Afromontane Research Articles

Diurnal Activity Budgets and Feeding Habits of Grivet Monkey (Chlorocebus aethiops aethiops) in Fragmented Moist Afromontane Forest

ABSTRACTGrivet monkeys (Chlorocebus aethiops aethiops) are opportunistic omnivores and extremely adaptable in both rural and urban environments. A study was conducted out in human‐dominated fragmented moist Afromontane forest of wondo genet to investigate the diurnal activity budgets and feeding habits of grivet monkey. Data collection was carried out from February to September 2022 covering both wet and dry seasons. During each scan, individuals were recorded as performing one of the following activities: feeding, moving (searching for food), resting, grooming, playing and others such as drinking, vocalisation and defecation, or aggression and sexual activity. Dietary composition and preferences were assessed using scan sampling method. Proximate analysis was conducted to examine the nutritional makeup of feeding food items. The greatest proportion of the activity time budget of the grivet monkey was devoted to feeding, resting and moving, with relatively higher time devoted to feeding and moving and less time devoted to resting when compared with grivet monkeys inhabiting natural habitats. Grivet monkey utilised 42 food items grouped into 41 plant species and 1 insect. Psidium guava and Desmodium intortum, relatively with higher crude protein and less fibre, were the most preferred plants consumed. The study has pointed out that grivet monkeys in the human‐dominated landscape of Wondo Genet remnant moist afromontane forest tend to prefer to consume on fruit tress such as Persea americana, Mangifera indica and Psidium guava, which contain high nutritional content that are planted and managed around homesteads. It is recommended to plant and sustainably manage grivet monkeys' natural foods in human‐dominated landscape of Wondo Genet remnant moist afromontane forest to sustainably conserve the species and avoid/reduce human‐grivet monkey conflict.

Aboveground biomass estimation and mapping using Sentinel-2 data in a dry afromontane forest

ABSTRACT Forest biomass estimates are required for many applications, including accounting for the role of forests in the global carbon cycle, supporting sustainable forest management and making informed decisions. For all these applications and others, accurate and reliable forest biomass estimates are required. This study evaluated the potential of Sentinel-2 data for predicting and mapping aboveground biomass (AGB) of a dry Afromontane Forest in Tigray, Northern Ethiopia. Multiple linear regression was employed to model the relationship between AGB and Sentinel-2-derived spectral variables. The evaluation criteria for best-fit model selection were based on the coefficient of determination (R2), root mean square error (RMSE, %), and bias (Bias, %). All the spectral variables evaluated here were significantly correlated with AGB (p < 0.01). The model that includes a fraction of photosynthetically active radiation (FAPAR), leaf area index (LAI), Band 2 and Band 3 as predictor variables provided the best predictive performance for AGB in the study area (R 2 = 0.38, RMSE = 13.62 Mg ha−1 and Bias = -3.10 Mg ha−1). The predicted AGB of the study area ranges from 0.1 to 141.8 Mg ha−1, with a mean value of 12.4 Mg ha−1. The results from this study suggested that Sentinel-2 data can be potentially applied for estimating and mapping AGB in dry Afromontane forests.

Highland forest dynamics across equatorial East Africa during the end of the African humid period

Tropical mountain ecosystems hold immense ecological and economic importance, yet they face disproportionate risks from shifting tropical climates. For example, present-day montane vegetation of East Africa is characterized by different plant species that grow in and are restricted to certain elevations due to environmental tolerances. As climate changes and temperature/rainfall zones move on mountains, these species must rapidly adjust their ranges or risk extinction.Paleoenvironmental records offer valuable insights into past climate and ecosystem dynamics, aiding predictions for ongoing climate change impacts. In particular, warming and wetting in tropical East Africa during the mid-Holocene resulted in both lowland and highland forest expansion. However, the relative impacts of rainfall and temperature change on montane ecosystems along with the influence of lowland forest expansion on montane communities is not completely understood. We use fossil pollen to study the vegetation changes in two lakes at different altitudes in the Rwenzori Mountains, Uganda: Lake Mahoma (Montane Forest belt) and Upper Kachope Lake (Afroalpine belt). Further, using the newly relaunched African Pollen Database and recent temperature reconstructions, we provide a regional synthesis of vegetation changes in the Rwenzori and then compare this with changes observed from other equatorial East African montane sites (particularly Mt Kenya).In the early to mid-Holocene in the Rwenzori Mountains, trees common today in lowland forests dominated, driven largely by warmer temperatures. After 4000 years ago (4ka), Afromontane forest trees along with grasses progressively replaced lowland trees. Not all sites experienced identical transitions. For instance, at Lake Rutundu on Mt Kenya at the same elevation as Lake Mahoma, bamboo expansion preceded Afromontane forest growth, likely influenced by variations in fire. Variance partitioning indicates that each site responded differently to changes in temperature and rainfall. Therefore, these site-specific ecological responses underscore the importance of considering biogeographic legacies as management strategies are developed, despite similarities in modern ecology.

