Forecast Models Research of Stands Basal Area Growth for Pinus tabulaeformis

It was incompatible to model thinned stands and unthinned stands separately, so it was necessary to study and establish the unified models. Using forest inventory data, based on Schumacher model, through introducing the dummy variables and thinning indexes to establish the stands basal area growth forecast models of Pinus tabulaeformis in Beijing respectively, and made the thinned stands and unthinned stands together to establish unified models.After inspection,on the forecast effect for stands basal area of Pinus tabulaeformis, forecast accuracy of model with dummy variables was 87.99% as a minimum; followed by the model with thinning indexes, forecast accuracy was 88.36%;forecast effect of model with dummy variables and thinning indexes was the best, forecast accuracy was as high as 88.61%.The models was applicable for thinned stands and unthinned stands, it was more convenient for application in practice.