Woody species diversity, structure and regeneration status of Omo National Park, Southern Ethiopia

Information on species composition, structure, and diversity is essential to introduce and select different management activities to improve the forest productivity. Accordingly, species composition, structure, diversity, and regeneration status of trees were assessed in the Dindin natural forest. In this forest, trees or shrubs having ≥2.5 cm diameter at breast height and height >1.5 m were identified and measured in 35 quadrats of 20 m × 20 m. Regeneration status was assessed in 5 m × 5 m subplots that were laid within each main plot to sample seedling and sapling. Woody species diversity, density, basal area, and importance value index were calculated. To prioritize conservation efforts, the study utilized factors such as the importance value index, seedling and sapling densities, and population structure. A total of 42 woody tree species representing 30 families were recorded in the forest. The diversity and evenness of woody species in the Dindin forest were 2.66 and 0.70, respectively. Woody species density was 1403 individual ha−1, and the total basal area was 35.54 m2ha−1. About 480 seedlings per hectare were recorded in the Dindin forest. The research yielded practical insights into the dominance, population structure, importance value, and regeneration status of tree species. The analysis of population structure indicates that certain dominant species are experiencing inadequate regeneration. In addition, multiple nondominant shrubs and tree species within the forest are also at risk of extinction due to insufficient regeneration. Therefore, these important findings play a crucial role in the formulation and implementation of effective strategies to restore and rehabilitate the studied forest.

The purpose of this study was to investigate the biodiversity and structure of woody plants of HGs in the Basona Worana district (BWD). For this, six kebeles and 138 HGs from three agroecologies of BWD were selected using various sampling techniques. The plot size used per HG was 400 m2. Diversity and important value indices (IVIs) were computed. For their structural analysis, the diameter at breast height (DBH) and height were also measured for trees and shrubs fulfilling the standards (diameters at breast height (DBH) ≥2.5 cm and height >2 m). Thus, a total of 42 woody species belonging to 37 genera and 26 families were identified. Fabaceae was the most abundant family, followed by Euphorbiaceae. Trees were the dominant habit. The richness in Kola HGs (33) was higher than Dega (14) and Woinadega (19) HGs, with an overall mean richness of 4.14 per HG of BWD. The Shannon, Simpson, and evenness indices for HGs in the district were 1.05, 0.55, and 0.75, respectively, showing their moderate diversity with even distribution. The Sorenson's similarity of HGs between Dega and Woinadega, Kola and Dega, and Kola and Woinadega were 40%, 28%, and 32%, respectively. The multiple site similarities of woody species among three ecological zones (36%) were still <50%, showing no similarity. The overall DBH and height classes' patterns of the woody species individuals abruptly decreased towards their highest classes. Similar DBH and height classes' patterns of woody species individuals were also observed in Kola and Woinadega agroecologies, indicating their selective tree cutting. The mean values of DBH, height, basal, and crown areas of the woody species in the district were ∼14 cm, ∼6 m, ∼29 m2·ha−1, and 5 m2, respectively. Based on IVI, most of the HGs were dominated by Eucalyptus globules (93.35), followed by Eucalyptus camaldulensis (45.04), Rhamnus prinoides (22.4), and Cupressus lusitanica (22.33). Hence, actions should be taken to promote the diversity and managing of HGs' woody species of BWD.

The plant biomass is an important ecosystem function of forests and plays a fundamental role in the material cycle and energy flow. The diameter at breast height (DBH) and height of plants with DBH ≥1 cm were surveyed in tropical cloud forests in Jianfengling Mt., Bawangling Mt., and Limushan Mt. with forest aboveground biomass (AGB) being calculated with an allometric model. We assessed variations in AGB across different plot sizes, DBH classes, and plant height classes in the three tropical cloud forests. The results showed that AGB in the three tropical cloud forests consistently changed across plot sizes, with the AGB being significantly higher in Jianfengling Mt. and Limushan Mt. than the Bawangling Mt., due to the influences of precipitation and air temperature. AGB of Jianfengling Mt., Bawangling Mt., and Limushan Mt. was mainly distributed in trees with DBH ≥ 30 cm, accounting for 33.0%, 32.1%, and 52.8%, respectively. For the patterns of AGB across height classes, AGB was mainly distributed in plants with height ≥7 m in Jianfengling Mt. and Bawangling Mt. accounting for 79.9% and 70.1% of the total AGB. The ABG in Limushan Mt. was mainly distributed in plants with a height ≥9 m, accounting for 87.7% of the total AGB. Changes in AGB across the three tropical cloud forests were consistent at different DBH and height classes with an AGB being mainly distributed in large trees.KeywordsTropical cloud forestAboveground biomassDBH classHeight class