Revealing suitable habitats for Juniperus procera and Olea europaea tree species in the remnant dry Afromontane forests of Ethiopia: Insights from ensemble species distribution modeling approach.

Human activities and climate change pose a significant threat to the dry Afromontane forests in Ethiopia, which are essential for millions of people both economically and ecologically. In Ethiopia, trees are planted elsewhere even if they are not likely to be well suited to the area. This study aims to identify the suitable habitat for the most exploited Juniperus procera (J. procera) and Olea europaea (O. europaea) tree species in northern Ethiopia. As inputs, least correlated temperature, moisture, soil, and topographic variables were selected through a stepwise procedure. The study evaluated five individual and ensemble models using the area under the curve (AUC) and true skill statistic (TSS) values. The ensemble model outperformed with mean AUC of 0.95 and TSS of 0.78 for J. procera, while securing the second position for O. europaea with an AUC of 0.88 and TSS of 0.71. Climatic factors emerged as the most influential, followed by soil and topography. Suitable areas for both species were found when Isothermality (Bio3) values range from 52% to 62%, temperature seasonality (Bio4) of 16-29°C. Moreover, well drained soils with soil texture not heavier than sandy clay, and soil organic carbon ranging from 5 to 42 g kg-1 were found suitable. The optimal suitable altitude for J. procera and O. europaea was determined to be 2200-2600 and 2100-2500 m.a.s.l., respectively. The suitable areas for J. procera and O. europaea were estimated to be 3130 and 3946 km2, respectively. Furthermore, potential plantation areas were identified beyond Desa'a and Hugumbirda Grat-Kahsu protected forests, covering 2721 km2 (86.9%) for J. procera and 3576 km2 (90.6%) for O. europaea. These findings hold significance for the conservation and sustainable management of these valuable tree species in northern Ethiopia. We recommend implementing a similar approach for other locally restricted dry Afromontane tree species with wider potential distribution.

Influence of wildfires severity on tree composition and structure in Aberdare Afromontane Forest Ranges, Kenya

Wildfires strongly impacts on the forest ecosystems, with poorly understood consequences on the composition, diversity and structure within Afromontane forests of Eastern Africa. The impacts of wildfire on vegetation were investigated one year after the fire occurrence season. The burn severity was evaluated using Sentinel-2 satellite derived spectral index known as dNBR (difference Normalized Burn Ratio). This was used to delineate wildfire into low and high severity classes. We investigated the effects of wildfires using 36 plots of 15m radius distributed in high and low burn severities while others were laid in unburnt areas. Our findings indicated that tree height, basal area and density were significantly different along severity classes (p = 0.003, p=0.007 and p<0.000 respectively). However, diameter at breast Height was not significant along severity classes (p=0.185). The most ecologically important species based on Important Value Index (IVI) within the fire affected areas were Juniperus procera, Nuxia congesta, Olea europaea subsp. cuspidata, Protea kilimandscharicum and Scurtia myrtina. Among the five dominant tree species, the density of Protea kilimandscharicum and Olea europaea subsp. cuspidata were significant along the fire severities (p<0.05). Interaction of vegetation zones and wildfire severity indicated that only height was significant (p= 0.000) while all the other tree variables and species diversity index were insignificant; DBH (p=0.053), basal area (p=0.606), tree density (p=0.389), Shannon Weiner diversity index (p=0.843), Simpson dominance index (p=0.490) and Pielou's evenness index (p=0.248). Whereas this study was on a short-term post-fire effects on vegetation, it has shown remarkable findings which can guide restoration and management of fire affected landscapes. The study recommends evaluation of long-term regeneration and recovery to guide integrated fire management within Afromontane Forest Ecosystems.

