A Preliminary Study On The Relationship Between Surface Pollen Assemblage And Modern Vegetation On Xinglong Mountain

Surface pollen assemblages and their relationships with the modern vegetation and climate are the foundation for the recovering palaeo-environment and palaeo-vegetation.The promising trends are to link pollen analysis more closely with the topics of ecology and numberial analysis. In this study, we summarize the characteristics of surface pollen assemblages and their quantitative relationship with vegetation and altitude in the typical ecological regions in Xinglong Mountain National Nature Reserve of Gansu province.The surface pollen assemblages have obvious distinctions in the different ecological regions. In the conifer forest communities, the conifer pollen percentages are more than 60%, broadleaf are less than 10% while shrubs and herbs are less than 30%. In the broadleaf forest communities, the broadleaf pollen percentages are near 40%, the conifer are less than 15% while the shrubs and herbs are less than 50%. In the shrubs, alm and steppe communities, the shrubs and herbs pollen percentages are more than 70%, the conifer are less than 20% while the broadleaf are less than 20%.The results of the surface pollen show that pollen assemblage matches the corresponding plants,but them are not always follow the linear corresponding.For example, the taxa of Pinus, Picea, Betula, Quercus, Artemisia and Chenopodiacea are over-representative;Compositae is very representive;Populus,Gramineae, Leguminosea, Ranunculus, Roseceae are under-representative. The study implies that Pinus pollen percentages are more than 30% where pine trees exist in the surrounding vegetation. The Picea pollen percentages are higher than 30%, where the Picea trees are d(?)minant in the communities, while less than 5% where the parent plants are far and apart. The Betula pollen percentages are near 30% where the Betula trees are dominant in the communities, while less than 10% where the parent plant are rare or absent. The Quercus pollen percentages are higher than 40% where the Quercus trees are dominant in the communities, while less than 5% where the parent plants not rich or absent. The Populus pollen percentages are less than 2% at pure Populus communities, while cannot be recorded easily where the Populus trees mixed with other trees in the communities. The Grammineae pollen percentages are less than 8% where the Grammineae plants are dominant in the communities, while can be usually recorded where the parent plants are not rich but always less than 4%. The Rosaceae pollen percentages are less than 4% where the Rosaceae plants are dominant in the communities, while can be usually recorded with extremely low percentages.The results of the Clustering Analysis divide the forest samples into 4 groups such as Betula forest, broadleaf forest, Picea forest and Quercus forest, showing close relationships between the pollen assemblages and forest communities. The brushes samples are divided into 4 groups, whose results are not as good as forest samples.The results of the Principal Components Analysis divide the forest samples into 4 groups such as Betula forest, Populus forest, Picea forest and Quercus forest, showing close relationshipsbetween the pollen assemblages and forest communities. The first axis shows the relationship between the samples and humidities based on the ecological environments of each group;the second axis shows the relationship between the samples and altitudes based on the altitudes of each sample.The brushes samples are divided into 3 groups, whose results also imply close relationships between the pollen assemblages and forest communities. The first axis shows the relationship between the samples and humidities based on the ecological environments of each group;the second axis shows the relationship between the samples and altitudes based on the altitudes of each sample.