A Study On Logistic Model

Logistic model is one of core theory in population ecology.It almost the only model to describle population growth for about one hundred. Logistic model may describle the population's quantity dynamic such as the fish population's growth;Determinating the relation of harvest and time;Describing a certain object's growth process like determination the environment capacity in ecotourism region.Managing forestry resource ;Forecasting social possessive quantity of durable commodity and social output value exponent ,and so on.Aslo as theory basis of others complexity models such as Lotka-Volterra model.Logistic model is used abroadly not only in natural science but in social science .So it become very necessarily to analyse and discourse systematically upon its occurrence ,development,evolvement and classification etc.Detailedly expatiating on Logistic model's engendering,ecological meaning and classification. Analysing its disadvantages ; Aiming at these disadvantages.different academician gained correspondence renewed Logistic model.The renewed models as follows: Hallam model;Smith Logistic model;Cui-Lawson Logistic model; ZhangDayong self-adaptive model; WuChengzheng model ;LiXinyun Logistic model ; SongDingquan renewed Logistic models ZhongJiansheng self-memory Logistic.The practical tested:self-momery Logistic modelis superior to Logistic model.The forecast Logistic model as follow:Different renewed Logistic models have their advantages and disadvantages.but whether which model or not,different methods of parameters fitness,the results have distinctly differentia.the Modified simplex method is superior to linear change method when forecast social possessive quanitity of durative commodity.Two forecast Logistic models areUsing Logistic model and self-memory model to forecast social output value exponent;The modified simplex method precede to linear transform method with the same model. Obviously parameters fitness method of Logistic are very important in practical. There are lots of methods of fitting Logistic model. The practical showed that Modified simplex method is superior to the others'with its manipulation simple.calculation capacity small,quick-velocity ,fitness value precision etc.Using Modified simplex method to fit Betula Lumimiferra population's Logistic model and its renewed models.The results as follows:Zhang-model: 6.383079Song-models: (1) The order as the Square sum of residues:Song 1 model >Zhang -model>L-model>Song2-model>Li-model>Cui-model. Using several renewed Logistic models to fit Betula luminifera population and compare the results in order to offer a theory method for Population ecology dynamic research.