Exploring the role of canopy cover and environmental factors in shaping carbon storage in Desa’a forest, Ethiopia

BackgroundDry Afromontane forests play a vital role in mitigating climate change by sequestering and storing carbon, as well as reducing greenhouse gas emissions. Despite previous research highlighting the importance of carbon stocks in these ecosystems, the influence of canopy cover and environmental factors on carbon storage in dry Afromontane forests has been barely assessed. This study addresses this knowledge gap by investigating the effects of environmental factors and vegetation cover on carbon stocks in Desa’a forest, a unique and threatened Afromontane dry forest ecosystem in northern Ethiopia. Data on woody vegetation, dead litter, grass biomass, and soil samples were collected from 57 plots. A one-way analysis of variance (ANOVA) was performed at a 95% confidence level (α = 0.05) to examine the influence of canopy cover and environmental factors on the carbon stocks of various pools.ResultsAmong the 35 woody species identified, Juniperus procera was the most dominant, while Carissa edulis Vahl and Eucalyptus globulus were the least dominant. The average total carbon stock was 92.89 Mg ha−1, with contributions from aboveground carbon, below-ground carbon, litter carbon, grass carbon, and soil organic carbon. Among the carbon pools, soil organic carbon had the highest carbon stock, accounting for 76.8% of the total, followed by above-ground biomass carbon at 17.7%. Significant variations in carbon stocks were found across altitude class and canopy level but not slope and aspect factors.ConclusionsIn summary, altitude and canopy level were found to significantly influence carbon stocks in Desa’a forest, providing valuable insights for conservation and climate change mitigation efforts in dry Afromontane forests. Forest intervention planning and management strategies should consider the influence of different environmental variables and tree canopy levels.

Challenges and a Strategy for Successful Restoration of Dry Evergreen Afromontane Forests of Ethiopia

Challenges and a Strategy for Successful Restoration of Dry Evergreen Afromontane Forests of Ethiopia

Network resilience of plant-bee interactions in the Eastern Afromontane Biodiversity Hotspot

Interaction network resilience can be defined as the ability of interacting organisms to maintain their functions, processes or populations after experiencing a disturbance. Studies on mutualistic interactions between plants and pollinators along environmental gradients are essential to understand the provision of ecosystem services and the mechanisms challenging their network resilience. However, it remains unknown to what level ecological changes along climatic gradients constrain the network resilience of mutualistic organisms, especially along elevation gradients. We surveyed bee species and recorded their interactions with plants throughout the four major seasons (i.e. long and short rainy, and long and short dry) on 50 study sites positioned along an elevation gradient (525 m to 2,530 m asl) in the Eastern Afromontane Biodiversity Hotspots in Kenya, East Africa. We calculated bee and plant network resilience using the network resilience parameter (βeff) and assessed changes in bee and plant network resilience along the elevation gradient using generalised additive models (gams). We quantified the effects of climate, bee and plant diversity, bee functional traits, network structure, and landscape configuration on bee and plant network resilience using a set of multi-model inference frameworks followed by structural equation models (SEM). We found that bee and plant species exhibited higher levels of network resilience at higher elevations. While bee network resilience increased linearly across the elevation gradient, plant network resilience increased exponentially from ∼1500 m and higher. Bee and plant network resilience increased in areas with reduced mean annual temperature (MAT) and decreased in areas with lower mean annual precipitation (MAP). Our SEM model showed that increasing temperatures indirectly influenced plant network resilience via network modularity and community assemblage of bees. We also found that MAP had a direct positive effect on plant diversity and network resilience, while the fragmentation of habitats reduced richness of plant communities and enhanced network modularity. In conclusion, we revealed that mutualistic networks showed higher network resilience at higher elevations. We also unveiled that climate and habitat fragmentation directly or indirectly influences the network resilience of plants and bees via the modulation of community assemblages and interaction networks. These influences are lower at higher elevations such that these systems seem better able to buffer against extinction cascades. We thus suggest that, management efforts should be geared at consolidating natural habitats. In contrast, restoration efforts should aim at mitigating climate change effects and harnessing the ability of mutualists to reconnect broken links to improve the network resilience and functioning of East-African montane ecosystems.

