scholarly journals Fitting Linear and Non Linear Growth Models for Selected Plantations in Omo Forest Reserve Southwestern Nigeria

2020 ◽  
pp. 19-29
Author(s):  
E. T. Adedeji ◽  
A. S. Akinbowale ◽  
O. A. Akinbode
Keyword(s):  
Linear Models ◽  
Tectona Grandis ◽  
Pinus Caribaea ◽  
Southwestern Nigeria ◽  
Forest Reserve ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Non Linear ◽  
Nauclea Diderrichii ◽  
The Relationship

This study was conducted to assess the suitability of forest models in Tectona grandis, Pinus caribaea and Nauclea diderrichii stands at Omo forest reserve, Ijebu East, Ogun State, Southwestern Nigeria. Temporary sample plots of equal size (25 m x 25 m) were laid while complete enumeration were carried out in each sampled plot and tree growth variables such as diameter at breast height (dbh), diameter at the top (dt), diameter at the middle (dm) and diameter at the base (db) as well as total height of all trees were measured. Simple linear models and six non linear models were developed and assessed for the selected plantation. The linear model developed _ R-squared ranged from 77% to 93%. The least R- square was obtained in Tectona grandis plantation and the highest was obtained in 93% Pinus caribaea. All the models have high F values ranging from 234.71 to 2965.40. In Tectona grandis plantation, Logistic power model, gave a good fit in describing the relationship between diameter at breast height and volume with AICC values of -2368.92, 0.22 each. The Sigmond models that gave a good fit in describing the relationship between the diameter at breast height and volume in Pinus caribaea were Weibull model (-719.19, 0.09) while Gompertz relation is the best for Nauclea diderrichii, respectively. The various models generated in the study are highly recommended for use in estimating the growth characteristics of the plantation in the future.

scholarly journals Assessment of land-cover changes and carbon sequestration potentials of tree species in j4 section of Omo Forest Reserve, Ogun State, Nigeria

2020 ◽  
Vol 22 (1) ◽  
pp. 137-152
Author(s):  
A.A. Adeyemi ◽  
S.O. Adeleke
Keyword(s):  
Tree Species ◽  
Carbon Stock ◽  
Forest Type ◽  
Stand Density ◽  
Tectona Grandis ◽  
Natural Forest ◽  
Gmelina Arborea ◽  
Pinus Caribaea ◽  
Forest Reserve ◽  
Nauclea Diderrichii

We evaluated carbon stock accumulation on potential of tree species in five forest-types in Omo Forest Reserve of western Nigeria. This included four forest plantations and a natural forest of mixed species. The reserve was stratified into Gmelina arborea, Tectona grandis, Pinus carebeae and Nauclea diderrichii plantations as well as natural forest. Each forest-type was assessed using circular plot method. Plot points were pre-determined using remote sensing. For each point, two circular plots were established, the main plot with a radius of 12.61 m (500 m2 ) and the subplot with a radius of 5.64 m (100 m2 ). In each plot, tree Dbh and height were measured for trees with Dbh ≥10 cm, while only trees with Dbh <10 cm but >2 cm (i.e. 2 cm ≤ Dbh < 10 cm) were considered in the sub-plot. Soil samples were also collected at 10 locations with 2 each in the north, south, east, west and at the plot centre, in each forest-type. The samples were analysed to obtain soil organic carbon. Above- and belowground biomass and carbon stocks were estimated using the appropriate allometries formulated for the tropics. All empirical relationships were included in the existing allometries with Dbh and height as predictors. Landsat images of the reserve in 1991, 2000, 2014 and 2019 were processed and analysed to assess forest degradation. The results revealed that 23-year-old Pinus caribaea plantation  sequestered more carbon (35.78±2.73 tons/ha) than 35-year-old Gmelina arborea (18.96±1.82 tons/ha), 43-year-old Tectona grandis (17.75±2.13 tons/ha) and 43-year-old Nauclea diderrichii (17.36±1.87 tons/ha) plantations and natural forest (21.98±2.38 tons/ha). The study showed that stand density influences carbon stock accumulation of forest. It was observed that individual stems of Pinus caribaea were better carbon accumulators than Gmelina arborea, Tectona gransdis and Nauclea diderrichii. The same trend was observed for CO2 captures as Pinus caribaea captured 131.31±10.02 tons/ha with Nauclea diderrichii the least, having a value of 63.71±6.9 tons/ha. Keywords: Biomass, Carbon stock, Degradation, Forest-type, Stand density

scholarly journals Model of mixed effects of height dependence on tree diameters in pine stands

