Population status of Boswellia papyrifera woodland and prioritizing its conservation interventions using multi-criteria decision model in northern Ethiopia.

Boswellia papyrifera woodland provides considerable economic, ecological and socio-cultural benefits in the drylands of Ethiopia. However, its populations are in rapid decline due to human pressure and environmental degradation. As a consequence, the species is now considered being endangered, demanding an urgent conservation intervention to sustain its existence. This study was carried out in the Abergele district, northern Ethiopia, with objectives to characterize the current population structure of B. papyrifera and prioritize its potential conservation intervention alternatives using Analytical Hierarchy Process (AHP) modelling techniques. The woody species related data were collected from 33 sample plots randomly established in the study area. Data related to the potential intervention alternatives and their evaluating criteria were collected from experts, personal experiences and intensive literature reviews, and then validated using stakeholders' focus group discussion. Four candidate alternatives were then considered for the AHP: 1) free grazing with no tapping resting period (FGNTR), 2) free grazing with a rotational tapping (FGRT), 3) area exclosure with medium tapping resting period (AEMTR), and 4) area exclosure with long tapping resting period (AELTR). The results showed that the population structure of B. papyrifera is unstable and is characterized by low density (266 trees ha-1), absence of regeneration and saplings (DBH<10 cm) due to different interrelated disturbances such as overgrazing, over tapping, pests, agricultural expansion and poor managements. The overall priority ranking value of all stakeholders using the AHP techniques also indicated that AEMTR (with overall rank value of 0.352) and AELTR (0.294) as the best alternatives strategies, respectively, for sustainable B. papyrifera woodland conservation. For the success of these strategies, their economic impacts at their early implementation stages (5-10 years) should be minimized by collecting different non-timber forest products from the woodland. Continuous capacity building training on sustainable utilizations and managements of B. papyrifera woodland should also be provided for all relevant stakeholders.

Multi-century tree-ring precipitation record reveals increasing frequency of extreme dry events in the upper Blue Nile River catchment.

Climate-related environmental and humanitarian crisis are important challenges in the Great Horn of Africa (GHA). In the absence of long-term past climate records in the region, tree-rings are valuable climate proxies, reflecting past climate variations and complementing climate records prior to the instrumental era. We established annually resolved multi-century tree-ring chronology from Juniperus procera trees in northern Ethiopia, the longest series yet for the GHA. The chronology correlates significantly with wet-season (r = .64, p < .01) and annual (r = .68, p < .01) regional rainfall. Reconstructed rainfall since A.D. 1811 revealed significant interannual variations between 2.2 and 3.8 year periodicity, with significant decadal and multidecadal variations during 1855-1900 and 1960-1990. The duration of negative and positive rainfall anomalies varied between 1-7 years and 1-8 years. Approximately 78.4% (95%) of reconstructed dry (extreme dry) and 85.4% (95%) of wet (extreme wet) events lasted for 1 year only and corresponded to historical records of famine and flooding, suggesting that future climate change studies should be both trend and extreme event focused. The average return periods for dry (extreme dry) and wet (extreme wet) events were 4.1 (8.8) years and 4.1 (9.5) years. Extreme-dry conditions during the 19th century were concurrent with drought episodes in equatorial eastern Africa that occurred at the end of the Little Ice Age. El Niño and La Niña events matched with 38.5% and 50% of extreme-dry and extreme-wet events. Equivalent matches for positive and negative Indian Ocean Dipole events were weaker, reaching 23.1 and 25%, respectively. Spatial correlations revealed that reconstructed rainfall represents wet-season rainfall variations over northern Ethiopia and large parts of the Sahel belt. The data presented are useful for backcasting climate and hydrological models and for developing regional strategic plans to manage scarce and contested water resources. Historical perspectives on long-term regional rainfall variability improve the interpretation of recent climate trends.

Conservation of the Ethiopian church forests: Threats, opportunities and implications for their management.

In the central and northern highlands of Ethiopia, native forest and forest biodiversity is almost confined to sacred groves associated with churches. Local communities rely on these 'church forests' for essential ecosystem services including shade and fresh water but little is known about their region-wide distribution and conservation value. We (1) performed the first large-scale spatially-explicit assessment of church forests, combining remote-sensing and field data, to assess the number of forests, their size, shape, isolation and woody plant species composition, (2) determined their plant communities and related these to environmental variables and potential natural vegetation, (3) identified the main challenges to biodiversity conservation in view of plant population dynamics and anthropogenic disturbances, and (4) present guidelines for management and policy. The 394 forests identified in satellite images were on average ~2ha in size and generally separated by ~2km from the nearest neighboring forest. Shape complexity, not size, decreased from the northern to the central highlands. Overall, 148 indigenous tree, shrub and liana species were recorded across the 78 surveyed forests. Patch α-diversity increased with mean annual precipitation, but typically only 25 woody species occurred per patch. The combined results showed that >50% of tree species present in tropical northeast Africa were still present in the 78 studied church forests, even though individual forests were small and relatively species-poor. Tree species composition of church forests varied with elevation and precipitation, and resembled the potential natural vegetation. With a wide distribution over the landscape, these church forests have high conservation value. However, long-term conservation of biodiversity of individual patches and evolutionary potential of species may be threatened by isolation, small sizes of tree species populations and disturbance, especially when considering climate change. Forest management interventions are essential and should be supported by environmental education and other forms of public engagement.