The Great Rift Valley is a more pronounced biogeographic barrier than the Blue Nile Valley for six Ethiopian Highland passerines in the eastern Afromontane biodiversity hotspot

ABSTRACT The Ethiopian Highlands are divided by lowland biogeographic barriers, including the Blue Nile Valley (BNV) and Great Rift Valley (GRV). We show that the GRV is a more pronounced phylogeographic break than the BNV for 6 focal passerines. Previous research suggests that the BNV greatly shaped phylogeographic patterns in relatively sedentary montane taxa such as frogs and rodents, whereas the GRV shaped phylogeographic patterns in volant taxa such as birds. However, no previous research simultaneously compares the impact of each valley on phylogeographic patterns in birds, and as these barriers vary in geographic extent and topography, the relative extent of their effects on gene flow is unclear. Using whole-genome resequencing, we quantified genetic variation in 6 montane forest passerines in the Ethiopian Highlands and found that their phylogeographic patterns varied, with general trends distinct from those of taxa that were previously studied across the same barriers. Genetic variation was assessed by estimating genome-wide genetic diversity (HO), demographic history, phylogeographic structure, and phylogeographic concordance among taxa. Population pairs flanking the GRV showed higher FST and more distinct population clusters in principal component analysis than those separated by the BNV. HO was broadly consistent across populations, excluding noticeable reductions in 2 populations (1 population each in 2 separate species). The overall phylogenetic signature and concordance across study taxa supported populations separated by the BNV as sister and populations southeast of the GRV as most distinct.

Evidence of thermophilization in Afromontane forests

Thermophilization is the directional change in species community composition towards greater relative abundances of species associated with warmer environments. This process is well-documented in temperate and Neotropical plant communities, but it is uncertain whether this phenomenon occurs elsewhere in the tropics. Here we extend the search for thermophilization to equatorial Africa, where lower tree diversity compared to other tropical forest regions and different biogeographic history could affect community responses to climate change. Using re-census data from 17 forest plots in three mountain regions of Africa, we find a consistent pattern of thermophilization in tree communities. Mean rates of thermophilization were +0.0086 °C·y−1 in the Kigezi Highlands (Uganda), +0.0032 °C·y−1 in the Virunga Mountains (Rwanda-Uganda-Democratic Republic of the Congo) and +0.0023 °C·y−1 in the Udzungwa Mountains (Tanzania). Distinct from other forests, both recruitment and mortality were important drivers of thermophilzation in the African plots. The forests studied currently act as a carbon sink, but the consequences of further thermophilization are unclear.

Improved mapping of highland bamboo forests using Sentinel-2 time series and machine learning in Google Earth Engine

Recent advances in the application of spectral bands from satellite observations and machine learning algorithms (MLA) in the Google Earth Engine (GEE) cloud-computing platform have been demonstrated to enhance the accuracy of mapping forest resources. This study presents a novel method for mapping the natural distribution of highland bamboo (Oldeania alpina) using spectral bands and three machine learning algorithms, namely random forest, gradient tree boosting, and classification and regression tree. First, spectral bands, vegetation indices and textural features including contrast, entropy and inverse difference moment were derived from the Sentinel-2 elevation data. Second, observations were categorized as the dry season (December–February), short rainy season (March-May), main (long) rainy season (June-August), wet season (September–November) and annual composite. Third, the machine learning algorithms were tested using 1882 ground control points collected from field and high spatial resolution images. Finally, the best-performing machine learning algorithm was used to classify and map bamboo forests. The five land cover categories identified were bamboo stands, natural forest, other vegetation, non-vegetated areas and water bodies. The result shows that the random forest classifier is a robust algorithm with an overall accuracy of 94% considering all the annual composite’s spectral, vegetation and textural variables. The highland bamboo coverage (91 km2) in the Andracha district provided valuable insights. Bamboo stands were mostly distributed in the southern and southeastern parts of the district. Here, we show that image compositing and multiple input parameters using machine learning techniques can overcome challenges facing land cover classification, which can hinder accurate mapping of Afromontane forests. We conclude that the incorporation of vegetation indices and textural features in land cover classification increases accuracy of mapping natural highland bamboo coverage and distribution. The application of this new method is a promising prospect not only in Ethiopia but also in Afromontane forests elsewhere in Africa.

In Vivo Antidiarrheal Potential of the Leaf Extract of Maytenus addat (Loes.) Sebsebe and Its Major Compound.