2021 ◽  
Author(s):  
Н.Н. Дубенок ◽  
В.В. Кузьмичев ◽  
А.В. Лебедев
Keyword(s):  
Fixed Effects ◽  
Mixed Effects ◽  
Mixed Effects Model ◽  
Fixed Effects Model ◽  
Permanent Sample Plots ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Russian State ◽  
Pine Stands ◽  
The Relationship

Основными исходными данными для определения запаса служат результаты обмеров диаметров и высот деревьев. Но обмеры диаметров деревьев на высоте груди выполнить намного проще, чем обмеры высот, поэтому ограничиваются замерами высот 15–25 деревьев. Цель исследования – по материалам измерения модельных деревьев в сосновых древостоях выбрать наиболее адекватную простую модель, которая передает зависимость между высотой деревьев и диаметром на высоте груди. Объектом исследования послужили сосновые древостои искусственного происхождения на постоянных пробных площадях в Лесной опытной даче Российского государственного агарного университета – МСХА имени К.А. Тимирязева. В работе используются данные обмеров деревьев на 17 постоянных пробных площадях с 1934 по 2005 гг. Возраст древостоев на момент проведения измерений от 50 до 125 лет. По итогам проведения 77 перечетов массив данных составил 1157 наблюдений. И модель фиксированных эффектов, и модель смешанных эффектов адекватно описали зависимость между высотами и диаметрами деревьев в культурах сосны. Но, как и ожидалось, первая модель имеет худшие значения метрик качества по сравнению со второй. Модель со смешанными эффектами более точно предсказывает значения высот по сравнению с моделью фиксированных эффектов. Недостающие значения высот большого количества деревьев на участке можно вычислить более точно с помощью модели смешанных эффектов, а не применения модели фиксированных эффектов или использования только фиксированной части (средний отклик) модели смешанных эффектов. Применение разработанной модели должно ограничиваться только в тех условиях, к которым относятся экспериментальные материалы The main data for the stock of research results is the diameter of measurements and heights of trees. But measurements of the diameter at breast height are much easier to perform than measurements of heights, therefore, they are limited to measuring the heights of 15–25 trees. The aim of the study is to select the most adequate simple model based on the measurements of model trees in pine antiquities, which conveys the relationship between the height of trees and the diameter at breast height. The object of the study was pine stands of artificial origin on permanent test plots in the Forest Experimental Station Russian State Agararian University – Moscow Timiriazev Agricultural Academy. The work uses data from tree measurements on 17 permanent sample plots from 1934 to 2005. The age of the stands at the time of measurements was from 50 to 125 years. As a result of 77 enumerations, the data array amounted to 1157 observations. Both the fixed effects model and the mixed effects model adequately describe the relationship between heights and diameters of trees in pine stumps. But, as expected, the first model has worse quality metrics than the second. The mixed effects model more accurately predicts heights from the fixed effects model. The missing heights of a large number of trees on a site can be calculated accurately using mixed effects models, rather than using fixed effects models or using only a fixed portion (mean response) of the mixed effects model. The application of the developed model should be limited only in those conditions to which the experimental materials are applied.

scholarly journals Unexplained Relationships of Height-Diameter of Three Tree Species in a Tropical Forest.

2013 ◽  
Vol 6 (3) ◽  
pp. 196-204
Keyword(s):  
Tree Species ◽  
Coefficient Of Determination ◽  
Multivariate Models ◽  
Forest Reserve ◽  
Permanent Sample Plots ◽  
Tree Distance ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Bivariate Models

