横断山区垂直带谱的分布模式与坡向效应

Spatial Pattern and Exposure Effect of Altitudinal Belts in the Hengduan Mountains

根据收集到的横断山区山地垂直带谱数据,对山地垂直带的坡向效应和空间分布规律进行了分析和研究。结果表明:1)主要的垂直带和垂直带界线如林线、暗针叶林带、雪线等的纬度和经度地带性分布规律明显并且分布模式都相似,纬向上呈开口向下的二次曲线分布模式,经向上呈开口向上的二次曲线分布模式,两者共同形成"双曲抛物面"分布模式,充分反映了横断山区的环境与生态的复杂性和独特性,也进一步丰富和发展了山地垂直带谱的二次曲线假说;2)横断山区山地垂直带谱表现出明显的基于水分驱动的坡向效应,主要表现为同一山体的东、西坡往往具有不同的基带和带谱结构,相同类型的带谱出现的海拔和分布范围不同,迎风坡表现出较为湿润的类型和带谱结构,而背风坡则表现出更为干旱的类型和组成结构;横断山区的坡向效应主要是由于山体对当地盛行季风的影响,造成迎风坡和背风坡水热条件相差很大,从而发育不同的山地垂直带谱类型。从横断山区山地垂直带谱的空间分布规律来看,28°～29°N、98°～101°E范围内,即大致在澜沧江以东-雅砻江以西,山地垂直带谱普遍表现出干热的特点,为横断山区干热气候的核心地带。但如何定量分析山地的坡向效应尚有待于进一步的研究和讨论。此外、数据质量和数据误差也对分析的结果,尤其是空间分布模式的数学模拟结果产生一定的影响,在以后的研究中尚需进一步完善。

This paper analyses the exposure effects and spatial pattern of altitudinal belts in the Hengduan Mountains based on nearly 80 spectra of altitudinal belts in the study region.The result shows that：1）The main altitudinal belt lines,such as forest line,the upper limit of dark-coniferous forest and snow line,have similar latitudinal and longitudinal spatial patterns,namely,arched quadratic curve as with changing latitudes and concave quadratic curve along longitudinal direction This pattern can be called ＂Hyperbolic-paraboloid model,＂ revealing the environmental and ecological complexity and speciality of the study region.This result further validates the hypnosis of the quadratic model for the spatial pattern of mountain altitudinal belts.The spatial pattern of altitudinal belt limits also clearly shows that the region between the Lancang River and the Yalong River（28°-29°N and 98°-101°E）is the drought and hot core of the study region.2）The spatial pattern of altitudinal belt spectra is closely related with moisture-related exposure effect in the Hengduan Mountains.Different combination（spectra）of altitudinal belts and different base belt types appear in windward and leeward flanks and even in the same flanks of different ranges.This is closely related with the parallel mountain ranges of the Hengduan Mountains,which,at nearly right angle with the moving direction of prevailing moisture-laden air masses from west and east,hold up the warm and wet monsoon wind from moving into the core region and result in different moisture condition in windward and leeward flanks.However,how to quantitatively describe the moisture-related exposure effect needs in-depth study.In addition,data quality and data accuracy at present also affect the result of quantitative modeling and should be improved with RS/GIS in the future.