海南天然林与橡胶林蜘蛛多样性比较

为探索天然林和橡胶林蜘蛛多样性现状,于2010年8月在海南黎母山自然保护区选取天然林和橡胶林,采用扫网法、陷阱法和单位面积法收集蜘蛛标本,分析两种林型之间蜘蛛组成、多样性和功能群差异,并以蜘蛛科和数量分布为属性进行主成分分析(PCA),探讨林型中样方之间蜘蛛群落的相似性。共采集蜘蛛标本3609头,用于统计分析的成蛛969头,归属于23科,162种。天然林20科,100种,优势类群为跳蛛科、球蛛科和园蛛科;橡胶林17科,87种,优势类群为肖蛸蛛科、狼蛛科和猫蛛科。从蜘蛛的数量分布看,橡胶林蜘蛛个体密度显著高于天然林;而天然林多样性指数和丰富度指数显著高于橡胶林。橡胶林中结圆网型和游猎型蜘蛛显著高于天然林,结皿网型显著低于天然林,伏击型不存在显著性差异。PCA分析结果表明,24个样方趋于分成天然林和橡胶林2组,并且天然林样方之间相似性极高,而橡胶林样方之间相似性相对较低。以上结果表明:(1)橡胶林替代天然林后蜘蛛群落结构发生变化,多样性降低;(2)增加生境结构的复杂性和减少人为干扰对保护和恢复物种多样性有重要意义。

Composition and diversity of spiders in the rubber plantation and natural forest of Hainan Island, China

The present study compares the community dynamics of spiders in the rubber plantation of Hainan Island to those of spiders in the island''s natural forest. Hainan, which is the fifth largest rubber producer in the world, is the second largest island in China. It features a tropical climate, and is located in the South China Sea. Rubber plantations are commonly considered "Green Deserts", as the expansion of rubber plantations has caused a series of ecological problems, including habitat fragmentation, biodiversity loss, habitat loss, soil erosion, and climate change. Of the arthropods, spiders comprise a group known to measure changes in habitat structure, habitat type, wind, and temperature exposure, and play key ecological roles as predators. Spider assemblages, which are easily sampled, are useful indicators that can be used to compare the biodiversity of various environments and assess the effects of disturbances on diversity. Because spiders are generally found in forests in high abundance, they form a good model taxa for biodiversity studies. In addition, their distributions and abundances are linked to the structural attributes of their habitat. They play key functional roles in ecosystems, and their abundance, richness, and community structure in tree canopies are associated with the complexity of the ecosystem''s vegetative structure. To compare the composition and diversity of spiders in a natural forest and a rubber plantation, spider communities in 6 plots (three repetitions for each forest type) were investigated during four field trips in August 2010, using pitfall traps, direct searching, and sweep-netting. The similarity analysis of samples from the natural forest and rubber plantation was conducted via the principal component analysis (PCA) of spider families and numbers of individuals. A total of 3609 individual spiders were collected from the two forests, 969 of which were identifiable adults representing 23 families and 162 species. From samplings of the natural forest, 20 families and 100 species were identified, in which the most abundant families were Salticidae, Theridiidae, and Araneidae. From the rubber plantation samples, 17 families and 87 species were identified, in which the most abundant families were Tetragnathidae, Lycosidae, and Oxyopidae. The abundance of spiders in the rubber plantation is significantly higher than that in the natural forest, but the Shannon -Wiener (H''), Simpson index (D), Evenness (J), and Richness (D_mg) are significantly higher in the natural forest than in the rubber plantation. In the rubber plantation, the abundance of orb weavers and cursorial hunter-spiders is significantly higher than that in the natural forest, while no significant difference can be detected between sheet-line weaver spiders and ambush predator spiders in the two forests. The results of the PCA indicate that the natural forest and rubber plantation are highly differentiated, with the sampling plots in the natural forest having a much higher degree of similarity than those in the rubber plantation. These results suggest that (1) spider community structure varies and its diversity decreases when rubber plantations replace natural forest, (2) increasing the complexity of habitat structure and reducing anthropogenic disturbance is a meaningful way to conserve and restore biodiversity.