Timberline Changes And Environmental Evolution Of The Northern Slope Of Changbai Mountain Since 1500a

The nature of vertical zone is the most significant feature of mountain.Among many ecological transition zones in the mountains,the timberline is an important ecological boundary.It is the product of long-time climate change.Due to the unstable state of the climate,it reflects sensitively on the global and regional climate changes, which has gained vast attention.Deducting the study of ancient climate and the changes of alpine timberline on the opposite side is predict the future of alpine climate change with certain theoretical basis.Phytolith is considered as a new stand-by indicator of environment,can reflect the local vegetation conditions,can restore the ancient vegetation and the ancient climate.This article have it applied to the study of timberlineis.The reseach stand on the basis of the northern slope of Changbai Mountain, I select six typical vegetation quadrat from various vertical zones and collect the leaves of woody plants and surface soil.I select 30cm peat profiles in Chichi peat for phytolith analysis, through experiments get the phytolith characteristics of different families and genera of morphology.Through the phytolith morphology from the surface soil we can speculate the availability of its original parent plants.I applied the phytolith characteristics of timberline to the peat profiles obtained the timberline change since 1500a and restore the ancient temperature and the ancient vegetation.The results prove that:1.With the increase in altitude, the vertical vegetation zones in the northern slope of Changbai Moutain with typical woody plants can produce different characteristic patterns of phytolith,the content of cold-type phytolith has a upward trend,while the content of warm-type phytolith has a downward trend.2.The vertical vegetation zones at the northern slope of Changbai Mountain have various kinds of phytolith types with rich topsoil, which can identify the woody phytolith, and it has a corresponding relationship with the phytolith of the plant on the surface.3.The phytolith assemblage feature of the timberline is significant. The percentage of woody phytolith is in sharp drop, and it dropped to 0.6 percent in the tundra zone, while the percentage of herbaceous phytolith increased..4.The age of the peat profile in Chichi, which is 30cm thick, is 1500aB.P. .By regression analysis, we have infered five ancient temprature in different layers of peat profiles, that is, 3.5℃,–0.7℃,–8.7℃,3℃and–3.8℃。5.Since 1500aB.P., the vegetation around Chichi of Changbai Mountain may have experienced a succession process,that is,Conifer mixed forest zone----the dark Coniferous forest zone-----Alpine tundra zone---Conifer mixed forest zone--Betula ermanii forest zone.6.In the years between 1500-1250,the timberline of Changbai Mountain increased by about 1,000 meters,in the years between 1250-1000,the timberline increased by about 400-500 meters,in the years between 1000-500,the timberline descend by about 200 meters,in the years between 500-250,the timberline increased by about 1000 meters,since 250 meters,the position of the timberline is consistent with the present.