Woody species diversity, structure and regeneration status of the church forests in West Gojjam Zone, Northwestern Ethiopia

We investigated the structure and composition of Spirostachys africana woodlands in Gonarezhou National Park (GNP), southeast Zimbabwe. We divided the GNP into three strata, namely northern, central and southern GNP, based on physical feature such as major perennial rivers. The main objective was to determine whether the structure and composition of S. africana woodlands varied across the GNP. In addition, we evaluated whether herbivory and fires played important roles in influencing the structure and composition of S. africana woodland stands. A stratified random sampling design was used and data were collected from a total of 60 sample plots. The following variables were recorded in each study plot: woody plant height, species name, plant status (alive or dead), fire or browse evidence and number of stems per plant. A total of 2,588 woody plants comprising of 73 woody species were recorded from the sampled S. africana woodlands in the GNP. Our results showed that woody species diversity, woody plant heights, shrub density, density of dead plants, sapling density, density of fire damaged plants, and number of stems per plant were significantly different across the S. africana woodlands in GNP. In contrast, only densities of trees and browsed plants did not differ significantly across the GNP. Most plots in the southern GNP had higher tree and sapling densities and taller trees whereas those in the northern GNP had higher densities of fire damaged plants. In addition, plots from central GNP were characterised with higher shrub densities of S. africana woodlands. Overall, our results suggest that there are both structural and compositional differences of S. africana woodland stands across the GNP. Evidence of herbivory did not differ significantly across the GNP suggesting that plants were uniformly affected by herbivores. However, fire evidence seemed to vary across the GNP, with areas having frequent fires being more degraded and having to some extent more woody vegetation species diversity.

Conserving biodiversity is a challenge in terrestrial environments. Anthropogenic landscape with various land uses has a role in biodiversity conservation. Thus, this study aimed to analyze the diversity, stand structure, regeneration status, and preferences of woody species in Koore’s agricultural landscape, in Southern Ethiopia. Data were collected from 105 plots that randomly assigned to a stratified different land use types. The study found a total of 73 woody species across 33 families. The Fabaceae family was the dominant with 20.5% of the species, followed by Rosaceae (6.8%) and Myrtaceae (5.5%). Agroforestry demonstrated the highest value of Shannon diversity (H′) (4.04), evenness indices (E) (0.58), and good regeneration. About 19.2% of woody species recorded from farmland, grazing, and woodland showed poor regeneration. Acacia nigra , Acacia abyssinica , and Podocarpus falcatus that recorded without seedling and sapling are under risk of extinction. Agroforestry land use has been identified as a better land use type in promoting diversity and regeneration of woody species. Therefore, we recommended the promotion of agroforestry for woody species diversity conservation. Due emphasis should be given to save those woody species under the risk of extinction and low IVI values. The findings from this study are vital for effective ecological management.

Understanding the structural pattern and regeneration status of tree species is an important measure taken to assess the vegetation dynamics and their destruction factors species as well as management history and ecology of the forest. This study was conducted with the objective to assess the species diversity, structure, and regeneration status of woody species in Kenech natural forest, Ethiopia. Systematic random sampling method was employed as a sampling design for the collection of vegetation data. Accordingly, 40 plots of 20 m × 20 m were laid at every 100 m along four parallel transect lines following altitudinal gradient. Any woody species of trees and shrubs with the diameter at breast height (DBH) ≥2.5 cm was measured at 1.5 m from the ground. In each sample plots, all woody species seedling, sapling, and mature woody species were counted and recorded. A total of 80 plant species categorized into 67 genera and 28 families were recorded and identified, for description and analysis of vegetation structure. Structural analysis of the Kenech natural forest revealed a density of 840 stems/ha and a total basal area of 56.8 m2/ha. About 80.36% of the individuals are found in the first two classes (2.5–10 and 10–20 cm). The general pattern of DBH class distribution of woody species in the study area revealed an inverted J shape indicating the presence of a high density of trees in the lower DBH class than in the higher. The most dominant tree species relatively with the highest importance values recorded in the area were Pouteria adolfi-friedericii, Podocarpus falcatus, Celtis africana, Mimusops kummel, Pyschotria orophila, and Olea capensis subsp. macrocarpa. Forty-two species (64.61%) were represented by both seedling and sapling class, whereas 9 species (13.84%) were not regenerating.

