Ecology, Carbon Stock Quantification and Formulation of Allometric Models for Some Trees of Sele-Nono Forest, Southwest Ethiopia: Implication for Biodiversity Conservation and Climate Change Mitigation
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Date
2019-06-03
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Addis Ababa University
Abstract
This study presented the vegetation ecology, carbon stock quantification and formulation of allometric models for some trees of Sele-Nono Forest, Ethiopia. A total of 90 permanent plots were distributed in the study area using stratified random sampling techniques. The ecological studies such as plant diversity analysis, cluster analysis, ordination analysis and vegetation structure were carried out using data obtained from 25 m x 25 m (625 m2) plot size; whereas 35 m by 35 m (1225 m2) plots superimposed on the 25 m by 25 m plots were used for carbon stock study. Shannon-Wiener diversity index was used to assess species diversity and evenness. A hierarchical cluster analysis was used to identify plant communities. Frequency, density, basal area, importance value indices (IVI), size class distribution and profile diagram were also used to analyse the vegetation structure of the study area. Density of seedling and sapling of woody species were computed to determine the regeneration status of woody species. Priority ranking of threats by the local people was used to rank the threats that have been affecting the forest. Canonical Correspondence Analysis (CCA) was used to study the influence of environmental factors on the distribution of plants in the study area. Regression graphs, paired t-test and cross validation statistics were used to validate existing and newly formulated allometric models. This study produced seven plant community types. Result showed that Sele-Nono forest is a reservoir of diverse vascular plant species (414 species) of which 59 were new records to the flora of Illubabore (IL) region. CCA suggests that a number of environmental factors such as elevation and slope (topographic factor), Organic matter and Nitrogen (edaphic factors) and disturbance were the main drivers for the current distribution of plant species in Sele-Nono Forest. The vegetation structure of the study forest was mainly characterized by low stature & 2-3 storey of trees with high density of stems (20, 939 stems/ha). Moreover, the forest was mainly characeterized by poor regeneration status of woody species. Besides this study validated some allometric models; and also presented newly formulated allometric models for some common trees in the study area. Results also showed that carbon is stored in forests predominantly in soils, above & below ground biomass, and lying dead woods respectively. It was also found that the mean total carbon stock density of the forest was estimated at 284.81±107.81 t C/ha. Moreover, the equivalence of atmospheric Carbon dioxide removed due to the current stand of Sele-Nono Forest was estimated at 157.12 Mega tons (Mt) of CO2 (1Mt = 106t) indicating that the study forest is a potent place for carbon sinks and plays significant role in climate change mitigation. However, Sele-Nono Forest is also being affected by anthropogenic factors fundamentally due to deforestation for agricultural land expansion and degradation through selective logging. Hence, putting the forest in a biosphere reserve under UNESCO is paramount for sustainable conservation of the forest. Moreover, attention shall be given by the National REDD+ Ethiopia to sustain its role as carbon sink to mitigate climate change.
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Allometric Model, Carbon Stock, Ecology, Model Validation, Regeneration, Ordination, Vegetation Structure, Sele-Nono Forest