四川螺髻山表土和化石孢粉揭示的环境生态意义

通过四川螺髻山（1984、2017年）表土和化石孢粉与植被的关系分析发现：孢粉组合中木本植物含量（91.0%）占绝对优势，松属、冷杉属、青冈属、常绿栎类、落叶栎类、桤木属、杜鹃花科、禾本科和蒿属为主要花粉类型；人工次生林花粉组合能很好地反映母体植被的群落特征，并可指示优势种的存在和人类活动痕迹；针阔混交林花粉组合能较好地反映群落整体特征，花粉类型能与母体植被中优势种较好地对应；常绿阔叶林、针叶林和灌丛草甸的花粉组合难以反映母体植被的群落特征。DCA表明，花粉谱的百分含量，能较好地区分人工扰动植被和天然植被，但人工次生林、常绿阔叶林和针阔混交林之间以及针叶林和灌丛草甸之间未能区分。30年前后表土孢粉组合变化明显，1984年样品以松属、青冈属和桤木属等花粉为主，而2017年采样分析中松属、桤木属花粉占绝对优势。随着人类活动的加强，部分地区松树和桤木大面积飞播或种植，表土孢粉组合对当地植被指示意义与扰动强度呈负相关关系。现生植被与表土孢粉组合的差异能为恢复古植被和古环境提供参考，但原生植被已经被破坏地区的孢粉图谱，就很难作为重建历史时期植被的根据。本研究可以为亚热带山地利用孢粉学恢复第四纪时期植被与气候，探讨人类活动与环境的关系提供理论依据和实践参考。

Ecological and environmental significance of the surface and fossil pollen in the Luoji Mountains, Sichuan

Surface pollen (sampled in 1984 and 2017) and fossil pollen, collected in the Luoji Mountains in Sichuan Province, Southwest China, were used to analyse the relationship between pollen assemblages and their associated vegetation. Arboreal pollen constituted 91.0%, and the main pollen taxa were Pinus, Abies, Cyclobananopsis, evergreen Quercus, deciduous Quercus, Alnus, Ericaceae, Gramineae, and Artemisia. On the whole, pollen assemblage-vegetation community associations were strong for artificial and secondary forests, moderate for coniferous-deciduous broadleaf mixed forest, and weak for evergreen broadleaved forest, coniferous forest and shrub-meadow. In addition, detrended correspondence analysis showed that disturbed and natural vegetation can be effectively distinguished by pollen spectra. However, artificial and secondary forests, evergreen broadleaved forest, coniferous-deciduous broadleaf mixed forest, coniferous forest, and shrub-meadow were not accurately represented by their pollen spectra. There was a significant difference in surface pollen assemblages over the past 30 years. The main pollen taxa were Pinus, Cyclobananopsis and Alnus in 1984, and Pinus and Alnus in 2017. Under increasing human activity, Pinus yunnanensis and Alnus cremastogyne have large-scale cultivation which has induced an inverse correlation of disturbance intensity between surface pollen assemblages and their associated vegetation. The relationship between surface pollen assemblages and the existing vegetation can provide a reference for reconstruction of palaeovegetation and the palaeoenvironment. However, pollen spectra where native vegetation has been destroyed cannot be used to reconstruct palaeovegetation. This study provides theoretical support and a practical reference for reconstructing the palaeovegetation and palaeoclimate of the Quaternary, and can also aid understanding of the relationship between human activities and the environment.