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ABSTRACTLand uses and soil and water conservation (SWC) structures affect topsoil moisture and carbon stocks, particularly in the water deficit semi-arid environment of the northern Ethiopian highlands. This study was undertaken to assess the effects of land use and SWC structures on topsoil moisture, biomass, and soil carbon. Soil moisture was measured manually using gravimetric methods and theta probes with data loggers. Vegetation was inventoried and soil samples collected to assess carbon stocks of biomass and soils of different land uses. Merebmiti catchment had higher average gravimetric soil moisture content (GSMC; 24%) in wetlands, with the lowest (13%) in exclosures, whereas Mayleba catchment had relatively higher GSMC (14%) in exclosures and the lowest (8%) in rangelands. In both catchments, GSMC was higher at sampling locations closer to SWC structures than farther away. Merebmiti had significantly more biomass carbon (28.9 Mg ha−1) than Mayleba (6.32 Mg C ha−1). Higher soil organic carbon stocks were found in exclosures (46.1 ± 2.20 Mg ha−1) and wetlands (62.1 ± 2.9 Mg ha−1) than in frequently cultivated croplands (24.3 ± 1.4 Mg ha−1). Effective management of land use and implementation of SWC structures remarkably improves topsoil moisture content and carbon stocks in these catchments.

Purpose: The main objective of this study was to assess the physiochemical properties and phytotoxicity of compost made from different organic waste materials sourced from local markets. Methods: The Stack pile composting was carried out with market waste, sawdust, rice straw, and swine manure in four different combinations. Parameters such as temperature, pH, nitrogen, phosphorus, potassium, and heavy metal concentrations were monitored. Germination test with water extracts of the composts was done to assess phytotoxicity of the composts. Results: All compost piles recorded temperatures of 38 °C slightly above the recorded ambient temperature of 34 °C at the start of composting. The pH value ranged from 7.12 to 8.2 for the different compost types. The total organic carbon and total nitrogen values ranged from 27.05–31.06 to 0.77–0.97%, respectively. The total phosphorus and total potassium values ranged from 0.2–1.87 to 0.39–2.3%, respectively, for different compost types. The C/N ratio values ranged from 29.09:1 to 36.22:1. All the composts had heavy metal concentrations below the Canadian Council of Ministers of the Environment standards. Germination indices, a measure of plant vs supporting potential, ranged from 80 to 99% for Solanum lycopersicum, 170 to 198% for Cucumis sativus, and 114 to 166% for Brassica oleracea. Conclusion: The study confirms the notion that composting municipal solid waste is a viable organic waste management strategy, and with the potential to enhance waste management system, while promoting cultivation of vegetables for food security.

Forests form a major component of the carbon (C) reserves in the world’s ecosystems. However, little is known on how management influences C stocks of woody vegetation, particularly in dry areas. We developed regression models for two dominant tree species to predict C stocks and quantified the potential of community managed forests as C sinks. Plots were randomly selected from community-managed natural forest, herbivore exclosures, and from communal grazing land. Tree and shrub biomass were estimated using a regression model on the most dominant woody species while herbaceous biomass was determined using destructive sampling. The simplest model, based on only one single predictor variable, showed a good fit to the data for both species (Juniperus proceraand Acacia abyssinica). Diameter at breast height (r2> 0.95) was a more reliable predictor than height (r2> 0.54), crown diameter (r2> 0.68) (p< 0.001). The C content of the total biomass for the managed natural forest and the exclosure were estimated as, 58.11 and 22.29 Mg ha−1, respectively, while that for the grazing land was 7.76 Mg ha−1, and the mean carbon content between the three land uses were significantly different (p< 0.05). We conclude that forests managed by the community have a high potential for C sequestration and storage and their conservation should be promoted.

