论文部分内容阅读
DENTROL模型是根据全国杉木造林密度试验和杉木林抚育间伐强度试验的结果,参照新编的全国杉木人工林经营数表,分别杉木分布带、区和地位指数级,编制成的优化密度控制计算机模型。它主要以内部收益率为目标函数,辅以其它指标,实行全局优化判别。优化密度控制包括初植密度、间伐开始期、间伐强度、间伐次数、保留密度、主伐年龄和培育目标的确定,使最终的内部收益率为最大或接近最大。以12块抚育间伐试验标准地的数据,对模型的材积生长预测的精度进行检验,结果表明模型的材积预测标准差为±8.9％,系统误差为1.8％,符合生产实际的要求。根据计算,采用优化密度控制比非优化的对照区,按全国平均,每公顷净现值可提高321.7元,即提高17.0％。如仅以主要商品材基地——杉木分布区中带计算,则可提高经济效益47.3％,即每公顷可提高净现值892.4元。
DENTROL model is based on the results of the national fir planting density test and fir fir tree tending thinning strength test, with reference to the newly compiled national fir plantation management table, respectively, the distribution of the fir zone, area and status index level, compiled optimized density control computer model . It is mainly based on the internal rate of return as the objective function, supplemented by other indicators, the implementation of global optimization. Optimized density control includes initial plantation density, beginning of thinning, thinning intensity, number of thinning, retention density, cutting age, and cultivation objective, resulting in a maximum or near-maximum final IRR. The data of 12 standard tending thinning tests were used to test the accuracy of volume growth prediction. The results showed that the standard deviation of volume prediction was ± 8.9% and the systematic error was 1.8%, which accorded with the actual production requirements. According to the calculation, using the optimized density control over the non-optimized control area, according to the national average, the net present value per hectare could be increased by 321.7 yuan or 17.0%. If the calculation is made only in the middle zone of the main commodity timber and the fir distribution area, the economic benefit will increase by 47.3%, that is, the net present value will increase by RMB 892.4 yuan per hectare.