Comparison of Woody Species Diversity and Soil Organic Carbon in Coffee-Based Forests and Natural Forests in Ethiopia

Ethiopia is the origin of coffee arabica, which grows in moist Afromontane forests. Today, the expansion of coffee production to adjacent natural forests is high. The current study aims to compare species diversity, richness, regeneration, and soil physico-chemical properties of forests without and with coffee for conservation. A result showed that Forests without coffee have better mean species richness (45.86), Shannon wiener diversity index (2.69), Evenness (0.85), and Simpson (2.94) than forests with coffee. Forests without coffee had a higher percentage of soil carbon storage (mean 147.18) than forests with coffee (Mean 120.25). Forests without coffee are better for all comparisons. Documentation of woody species will be required for both systems for immediate conservation

Physical and chemical properties of soils in Gera moist Afromontane forest, southwest Ethiopia

Abstract Soil is the centre of plant growth and, in turn, plants are important elements in soil creation. This points to a strong positive correlation between forest growth dynamics and soil qualities. However, the decline in the biological, chemical and physical characteristics of forest soils alters this link. Therefore, the objective of the study was to determine the physical and chemical properties of soils in the Afromontane rainforest of Gera as inputs for vegetation and land management. A systematic random sampling design was used to collect a soil sample. Twenty main plots with a size of 20 m by 20 m pits measuring (0.5) m by (0.5) m, one in the centre and four in the corners, were dug for the collection of soil samples. Soil samples were collected to a depth of 0 - 20 cm using an auger because the soil has a similar profile and is mixed to form a soil composite. From the composite sample, twenty samples were randomly selected as a working sample. Descriptive statistics and inferential statistics were carried out to analyze the data using SAS software. The sampled soil contains an average of 56.93 % sand, 26.22 % silt and 16.36 % clay. The average bulk density of the forest is 1.49 g cm-3. The forest contains 3.91 and 6.74 % organic carbon and matter, respectively. The analysis revealed that sandy loam accounts for 70 % of the texture classes in the Gera forest. Total nitrogen was highly correlated with organic carbon and matter, and magnesium and calcium were highly correlated with cation exchange capacity, while sodium was highly correlated with electrical conductivity. Further study on other soil physico-chemical properties will be required for rapid rehabilitation of the Gera forest for site species that match and sustain the forest.Resumen El suelo es el centro de crecimiento de las plantas y, a su vez, las plantas son elementos importantes para la creación del suelo. Esto señala una fuerte correlación positiva entre la dinámica del crecimiento forestal y las cualidades del suelo. Sin embargo, la disminución de las características biológicas, químicas y físicas de los suelos forestales altera este vínculo. Por lo tanto, el objetivo del estudio fue determinar las propiedades físicas y químicas de los suelos del bosque húmedo afromontano de Gera como insumos para la vegetación y el manejo del territorio. Se utilizó un diseño sistemático de muestreo aleatorio para recolectar una muestra de suelo. Se cavaron veinte parcelas principales con un tamaño de 20 m por 20 m pozos que miden (0.5) m por (0.5) m, una en el centro y cuatro en las esquinas, para la recolección de muestras de suelo. Las muestras de suelo se recolectaron hasta una profundidad de 0 - 20 cm usando un sinfín debido a que el suelo tiene un perfil similar y se mezcla para formar un compuesto de suelo. De la muestra compuesta, se seleccionaron al azar veinte muestras como muestra de trabajo. Se llevaron a cabo estadísticas descriptivas y estadísticas inferenciales para analizar los datos utilizando el software SAS. El suelo muestreado contiene una media de 56.93 % de arena, 26.22 % de limo y 16.36 % de arcilla. La densidad aparente promedio del bosque es de 1.49 g cm-3. El bosque contiene 3.91 y 6.74 % de carbono orgánico y materia, respectivamente. El análisis reveló que el franco arenoso representa el 70 % de las clases de textura en el bosque de Gera. El nitrógeno total estaba muy correlacionado con el carbono orgánico y la materia, y el magnesio y el calcio estaban altamente correlacionados con la capacidad de intercambio catiónico, mientras que el sodio estaba altamente correlacionado con la conductividad eléctrica. Se requerirá más estudio sobre otras propiedades fisicoquímicas del suelo para la rehabilitación rápida del bosque de Gera para especies del sitio que coincidan y sostengan el bosque

