The Effect of Mountain Base Elevation on the Altitude of Timberline in the Southeastern Eurasia:A Study on the Quantification of Mass Elevation Effect

This paper focuses on the method of quantifying the phenomenon of mass elevation effect(massenerhebungs effect).Geographers have taken notice of mass elevation effect and its influence on mountain altitudinal belts for more than 100 years.But so far,our knowledge on mass elevation effect has been very limited,let alone its quantitative effect on mountain altitudinal belts.Geographers and botanists have established many unitary or dibasic fitting models between mountain altitudinal belts' distribution and longitude or latitude,or both.But most of these models involve small scales and could not be expanded to other regions;while others are established for the northern hemisphere or the whole globe with very low precision.The reason is that these models neglect one of the most important factors controlling the distribution of altitudinal belts—mass elevation effect.It is well known that the higher the mountain range,the greater the mass elevation effect is.So,mountain's base altitude could be a represent of mass elevation effect.We collect 173 samples of forest line distribution,and use latitude,longitude and mountain base elevation(MBE) as independent variables to build a multiple linear regression equation for timberline altitude in the southeastern Eurasian continent.The result turned out that the contribution of latitude,longitude and mountain base elevation to timber line distribution reaches 30.60%,26.53%,and 42.87%,respectively.North of northern latitude 32°,the contribution for each of the three factors amounts to 53.08%,21.25%,and 25.67%,respectively;to the south,the contribution is 14.94%,48.98%,and 36.08%,respectively.The results indicate that MBE,serving as a proxy indicator of mass elevation effect,is a significant factor determining the elevation of altitudinal belts.Compared with other factors,it is more stable and independent in affecting forest line elevation.Of course,mass elevation effect is also determined by other factors,including mountain's volume,the distance to the edge of a land mass,the structures of the mountains nearby,etc.They need to be included in the study of mass elevation effect in the future.