Associations between bivariate variables relative to the unexplained relationships of height-Dbh (diameter at breast height) models were investigated. Seven permanent sample plots measuring 40m by 250m at Omo Forest Reserve were used to assess the relationships between height and diameter at breast height of three tree species as affected by the variables of neighbouring trees. The result showed differences in the coefficient of determination of the bivariate models and multivariate models. The models arrived at for each of the species and for the bivariate models are: Scottelia coriaceae: Ht = 2.59 + 0.473D+ 0.0012D2 for 5cm ≤ D ≤100cm (R2 = 0.70) Sterculia rhinopetala: Ht = 5.96 + 0.467D+ 0.00296D2 for 5cm ≤ D ≤100cm (R2 = 0.77) Strombosia pustulata: Ht = 2.02 + 0.722D+ 0.00581D2 for 5cm ≤ D ≤ 60cm (R2 = 0.81) Where both Ht and D are height and Diameter at breast height. While on the other hand the multivariate models that considered the effect of neighbouring trees are: Scottelia coriaceae: 2 1 2 3 4 Ht = 3.74 + 0.41x −1.14x + 0.205x +1.278x (R = 0.723) Sterculia rhnopetala: 2 1 2 3 4 Ht = 6.18 + 0.2601x +1.163x + 0.438x − 0.442x (R = 0.608) Strombosia pustalata: 2 1 2 3 4 Ht = 6.84 + 0.399x − 0.318x − 0.138x − 0.838x (R = 0.650) x1 = diameter at breast height, x2 = Mean neighbouring tree distance, x3 = Frequency of the neighbouring tree and x4 = Position of the crown.

scholarly journals Fluxes in litter decomposition in three selected indigenous species and teak in a converted rainforest ecosystem in southwestern Nigeria

2012 ◽  
Vol 47 (3) ◽  
pp. 333-338
Author(s):  
AF Ojo ◽  
O Kadeba ◽  
J Kayode
Keyword(s):  
Litter Decomposition ◽  
Tree Species ◽  
Soil Nutrient ◽  
Tectona Grandis ◽  
Indigenous Species ◽  
Southwestern Nigeria ◽  
Forest Reserve ◽  
Nutrient Pool ◽  
Indigenous Tree Species ◽  
Litter Nutrients

The study investigated the rate of litter decomposition in three prominent litter releasing indigenous tree species in the natural rainforest and an exotic species Teak, Tectona grandis Lim., in the adjacent plantation in Akure forest reserve, southwestern Nigeria. Results showed that teak had the highest litter decomposition rate and Mansonia altissima the least. There was no relationship between the rates of decomposition among all species examined. The implication is that teak litter had the highest probability of releasing litter nutrients into the soil nutrient pool than any of the selected indigenous tree species while Mansonia altissima had the least. However all species had high decomposition rates. This implies that soil fertility will be maintained if any of the tree species were to be used for monoculture plantations. DOI: http://dx.doi.org/10.3329/bjsir.v47i3.13069 Bangladesh J. Sci. Ind. Res. 47(3), 333-338 2012

scholarly journals Development and Evaluation of Models for the Relationship between Tree Height and Diameter at Breast Height for Chinese-Fir Plantations in Subtropical China

PLoS ONE ◽  
2015 ◽  
Vol 10 (4) ◽  
pp. e0125118 ◽  
Author(s):  
Yan-qiong Li ◽  
Xiang-wen Deng ◽  
Zhi-hong Huang ◽  
Wen-hua Xiang ◽  
Wen-de Yan ◽  
...  
Keyword(s):  
Tree Height ◽  
Chinese Fir ◽  
Subtropical China ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
The Relationship

scholarly journals Structure of Plants across Habitat Types in Amurum Forest Reserve, Plateau State Nigeria

2021 ◽  
Vol 25 (5) ◽  
pp. 847-850
Author(s):  
N. Janfa ◽  
M.J. Francis ◽  
C. Kambai ◽  
M.S. Chomini ◽  
S.A. Popoola ◽  
...  
Keyword(s):  
Habitat Type ◽  
Height Distribution ◽  
Gallery Forest ◽  
Diameter Class ◽  
Habitat Types ◽  
Forest Reserve ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Rocky Outcrop ◽  
Plateau State

