麻疯树人工林单木生物量与生产力模型研究

The Individual Biomass and Productivity Model of Jatropha curcas Plantation

回归分析法是构建单木生物量模型进而估算群体生物量的基本方法。本文研究了攀枝花市马店河一个麻疯树4年人工林生物量与生产力模型的构建过程,运用相关生长定律分析参数合理性,并筛选了适宜的模型构建参数。首先,用地径、高度、D2H、树冠直径、冠幅、枝下高、树冠垂直投影体积这些灌木生物量测定中经常采用的外部形态指标构建麻疯树单木生物量模型,得到拟合性最好的幂函数、抛物线、对数函数模型。其次,采用树体构型指标,如枝条数量(不同年龄枝级)与分支率(总体分支率、)参数构建单木生物量模型,得到相关性不等的幂函数、抛物线模型。用年龄平均法与直径增量法同时估算了麻疯树单木生产力,分别为Pa=4.93±3.92 kg.a-1,Pd=4.59±3.82 kg.a-1,方差分析差异不明显。经回归,获得单木生产力模型。通过排序,获得对生产力贡献较大的因子,并对筛选的因子进行多元回归,得到Y=∑AiXi(其中Ai为第i个常数,Xi为第i个变量,i为测定变量总个体),提高了估算的精确度。分析表明,地径、冠幅直径、冠幅、冠幅垂直体积都能较为准确的估算单木生物量、生产力,但生殖生物量估算相关系数在0.8以下(0.607<r2<0.753),精确度不高,表明生殖自身特性的独特性。

The regressing analysis is the basic method of establishing the individual biomass model and appraising the population biomass.In this paper,studies were made of the model building process of individual biomass in a 4 year-old plantation of Jatropha curcas,and the allonetry law was used to analyze the reasonability of establishing parameters and select the fit parameters.Firstly,the leaf,truck and branch,root,reproduction biomass and total biomass models were established by use of these common parameters such as diameter,height,D2H,tree crown diameter,crown area,height between land surface and the down first branch,vertical volume of tree crown,to get the higher correlation power,paullic and logarithic models.Secondly,by using the tree architecture parameters,such as branch amounts（different age class） and bifurcation（total and step bifurcation） to establish the model,we got the different coefficient models of power and paullic.The individual productivity of individual J.curcas was measured by diameter-increasing ratio and age averaging-production,respectively being Pa=4.93±3.92 kg·a-1,Pd=4.59±3.82 kg·a-1,which was no significant difference after ANOVA analysis.As a result of the regression,the function relationship between two kinds of productivity and parameters was got.Through factor selection,we gained nine factors which were mostly contributory to total biomass,reproductive biomass and productivity,and built the polyparameter models：Y=∑i oAiXi（Ai,the ist constant,Xi,ist variety,i,total samples）,which improved the accurate degree of biomass estimation.Summarily,the diameter,crown diameter,crown area,vertical volume of crown and amount of one-year-old branch could accurately appraise the biomass and productivity.However it was difficult to get the better estimating model of reproductive biomass,and the coefficient was relatively lower（0.607〈r2〈0.753） than 0.8 and the accuracy was not high,which also probably implied the peculiarity of reproductive behavior.