THE MODERN POLLEN DISTRIBUTIONAL CHARACTERISTICS AND THEIR RELATIONSHIP TO VEGETATION,CLIMATE IN LAKE WUXU AND THE SURROUNDING MOUNTAINS,SOUTHWESTERN SICHUAN PROVINCE
This study conducted modern pollen analysis in Lake Wuxu(29.1499°～29.1605°N,101.3970°～101.4081°E)and the surrounding mountains in southwestern Sichuan Province.A total of 24 mountain surface samples(23 moss samples and 1 topsoil sample)were collected across 8 different vegetation communities,ranging in elevation from 3499 m to 4269 m.A total of 20 lake surface samples(top 1 cm column sample)were collected at various locations and depths in the lake.Furthermore,utilizing data from 756 weather stations in China spanning from 1981 to 2010,the thin plate spline interpolation algorithm was employed to derive the corresponding MAT,MST,MWT,MAP,MSP,and MWP for each mountain surface sample point.By integrating the outcomes of vegetation surveys and Redundancy Analysis(RDA),we analyzed the pollen assemblages of surface samples from mountainous region and lake area,and explored the relationship between pollen,vegetation,and climate.The main results are as follows:The pollen analysis conducted on mountain surface samples reveals notable variations in pollen assemblages across different vegetation communities,which highlight distinct representative components and well reflect the compositional characteristics of their parent plants,with the exception of the Quercus guyavifolia forest/shrub zone.The calculated pollen R value for the four dominant tree species indicate that the pollen of sclerophyllous evergreen Quercus(1.65)is highly representative,while Abies(0.50),Picea(0.30),and Larix(0.21)exhibit low representativeness.The RDA results of 22 zonal mountain surface samples indicate that species such as sclerophyllous evergreen Quercus,Picea,Larix and Rosaceae show a strong positive correlation with MAT,Abies shows a strong positive correlation with MSP,and species such as Cyperaceae,Ranunculaceae and Ericaceae exhibit a strong positive correlation with MAP.The pollen analysis conducted on lake surface samples reveals that lake current,the surrounding vegetation distribution,and surface runoff are the main factors influencing the dispersal and distribution of pollen in the lake area.These three factors in turn lead to the differential enrichment of medium-large pollen(such as Pinus,Abies,and Ericaceae)and small pollen(such as sclerophyllous evergreen Quercus,Betula,and Rosaceae)in the lakeshore and lake center zone respectively,the differential enrichment of Abies and sclerophyllous evergreen Quercus pollen in the western and eastern parts of the lake respectively,and the enrichment of Cyperaceae pollen and fern spore in the estuarine region.Comparing surface samples from mountainous region and lake area comprehensively,it was found that the pollen assemblages in lake surface samples mainly represents the average vegetation state around the lake and in the upstream of the watershed,which exhibit higher regional representativeness and stability compared to mountain surface samples.Therefore,we recommend using lake surface samples to construct modern pollen databases and guide fossil pollen studies.
pollen analysismodern pollen rainvegetation zoneLake WuxuSouthwestern China
万方数据
维普
