灵武白芨滩柠条固沙林演替过程中林下草本植物多样性特征

Characteristics of herbaceous plant diversity in the understory of Caragana korshinskii sand-fixing forest of Baijitan in Lingwu

林下植物物种组成对柠条固沙林的稳定性及生态环境的影响至关重要。本研究采用空间代替时间的方法,选取毛乌素沙地西南边缘不同种植年限(3、5、10、20、30、40、50、60和70 a)柠条固沙林为研究对象,对林下草本植物物种组成及多样性进行调查与分析。结果表明,1)各种植年限中,10 a时草本植物的物种数最少,40 a时草本植物的种类最多,截止到2020年8月为止,植物种数达到38种。2)随着林龄的增加,一年生草本植物的重要值逐渐降低,多年生草本植物的重要值逐渐升高。3)柠条固沙林下草本植物的丰富度指数、多样性指数、均匀度指数在3~10 a时变化一致,随林龄的增加而降低,10~40 a时丰富度随林龄的增加而增加,10~30 a时多样性和均匀度指数也随林龄的增加而增加,40~70 a时,各项指标趋于平稳。4)3~30 a林下草本植物群落相似性指数波动较大,到30 a之后林下草本植物群落相似系数指数变幅不大,逐渐趋于平稳。这表明在柠条群落建立30 a后,柠条林下草本群落已逐渐趋于稳定。种植柠条有助于荒漠生态系统的恢复,并在种植30 a时适当的抚育管理,将有利于林下草本多样性的维持。

Species composition of understory vegetation is important for the stability and ecological function of Caragana korshinskii forests.In this study,a spatial method rather than temporal method was used to investigate and analyze the species composition and diversity of understory herbs in C.korshinskii sand-fixing forests of different ages(3,5,10,20,30,40,50,60,and 70 a)located at the southwest edge of Mu Us Sandy Land.The results showed that:1)In each planting year,the number of herb species was the lowest at 10 a and the highest at 40 a,and the total number of plant species reached 38 up to August 2023;2)With an increase in stand age,the importance value of annual herbaceous plants gradually decreased,and that of perennial herbaceous plants gradually increased;3)The richness,diversity,and evenness indices of herbage in the C.korshinskii forest changed uniformly between 3~10 a,and decreased with the increase in stand age.Richness increased with the increase in stand age between 10~40 a.Diversity and evenness indices also increased with the increase in stand age between 10~30 a,and all indexes stabilized between 40~70 a;and 4)The similarity index of the understory herbaceous community fluctuated greatly between 3 to 30 a,but after 30 a,the similarity coefficient index of the understory herbaceous community exhibited minimal variation and gradually stabilized.This indicates that the herb community in the C.korshinskii forest gradually stabilized after 30 a of its establishment.Cultivation of C.korshinskii is conducive to the restoration of the desert ecosystem,and its proper care and management after 30 a of cultivation will be conducive to the maintenance of herb diversity in the forest.