Diarrhea continues to be one of the top causes of death in children under the age of five, particularly in developing nations. In Ethiopian traditional medicine, a variety of medicinal plants are used to treat diarrhea. One of these plants is Maytenus addat (Loes.) Sebsebe (fam. Celastraceae), which is endemic to the Afromontane forests, especially along forest margins, of Ethiopia. The air-dried powdered leaves of M. addat were macerated with 80% methanol to yield a crude extract. Additionally, the powdered plant material underwent sequential solvent extraction using chloroform, methanol, and water to obtain solvent fractions. The 80% methanol leaf extract, solvent fractions, and an isolated compound from M. addat were evaluated for their antidiarrheal activity using castor oil-induced diarrheal model, anti-enteropooling test, and charcoal meal test in mice. The results showed that the 80% methanolic leaf extract significantly reduced the onset of diarrhea, the weight of feces, and the frequency of defecation in all the tested doses. The methanol and water fractions of the hydroalcoholic extract also exhibited dose-dependent antidiarrheal activity, with the methanol fraction showing the highest activity at 400 mg/kg dose. Subsequently, the most active methanol fraction was subjected to C-18 solid phase extraction, resulting in the isolation of a 3-hydroxyflavone, identified as quercetin by ESI-qToF-MS, 1H, and 13C-NMR spectroscopic techniques. Quercetin demonstrated a strong antidiarrheal activity in a dose-dependent manner. Thus, the present study provided evidence that the leaves of M. addat possess genuine antidiarrheal activity upholding the traditional medicinal use of the plant for the treatment of diarrhea. The findings also suggest that quercetin is responsible, in full or in part, for the activity of the plant.

Composition and Structural Diversity of Woody Species in the Wof Ayzurish Forests, the Dry Afromontane Forest of the Northern EthiopiaI

Dry Afromontane Forest (DAF) is the largest Afromontane section and plays a fundamental role in preservation of species biodiversity. Despite its biodiversity, DAF is the most altered and threatened in the Ethiopian ecosystem. With the exception of a few isolated pockets left in some sacred places and protected areas of the country, most of forests are inaccessible. The scenario is not different for the present study forest. Therefore, the objective of the present study is to investigate woody species diversity, structure and regeneration status of Wof Ayzurish Forest, which is a dry Afromonatane in North Shewa of Ethiopia. A systematic method was employed whereby 67 quadrats set in 8 parallel lines transecting at 300-meter intervals and quadrats at 150-m distance. All trees and shrubs with diameters of breast height > 2.5 cm and height > 2 m were measured. The results revealed that Wof Ayzurish Forest harbors 76 species of woody plants that belong to 68 genera and 47 families, with Asteraceae, Fabaceae, and Solanaceae displaying the highest diversity. Shrubs had the highest composition than trees. The most abundant plants were Dodonaea viscosa subsp. angustifolia, Carissa spinarum, Juniperus procera, Olinia rochetiana and Olea europaea subsp. cuspidata. Dodonaea viscosa subsp. angustifolia was the most prominent plant, occurring in 98.5 % of all sample plots. The DBH and height classification pattern exhibited that the forest had a classic inverted J-shape, dominated by smaller trees and shrubs, indicating a secondary stage of regeneration. Total basal area (BA) for trees and shrubs DBH > 2.5 cm was 18.03 m2 ha−1. Remarkably, five species accounted for 57.45 % of the basal area, indicating that higher numbers of individuals concentrated in lower DBH classes. By using R software, agglomerative hierarchical cluster analysis and Canonical Correspondence Analysis (CCA) has done to identify plant community types and examine the relationship between plant community types and environmental variables, respectively. Three significantly different (p < 0.05) plant community types were identified. The CCA results showed that species diversity and community composition among community types were significantly influenced by altitude and human disturbance such as expansion of agriculture, cuttings, and grazing. Therefore, it is recommended that community-based methods and awareness creation should be devised in order to implement sustainable forest conservation.

Modelling wildfire risk using GIS and Analytical Hierarchy Process (AHP) in Aberdare afromontane forest ranges, Kenya

The knowledge of wildfire risk is crucial to sensitize and create awareness on fire prevention strategies and mobilization of resources to counter the spread after early detection. This study was undertaken to determine the most important environmental and anthropogenic factors associated with wildfire risk in Aberdares ranges. An integrated participatory decisions and geospatial analysis was used. A pair wise comparative analysis of seven factors namely: proximity to roads, proximity to farming areas within the forest, mean precipitation, elevation, slope, land cover and NDVI was undertaken to attribute weight of each factor in relative to the other though Analytical Hierarchy Process (AHP). A wildfire risk equation was developed using the criteria weights of respective factors and risk map developed using QGIS version 3.16. Results indicated that land cover (0.39) and NDVI (0.23) were the most important factors in developing wildfire risk maps while proximity to roads (0.04) was the least. Wildfire risk maps shows that Aberdare ranges is within low (43%) and moderate (30%) risk zone and the area occupied by high and very high zones is 13% and 4 % respectively. The study recommends testing the applicability of developed method in other areas with different climatic and land cover characteristics.

