长白山地区龙井县农田生态系统的演变机制及调控战略研究

STUDIES ON EVOLUTION MECHANISM AND CONTROL STRATEGY FOR FARMLAND ECOSYSTEM IN LONGJING COUNTY

The evolutional characteristics and mechanism of farmland ecosystem in Longjing county are studied in this paper in terms of macroscopic view. The models on system function in response to anthropological factor and natural factor are established, and measures that should be taken for further steady development of the system are proposed. Result from analysis shows that there are 3 obvious characteristics on evolution of farmland ecosystem since 1949. (1) The System function have rosen fluctuationa-lly with a rise due to increasing input of artificial energy and a fluctuation due to varying greatly in temperature during growth yearly; (2) Farmland soil has been gradually degenerated due to i ) inputs fewer than outputs in farmland ecosystem and ii ) rather serious water and soil losses as a potential reason for the system function fluctuation getting bigger, (3 ) The kinds of crops planted are increasingly diversified that is mainly related to policy change. The macroscopic control strategy for steadily improving the system function has been suggested. In order to carry out the strategy, it is pointed out that three kinds of complex ecosystem should be established and perfected in Longjing county: (1) plant-raise-process complex ecosystem in plain region; ( 2 ) forest-farmland-grassland complex ecosystem in hill and platform region; ( 3 ) forest-special product-herd complex ecosystem in low mountains.