Aboveground Biomass Models for Indigenous Tree Species in the Dry Afromontane Forest, Central Ethiopia

The application of biomass models for quantifying forests’ above-ground biomass is essential for sustainable forest management. However, lack of knowledge in modelig biomass of individual tree growth hinders the sustainable management of Dry Afromontane forests. In this study, models to estimate above-ground biomass were developed for Rhus ruspolii, Ekebergia capensis, and Nuxia congesta. To develop the models, a total of 45 trees from different diameter classes were selected, felled, and divided into different biomass compartments. For the model’s development, diameter at breast height (DBH), total height (TH), diameter at stump height (DSH), and wood density (WD) were used as independent variables. Models’ performances were evaluated using RSE, adjusted coefficient of determination, and AIC. Also, model validations were done by using rRMSE, mean absolute deviation, bias, and coefficient of variation. Models 5 (Adj-R2 = 0.92), 6 (Adj-R2 = 0.97), and 8 (Adj-R22 = 0.82) were the best fitted models for Nuxia congesta, Ekebergia capensis, and Rhus ruspolii, respectively. The average wood densities of Ekebergia capensis, Nuxia congesta, and Rhus ruspolii were 0.59, 0.50, and 0.69, respectively. The variation between observed biomass and estimated biomass using new models was statistically not significant (p>0.05). Thus, the biomass models developed here can be important tools to accurately estimate above-ground biomass in the Menagesha Suba forest and can be integrated into decision support tools

Species specific allometric equations, biomass expansion factor and wood density of native tree species in dry afromontane forest of Ethiopia

Abstract Forest is the second largest store house of carbon released from different sources. However, limited allometric equations are available to determine its contribution for carbon cycle. The objective of study was to develop species specific allometric equations, establish database for Biomass Expansion Factor (BEF) and Wood Density (WD) to five tree species, namely Apodytes dimidiata, Cassiopourea malosana, Celtis africana, Ilex mitis and Myrica salicifolia grown in dry afromontane forest of Ethiopia. The sampled tree diameter at breast height (dbh) and their total height (ht) ranged from 7 to 48 cm and 6.7 to 23.4 m respectively. A total of 62 sample trees harvested from different diameter classes of each species and divided in to different biomass compartments (stem, big branches &gt; 7cm), small branches (2-7cm) and twigs and foliage (&lt; 2cm). To determined WD, total of 186(stem position) and108 sample disks (big branches till 7cm dbh were sampled. Oven dried at temperature of 105oc and 70oc for 72 and 24hrs for wood and foliage respectively. A set of log transformed models relating total above ground biomass to dbh, ht, WD and average crown diameter as independent variables were fitted following R-software version 4.0.1. The best biomass models were found to be having lower AIC, residual standard error and higher adj.coefficient of determination. The BEF and WD of aforementioned tree species were ranged from1.19 to 1.40 and 0.53 to 0.74 gcm− 3 respectively. Species specific allometric equations were better than generalized allometric equation for estimation of above ground biomass of Chilimo dry afromontane forest.</jats:p

Aboveground Biomass Models for Indigenous Tree Species in the Dry Afromontane Forest, Central Ethiopia