Dry evergreen Afromontane forests are severely threatened due to the expansion of agriculture and overgrazing by livestock. The objective of this study was to investigate the composition of woody species, structure, regeneration status and plant communities in Seqela forest, as well as the relationship between plant community types and environmental variables. Systematic sampling was used to collect vegetation and environmental data from 52 (20 m x 20 m) (400 m2) plots. Density, Diameter at Breast Height (DBH), basal area, frequency, and importance value index (IVI) of woody species were computed to characterize the vegetation structure of the forest. Agglomerative hierarchical cluster analysis and Canonical Correspondence Analysis (CCA) with R software were used to identify plant communities and analyse the relationship between plant community types and environmental variables, respectively. A total of 68 woody plant species belonging to 63 genera and 44 families were identified. The Shannon diversity index and evenness values of the study area were 2.12 and 0.92, respectively. The total basal area and density of woody species were 27.4 m2 ha−1 and 1079.3 individual ha−1, respectively. The most frequent woody species in the Seqela forest included Albizia gummifera (51.92%), Croton macrostachyus (44.23%), Olinia rochetiana and Teclea nobilis (36.54%). Additionally, the most dominant species, as indicated by their importance value index (IVI), were Erythrina brucei (IVI = 11.24), Prunus africana (IVI=8.68), and Croton macrostachyus (IVI=7.38). Four plant community types were identified: Albizia gummifera - Ekebergia capensis, Prunus africana - Croton macrostachyus, Vachellia abyssinica - Dombeya torrida and Schefflera abyssinica - Teclea nobilis. The CCA results showed that the variation of species distribution and plant community formation were significantly (P < 0.05) related to altitude, organic matter, aspect, slope and soil available phosphorus. The regeneration status assessment of the forest revealed a good regeneration status, which was linked to diverse and abundant seed bank in the soil can ensure a continuous supply of seeds for regeneration; therefore, it is recommended to implement periodic soil seed bank assessments to monitor seed diversity and abundance and inform targeted conservation actions.

Dry evergreen Afromontane forests are severely threatened due to the expansion of agriculture and overgrazing by livestock. The objective of this study was to investigate the composition of woody species, structure, regeneration status and plant communities in Seqela forest, as well as the relationship between plant community types and environmental variables. Systematic sampling was used to collect vegetation and environmental data from 52 (20 m x 20 m) (400 m2) plots. Density, Diameter at Breast Height (DBH), basal area, frequency, and importance value index (IVI) of woody species were computed to characterize the vegetation structure of the forest. Agglomerative hierarchical cluster analysis and Canonical Correspondence Analysis (CCA) with R software were used to identify plant communities and analyse the relationship between plant community types and environmental variables, respectively. A total of 68 woody plant species belonging to 63 genera and 44 families were identified. The Shannon diversity index and evenness values of the study area were 2.12 and 0.92, respectively. The total basal area and density of woody species were 27.4 m2 ha-1 and 1079.3 individual ha-1, respectively. The most frequent woody species in the Seqela forest included Albizia gummifera (51.92%), Croton macrostachyus (44.23%), Olinia rochetiana and Teclea nobilis (36.54%). Additionally, the most dominant species, as indicated by their importance value index (IVI), were Erythrina brucei (IVI = 11.24), Prunus africana (IVI=8.68), and Croton macrostachyus (IVI=7.38). Four plant community types were identified: Albizia gummifera - Ekebergia capensis, Prunus africana - Croton macrostachyus, Vachellia abyssinica - Dombeya torrida and Schefflera abyssinica - Teclea nobilis. The CCA results showed that the variation of species distribution and plant community formation were significantly (P < 0.05) related to altitude, organic matter, aspect, slope and soil available phosphorus. The regeneration status assessment of the forest revealed a good regeneration status, which was linked to diverse and abundant seed bank in the soil can ensure a continuous supply of seeds for regeneration; therefore, it is recommended to implement periodic soil seed bank assessments to monitor seed diversity and abundance and inform targeted conservation actions.

