土壤因子对莫索湾梭梭林林下植被分布和多样性的影响

Effects of Soil Conditions on Undergrowth Species Distribution and Diversity in Haloxylon Ammodendron Forest in Mosuowan

[目的]研究土壤因子对古尔班通古特沙漠西南缘莫索湾地区天然梭梭林、天然—人工梭梭林、人工梭梭林林下植被分布和物种多样性的影响,为该区物种多样性保护提供理论依据。[方法]采用典范对应分析法(canonical correspondence analysis,CCA)和广义加型模型(generalized additive model,GAM)分析了6个土壤因子(共8个指标)与物种分布和多样性之间的关系。[结果](1)土壤水分、电导率、pH值和生物结皮的发育是影响植物分布的主要土壤因子。刺沙蓬和狭果鹤虱主要分布在土壤水分和电导率较高的林地,细裂补血草分布在高pH值环境中,虫实分布在土壤水分和电导率较低,同时生物结皮发育较好的林地,甘新念珠芥和滨藜对环境的适应能力较强,各生境均有分布,自然更新的梭梭幼苗分布随着土壤水分、电导率降低和生物结皮增加相对重要值逐渐增大;(2)土壤水分、电导率、pH值和土壤质地是影响物种多样性的主要因素。物种多样性指数与土壤水分和粉粒含量呈极显著正相关(p<0.01),与电导率和pH值呈极显著负相关(p<0.01),在土壤水分较低的环境条件下(2.19%~6.28%),土壤水分是影响多样性指数的最主要因子,当土壤水分>8.0%时,多样性指数趋于稳定,同时,土壤pH值>9.0时,多样性指数有明显下降趋势。[结论]梭梭林林下植被的分布和物种多样性是由土壤水分、电导率和土壤质地为主的多种土壤因子综合作用的结果。

[Objective] The effects of soil conditions on species distribution and diversity under Haloxylon ammodendron Forest were researched to provide references for biodiversity preservation. [Methods] Methods of canonical correspondence analysis and generalized additive model were used to analyze the effects of soil factors on species distribution and diversity under Haloxylon arnmodendron forest in Mosuowan. The forest is located in the southwest of Gurbantunggut Desert, have three types as natural, natural-artificial and artificial Haloxylon arnmodendron forests. [Results] （1） Soil water（SW）, electrical conductivity（EC） and biological crust were the main factors of species distribution. Salsola ruthenica and Lappula semiglabra tend to distribute in high levels of soil water and electrical conductivity; whereas Timonium leptolobum prefer growing in soil with high pH value, for Corispermum hyssopifolium, conditions of low soil water and electrical conductivity, and of having biological crust, were seemed to be more preferable. Neotorularia korolkowii and Atriplex patens have good adaptability and can establish and distribute in all three forests. Natural regeneration of Haloxylon ammodendron was found increased with the decreases of SW and EC, increased with the increase of biological crust. （2） SW, EC, pH value and soil structure were the main influence factors of diversity. There were high significant positive correlations（p〈0.01） between species diversity indices and contents of SW and silt, and there were significant negative correlation（p〈0.01） between species and values of EC and pH. Under the condition of low soil water, about 2.19% and 6.28%, soil water was found to be the most factor that influence species diversity. When SW〉8%, species diversity tend to be stable when SW increase. Species diversity decline obviously when pH value〉9.0. [Conclusion] Undergrowth species distribution and diversity in Haloxylon ammodendron forest were influenced by a variety of soil factors, in which SW and EC played the most important role.