The application of biomass models for quantifying forests’ above-ground biomass is essential for sustainable forest management. However, lack of knowledge in modelig biomass of individual tree growth hinders the sustainable management of Dry Afromontane forests. In this study, models to estimate above-ground biomass were developed for Rhus ruspolii, Ekebergia capensis, and Nuxia congesta. To develop the models, a total of 45 trees from different diameter classes were selected, felled, and divided into different biomass compartments. For the model’s development, diameter at breast height (DBH), total height (TH), diameter at stump height (DSH), and wood density (WD) were used as independent variables. Models’ performances were evaluated using RSE, adjusted coefficient of determination, and AIC. Also, model validations were done by using rRMSE, mean absolute deviation, bias, and coefficient of variation. Models 5 (Adj-R2 = 0.92), 6 (Adj-R2 = 0.97), and 8 (Adj-R22 = 0.82) were the best fitted models for Nuxia congesta, Ekebergia capensis, and Rhus ruspolii, respectively. The average wood densities of Ekebergia capensis, Nuxia congesta, and Rhus ruspolii were 0.59, 0.50, and 0.69, respectively. The variation between observed biomass and estimated biomass using new models was statistically not significant ( p &gt; 0.05 ). Thus, the biomass models developed here can be important tools to accurately estimate above-ground biomass in the Menagesha Suba forest and can be integrated into decision support tools.</jats:p

Woody Species Composition, Structure, and Soil Seed Bank of the Degraded Parts of the Gera Moist Afromontane Forest, Southwestern Ethiopia

Ethiopia’s forest coverage is decreasing from time to time due to agricultural expansion, settlements, misuse of existing forest resources, and a lack of awareness and sense of ownership among the local population. Not only forest coverage but also species composition and diversity are decreasing in the country. The current study aims to investigate the woody species composition, structure, regeneration, diversity, and distribution of the soil seed bank in a degraded part of the Gera moist Afromontane forest. A systematic random sampling technique was used to collect tree data. Twenty representative sample square plots, each measuring 400 m2 for trees and shrubs, were established. Inside the main plots, five subplots measuring 9 m2 were assigned for regeneration data collection. Another five subplots were also marked for soil seed bank data collection that are 9 cm deep and 15 cm wide. The forest had twenty-one woody species that belonged to seventeen families. The Shannon–Wiener, Simpson’s indices, and evenness of the whole forest were recorded to be 2.17, 0.82, and 0.42, respectively. Syzygium guineense had the highest species-specific value indices (68.49), accounting for 22.83 percent of the total. The first DBH and height class patterns encompass over 61.16 and 59.92 percent of the total individuals, respectively. There were two growth phases (seedling and saplings) missing in three tree species (Allophylus abyssinicus, Olea welwitschii, and Schefflera abyssinica). The soil seed bank in the forest contained 77 plant species belonging to 41 families. Compared to other moist Afromontane forests, the Gera forest has a smaller composition of woody species and medium diversity. The soil seed bank did not significantly contribute to the restoration of the forest

Species-Specific Allometric Equations, Biomass Expansion Factor, and Wood Density of Native Tree Species in the Dry Afromontane Forest of Ethiopia

A forest is a storehouse of carbon released from different sources when the activities of sustainable forest management, planting, and rehabilitation exist. However, few allometric equations are present to determine its contribution to carbon reduction. The target of the study was to develop species-specific allometric equations and establish a database for biomass expansion factor and wood density for five tree species grown in the dry Afromontane forest of Ethiopia. A direct or destructive sampling method was used on 62 trees from different diameter classes. The diameter at breast height and the total height of selected trees ranged from 7 to 48 cm and 6.7 to 23.4 m, respectively. Trees were felled and divided into various biomass sections. Stem and big branch discs were sampled to determine the wood density and volume of the trees. Sample wood and foliage were oven-dried for three days and two days at 105°C and 70°C, respectively, to get their dry weight. Total above-ground biomass was regressed using diameter at breast height, total height, wood density, and average crown diameter as independent variables. R software version 4.0.1 was used to fit the biomass equations. The best biomass models were determined to have lower AIC and RSE and highest adj. R2. The biomass expansion factor and wood density of five tree species ranged from 1.19 to 1.40 and 0.53 to 0.74 g/cm−3, respectively. Species-specific allometric equations were better than both mixed species and pan tropical models for the assessment of above-ground biomass in the Chilimo dry Afromontane forest of Ethiopia