Construction of productivity prediction model of Hybrid acacia forest in Thua Thien Hue province
Keywords:
Dummy variable, multivariate regression, prediction model,, Hybrid acacia, productivityAbstract
Hybrid acacia is predominantly species in forest plantation in Thua Thien Hue province. The study has relied on some factors those have a major influence on the productivity of Hybrid acacia forest those are pure plantation, the same forest age and were harvested at the 6 - years old forest in Thua Thien Hue to build productivity prediction models. The study has used methods of multivariate regression correlation to predict the productivity. The study has test 4 types of regression model in which the qualitative variables can be used as coded variables or Dummy variables. The prediction models have built for the 2 types of forest cultivation model (extensive and intensive) and for overall the study area. With 250 forest plots for building models and 87 forest plots for testing models, the study has tested and built 12 models (4 models for overall study area, 4 models for extensive cultivation, and 4 models for intensive cultivation). The results shown that model with slope and altitude factors are used as the quantitative variables and other qualitative factors are used as Dummy variables will be the best results with the highest regression correlation is 0.92 and lowest relative prediction error is 4.62%. The specific models are:
productivity = 54.040 + 21.123 (T2) + 9.194 (Day5) - 14.230 (Day1) -27.621 (DatE) - 0.322 (dodoc) - 0.022 (docao) - 2.884 (CG2) - 4.539
(Day2) + 3.518 (M3) - 8.989 (N3) - 6.649 (N4). However, it needs to have
more in - depth analytical studies to other influences factors on productivity as well as to older Hybrid acacia forests.
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