农业生态系统生产力在生态系统健康中的指示性作用

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。

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

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 yield 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.