应用稳定同位素测定贵州凤冈麻湾洞洞穴陆生动物的食物来源及营养级

以贵州凤冈麻湾洞洞穴生态系统为研究对象,运用δ13C、δ15N测定了洞穴动物及其有机碳源的同位素比值,分析了洞穴生态系统的营养级关系及洞穴动物食源。结果表明:洞内植物δ13C范围为-41. 78‰^-38. 80‰,较洞外植物低;δ15N范围为-1. 31‰~1.23‰,在洞外陆源有机质δ15N范围内;洞穴土壤有机质的δ13C范围为-31. 09‰^-24.95‰,δ15N范围为-1.08‰~7.72‰;洞穴动物δ13C范围为-30.41‰^-12.02‰,δ15N范围为2.07‰~8.94‰;洞穴土壤有机质对动物的食源贡献率超过72%,远高于植物对动物的食源贡献率,即洞穴土壤有机质是洞穴动物的主要食物来源。麻湾洞生态系统主要由4个营养层次组成:植物为第一营养层次;闪夜蛾、螺类、马陆类处于第二营养层次;裸灶螽、长头地蜈蚣处于第三营养层次;蜘蛛类处于第三或第四营养层次。即大部分同种(或同类群)动物在洞穴中所处的营养级位置相对稳定,少部分同种动物在不同光带或同种类群的不同种动物在同一光带所处的营养级位置有差异。

Using stable isotopes to assess food source and trophic level of terrestrial animals in Mawan cave of Fenggang in Guizhou

We measured the isotope ratios ofδ13C andδ15N in cave animals and their organic carbon sources in Mawan cave of Fenggang,Guizhou,and further analyzed trophic level relationship and food sources of the cave ecosystem.The results showed that the values of plantδ13C in the cave ranged from-41.78‰to-38.80‰,which is lower than that of plants out the cave.Theδ15N of plants in the cave ranged from-1.31‰to 1.23‰,which is within the range of terrestrial organic matter.Theδ13C of soil organic matter in the cave ranged from-31.09‰to-24.95‰,while theδ15N of soil organic matter in the cave ranged from-1.08‰to 7.72‰.Theδ13C of cave animals ranged from-30.41‰to-12.02‰,while theirδ15N ranged from 2.07‰to8.94‰.The contribution rate of cave soil organic matter to animals was more than 72%,being higher than that of plants,indicating that soil organic matter was the main food source for cave animals.There were four trophic levels in the food web.Plants were the first trophic level.Tipula sp.,Gastropoda,and Diolopoda were the second trophic level.Distrammena sp.,Mecistocephalus sp.were the third trophic level.Most of Araneae groups were the third or fourth trophic level.Our results indicate that the trophic levels of most animals were relatively stable in the cave.A few animals from same species have different trophic levels in different light zones,whereas different species belonging to the same group would be at different trophic levels in the same light zone.