农业生态系统生产力在生态系统健康中的指示性作用

Research on indication of eco-system productivity for eco-system health

生态系统生产力的变化是区域生态系统变化的主要表现形式,其波动性反映生态系统的稳定水平。以耕地单产代表农业生态系统生产力,从而将耕地单产的波动作为生态系统稳定性的指标,以吉林省西部乾安县为例,进行了区域生态系统的稳定性变化分析,并从土地利用结构角度出发进行了退化原因的阐释。研究表明:政策因素、综合投入和气候因素不是决定耕地单产波动的主要因素,生态系统的稳定性及健康与耕地单产的波动性变化密切相关,是区域农业生态系统生产力(耕地单产)波动的根本干扰源。1949-2000年间,以1982年为转折点,乾安县的生态系统变化经历了两个阶段:基本健康稳定阶段和生态系统退化、稳定性被破坏的阶段。表现在土地利用类型上为森林景观的大面积减少、湖沼的消退和盐碱地的大面积扩散。图5,表1,参6。

Change in land productivity is the main present from of regional eco-system change, fluctuation of which reflect the stability of ecosystem.The paper select the yield per ha as instructive index to analysis the change of eco-system stability and some expatiation were done from the point of view of land-use structure.The results show, policy, synthetical devotion and climate are not the crucial factors influenced the wave of field per ha , in which the stability of eco-system play import role and become the basic disturbing factor. During the year 1949 to 2000,taken the 1982 as a turning point, eco-system in Qian＇ an county experienced two step： healthy stable step and unhealthy degenerative step,which can be represented by the reduction of forest, fadeaway of lake and marsh and expansion of saline-alkalized landscape from the change of land use.