The Study On Ecological Disturbance Response Mechanism:the Decay Law

Effects of disturbance are inherent, generous and inevitable in an ecosystem. Various types of disturbance to the ecosystem exist, such as landslide, flood, pasturing and wildfires, due to constantly actions on the ecosystem by nature and humans. Ecological factors are changed constantly caused by these disturbances, and these changing behaviors are either unexpected and strong or gradual and weak. It is because of the significance and prevalence of the disturbance to human society, economy and environment that ecological disturbance response mechanism is focused by the academia. This study mainly pays attention on ecological disturbance and its response mechanism caused by LUCC which is a man-made factor.The decay law is tried to discuss in this work based on the ecological disturbance response mechanism. The survey region is decided in the area of Hanjiang River Basin in Hubei Province. The relations between LUCC disturbance and the primary response object, secondary response object as well as the system response object are obtained with the help of GIS, based on four temporal phases of the image of Landsat TM and professional data. The decay law of LUCC disturbance is proved in this thesis. The major achievements are listed as follows:(1) The principle and method of system identification for ecological disturbance response mechanism is put forward, and the model of the decay law is constructed. This project confirms the object selection method of principle response, secondary response and system response, and the system identification is conducted. The model of the ecological disturbance-response is constructed combined with the theory of the decay law.(2) The empirical research on ecological disturbance response mechanism and the decay law has been carried on the Hanjiang River Basin. The empirical research on ecological disturbance response mechanism and the decay law has been done on the Hanjiang River Basin using the method of remote sensing (RS) and geographic information system (GIS), based on the achievement (1) and the actual data in the year of 1995,2000,2005 and 2010.The results show that:(1) The ecological disturbance of LUCC in Hanjiang River Basin is growing. Land use intensity in the year of 1995,2000,2005 and 2010 are 263.31,264.34,268.01 and 270.34, respectively. It implies that urbanization is accelerating, which reflects the improvement of intensity and development of land.(2) The response to ecological disturbance of human-land system is in accordance with the decay law. In the year of 1995,2000,2005 and 2010 in Hanjiang River Basin, principle responses are 1.9227,1.3784,-0.455 and -2.8454, respectively; secondary responses are 1.6078,1.1106,-0.5854 and -2.9330, respectively; system responses are 1.4448,1.0989,-0.5877 and -2.9560, respectively. These data indicate that LUCC disturbance level to the principle, secondary and system response objects are decreasing gradually. These response objects decrease also compared to their response levels.This study put forward a new theory to explain regional ecological disturbance response mechanism of human-land system. Then, the principle and method of system identification for ecological disturbance response of human-land system is put forward. And the Hanjiang River Basin is given as an example to demonstrate the decay law. The research achievements of the Hanjiang River Basin are of positive significance to ecosystem management, coordination of human-land relationship, regional sustainable development.