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Statistical relationship between leaf litter and tree growth characteristics of Tectona grandis species

100%

Eguakun F. S., Job M.

World News of Natural Sciences

2018

vol. 18

issue 2

252-261

Forest productivity relies on the quantity and quality of litter as this influences nutrient cycling in the ecosystem. Many studies have been carried out on litter fall, but few attempts has been made to relate litter fall nutrient content with tree growth variables The aim of this work was to investigate basic relationships between the leaf litter nutrient content of Tectona grandis and tree growth characteristics. The study was done at the arboretum of the Department of Forestry and Wildlife Management, University of Port Harcourt, Rivers State, Nigeria. Data were collected from four (4) randomly selected 20m × 20m (0.04ha) plots. Within each plots, four (4) litter traps at 8m apart was set at random to collect litter on a weekly basis, while tree growth variables were measured on trees around the trap. The collected litter was put into zip-lock bags and taken to the laboratory for nutrient content analysis. Nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sodium (Na), magnesium (Mg) content and pH were included in this. The result shows that the average weekly leaf litter collected from the trap was 11.8g. In terms of average nutrient content, Nitrogen had the highest average at 1.8, while Sodium (Na) had the lowest value at 0.14. Among the tree growth variables, only height had a positive correlation with litter collected. The results also show that Nitrogen micronutrient content was related to the amount of litter collected (0.536). In addition, all the exchangeable base analysed in the study were also related to the amount of litter collected. Conclusively, the amount of litter produced is a major indicator of primary productivity because as litter quantity increases, available nutrient content for plant growth also increases, hence, having influence on tree height.

Tree basal area models and density for selected plantation species in swamp forest zone of Rivers State, Nigeria

81%

Oyebade B. A., Eguakun F. S., Duru B. N.

2020

vol. 30

issue 2

271-286

Individual-tree models of basal area growth and density were developed for seven plantation species in swamp forest zone of Rivers State, Nigeria. Tree growth data were collected from pure permanent sample plots of seven plantation species within the study area with measurements of diameter at breast height (cm), diameter at the base (cm), total height of tree (m), and also the number of tree per plot was taken and obtained from plantation records. The Quantitative data collected from these selected plantation species were subjected to descriptive analysis, correlation and regression analyses. Linearized models for description of relationship between BA and other growth attributes were developed. The results of the major growth variables by species in the study area showed that Treculia africana has the highest dbh mean value 30.804 ±2.031 (cm) with density 0.0022 and basal area per hectare 1.79×10–4 (m2). Similarly, the results also showed that Nauclea dedirrichii has the lowest dbh mean value 08.484 ±0.339 (cm) with basal area 3.92×10–5 (m2) and density 0.0063 per hectare. The results of correlation analyses showed general associations between basal area and the growth attributes by species with coefficients of correlation ranging from –0.023 to 0.999. The results similarly revealed distinct variations by species in density, basal area and tree number in the study area. The results of relationship between basal area and other growth variables showed significant model fit (best fit) with diameter attributes with model order: LNBA = b0 + b1lnDb + b2Dbh2 in Enthandrophragma angolense (R2 - 0.964, RSME – 0.837). The results of the study revealed that there were significant variations in the growth attributes by species in the study area; with significant associations between the basal area and major growth variables evaluated in the study, while the selected best adjudged fit model in the study area could be reasonably used for predicting basal area which is critical in cubical volume estimation and sustainable management of the study area.

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2 World News of Natural Sciences

1 2020

1 2018

2 Eguakun F. S.

1 Duru B. N.

1 Job M.

1 Oyebade B. A.

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Statistical relationship between leaf litter and tree growth characteristics of Tectona grandis species

Tree basal area models and density for selected plantation species in swamp forest zone of Rivers State, Nigeria