This study was conducted to suggest the necessity of regulated stand density control in order to maintain the ratio of height to diameter at breast height (H/D ratio) of Hinoki cypress (Chamaecyparis obtusa) and Japanese cedar (Cryptomeria japonica) in South Korea. A total of 2,000 (1,000 each) Hinoki cypress and Japanese cedar were cut from various regions of South Korea, and their diameter at breast height (DBH), height and clear length were measured. The two species’ regional means of H/D ratio and crown ratio were then computed and compared to find the relationship with tree growth. The result of analyzing the relationship between the H/D ratio and tree growth by DBH class is as follows, 77.0% for small DBH class, 62.5% for medium DBH class, and 45.9% for large DBH class, with overall mean of 61.8%. The annual means of DBH growth were 4.6 mm, 7.4 mm, and 8.2 mm respectively for small, medium, and large DBH classes. As the DBH class went up, the H/D ratio decreased, showing a negative correlation (p < 0.0001) with the tree growth rate. However, the crown ratio showed a significant correlation with tree growth. Japanese cedar’s H/D ratios by DBH class were 100.5% for small, 74.9% for medium, and 53.6% for large, while its mean annual DBH growth were 5.1 mm, 7.6 mm, and 10.0 mm, from small to large DBH class respectively. Similar to that of Hinoki cypress, Japanese cedar’s H/D ratio showed a negative correlation with the growth rate (p < 0.0001), but no significant relationship could be established between the crown ratio and the tree growth. In both arboreal species, the correlation between the H/D ratio and growth rate is negative, and no significant correlation could be formulated between crown ratio and tree growth. In conclusion, both tree species tended to have a higher H/D ratio and a lower growth rate in small DBH class, while H/D ratio decreased and growth rate increased As DBH class got larger.

This study in the dry tropical woodlands of SE Angola in Cuando-Cubango Province assessed the diversity and composition of woody species in fallows compared to those in mature woodlands. We assessed the population structure of the most harvested woody species by calculating size class distribution and evaluated their regeneration potential based on the density of saplings. The vegetation was surveyed in 20 plots of 20 × 50 m (1000 m2). In each plot, we measured the diameter at breast height (DBH) of all woody species with DBH ≥ 5 cm. The saplings were counted, identified and recorded; 718 individuals, corresponding to 34 species in 32 genera and 15 families were recorded. The size class distribution of target woody species showed three different patterns in fallows and mature woodlands. In general, most of the smaller diameter classes had more individuals than the larger ones did, showing that the regeneration may take place. However, in some diameter classes, the absence of larger stems indicated selective logging of larger trees. Few saplings were recorded in the fallows or mature woodlands; fire frequency and intensity is probably the main obstacle for seed germination and seedling survival rates in the studied area.

The management of regeneration plays a vital role in sustainable forest practice by ensuring the future growing carbon stock and serving as an indicator of the forest condition of an area. In premises of the above-mentioned facts, the current study was conducted to investigate the population structure and regeneration status of woody species as an indicator for forest condition and to provide information on sustainable management of the woody plants in Chilimo-Gaji Forest. The data collection was done using a preferential sampling technique as a sampling design and a total of 36 plots with a size of 20 m × 20 m (400 m2) was laid out for the woody species. In each sample plot, all woody species seedling, sapling and mature tree/shrubs were counted and recorded. And their diameter at breast height (DBH) was measured at 1.5 from the ground with DBH ≥ 2.5 cm. A total of 42 species of vascular plants belonging to 34 genera and 28 families were recorded and identified from the 36 study plots. The total density of woody plant species in all the 36 sampled plots of the study area was 3328.47 individuals ha-1. The total density of seedlings, saplings and trees/shrubs were 1743.75, 827.08 and 757.64 ha-1, respectively. The regeneration status of individual tree species showed differences as 26% had good regeneration, 43% had fair regeneration, 7% had poor regeneration, 7% lacked regeneration, and 17% have appeared as newly regenerating. The cumulative species DBH class distribution of the study area was inverted J-shape distribution indicating stable population status or good regeneration status. Key words: Chilimo-Gaji, Dry Afromontane, regeneration, vegetation structure.

