贵州水城仲河剖面二叠纪-三叠纪之交底栖群落的物种多样性与功能多样性转变

为了定量化恢复晚二叠世末期生物大灭绝对底栖群落的物种多样性和功能多样性的影响，对浅海碎屑岩台地相区的贵州水城仲河剖面开展宏体化石采集和分析，识别和划分古群落，选择优势度、香农指数、均匀度等代表物种多样性指数，生态功能群数量和功能均匀度代表功能多样性指数. 共采集1 340枚化石标本，经鉴定得到30属33种，其中双壳类可归纳为两个生物带:晚二叠世长兴期的Hunanopecten exilis顶峰带和早三叠世Griesbachian早期的Pteria ussurica variabilis顶峰带. 根据化石属种的地层分布、保存状况，结合聚类分析方法识别出3个古群落:Astartella obliqua-Tethyochonetes quadrata群落、Pteria ussurica variabilis-Claraia wangi群落和Pteria ussurica variabilis-Unionites canalensis群落. 自晚二叠世长兴期末期至早三叠世Griesbachian早期，古群落的优势度上升、香农指数降低、均匀度下降，功能群丰富度降低，功能均匀度上升，这指示晚二叠世末生物大灭绝对浅海碎屑岩相区的底栖群落的组成和功能均有显著的破坏. 此外，结合华南浅海和深海相区的古群落数据，发现底栖群落的物种多样性指数和功能多样性指数在晚二叠世末生物大灭绝中均遭受损失，但是浅海底栖群落受影响较高. 

Taxonomic Diversity and Functional Diversity of Benthic Communities during Permian-Triassic Crisis at Zhonghe Section,Shuicheng, Guizhou Province

In order to evaluate the impact of the End-Permian mass extinction on the taxonomic diversity and functional diversity of benthic communities, this study carried out a successive collection of macrofossils through the Permian-Triassic boundary sequence at the Zhonghe Section, Shuicheng, Guizhou Province, and reconstructed the palaeocommunities. The taxonomic diversity is indicative of the Shannon index, dominance index and evenness index, while the functional diversity includes functional group richness and functional evenness. A total of 1 340 fossil specimens were collected in this study, and they could be assigned to 33 species in 30 genera, and could be grouped to two bivalve zones: the Hunanopecten exilisacme zone in the Changhsingian (Late Permian), and the Pteria ussurica variabilisacme zone in the Early Griesbachian (Early Triassic). Three paleocommunities were identified through cluster analysis: Astartella obliqua-Tethyochonetes quadrata community, Pteria ussurica variabilis-Claraia wangi community and Pteria ussurica variabilis-Unionites canalensis community. The Shannon index decreased, dominance increased, evenness decreased, functional group richness decreased and functional evenness increased, indicating that the End-Permian mass extinction significantly damaged the composition, structure and function of the shallow marine benthic community. Besides, in combination with various paleocommunities from South China, it is found that both the species diversity index and the functional diversity index of the benthic community changed synchronously between shallow and deep marine environments. However, the shallow marine paleocommunities were more affected than their counterparts from deep sea.