Pollen Assemblages In Moss Samples From Dabie Mountains And Their Relationship With Vegetation

Dabie Mountain is located in th e central part of China.The study of pollen assemblage characteristics in deciduous broad?leaved and evergreen broad?leaved mixed forest communities and their relationship with vegetation is helpful to understand the relationships between pollen,vegetation and climate in this area,and also has a guiding role in predicting future environmental changes.There are many types of collectors available for pollen collection in topsoil,each of which has its own advantages and disadvantages.Therefore,the selection of appropriate collectors can promote the study of modern pollen process.As a good pollen collector,the moss samples selected in this study are easy to collect and handle.Their pollen comes from local and extraregional vegetation,which is conducive to the study of pollen combination and different distances.The relationship between vegetation composition.In July 2017,our team conducted a detailed field sample collection and vegetation survey in Dabie Mountains,Anhui Province,collected 30 moss samples and investigated the vegetation characteristics within 10 meters and 100 meters of the sample sites.In this study,pollen assemblage characteristics of different community types of bryophytes were analyzed based on vegetation survey data,and the relationship between pollen assemblage and vegetation composition in bryophyte samples was studied.Pollen assemblage characteristics of top communities in deciduous broad?leaved and evergreen broad-leaved forests and their indicative significance to vegetation composition were expounded.The results are as follows:(1)Through the difference of pollen size,polar equatorial axis ratio,type of germination aperture and outer wall morphology,the pollen samples of bryophytes were identified,the families and genera belonging to different pollen mother vegetation were distinguished,and the pollen morphological data with more percentage in the pollen combination were analyzed,21 main pollen morphological characteristics were obtained.(2)29 881 pollen grains and 89 pollen types were identified from 30 samples.The dominant pollen types were arbor plants(83%),Pinus(62.1%),Quercus(10.4%)and Pterocarya stenoptera(2.8%).The results showed that the pollen assemblage of the top community in deciduous broad?leaved forest was dominated by arbor plants(83%),mainly Pinus(62.1%),Quercus(10.4%)and Pterocarya stenoptera(2.8%).(3)According to the composition of genera and species of vegetation and the difference of absolute coverage of plants,30 sample sites were divided into five main community types,including Pinus taiwanensis or Pinus massoniana forest community,Pinus taiwanensis?Quercus pubescens forest community,Bamboo pubescens forest community and Chinese fir forest community,and the vegetation coverage changes of different families and genera at different distances of each sample site were obtained.(4)The principal coordinate analysis of pollen assemblages and vegetation composition at different distances showed that there were differences between pollen assemblages and vegetation composition in the range of 0?100 m at each sample point,and has obvious community specificity.It is similar to the vegetation composition in the range of 0-1500 m,and shows regional homogeneity.It should indicate the vegetation composition in the region.The pollen content of Pinus and Pterocarya stenoptera was higher than that of vegetation coverage;the pollen content of Quercus and Liquidamber formosana was similar to that of vegetation coverage;the total pollen content of Cunninghamia lanceolata and Castanea is less than 3%,but the vegetation coverage in the corresponding region is nearly five times as much as the pollen content.Therefore,vegetation information contained in low representative pollen types should be taken into account when interpreting stratigraphic pollen assemblages,and the influence of topographic factors should be paid attention to.