横断山——云南高原干热河谷形成原因研究

CAUSES FOR THE FORMATION OF DRY-HOT VALLEYS IN HENGDUAN MOUNTAIN-YUNAN PLATEAU

云南高原是青藏高原“高原地理效应”影响的独特地域。云南山原的自然地带性以热带为其特征 ,地形海拔变化使得水分和热量出现垂直分异 ;云南山原的垂直自然带的基带通常是河谷地带 ,深切的河谷往往更能反映水平地带性的状况 ,但在横断山———云南高原的怒江、澜沧江、元江、金沙江、南盘江部分河段出现了独特生态气候景观的干热河谷地域。关于干热河谷的形成原因 ,历来有“原生论和次生论”两种观点 ,本文从自然环境的整体性观点出发 ,归纳分析出与干热河谷联系紧密的 4个因素 : ①区域气候环境和水热平衡变化 ; ②植物逆向演替和生态环境退化 ; ③土地结构和河谷坡地退化 ; ④人为干扰影响。对以上 4个因素进行了分析研究 ,总结出干热河谷形成原因的“双生论” ,并对干热气候类型进行了初步分类。

Qinghai Tibet Plateau is a unique region impacted by “plateau geographical effect”. Natural zonality of Yunnan highland is uniqueness in tropics where vertical differentiation in water and heat occurs due to changes in relief and altitude;the base belt of vertical natural zone of Yunnan highland is usually valley area,the deep dissected valleys can even better reflect horizontal zonal conditions.However,dry hot valleys of special ecoclimatic landscapes occur in part of the river sections of Nujiang,Lancangjiang, Yuanjiang,Jinshajiang and Nanpanjiang on Hengduan Mountain Yunnan Plateau.Two view points on the causes of formation of dry hot valleys have existed,namely,primary induced theory and secondary induced theory.The paper,approaching from the integral point of view of natural environment,summarizes and analyzes four factors closely related to dry hot valleys: 1)regional climatic environment and water heat balance; 2)adverse succession of plants and eco environmental degradation' 3)land structure and valley sloping land degradation; 4)artificial interference.The point of dual induced theory related to the causes of formation of dry hot valleys are indetified and priliminary classification of the dry hot climatic types was done.