Climate variability added to anthropogenic pressures leads to habitat fragmentation, degradation and loss of forest ecosystem resources in Burkina Faso. Studying vegetation structure and woody species composition is important in monitoring vegetation dynamics for efficient forest management. This study was carried out to characterize woody vegetation along a climatic gradient. Stratified sampling according to four vegetation types was conducted in 120 plots in two protected areas. The plot size was 30 m × 30 m in savannas and 50 m × 10 m in gallery forests. In each plot, all woody species with a diameter at breast height (DBH) ≥ 5 cm were systematically identified and measured. Diversity indices, structural parameters and species importance values were calculated and compared among the sites and vegetation types. Linear discriminant analysis (LDA) was used to characterize each vegetation type in each climatic zone. The species diversity, tree density and basal area of woody species increased significantly along the climatic gradient from north to south. Discriminant analysis identified two vegetation types: open vegetation (shrub savannas and tree savannas) with moderate species richness and structural characteristics and closed vegetation (woodland savannas and gallery forests) with higher species richness and structural characteristics. The size class distribution showed that irrespective of the climatic zone, each vegetation type has a stable structure. Compensation among species in different diameter classes does not allow the effect of the climatic gradient between the two sites on the diameter class size distribution to be observed. This study revealed that climate is the main driver influencing the diversity of woody species rather than the site-specific conditions at the two sites. In addition to climate, site ecological conditions affect the structural parameters. The results provide a rational basis for planning and management decisions to ensure the sustainable use of resources in the two protected areas.

Land degradation in the form of soil erosion is <i> one of the most serious problems in the worldwide</i>. Physical and biological soil and water conservation measures implemented by various land rehabilitation program is the best option to address this problem. This study was conducted to evaluate the effect of integrated soil and water conservation (SWC) practices on Woody Species Diversity, Structure and Regeneration in Southern Ethiopia. A total of 60 plots (3 land use*4 transect*5 quadrants), measuring 20 m*20 m each, were established along transect line laid for woody vegetation data collection. Woody species diversity in the study sites were determined using the Shannon (H’) and Simpson diversity index through the analysis of species richness and evenness of species. A total of 28 woody species, belonging to 15 families were identified. The diversity, richness, density and basal area of woody species were significantly higher in closure area with SWC (p<0.05) compared to the value in closure area without SWC and open grazing land. The inverted ’J’ shaped distribution of height and DBH exhibited in closure area with SWC, which has more potential to enhance vegetation regeneration. The findings generally confirmed that area closure with SWC practices was highly improved woody species diversity, structure and regeneration status. Accordingly, to improve the biophysical conditions of degraded hillside areas implementing of area closure with integrated SWC practices is a best option.

This study was conducted in Abbo Sacred Forest in Wonsho district, Sidama Zone of Southern Nations, Nationalities, and People's Region (SNNPR), southern Ethiopia, to investigate the woody species diversity, vegetation structure, and regeneration status of the forest. A systematic sampling design was employed to collect vegetation data. Sixty quadrats of 20 m × 20 m were laid at every 200 m interval between each quadrat and 400 m apart between each line transect following the altitudinal gradient. Quadrats of 20 m × 20 m were used to record DBH and the height of all woody plant species reaching a height of ≥2 m and a DBH of ≥2 cm. For the inventory of seedlings and saplings, five subplots of 2 m × 2 m, one at the center and the other four on each corner of the main quadrat, were used. DBH, height, seedling, and sapling density of woody species were recorded in each quadrat. The data were analyzed by using Shannon-Wiener diversity and equitability indices, and the structural analysis was carried out based on frequency, density, DBH, height, and basal area/ha-1. The importance value index was also computed. Regeneration status was computed by comparing the density data of saplings and seedlings with those of mature trees. A total of 63 woody species belonging to 56 genera and 35 families were identified. Three endemic species to Ethiopia were recorded. Analysis of selected woody species showed diverse population structures. The findings of this study revealed that small trees and shrubs dominated the forest, suggesting its status under a secondary stage of development. Some woody species require urgent conservation measures. Therefore, local and regional stakeholders should integrate and work together to develop and implement sound conservation and management strategies that encourage the sustainable utilization of forest resources.