Unique bird diversity in an Ethiopian church forest

AbstractToday, most of Ethiopia’s church forests are small forest patches surrounded by a degraded and anthropogenically modified landscape, mostly arable land. Nevertheless, these forest islands may still provide valuable habitats for typical forest species. It remains questionable whether these habitat remnants provide sufficient resources for forest species to successfully reproduce and persist in the long run. In this study, we assessed bird species based on point-counts in and around Tara Gedam Church Forest in northern Ethiopia. We observed birds in typical natural evergreen Afromontane forest (forest interior and forest edge) and in anthropogenic habitats, the semi-natural shrublands, agricultural land, and Eucalyptus tree plantations. We assigned ecological and behavioural characteristics to each of the bird species observed. Our results point to a specific bird community restricted to the forest interior and characterized by forest generalists and forest specialist birds. Along the forest edge, a mix of forest generalists and species of the open landscape can be found, creating mixed communities with high species overlap. The highest number of species was observed at the forest edge and in semi-natural shrubland, where both, open-land and forest species were found. On the other hand, the total number of species in the forest interior was comparatively low, with insectivorous and frugivorous typical forest species. Our results underline the fact that even small forest remnants are important for the conservation of forest species, which do not evade surrogate forest habitats.

Long-Term Volumetric Change Estimation of Red Ash Quarry Sites in the Afro-Alpine Ecosystem of Bale Mountains National Park in Ethiopia

The Bale Mountains National Park (BMNP) in Ethiopia comprises the largest fraction of the Afro-Alpine ecosystem in Africa, which provides vital mountain ecosystem services at local, regional, and global levels. However, the BMNP has been severely threatened by natural and anthropogenic disturbances in recent decades. In particular, landscape alteration due to human activities such as red ash quarrying has become a common practice in the BMNP, which poses a major environmental challenge by severely degrading the Afro-Alpine ecosystem. This study aims to quantify the long-term volumetric changes of two red ash quarry sites in the BMNP using historical aerial photographs and in situ data, and to assess their impact on the Afro-Alpine ecosystem. The Structure-from-Motion multi-view stereo photogrammetry algorithm was used to reconstruct the three-dimensional landscape for the year 1967 and 1984 while spatial interpolation techniques were applied to generate the current digital elevation models for 2023. To quantify the volumetric changes and landscape alteration of the quarry sites, differences in digital elevation models were computed. The result showed that the volume of resources extracted from the BMNP quarry sites increased significantly over the study period from 1984 to 2023 compared with the period from 1967 to 1984. In general, between 1967 and 2023, the total net surface volume of the quarry sites decreased by 503,721 ± 27,970 m3 and 368,523 ± 30,003 m3, respectively. The extent of the excavated area increased by 53,147 m2 and 45,297 m2 for Site 1 and 2, respectively. In terms of habitat loss, major gravel road construction inside the BMNP resulted in the reduction of Afro-Alpine vegetation by 476,860 m2, ericaceous vegetation by 403,806 m2 and Afromontane forest by 493,222 m2 with associated decline in species diversity and density. The excavation and gravel road construction have contributed to the degradation of the Afro-Alpine ecosystem, especially the endemic Lobelia rhynchopetalum on the quarry sites and roads. If excavation continues at the same rate as in the last half century, it can threaten the whole mountain ecosystem of the National Park and beyond, highlighting the importance of preventing these anthropogenic changes and conserving the remaining Afro-Alpine ecosystem.

