Effects of slenderness coefficient in crown area prediction for Tectona grandis Linn. f. in Omo Forest Reserve, Nigeria

J. U. Ezenwenyi, Onyekachi Chukwu


Crown area which is crown size, is closely related to the photosynthetic capacity of tree and it is an important parameter to characterize biomass, leaf area and wildlife habitats. Conversely, assessment of crown dimensions still remain one of the most difficult and tedious task in forestry. The difficult measurements and the sensitivity of crown dimension on management makes it desirable to develop estimation procedures based on variables that are easier to measure than crown extension itself. The main objective of this study was to develop and observe the effects of tree slenderness coefficient in predicting crown area for Tectona grandis in Omo Forest Reserve. Twenty temporary sample plots of size 20 m x 20 m were randomly selected across the stand ages (9, 11, 12 and 18 years). Tree growth variables measured from each plot include diameter at breast height (Dbh) ≥ 5 cm, total height (THt) and crown diameter (CD). The data was analysed using descriptive, correlation and regression analyses. Amidst the models developed and verified, double logarithmic function with adj. R2 = 62.0%, RMSE = 0.265% and PRESS = 0.263 gave the best fit and predictive ability. This was also supported by the undeviating bands of the graphical analyses of the residual. Conversely, the inclusion of TSC had impact on the predictive abilities of the models which implies that slenderness coefficient typically indicates the size of crown dimension, centre of gravity and a better developed root system. Therefore, it is recommended that the model can be used by forest managers for the development of stocking guideline.


Crown area; Dbh; Tectona grandis; Model; Tree slenderness coefficient

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Leites LP, Robinson AP. Improving taper equations of Loblolly Pine with crown dimensions in mixed-effects modelling framework. Forest Sci. 2004; 50: 204-212.

Dubravac T, Dekanic J, Vrbek B, Matosevic D, Roth V, Jakovljevic T, Zlatanov T. Crown volume in forest stands of pedunculate oak and common hornbeam. Period Biol. 2009; 111(4): 479-485.

Vrbek B, Pila I, Dubrava T, Novotny V, Dekani S. Effect of deposition substances on the quality of through fall and soil solution of pedunculate oak and common hornbeam forest. Period Biol. 2008; 110: 269-275.

Grote H. Estimation of crown radii and crown projection area from stem size and tree position. Ann Forest Sci. 2003; 60: 393-402.

Bella IE. A new competition model for individual trees. J Forest Sci. 1971; 17: 364-372.

Iwasa Y, Cohen D and Cohen JAL. Tree height and crown shape as results of competitive games. J Theor Biol. 1984; 112: 279-297.

Dubrasich ME, Hann DW, Tappeiner JC. Methods for evaluating crown area profiles of forest stands. Can J Forest Res. 1997; 27: 385-392.

Goelz JCG. Open-grown crown radius of eleven bottom-land hardwood species: prediction and use in assessing stocking. South J Appl Forestry. 1996; 20(3): 156-161.

Kaźmierczak K, Borzyszkowski W, Korzeniewicz R. Slenderness of 35-year-old pines from a dominant stand as an indicator of stand stability. Forestry Lett. 2015; 108: 32-35.

Korhonen L, Korhonen KT, Rautiainen M, Stenberg P. Estimation of forest canopy cover: a comparison of field measurement techniques. Silva Fennic. 2006; 40(4): 577-588.

Navratil S. Silvicultural systems for managing deciduous and mixedwood stands with white spruce understory. In: Silvicultural of temperate and boreal broadleaf-conifer mixture. Comeau PG, Thomas KD, eds. B.C. Ministry of Forests, Victoria. 1996: 35-46.

Eguakun FS, Oyebade BA. Linear and nonlinear slenderness coefficient models for Pinus caribaea (Morelet) stands in Southwestern Nigeria. J Agricult Vet Sci. 2015; 8(3): 26-30.

Jelonek T, Jakubowski M, Tomczak A. The effect of wind exposure on selected stability parameters of Scots pine stands. Ann Warsaw Univ Life Sci SGGW, Forestry Wood Technol. 2011; 74: 143-149.

Adesoye PO, Ezenwenyi JU. Crown diameter prediction models for Tectona grandis Linn. F. in Omo Forest Reserve, Nigeria. J Forestry Res Manag. 2014; 11: 72-87.

Ola-Adams BA. Biodiversity inventory of Omo Biosphere Reserve, Nigeria. Country Report on Biosphere Reserves for Biodiversity Conservation and Sustainable Development in Anglophone Africa. (BRAAF) Project. 1999.

Martin-Alcon S, Coll L, Aunos A. A broad-scale analysis of the main factors determining the current structure and understory composition of Catalonian sub-alpine (Pinus uncinata Ram.) forests. Forestry. 2012; 85: 225-236.

Wang Y, Titus SJ, Lemay VM. Relationship between tree slenderness coefficients and tree or stand characteristics for major species in Boreal mixed forest. Can J Forest Res. 1998: 28: 1171-1183.

Oyebade BA, Eguakun FS, Egberibin A. Tree slenderness coefficient (TSC) and tree growth characteristics (TGCS) for Pinus caribaea in Omo Forest Reserve, Nigeria. IOSR J Environ Sci Toxicol Food Technol. 2015; 9(3): 56-62.

Shimano KJ. Analysis of the relationship between diameter at breast height and crown projection area using a new model. Forest Res.1997; 2: 237.

Hinze WHF, Wessels NO. Stand stability in pines: an important silvicultural criterion for the evaluation of thinning and the development of thinning regimes: management paper. South Afr Forestry J. 2002; 196: 37-40.

Mason WL. Are irregular stands more windfirm? Forestry. 2002: 75(4): 347-355.


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