喀斯特断陷盆地区不同恢复阶段群落物种组成与多样性特征

Species composition and diversity of plant community at different restoration stages of karst graben basin

研究自然植被恢复过程中的物种组成、群落结构及生物多样性的变化,能够为人工促进植被恢复的树种选择与群落结构的优化配置提供重要依据。本研究以空间代替时间对喀斯特断陷盆地典型区云南省建水县不同天然植被(草丛、灌丛、乔木林)进行群落学调查,对不同恢复阶段的植物群落按乔木、灌木、草本进行分层,分析各恢复阶段植物群落的物种组成、水平和垂直结构、生物多样性。结果表明:在总面积为3200 m^2的12个样地中,共记录43科72属94种维管束植物,优势种以壳斗科(Fagaceae)、鼠李科(Rhamnaceae)、紫金牛科(Myrsinaceae)、蔷薇科(Rosaceae)、木犀科(Oleaceae)等科的植物为主;在草丛→灌丛→乔木林的恢复过程中,群落物种组成中的科数、属数、种数逐渐增加,低矮和小径级植物个体数所占比例逐渐减少,但整体仍以低矮的小径级植物为主。草本植物的丰富度和Shannon指数在植被恢复的初期即草丛阶段最大,而均匀度指数则以灌丛阶段最大;木本植物的丰富度和Shannon指数随着植被的恢复逐渐增大,但均匀度指数随着植被的恢复逐渐下降;随着植被的恢复,草本层和乔木层的生态优势度逐渐增大,灌木层的生态优势度逐渐减小;草本植物由早期一年或多年生的喜阳、耐旱、耐贫瘠的草本向抗逆性强的多年生草本过渡,并逐渐向中性和阴性转变,其中刺芒野古草(Arundinella setosa)能够很好地适应该地区的环境;薄叶鼠李(Rhamnus leptophylla)、铁仔(Myrsine africana)、假虎刺(Carissa spinarum)、小石积(Osteomeles anthyllidifolia)等阳性树种为该地区植被恢复的先锋种,其早期的出现为其他植物的恢复创造条件,后期又逐渐被喜阴的植物替代,在植被恢复初期可利用这些物种;在植被恢复后期,壳斗科的铁橡栎(Quercus cocciferoides)成为建群种,可在灌丛阶段植被恢复时利用该物种,也可以选择使用该物种植树造林;在整个植被恢复过程中,优势度从以矮小植物为主朝着高大植物发展、优势种寿命越来越长的趋势十分明显。

Understanding changes in species composition,community structure and biodiversity during natural vegetation restoration can provide important basis for the selection of tree species and the optimization of community structure in artificial vegetation restoration. In this study,different natural vegetations(herbosa,shrub and forest) in Jianshui County of Yunnan,a typical area of karst graben basin,were phytocoenologically investigated using the method of space-substitute-time. Plant communities were stratified into tree,shrub,and herb layers at different restoration stages. The species composition,horizontal and vertical structure,and biodiversity of plant communities at different restoration stages were analyzed. The results showed that a total of 94 vascular plant species belonging to 43 families and 72 genera were recorded in 12 plots with a total area of 3200 m^2. Dominant species were mainly from Fagaceae,Rhamnaceae,Myrsinaceae,Rosaceae,and Oleaceae. During the herbosa-shrub-forest restoration,the number of families,genera,and species in community composition increased,the proportion of short and small-stature individuals decreased,but the whole community was still dominated by short and small-stature individuals. Richness and Shannon index of herbaceous plants were the highest in the early stage of vegetation restoration,i. e.,the herbosa stage,while evenness was the highest in the shrub stage. Richness and Shannon index of woody species increased gradually with vegetation restoration,but evenness decreased gradually with vegetation restoration. With vegetation restoration,the ecological dominance of herbaceous layer and tree layer increased and that of shrub layer decreased. The herbaceous plants changed from the early annual or perennial herbs which were heliophilous,drought-resistant and tolerant of poor soil to the perennial herbs with strong resistance,and gradually changed to the neutral and sciophilous. Among them,Arundinella setosa could well adapt to the environment. The heliophilous tree species such as Rhamnus leptophylla,Myrsine africana,Carissa spinarum and Osteomeles anthyllidifolia were the pioneer species in this area. Their presence created conditions for other species,and they were gradually replaced by sciophilous species. These species could be used in the early stage of vegetation restoration. In the later stage of vegetation restoration,Quercus cocciferoides(Fagaceae) became a dominant species,which could be used in the shrub stage of vegetation restoration,or in the condition of artificial afforestation when conditions permitted. In the whole process of vegetation restoration,the predominance was shifting from short and small-stature species to tall and large-stature species,with increasing life span.