Exclusion of grazing animals and tree plantations were among the methods used for the restoration of degraded lands in tropical semiarid areas. Exclosures can foster secondary forest succession by improving soil conditions and modifying microclimate for understory growth. This paper compared the arbuscular mycorrhizal fungi (AMF) spore density, root colonization of woody plants and soil chemical properties under exclosure with increasing age, and grazing land at different slope positions. The study was conducted in northern Ethiopia from 12 exclosure sites paired each with adjacent grazing land in total from 24 sites with four treatments replicated three times. In the entire study, 216 plots were examined of which 108 were in exclosures and 108 in communal grazing lands. There were four age classes and three slope positions in each of the land uses. Composite soil and root samples were collected using nested plots measuring 100m2from four sides of 1763 plants for spore enumeration and root colonization. Soils for chemical properties were collected from the four corners and center of 5 m × 5 m plots. All the 61 woody plant species that belong to 41 families were colonized by AMF. Spore density and root colonization were significantly higher in exclosures as compared to grazing land and increased with increasing ages of exclosures. Foot slope had significantly higher spore density and root colonization than middle and upper slopes. Soil chemical properties were significantly higher in the exclosure, oldest age of exclosure, and foot slope position (except P). AMF spore density and root colonization were significantly positively correlated with soil chemical properties. Exclosures are helpful to restore the AMF spore density and root colonization of woody species and soil fertility.

In recent years, armed conflicts are globally on the rise, causing drastic human and environmental harm. The Tigray war in Ethiopia is one of the recent violent conflicts that has abruptly reversed decades of ecosystem restoration efforts. This paper analyzes changes in woody vegetation cover during the period of armed conflict (2020–2022) using remote sensing techniques, supplemented by field testimony and secondary data. Extent of woody vegetation cover was analyzed using Normalized Difference Vegetation Index (NDVI) thresholding method from Sentinel 2 images in Google Earth Engine, and scale of de-electrification was qualitatively analyzed from Black Marble HD nighttime lights dataset, acquired from NASA's Black Marble team. The magnitude, direction as well as the mechanisms of change in woody vegetation cover varied across the region and over time. Tigray's woody vegetation cover fluctuated within 20% of the landmass. Mainly scattered to mountainous areas, the dry Afromontane forest cover declined from about 17% in 2020 to 15% in 2021, and 12% in 2022. About 17% of the overall decline was observed between 500 m and 2000 m elevation, where there is higher anthropogenic pressure. Land restoration practices meant to avert land degradation and desertification were interrupted and the area turned warfare ground. In many areas, forests were burned, the trees cut and the area became barren. The suspension of public services such as electricity for household or industrial use created heavy reliance on firewood and charcoal, further threatening to compound weather and climate. The magnitude of disturbance in a region that is already at a very high risk of desertification requires urgent national and international attention. Continued ecosystem disturbance could eventually make the domain part of a wider desert connecting the Sahel to the Afar Triangle, a scenario which may render the area uninhabitable.

Introduction: Pastoralism and agro-pastoralism are the major modes of life in arid and semi-arid rangelands. However, rangeland quality and quantity are rapidly deteriorating due to a number of natural and human-induced factors, one of which is bush encroachment. Little is known on how bush encroachment affects the ecosystem functions and services expressed in terms of the native vegetation composition and structure, status of the soil seed bank, soil chemical and physical properties, and the abundance of mycorrhiza spores. Methods: We assessed woody species in 64 plots distributed across four levels of Prosopis juliflorainvasion (high, medium, low, and none) at two sites, Amibara and Gewane, in the Afar Region, Ethiopia. We collected composite soil samples to investigate the soil seed bank, mycorrhizal associations, and spore abundance. Results: Plant biodiversity was generally low, with eight and four woody species in Gewane and Amibara, respectively. Prosopis juliflorawas dominant in highly, moderately, and lowly invaded areas while Acacia senegal dominated the non-invaded areas. The average number of P. julifloraindividuals ranged from 3/ha at non-invaded areas in Gewane to 4200/ha at highly invaded areas in Amibara while the total individual number of native woody species ranged from 0 to 88/ha at highly and lowly invaded areas, respectively. The population structure of trees/shrubs in all invasion areas showed an inverted J-shaped distribution, characterized by a high abundance of small individuals. Prosopis juliflorainvasion was associated with high soil OC, Na, Ca, P, bulk density, and moisture content. Herbaceous seed numbers and species richness were highest in the moderately and highly invaded areas. All sampled tree species were associated with mycorrhiza but the percentage of root length colonization by different arbuscular mycorrhizal fungus structures varied significantly (p&lt; 0.05) across invasion categories and sites. Conclusions: Our results revealed that although P. juliflorainvasion negatively impacted the availability of native woody livestock forage species, it had a positive effect on most soil physical and chemical properties. Such variable effects call out for sustainable management practices when invaded areas are restored.