The Amurum Forest Reserve is one of the nature reserves in Plateau State North central Nigeria. Strict Nature reserve is prominent among the methods for in situ conservation of biodiversity in Nigeria and also the world at large. A study was conducted in the Forest across three habitat types in order to measure tree height and diameter at breast height (dbh) of trees. 50m x 50m plots were marked across the habitat types by simple random sampling technique. Trees and shrubs were identified to species level. Measurement were limited to all woody plants with diameter at breast height (dbh) of ≥ 10cm. Data collected was analyzed in excel. A total of 397 woody species were identified during the study period. 87.7 of the plants were shrubs while 12.3% were trees. The gallery forest had the highest diameter class(30-35cm) followed by the savanna(25-30cm) and lastly the rocky outcrop with the diameter class of 20-25cm.The rocky outcrop had the highest number of trees with the lowest dbh (10-15cm) while the gallery forest had more trees in the highest diameter class (30-35) (Figure 2). The highest mean height distribution in the Gallery forest shows that the plant communities in this habitat type has grown over the years without disturbance since the place is a protected site. Therefore, other surrounding bushes should be protected in order to preserve species from local extinction.

scholarly journals Competition in Abies kawakamii forests at subtropical high mountain in Taiwan

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0254791
Author(s):  
Wei Wang ◽  
Min-Chun Liao ◽  
Hsy-Yu Tzeng
Keyword(s):  
Plant Species ◽  
Spatial Patterns ◽  
Subtropical High ◽  
High Mountain ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Dominant Component ◽  
Understory Composition ◽  
The Relationship ◽  
Competition Indices

The spatial patterns of plant species reflect the competitive pressures on individuals. To generate Competition indices (CI), we measured the diameter at breast height (DBH), crown volumes (CV) and the distances between trees. In this study, Abies kawakamii were divided based on the dominant component of the understory (moss or bamboo) to (1) investigate the relationship between the CI and stand structural attributes (SSAs); (2) compare the inter- and intraspecies; CIs as well as living and dead individual CIs; and (3) examine the relationship between the DBH and CI. The current findings indicate that the understory composition affected the CI and SSAs. The interspecies CI was larger than the intraspecies CI when bamboo-dominated the understory. In contrast, the intraspecies CI was larger than the interspecies CI when the understory was dominated by moss. The CI of dead individuals was higher than that of live individuals due to the biological characteristics and regeneration needs of Abies. Additionally, sensitivity to the environment and available resources may exert more pressure on young individuals than mature individuals.

scholarly journals Variations of Density and Compressive Strength Before and After Charring of Some Selected Construction Timber Species of Southwestern Nigeria

2017 ◽  
Vol 2 (2) ◽  
Author(s):  
Oluwaseun A Adetayo ◽  
Bamidele IO Dahunsi
Keyword(s):  
Compressive Strength ◽  
Tectona Grandis ◽  
Percentage Change ◽  
Timber Species ◽  
Fire Exposure ◽  
Southwestern Nigeria ◽  
Before And After ◽  
Density Values ◽  
Nauclea Diderrichii ◽  
Milicia Excelsa

This study aimed to evaluate the percentage variations of density and compressive strength of some selected timber species mostly used for constructional purposes in Southwestern Nigeria after undergoing fire exposure. The species are: Terminalia superba (Afara), Milicia excelsa (Iroko), Nauclea diderrichii (Opepe), Khaya ivorensis (Mahogany), Mansonia altissima (Mansonia), Tectona grandis (Teak).The densities and the compressive strengths of the species were determined at Moisture Contents (MC) of 9.0, 12.0, and 15.0%. Nine specimen per species, were exposed to fire at various temperature ranges.The results of analysis by variance revealed that at 9% MC, Mahogany had the lowest density value of 439±10.58Kg/m³. At 12 and 15% MC, Afara had the lowest density values of 444±4.18Kg/m³ and 469±7.07Kg/m³ respectively. At 9, 12 and 15% MC, Opepe had the highest density values of 630±28.85Kg/m³, 686±22.64Kg/m³ and 752±17.22Kg/m³ respectively. Afara of 9, 12 and 15% MC had the lowest compressive strength parallel to the grain values of 9.59±1.08N/mm2, 9.59±1.08N/mm2 and 8.13±1.01N/mm2 respectively, while Mahogany had the highest compressive strength parallel to the grain values of 16.57±0.50N/mm2, 15.17±0.49N/mm2 and 12.12±0.42N/mm2 at the three MC levels. Post fire exposure revealed that Afara had the highest percentage change in density and compression in parallel values, while both Iroko and Mahogany exhibited the lowest percentage change in density and compression in parallel values. This study indicated that Mahogany and Iroko species which had lowest post fire change in density and compression in parallel values are useful and recommended to ensure the safety in case of fire outbreaks.

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