燃料换代历史与森林分布变迁——以近两千年长江上游为时空背景

清代中叶以前长江上游在使用传统的生物质燃料时期燃料总体十分富足,唐宋元明时期个别煮盐业发达的地区出现了薪材匮乏的现象,但并不影响总体的生物质燃料的丰富充足状况。长江上游最早在汉代就开始发现火井,并在晋代利用天然气作为手工业燃料,但直到清代才逐渐在川东、川南部分地区盐业中广泛使用,而在生活中较多使用天然气等液化气是20世纪80年代以来的事。煤炭在中国也是早在汉代就开始,在长江上游的使用早在唐宋就出现,但很长时期内不论是在生产中或是在生活中都是煤炭与木材、木炭并用。近代以来,城市生活和生产煤炭使用范围扩大,但农村受多方面的制约,煤的使用程度并不十分普及,直到今天,农村生物质燃料仍为主体。由于人口压力、工业化过程中燃料换代不能实现,清中叶以来至20世纪80年代,是长江上游生物质燃料的危机时期,也是从生物质燃料向非生物质燃料转换的转折时期,其中20世纪60年代至80年代达到顶峰。近十多年来,由于液化气、煤炭、沼气、电力等非生物质燃料大量使用,燃料换代加速,加上城市化背景下农村实际生活人口减少、环境保护意识增强、烹熟可食用品增多,虽然生物质植物燃料在农村仍为主体燃料,但城市乡村的生物质燃料薪材采伐量大大减少,森林生态环境的压力减弱。

A Study on the Relationship between the Repalcement of Fuel and the Distribution of Forest in the Upper Reaches of Changjiang River for Recent two thousand years

The upper reaches of Changjiang River were rich of fuels before the middle period of Qing Dynasty when people made use of traditional biologic fuels. In Tang-Song-Yuan-Ming Dynasties,some areas which had developed salt industry came out the situation that lacking of firewood ,but it couldn't affect the whole situation of adequate biologic fuels. From the middle period of Qing Dynasty to 1980s,it was the critical time for the biologic fuel in the upper reaches of Changjiang River, and it was also the transitional period that non-biologic fuels converted to biologic fuels. From 1960s to 80s, it was the crest of this crisis. In recent decades, because of the acceleration of non-biologic fuels taking place of biologic fuels ,the pressure of forest environment have decreased.