湿地植被对北京地区蜻蜓生态分布的影响

Effects of wetland vegetations on ecological distribution of Odonata species in Beijing,China

蜻蜓目(Odonata)昆虫是半变态类(Hemimetabola)昆虫,它的一生经过卵、若虫和成虫3个阶段。和其他水生昆虫一样,蜻蜓目昆虫是淡水生物群落的重要组成部分,对淡水生态系统起到重要作用。蜻蜓目昆虫在其生活史中,取食、交配等活动离不开水生植物和水域附近的植被。为了研究蜻蜓栖息生境中的湿地植被特征对蜻蜓生态分布影响,对北京地区不同湿地类型的17块样地中296个样方分布的蜻蜓种类、多度以及湿地植被的特征和植物多样性进行调查,记录到蜻蜓6科26属36种,维管植物40科99属150种。应用TWINSPAN对蜻蜓种类和样地进行双向聚类分析,所有样地被划分成为四组。同时,将植被特征因子和湿地植物的多样性视为影响蜻蜓数量及分布的因子进行CCA分析。结果表明:湿地植物的丰富度与植物群落结构的完整性是影响蜻蜓分布的主要因素;各湿地植被特征因子对于蜻蜓生态分布的影响不一,依贡献率由大及小依次为浮水植物层盖度、湿生植物盖度、Gleason丰富度指数、沉水植物层盖度、G-F多样性指数、挺水植物层盖度。并且首次应用G-F多样性指数分析湿地植物的多样性。对于蜻蜓栖息地的保护、城市中对于湿地的兴建和改造也提出了相关保护建议。

Dragonflies are Hemimetabola insects, which spend the longest period of their life spans as larvae in the aquatic phase. Wetland habitats and vegetation are important for the whole life history of dragonflies. This paper demonstrates the relationship between wetland vegetation and the ecological distribution of dragonflies in the Beijing area. It also comments on the conservation of dragonflies and their habitats. Field studies were carried out between May 2001 and August 2004 to study the diversity of dragonflies in the area. A total of 36 species of Odonata were reported, belonging to 26 genera and six families. The characteristics and diversity of wetland vegetation were also studied by sampling 296 quadrats at 17 randomly selected plots representing different wetland types in Beijing including rivers, reservoirs, lakes and montane streams. Information was collected regarding dragonfly species and encounter rate and also composition of aquatic plants, coverage of floating-leaved aquatic plants, phreatophytes, sub-emergent aquatic plants and emergent aquatic plants. The G-F index and Gleason richness index were used to assess the diversity of wetland plants. By employing the Two-way Indicator Species Analysis （TWINSPAN） and Canonical Correspondence Analysis （CCA）, the 17 plots were divided into four groups, each of which supported different dragonflies and may and thus shed light on habitat preferences. CCA ordination demonstrated that the richness of aquatic plants and the integrality of wetlands vegetation communities played the most significant roles. It suggested aquatic plants may supply habitat for dragonflies in their foraging, emergence, copulation and oviposition. Results of an assessment of key ecological factors of wetland vegetation show that coverage of floating-leaved aquatic plants is the most important single factor affecting the distribution of Odonata species. Other factors are coverage of phreatophytes （ Gleason richness index）, coverage of sub-emergent aquatic plants （ G-F index）, and coverage of emergent aquatic plants. Wetland vegetation, richness of aquatic plants and integrality of wetlands vegetation communities have profound effects on the ecological distribution of dragonflies in the Beijing area. However, the construction of urban wetlands involves the clearing of aquatic plants and the introduction of exotic plants into water bodies. Therefore, the integrality of wetlands vegetation should be preserved and managed.