作 者 ：李铭红,宋瑞生,姜云飞,赵谷风,付海龙,郑英茂,于明坚
期 刊 ：生态学报 2008年 28卷 3期 页码：1137~1146
Keywords:evergreen broad-leaved forest, habitat fragmentation, plant diversity, edge effects,
摘 要 ：由于人类活动的严重干扰,使得我国的常绿阔叶林基本上已片断化。对位于浙、闽、赣、皖交界山区的6个以甜槠和木荷为建群种的片断化常绿阔叶林的植物多样性进行了研究,结果表明：（1）6个片断化样点共有物种69~142种。其中乔木层共有24~39种,Simpson 指数（λ）为0.793 2~0.931 9,Shannon-Weiner指数（H′）为2.410 8~3.201 8,Pielou均匀度指数（J）为0667 6~0.813 2,Gleason指数（IG）为4.5816~8.209 8；灌木层共有45~120种,λ为0.830 9~0.955 8,H′为2.6257~37902,J为0.608 2~0.7903,IG为10.0216~17.2782；草本层共有6~23种,λ为0.5073~0.7639,H′为0.8783~1.8802,J为0.3822~0.5771,IG为0.9646~4.2871。（2）乔木层和灌木层分别在物种均匀度和丰富度上占有优势,此外,各片断化样点之间建群种比较类似,而林下灌木和草本种类则有明显差异。（3）人类干扰和片断化面积大小分别影响了乔木层和草本层的物种丰富度和多样性。（4）边缘效应明显,并且主要发生在林缘50m的范围内。从林缘到林内单位面积物种数根据片断化面积的大小分别呈现出上升和下降的格局,并且不同耐阴性的物种其分布密度表现出完全相反的特征。林缘0~50m的范围内,木本植物死亡率呈逐渐上升趋势,50m以后开始下降,林缘100m附近达到稳定。此外,林缘比林内具有更为丰富的藤本植物。
Abstract:The evergreen broad-leaved forest (EBLF), located in the subtropical area of East China, is one of China′s unique vegetation types, and also an important center of global biodiversity. However, because of human activities such as urban development, highway construction and land reclamation, most of the formerly continuous EBLFs have been damaged and become fragmented. To understand the patterns of plant diversity in the fragmented EBLFs, we selected six isolated fragments of the typical EBLFs in the mountain ranges at the boundary of Zhejiang, Fujian, Jiangxi and Anhui Provinces in East China. The six fragments are of similar age and have similar habitat conditions and constructive species (Castanopsis eyrei and Schima superba). For each fragment, we set up one or two transects of 20 m wide and 50-155 m long (depending on the size and shape of the fragments) from the edge towards the center of the forest. Each transect was divided into 5 m×5 m quadrats and in each quadrat all vascular species were recorded. We measured DBH, height and crown diameter of each individual tree and coverage, average height and number of individuals of each shrub and herb species. We found that : (1) In the six EBLF fragments, total number of plant species were 69-142; in the tree layer, species richness (S) was 24-39, Simpson index (λ) 0.7932-0.9319, Shannon-Wiener diversity index (H′) 2.4108-3.2018, Pielou’s evenness index (J) 0.6676-0.8132 and Gleason index (IG) 4.5816-8.2098; in the shrub layer, S was 45-120, λ 0.8309-0.9558, H′ 2.6257-3.7902, J 0.6082-0.7903 and IG 10.0216-17.2786; in the herb layer, S was 6-23, λ 0.5073-0.7639, H′ 0.8783-1.8802, J 0.3822-0.5771 and IG 0.9646-4.2871. (2) Composition and diversity in the shrub and herb layers varied greatly among the six EBLF fragments. Generally, S, λ, and H′ were the largest in the shrub layer, smallest in the herb layer and intermediate in the tree layer, whereas J was the largest in the tree layer and smallest in the herb layer. (3) Human disturbance and size (area) of the fragments were two major factors impacting plant diversity in the EBLFs, especially in the herb layer, and fragments size also affected species number per unit area. (4) Along the transects from the edge towards the center of the EBLFs, mortality rate of the woody plants gradually increased in the first 50 m distance, declined in the second 50 m, and kept stable after 100 m. Species number per unit area was significantly positively or negatively correlated with the distance from the edge to the center of the forests. The property (i.e. positive or negative) of the relationships depended on fragment size and also on whether shade-intolerant or shade-tolerant plants were considered. Moreover, abundance of lianas was markedly lower at the edge than in the interior of the EBLFs. The results support the opinion that plant species diversity was significantly affected by both distance from the edge and interaction of fragment attributes. We propose that changes in herb richness and liana abundance can be used as indicator of fragmentation degree and edge effects in the EBLFs, respectively.
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