Ethiopia is one of the countries with the most degraded forest resources. Information on tree structure is needed at some points in the process to assess the appropriateness of forest management. The objectives are to examine whether the Structure from Motion (SfM)-based photogrammetry can be used to derive the forest structural parameters, and how the tree structural parameters can vary by location. In this study, the possible applicability of low-cost SfM-based photogrammetry was evaluated for forest management and conservation purposes in the Adi Zaboy watershed of the Northern Ethiopian highlands. In the watershed, dwarf Acacia etbaica was sparsely distributed. Consequently, the full three-dimensional point clouds of the individual trees were generated, which provided a wide variety of tree structural parameters in a non-destructive manner. The R2 values for tree height, canopy width, and stump diameter were 0.936, 0.891, and 0.808, respectively, and the corresponding RMSE values were 0.128 m, 0.331 m, and 0.886 cm. In addition, differences in forest structure and composition were caused by differences in the environment. The SfM-based photogrammetry would provide fundamental information to meet the demand of sustainable forest management from a morphological point of view, especially in forests of Ethiopian highlands.

In northern Ethiopia, revegetation is necessary for preventing land degradation. However, planting seedlings show high mortality under arid climate. Biochar has the capacity to enhance seedling survival and symbiosis with arbuscular mycorrhizal fungi. We planted Olea europaea subsp. cuspidata and Dodonaea angustifolia into soil treated with biochar made from Acacia etbaica. We could not confirm the effects of biochar on the growth of these species; however, biochar was increased colonization of arbuscular mycorrhizal fungi. We concluded that application of biochar enhanced symbiosis with arbuscular mycorrhizal fungi under arid climate and was efficient for the revegetation in northern Ethiopia.

Rhamnus prinoide (Gesho) intercropping is a common practice with significant socioeconomic and ecological importance in Ganta-afoshum district. However, this practice is not well explored so far, especially from the perspective of its impact on sustainable land management while land degradation and low productivity is a challenge in the district. The objective of this study was to examine the effect of R. prinoide intercropping on soil nutrient and moisture. The study was conducted in Ganta-afoshum district, eastern zone of Tigray regional state where smallholder farmers practice R. prinoide intercropping. Soil samples were taken from farmland with dense, medium and sparse density of R. prinoide intercropping and from farmland without trees as a control for analysis. The density of the trees significantly affected the soil bulk density (P<0.05). Soil moisture content significantly increased with increasing soil depth and by the interaction effects of soil depth and density (P<0.05). Soil nitrogen concentration significantly influenced by the density and soil depth (P<0.05). Soil phosphorus and potassium concentration significantly affected by soil depth (P<0.05). Lower mean soil pH values were observed for soils under the farm with dense trees as compared to soils in open farm. Overall, the enhancing and exploitative effects of R. prinoide intercropping on soil nutrient and moisture is minimal. This could be the reason for being practiced and maintained by most farmers.

The development of forest monitoring methods for the plantation eucalypt forests in Ethiopia is crucial as eucalypts play an important role in the country's wood supply. We assessed the stand structure and estimated the total stem volume of a 30-year-old Eucalyptus globulus forest in the highlands (＞3000 m altitude) of northern Ethiopia. Census data were collected from 186 trees, of which 28 trees were destructively sampled. The forest stand density was 581 trees ha −1 , mean ± SD diameter at breast height was 21.2 ± 6.4 cm, and mean ± SD predicted tree height was 22.0 ± 4.2 m. The estimated stem volume was 269.7 m 3 ha −1. An allometric model to predict tree height was derived using the measured diameter at breast height of the sampled trees. Moreover, an allometric model was developed to estimate stem volume for standing trees in order to describe the relationship between the stem volume and diameter at breast height squared × tree height (incorporated as a compound variable), using data on 38 trees for which height could be measured reliably. The findings suggest that the diameter at breast height alone can be used to estimate stem volume, and thus may be useful for simple forest monitoring in the study region. This study is one of the few to assess the stand structure and stem volume of a high-altitude Eucalyptus plantation.

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