Crown-Stump Diameter Model for Parkia biglobosa Benth. Species in Makurdi, Benue State, Nigeria

Abstract

The crown of tree is the centre of physiological activity which gives an indication of the potential photosynthetic capacity on a tree. Though, its measurement remains a challenge in forest inventory task. The ability to predict crown diameter from stump diameter provides an effective technique of obtaining its estimate. This helps in detecting the excessive tree felling than actual requirements and wildlife suitability.The main objective of this study was to develop and test crown diameter prediction models for silvicultural management of naturally grown Parkia biglobosa within the University of Agriculture, Makurdi. Nine 100 m x 100 m temporary sample plots were established using simple random sampling method. Crown diameter and stump diameter were measured in all living P. biglobosa trees with stump diameter ≥10.0 cm. Least square method was used to convert the counted stumps into harvested crown dimension. Three linear and three non-linear models using stump diameter as the exploratory variable were developed and evaluated using the adjusted coefficient of determination (Adj.R 2 ), standard error of estimate (SEE), prediction error sum of squares (PRESS) and Akaike information criterion (AIC). The crown-stump diameter relationship was best described by the double logarithmic function with . 2 = 65.1%, = 0.1729, = 262.9998 = 717.56.The result showed that Crown diameter estimation was feasible even when the only information available is stump diameter.The resulting equation was tested for validation with independent data obtained from additional plots and was found to be desirable for estimating the crown diameter for Parkia biglobosa in Makurdi,

Nonlinear Height-Stump Diameter Models for Tectona grandis Linn. F Stands in Omo Forest Reserve, Nigeria

“…This implies that Dbh increase with the increase in stump diameter. This result is similar to the reports of Oyebade and Onyambo, (2011), Shamaki and Akindele (2013) and Chukwu et al (2017) that diameter at breast height (Dbh) and stump diameter (Ds) are highly correlated. Hence, to avoid co-linearity between the two growth variables (Ds and Dbh) as indicated by Huang et al (2003), only stump was selected as independent variable for developing models in this study.…”

“…The higher the Adjusted R 2 value the better the model, also the lower the RMSE and AIC the better the model. The efficiency of this procedure was confirmed by Navroodi et al (2016) and Chukwu et al (2017). Based on the model evaluation results, the square model was selected out of the four nonlinear candidate models.…”

“…The principle of using stump diameter alone was to help forest managers obtain information on the original structure of a forest after exploitation either by legal or illegal activities within the forest. Osho (1983), Westfall (2010), Özçelík et al (2010), Shamaki and Akindele, (2013) and Chukwu et al (2017) upheld this method stating that,estimating tree growth variables after exploitation can only be possibly done through the stumps diameter, as tree stump is possibly the only tree part left after logging.…”

“…These reasons include; describing the structure of a removed tree, creating historical records of past management activities, reviewing harvesting practices, assessing damage due to catastrophic events and establishing loss due to indiscriminate and/or illegal felling. Previous studies have shown that tree stump diameter (Ds) is highly correlated with diameter at breast height (Dbh), and as such have being used in place of Dbh to predict most tree growth variable especially in the case of illegal logging (Osho, 1983;Westfall, 2010;Özçelík et al, 2010;Shamaki and Akindele, 2013;Chukwu, et al, 2017).…”

Deriving Tree Crown Distributions from Diameter at Breast Height

“…To the wildlife manager, a forest with larger crowns could affect the abundance and distribution of fauna species, especially the herbivores. Because low light penetration to the forest floor means less grasses and shrubs for the herbivores (Chukwu et al, 2018).…”