index showed the opposite trend.The fluctuation pattern of the regional soil moisture content was consistent with the trend of plant community succession.Compared with deeper soil layers(40-60 cm),the role of shallow soil layers(10-30 cm) in the natural succession process of regional plants was more pronounced.