Quantitative And Semi-quantitative Relationship Between Surface Pollen And Climate On The Southern Slope Of Altai Mountains And Its Preliminary Application

Holocene climate change can predict future climate change trends.To study the history of Holocene climate change,sporopollen records are one of reliable paleoclimate and paleoecology indicators.In recent years,the climate change in the Altai Mountains,located in the grassland,desert and Northern Taijialin belts of Central Asia,has attracted much attention.However,the reconstruction of regional climate change is quite different,so further research is needed.To study the surface pollen on the southern slope of Altai Mountains in China,81 sample points were selected to analysis pollen assemblage;together with other published pollen data from Xinjiang region and meteorological environment data of several sample points,RDA analysis was carried out.On these basis,the relationship between pollen,vegetation and climate environment is explored;the applicability,indicative significance and altitude change of different types of pollen were discussed.The Holocene climate change in Kanas area of different ranges was reconstructed by pollen data.The results show that there is a good agreement between pollen assemblages and vegetation belts,in which the pollen assemblages of Pinus,Betula,Chenopodiaceae and Artemisia are super-representative,whereas the pollen assemblages of Picea,Larix,Ephedra,Cyperaceae and Caryophyllaceae mainly fall around their matrix as the poor dissemination.RDA results of pollen from southern slope of Xinjiang and Altai Mountains indicate that precipitation is the main factor controlling regional pollen assemblages,while temperature and altitude also contribute some effect.Caryophyllaceae,Cyperaceae and meadow have significant positive correlation.Meanwhile A/C(Artemisia/Chenopodiaceae)ratio is closely related to precipitation.Effected by altitude and precipitation,the A/C ratios in different regions of desert zone on the southern slope of Altai Mountains are gradually increased from west to east,moreover,in the vertical direction,the A/C ratio can reflect the dry-wet change of mountain body below 1700m,but after 1700m,the A/C ratio fluctuates irregularly.AP/NAP(Arboreal pollen/Non arboreal pollen)ratio clearly reflects regional forest range,indicating the distribution of different arbor from low to high elevation:Betula<Pinus<Picea<Larix,among which Picea and Larix have better cold tolerance and higher growth upper limit.Based on the surface pollen data and borehole pollen data of different areas in Kanas Lake,the climate change is quantitatively reconstructed.The study found the reconstruction results in different areas are basically the same:in Kanas Lake area,climate is relatively arid in early Holocene and gradually becoming humid in mid Holocene;the precipitation in late Holocene has a downtrend,but as a whole it is still relatively humid.The reconstruction results of large-scale data are more stable,while there are more fluctuant and lower values of the precipitation reconstructed by pollen data in Xinjiang and Altai Mountains.