峨眉山世界遗产地表土孢粉组合及其生态和古环境启示

通过峨眉山40个样点表土孢粉组合及其与植物群落之间关系的分析,结果表明:(1)花粉组合中木本植物含量(83.3%)占绝对优势,松属、杉科、桤木属、蔷薇科、桦属、枫杨属、蒿属、毛茛科和水龙骨科为主要孢粉类型;(2)中山常绿阔叶林花粉组合未能反映植被的群落特征;低山常绿阔叶林间人工次生林和常绿落叶阔叶混交林花粉组合只能反映母体植被的部分组成;针叶林花粉组合基本可以指示母体植被的群落特征;灌丛草甸花粉组合能够较好地反映母体植被的群落组成;针阔混交林花粉组合不仅可以很好地指示群落特征,花粉高含量类型还可以与植物群落优势种很好地对应;(3)主要花粉类型冷杉属、杜鹃花科、蔷薇科、珙桐属、槭属和盐肤木属具低代表性;枫杨属、栲属/柯属、桤木属和杉科花粉具超代表性;(4) DCA表明,通过花粉百分含量,能较好地区分人类扰动植被、阔叶林和针叶林,但常绿阔叶林、常绿落叶阔叶混交林和针阔混交林之间,针叶林和灌丛草甸之间难以区分;(5)利用孢粉学恢复热带亚热带常绿阔叶代表类群樟科群落和第三纪孑遗落叶阔叶属种珙桐群落时,受其主体植物花粉外壁薄,易破碎影响,原生植被优势种缺失;因此,孢粉实验改良和保存环境研究,与其他生物学指标(植物大化石和气孔器)综合分析在重建古植物群落中具有重要意义;(6)植物(如冷杉)花粉含量一定程度上能够指示其林分结构。本研究可为热带亚热带山地及相似地区利用孢粉学进行地质时期气候与环境重建提供理论支持和基础资料,并对植被生态恢复提供实践和参考。

Surface pollen assemblages, and their palaeo environmental and ecological significance in the Emei Mountains, Sichuan Province, China

Surface pollen of 40 samples collected in the Emei Mountains in Sichuan Province, southwest China, are used to analyse the relationship between pollen assemblages and their vegetation. The results show that the arboreal pollen is 83.3%, and the main pollen taxa are Pinus, Taxodiaceae, Alnus, Rosaceae, Betula, Pterocarya, Artemisia, Ranunculaceae, and Polypodiaceae. Evergreen broadleaved pollen assemblages are not well associated with the numerical characteristics of vegetation community in the mid-mountain area. However, pollen assemblages of the evergreen broadleaf plants in the artificial and secondary forest across the low-mountain area and the deciduous-evergreen broadleaf mixed forest represent moderately their community compositions respectively. The coniferous pollen assemblages reflect strongly their community on the whole. Shrub-meadow pollen assemblages correspond well with their community, and pollen assemblages from coniferous-deciduous broadleaf mixed forest represent accurately their communities. Abies, Ericaceae, Rosaceae, Davidia, Acer, and Rhus are under-represented, whereas Pterocarya, Castanopsis/Lithocarpus, Alnus, and Taxodiaceae are over-represented pollen taxa. In addition, a Detrended Correspondence Analysis (DCA) show that disturbed vegetation and broadleaved and coniferous forests can be effectively distinguished by pollen spectra. However, the evergreen broadleaved forest, deciduous-evergreen broadleaf mixed forest and the coniferous-deciduous broadleaf mixed forest, and the conifer and shrub-meadow are not accurately examined by the pollen spectra. The thin and broken outer walls of Lauraceae and Davidia pollen mean that these dominant species are missing when the pollen analysis results are used to reconstruct the tropical and subtropical evergreen broad-leaved forest (Lauraceae community) and the deciduous-evergreen broad-leaved forest (Davidia community). Furthermore, it is important to study experimental improvements and the preserved environment using other biological indicators (plant fossils and stomata) for attempting to reconstruct the palaeovegetation. The pollen content of some plants (such as Abies) can indicate its stand structure to a certain extent. This study provides theoretical support and basic data that can be used to reconstruct the palaeovegetation and palaeoenvironment. Pollen analysis can also be used to help restore other ecological systems in tropical and subtropical mountains and similar regions.