The change of plant diversity during natural recovery process of vegetation in Ziwuling area
The change of plant diversity during natural recovery process of vegetation in Ziwuling area
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作者：
Li Yu;S. Ming
由于水土流失严重，黄土高原生态系统处于严重退化状态。探讨研究区植被自然恢复过程中植物多样性的变化趋势具有重要的理论和实践意义。研究区位于中国陕西省抚县子午岭，东经109°11′，北纬36°05′。气候属暖温带半干旱气候，年平均降水量576.7mm，年平均气温9℃。它位于落叶阔叶林带的北部边界。为了研究自然演替过程中植物多样性的变化，选取了10个自然条件相似但演替年龄不同的样点，采用标准方法进行了野外调查和数据分析。结果表明，在近150a的恢复过程中，调查样方共发现植物128种，隶属于47科113属。其中豆科、禾本科、复合科和蔷薇科植物占总种数的50%左右，表明四大科植物在自然植被恢复中发挥着重要作用。演替过程中科、属、种累积数量(y)随时间t (a)呈对数变化：y=aln(t)+b。早期增加速度较快，约60%的物种在前30a恢复。在演替过程中出现最早的木本植物是中国桑树（Periploca sepium）和阿木槭（Acer ginnala），在12a ~ 150a的样方中频繁出现，说明这两种植物的生态位较广。因此，可以认为中国蚕树和黑龙江枫是人工植被建设的候选树种。草本层和灌木层植物物种丰富度指数（Gleason指数和Margalef指数）、多样性指数（Shannon-Wiener指数）和Pielou均匀度指数的变化可以用抛物线函数y= ~2+bt+c来描述，但不同层间的多样性变化是异步的。草本层（HL）、灌木层（SL）和乔木层（AL）的顶极期分别为70~80a、90~100a和100a以上。森林群落植物多样性的空间变化顺序为：
Due to serious soil and water loss, the ecosystem on the Loess Plateau is in a seriously degraded status. Discussion about the tendency of plant diversity change during the natural recovery process of vegetation in the studied area is very important both in theory and in practice. The studied area is located at Ziwuling in Fuxian county, Shaanxi province, China, at 109°11′E and 36°05′N. The climate is semi-arid in warm temperate zone with mean annual precipitation of 576.7mm and mean temperature of 9℃. It is in the north border of deciduous broad forest belt. In order to investigate the change of plant diversity during natural succession processes, ten sampling sites with similar physical conditions but different succession ages were selected and standard methods were applied for field survey and data analysis. Results showed that 128 plant species, which belonged to 47 families and 113 genera, appeared in the inventoried quadrats during the recovery process in nearly 150a. About 50% of the total species are Leguminocae, Gramineae, Compositae and Rosaceae, that suggested plants in four big families playing important roles in natural vegetation recovery. The accumulated number (y) of family, genus, and species in successional process varied logarithmically with the time t (a): y=aln(t)+b. Moreover, the increasing rate in early period was fast and about 60% of total species recovered in the first 30a. China silkvine (Periploca sepium) and amur maple (Acer ginnala) were the woody plants which appeared earliest in succession process and frequently appeared in quadrats from 12a to 150a, which shown that the niche of these two plant species was wide. Therefore it may suggest that China silkvine and amur maple be candidate plant species for artificial vegetation construction. The change of plant species richness index (Gleason index and Margalef index), diversity index (Shannon-Wiener index), and Pielou evenness index in herbaceous layer and shrub layer csn be described by a parabolic function: y=at~2+bt+c, but the change of diversity in different layers were asynchronous. The approximate time to climax period in herbaceous layer (HL), shrub layer (SL), and arbor layer (AL) were 70～80a, 90～100a, and over 100a, respectively. Plant diversity in forest communities varied spatially in the following order: HLSLAL.