Plant diversity of secondary forests in response to anthropogenic disturbance levels in montane regions of northeastern China
Plant diversity of secondary forests in response to anthropogenic disturbance levels in montane regions of northeastern China
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DOI：
10.1007/s10310-007-0033-9
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发表时间：
2007-09
影响因子：
1.5
通讯作者：
Jiaojun Zhu;Zhihong Mao;Lile Hu;Jinxin Zhang
中科院分区：
文献类型：
--
作者：
Jiaojun Zhu;Zhihong Mao;Lile Hu;Jinxin Zhang
通过立地因子分类，评价了人为干扰对东北山地森林结构和次生森林生态系统植物多样性的影响。 45 个样地包含 720 个上层物种子样地 (8 m × 8 m)、1,440 个林下物种样方 (2 m × 2 m) 和 1,440 个草本层物种样方 (1 m × 1 m)，通过位点变量和层次聚类将其聚类为 5 组（G1、G2、G3、G4 和 G5）分析。同时根据影响人为干扰的因素（D0-G2、D1-G1、D2-G3、D3-G5、D4-G4）确定五组对应的干扰水平。采用物种数、Margalef指数、Pielou指数、Shannon-Wiener指数、Simpson指数评价林上、林下、草本层和总体物种多样性；和 β-多样性（Whittaker 指数、Cody 指数）。由于人类干扰对木材的采伐量逐渐增加，林分断面积沿干扰水平呈下降趋势。物种多样性指数表明林上和林下物种在群体或干扰水平之间分布均匀。次生林生态系统中不存在绝对优势树种。立地因素和当前干扰强度的差异还不足以导致林上和林下物种的松散变化。草本层物种多样性指数在D3（G5）处呈现最大值；这可能表明当前的扰动强度足以导致草本层物种的变化。次生林内发现了核桃、水曲柳和刺五加三种珍稀濒危树种。这些珍稀濒危物种均出现在各个聚集类群或干扰水平中，说明研究区目前的干扰强度不足以影响珍稀濒危物种的分布。当前次生林的干扰可能不会导致林上和林下物种的稳定性和复杂性下降，但较高的干扰水平可能足以改变草本物种的栖息地适应性。
The effects of anthropogenic disturbances on forest structure and plant diversity of secondary forest ecosystems were evaluated based on the classification by site factors in the montane regions of northeastern China. Forty-five sample plots containing 720 sub-plots of overstory species (8 m × 8 m), 1,440 quadrats of understory species (2 m × 2 m), and 1,440 quadrats of herbaceous layer species (1 m × 1 m) were clustered into five groups (G1, G2, G3, G4 and G5) by site variables with Hierarchical Cluster Analysis. Meanwhile, the disturbance levels corresponding to the five groups were determined according to the factors influencing human disturbances (D0-G2, D1-G1, D2-G3, D3-G5, and D4-G4). Species diversities of overstory, understory, herbaceous layer and overall species were evaluated using species number, Margalef index, Pielou index, Shannon–Wiener index, and Simpson index; and β-diversities (Whittaker index, Cody index). Basal area of stands exhibited a decreasing trend along the disturbance level due to a gradual increase in the extraction of timber by the human disturbances. The indices of species diversity suggested that overstory and understory species were distributed evenly among the groups or disturbance levels. There were no absolutely dominant tree species in the secondary forest ecosystems. The differences in site factors and the current disturbance intensities were not intense enough to lead to loose changes in overstory and understory species. The species diversity indices exhibited the maximum values at D3 (G5) for herbaceous layer species; this may suggest that the current disturbance intensities were intense enough to lead the changes of herbaceous layer species. Three rare and endangered species (Juglans mandshurica,Fraxinus mandshuricaandAcanthopanax senticosus) were found within the secondary forests. These rare and endangered species appeared in each clustered group or disturbance level, which suggested that the current disturbance intensity in the study area was not strong enough to influence the distribution of rare and endangered species. The current disturbances in the secondary forests may not lead to a decrease in stability and complexity of the overstory and understory species, but the higher disturbance level may be intense enough to change the habitat fitness for the herbaceous species.