Modelling Crown-Stem Diameters Relationship for the Management of Tectona grandis Linn f. Plantation in Omo Forest Reserve, Western Nigeria

F. N. Ogana
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Abstract

Crown-stem diameter relationship is important for sustainable forest management. Effective forest management requires routine inventory data of tree crops for decision making. Therefore, in this study, crown-stem diameter relationship was modelled for the management of Tectonia grandis L. f. plantation in Nigeria. The dataset consists of 1919 trees measured from 35 sample plots. Three methods including ordinary least square (OLS), quantile regression (QR) and linear mixed model (LMM) were used to model the relationship between crown diameter (CD) and diameter at breast height (DBH). The model was used to estimate the limiting density, growing space and projection area. The result shows that the model from LMM was more suitable than OLS and QR. It explained 0.622 of the variation in CD with root mean squared error of 0.736. The study also shows e.g., that T. grandis trees of 25 cm DBH would occupy an equivalent area 36.32 m 2 and to avoid inter-tree competition the stand density should not exceed 275 Nha -1 . And if the plantation is to be thinned and clear-felled when mean DBH is 50 cm, density remaining after thinning would be 115 Nha -1 with average growing space of 9.3 m. This information would help in the management of the plantation.
尼日利亚西部奥莫森林保护区构造大林人工林管理的冠-茎径关系建模
冠茎直径关系对森林可持续经营具有重要意义。有效的森林管理需要树木作物的常规清查数据以供决策。因此,本研究对尼日利亚大地构造(Tectonia grandis L. f.)人工林的冠茎直径关系进行了建模。该数据集包括从35个样地测量的1919棵树。采用普通最小二乘法(OLS)、分位数回归(QR)和线性混合模型(LMM) 3种方法对冠径(CD)和胸径(DBH)之间的关系进行建模。利用该模型对极限密度、生长空间和投影面积进行估计。结果表明,LMM模型比OLS和QR模型更合适。它解释了0.622的CD变异,均方根误差为0.736。研究还表明,例如,25 cm胸径的大白杨树将占据36.32 m2的等效面积,为避免树间竞争,林分密度不应超过275 Nha -1。若在平均胸径为50 cm时进行疏伐,则疏伐后的剩余密度为115 Nha -1,平均生长空间为9.3 m。这些信息将有助于种植园的管理。
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来源期刊
Annals of Silvicultural Research
Annals of Silvicultural Research Agricultural and Biological Sciences-Forestry
CiteScore
2.70
自引率
0.00%
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