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对肯尼亚东南部泰塔(Taita)山区的3片破碎的森林进行了树种生物多样性评估,比较外来的松树、柏树、桉树人工林的物种多样性以及外来树种森林和本土森林物种多样性。研究地点为Ngangao(120 hm2)、Chawia(86 hm2)和Mbololo(185 hm2)。采用Y型设计设立32个样区,包含65个小样区。按树种记录每个小样区胸高直径5cm和5cm以上的幼树,同时也记录了各树木的更新情况(幼苗和树苗)。用 Shannon-weiner指数计算了物种的多样性和均匀度。导处的 Shannon指数被进一步转化成有效的数值,用于展示物种多样性的差别幅度。为了评估物种多样性的差别,进行单因素方差分析,为了分离均值,分别用Tukey HSD法和Duncan检测法验证偶数和奇数样品。采用Jaccard相似指数评估物种的类似性。共有58个树种的林木密度变化在每公顷10到2000棵树之间。森林类型和立地之间的物种多样性存在显著差异。本地森林的物种多样性比外来树种森林高;Chawia立地的物种多样性比Nganga和Mbololo立地高,且更新的树种数量也比其他2个立地多,包括野柠檬木(Xymalos monospora)、黑皮密花木(Rapanea melanophloeos)、和(几内亚蒲桃(Syzygium guineense),这些树种具有低干扰属性。这些发现说明,本地森林物种多样性比较高,正如热带地区所预期。Chawia立地的物种多样性高说明此地经历干扰比其他2个立地大。在Chawia地区发现有低干扰树种更新,说明有长期土壤种子库的存在。在Nganga和Mbololo地区发现的外来树种样地上的更新较差情况,可能是缺少种子库所致,因为很多人工林是造在裸地上(如Nganga地区),或者是因为某些树种固有的生理特性(相生相克)抑制了其他树种的更新。
Three species of fragmented forests in the Taita mountains of southeastern Kenya were assessed for biodiversity of species, comparing the species diversity of exotic pine, cypress and eucalyptus plantations with the species diversity of exotic and native forest species. The study sites were Ngangao (120 hm2), Chawia (86 hm2) and Mbololo (185 hm2). Y-design was used to set up 32 sample areas, including 65 sample areas. Saplings of 5 cm in diameter and 5 cm in height were recorded for each sample area by tree species. Tree regeneration (seedlings and saplings) was also recorded for each tree. Species diversity and evenness were calculated using the Shannon-weiner index. The Shannon index at the guide was further transformed into a valid number to show the difference in species diversity. To assess differences in species diversity, one-way ANOVA was performed and in order to separate mean values, even and odd samples were validated by Tukey HSD and Duncan assays, respectively. Jaccard similarity index was used to assess the similarity of species. A total of 58 tree species varied in density from 10 to 2000 trees per hectare. There are significant differences in species diversity between forest types and sites. The species diversity of native forests is higher than that of exotic species; the species diversity of Chawia habitats is higher than that of Nganga and Mbololo sites, and the number of tree species updated is more than that of the other two sites, including Xymalos monospora, Rapanea melanophloeos, and Syzygium guineense, which have low disruptive properties, suggest that species diversity in native forest is relatively high, as expected in the tropics, and high species diversity at the Chawia site Experienced disturbances larger than the other two sites. A low-disturbance tree update was found in the Chawia area indicating the presence of a long-term soil seed bank, which may be a lack of seed banks in poorly updated alien tree samples found in the Nganga and Mbololo areas As many plantations are made on bare land (such as the Nganga area) or because the inherent physiological characteristics (symbiosis) of certain tree species inhibit the regeneration of other species.