Patterns and drivers of the above- and below-ground carbon stock in Afromontane forest of southern Ethiopia: implications for climate change mitigation

Patterns and drivers of the above- and below-ground carbon stock in Afromontane forest of southern Ethiopia: implications for climate change mitigation

Mixed-Effects Height Prediction Model for Juniperus procera Trees from a Dry Afromontane Forest in Ethiopia

Tree height is a crucial variable in forestry science. In the current study, an accurate height prediction model for Juniperus procera Hochst. ex Endl. trees were developed, using a nonlinear mixed-effects modeling approach on 1215 observations from 101 randomly established plots in the Chilimo Dry Afromontane Forest in Ethiopia. After comparing 14 nonlinear models, the most appropriate base model was selected and expanded as a mixed-effects model, using the sample plot as a grouping factor, and adding stand-level variables to increase the model’s prediction ability. Using a completely independent dataset of observations, the best sampling alternative for calibration was determined using goodness-of-fit criteria. Our findings revealed that the Michaelis–Menten model outperformed the other models, while the expansion to the mixed-effects model significantly improved the height prediction. On the other hand, incorporating the quadratic mean diameter and the stem density slightly improved the model’s prediction ability. The fixed-effects of the selected model can also be used to predict the mean height of Juniperus procera trees as a marginal solution. The calibration response revealed that a systematic selection of the three largest-diameter trees at the plot level is the most effective for random effect estimation across new plots or stands.

Study of the Soil Seed Bank Composition in Arjo-Diga Humid Afromontane Forest under Different Land Use Types and Its Implications for the Restoration of Degraded Lands in Western Ethiopia

The soil seed bank present in forests serves as a crucial indicator of soil resilience following disturbances. The objective of this study was to investigate the composition, density, and vertical distribution of the soil seed bank in the Diga District of Western Ethiopia across four land use types: forestland, grassland, bare land, and shrubland. Soil samples were collected from plots measuring 225 square centimeters with a depth of 9 cm. A total of 108 soil samples were collected, representing the four land use types. Each plot was sampled at three different soil layers: 0–3 cm, 3–6 cm, and 6–9 cm depths. From the soil seed bank, 51 plant species were identified, with 46 (90.2%) being herbs, 3 (5.88%) trees, and 2 (3.92%) shrubs. The Asteraceae (13.30%), Poaceae (11.53%), and Fabaceae (9.61%) families exhibited the highest species composition, accounting for 38.44% of the total. Species richness varied significantly across all land use types and soil layers (p&lt;0.05), with shrubland having the highest species richness and bare land having the lowest count. The total seed bank density in the soil across all plots was 92153 seeds/m2, with the highest density observed in the top 3 cm of the soil layer. The first and second soil layers exhibited a high Jaccard similarity coefficient of 0.76. Forestland and shrubland displayed the highest Jaccard coefficient of similarity (0.72), while the lowest was observed between bare land and shrubland (0.43). There was greater species similarity between the first and second soil layers (0.76) and lower similarity between the middle and bottom layers (0.32). The study found limited similarity between aboveground vegetation and the soil seed bank due to the low regeneration of woody species. Forestland and shrubland exhibited a high Jaccard similarity coefficient to aboveground vegetation, while grassland had the lowest similarity coefficient. Based on the findings, it can be concluded that the shrubland land use types had high soil seed bank composition and density. Therefore, the conservation of shrubs in the Arjo-Diga Forest should be considered for the restoration of degraded areas, taking into account the soil seed bank in the shrubland ecosystem.

Woody Plant Assemblages of Recently Declared Village Land Forest Reserve in The Eastern Afromontane Biodiversity Hotspot

Understanding of species composition of village land forest reserves and their driving factors informs adequate development of effective restoration strategies and sustainable forest management of miombo woodlands. This study assessed the effects of human disturbance as well as environmental variables on woody plant species composition using 24 square plots of 10 x 10 m in a recently declared village land forest reserve in the Eastern Afromontane biodiversity hotspot of Tanzania. Ordination analysis technique canonical correspondence analysis was used to identify important vegetation gradients and significant factors that explain the spatial variation in species composition of woody plants. Results showed that, 779 individual woody plants were recorded, of which 379 were seedlings (48.6%), 102 saplings (13.1%) and 298 adults (38.3%). The three most dominant plant species were Brachystegia spiciformis (42.2%), Diplorhynchus condylocarpon (9%) and B. boehmii (8.7%), while the least were Multidentia crassa and Diospyros squarrosa with each species having less than 1% overall abundance. Pterocarpus angolensis, a highly protected and near-threatened tree species, was also recorded but with only very few individuals. Canopy cover and soil pH were the two most important variables explaining the spatial variation in species composition of woody plants. These results emphasise that village forests are important for preserving native and threatened tree species, and improved management should discourage all practices that change natural conditions of canopy cover and soil pH to safeguard the remaining village forests, biodiversity and rural livelihoods.