湘西南喀斯特石漠化地区植物多样性研究

Study on species diversity of plant communities in karst rocky desertification ecosystem of southwestern Hunan

以湘西南喀斯特石漠化生态系统环境为研究对象,采用野外样方调查和以空间代替时间的方法,研究了轻度、中度和重度3种不同等级石漠化环境下植物群落的结构特征、物种组成和植物多样性演变规律,旨在为湘西南喀斯特石漠化生态系统的恢复与重建提供理论支撑。结果表明:1)该石漠化地区植物调查记录共39科68属77种,其中灌木植物有28科40属47种,草本植物14科28属30种,3种不同等级石漠化样地中蔷薇科、壳斗科、菊科和禾本科等植物的种类和数量较多;2)在3种不同等级石漠化样地中,灌木层的物种丰富度为中度石漠化>重度石漠化>轻度石漠化,而Shannon-Wiener指数、Simpson指数和Pielou指数均是中度石漠化>轻度石漠化>重度石漠化;草本层的物种丰富度、Shannon-Wiener指数均随着石漠化等级程度下降呈现上升趋势,Pielou指数和Simpson指数表现为中度石漠化>重度石漠化>轻度石漠化;3)不同石漠化等级的植物相似性有较大差异,其中灌木层和草本层植物的相似性分别为21.28%和33.33%,轻度、中度和重度石漠化样地灌木层和草本层单独植物分别为8.51%～34.84%和6.67%～26.67%,而灌木层和草本层在不同石漠化样地之间的相似性分别在6.38%～12.77%和3.33%～6.67%之间。说明3个不同等级石漠化样地生活型的植物组成、多样性和群落相似性存在较大差异,随着石漠化程度的加深,在长期不加治理的情况下湘西喀斯特石漠化生态系统灌木化会更加严重。

Krast rocky desertification has been an important ecological issue impeding the economy and society development of southwestern China karst region.It is of great significance to study the plant diversity of the karst rocky desertification ecosystem.Based on these problems,by using field surveys and replacing space with time,the structural characteristics,species composition,and diversity of plant communities under different rocky desertification environments(light rocky desertification,LRD,moderate rocky desertification,MRD),and intense rocky desertification,IRD)were studied.The purpose is to provide theoretical support for the restoration and reconstruction of Karst rocky desertification ecosystem in Southwest Hunan.The results are as follows.1)The flora in the studied areas consists of39families,68genera,and77species,including28families,40genera and47species of shrubs,and14families,28genera and30species of herbs.However,it is mainly the types and quantities of plants in three kinds of rocky desertification plots,such as Rosaceae,Fagaceae,Compositae and Gramineae.2)In three different rocky desertification plots,the species richness of shrub layer ranked from high to low as MRD>IRD>LRD,and Shannon-Wiener index,Simpson index,and Pielou index sorted as follows:MRD>LRD>IRD;Species richness and Shannon-Wiener index of herb layer showed an increasing trend with the decrease of rocky desertification,and Pielou index and Simpson index showed a changing trend of MRD>IRD>LRD.3)There were great differences in plant similarity among different grades of rocky desertification.The similarity of shrub and herb layer plants in three different grades of rocky desertification plots were21.28%and33.33%respectively.The alone plants that is unique to shrub and herb layer plants in three different grades of rocky desertification plots were8.51%-34.04%and6.67%-26.67%,respectively;while the similarities between shrub and herb layers in different rocky desertification plots ranged from6.38%to12.77%and3.33%to6.67%respectively.The findings reveal that there were significant differences in the plant composition,diversity,and community similarity of life forms in three different grade rocky desertification plots.With the extending of rocky desertification,the shrub encroachment of the karst rocky desertification ecosystem in southwestern Hunan will become more severe in the case of long-term non-governance.