Diress Tsegaye

Regeneration Response of Juniperus procera and Olea europaea subsp cuspidata to Exclosure in a Dry Afromontane Forest in Northern Ethiopia

Abstract The Afromontane forests of northern Ethiopia have been degraded and fragmented for centuries. Recently, efforts have been made to restore these forests by protecting them from livestock interference. In this study, the natural regeneration of Juniperus procera Hochst. ex Endl. and Olea europaea L. subsp cuspidata (Wall. ex G. Don) Cif. is investigated under protected conditions after 3 years of enclosure and under open management systems in a dry Afromontane forest in northern Ethiopia. Data on the floristic and structural compositions of the vascular plants were collected using 32 randomly selected plots (20 m × 20 m), while nested plots (10 m × 10 m) were used to investigate the seedling bank at the protected and adjacent open sites. The results reveal that there was a significantly higher regeneration of O. europaea on the protected site than on the open site (P  =  0.01). However, there was no significant difference between the 2 sites for J. procera (P  =  0.16). Thus, protecting the degraded forest in northern Ethiopia seems to be an appropriate management option for the regeneration of O. europaea. The regeneration status of J. procera at both sites is poor, which indicates that protecting the forest from livestock and human disturbance is unlikely to lead to regeneration of this species. Further investigation of other factors that hinder the regeneration of J. procera is therefore recommended.

Is a wind-power plant acting as a barrier for reindeer Rangifer tarandus tarandus movements?

Reindeer herdsmen and authorities in Scandinavia fear detrimental effects from wind-power plants (WPs) on movements and area use of reindeer Rangifer tarandus tarandus. We tested the extent to which a WP represented a behavioural barrier for reindeer movement by comparing two neighbouring areas; one peninsula with and one without a WP. Both peninsulas had a parallel road and a power line bisecting them in a north-south direction. Presence of a larger or similar number of reindeer on the outer western compared to the inner eastern sections in both areas indicated no barrier effect from the WP. Furthermore, no clear barrier effects were found for reindeer movements during summer in the WP or neighbouring area, as reindeer have continued to cross back and forth between the inner and outer sections of the two areas. Contrary to our expectation, our finding contrasted with previous studies finding negative barrier effects from linear structures such as power lines and roads, suggesting considerable variation in the extent to which infrastructure acts as barriers.

Livestock Browsing, Not Water Limitations, Contributes to Recruitment Failure of Dobera glabra in Semiarid Ethiopia

Abstract The study used nursery and field experiments to investigate why recruitment of Dobera glabra (Forssk) Poir., a native food source for both humans and livestock, often fails in the semiarid rangelands of Afar, Ethiopia. We hypothesized that soil water limitations and browsing by livestock would be the primary mechanisms accounting for the failure of natural regeneration. We used three sets of experiments—1) seedling performance in response to shade and watering in a nursery, 2) field regeneration with and without browsing, and 3) regeneration beneath trees with and without browsing—to examine regeneration success. Seedlings were established in plots from seeds sown directly into the soil for nursery and field experiments, but natural germination occurred beneath trees. Survival and relative growth rates (RGR) were used to monitor seedling performance. Seedlings that received neither shade nor watering treatments had lower seedling survival (53 ± 15%) as compared with other treatment combinations. Highest seedling survival was recorded under shade and 1 d watering ṡ wk−1 treatment combinations (92 ± 1%). However, shade treatments had a minimal increase on seedling RGR. Water limitation is not a crucial limiting factor for D. glabra recruitment, as 53% of the seedlings survived without both shade and supplemental water for 1 yr. Field experiments, however, demonstrated that browsing greatly reduced seedling survival (below 15%) and suppressed growth of surviving seedlings, suggesting that browsing is the major factor preventing natural recruitment. Natural recruitment of D. glabra is unlikely with the existing continuous and intensive grazing/browsing in Afar rangelands, where the mobility of pastoralists is restricted. We suggest that planting nursery-raised seedlings in home gardens of settled pastoralists and establishment of grazing reserves in some key range sites that contain D. glabra could help offset the recruitment failure of native food species D. glabra in Afar rangelands.

Measuring effects of linear obstacles on wildlife movements: accounting for the relationship between step length and crossing probability

Animal movements in the landscape are influenced by linear features such as rivers, roads and power lines. Prior studies have investigated how linear features, particularly roads, affect movement rates by comparing animals movement rate measured as step lengths (i.e., the distance between consecutive observations such as GPS locations) before, during and after crossing of a linear feature. The null hypothesis has been that the length of crossing steps should not differ from other steps, and a deviation from this, mainly that steps are longer during crossing, has been taken as support for a disturbance effect of the linear feature. However, based on the simple relationship between the length of a step and its probability to cross a linear feature, we claim that this assumption is inappropriate to test for behavioural responses to linear features. The probability is related to the proportion of the total length of the trajectory (i.e., the path of movement) a step constitutes. Consequently, care should be taken when formulating hypotheses about how animal moves in relation to linear features in the landscape. Statistical tests should be set up with respect to the expected length based on the distribution of step lengths in the trajectory. We propose two methods that accounts for the bias in crossing frequency that is caused by step lengths, and illustrates their applications by using simulated animal trajectories as well as empirical data on reindeer in an area with a power line.

Allocation of degraded hillsides to landless farmers and improved livelihoods in Tigray, Ethiopia

ABSTRACT In the northern highlands of Ethiopia degraded hillsides have been allocated to landless farmers for tree planting since the mid-1990s. The authors assessed the effect of hillside plantations on the livelihoods of landless farmers in the eastern part of the Tigray Region by using transect walks, focus group discussions, and pretested questionnaires. A matched-pairs design was used to compare crop yields, livestock holdings per household, and household incomes to test the differences before and eight years after the intervention. In addition, regression analysis was used to capture variables influencing hillside management. The findings revealed that the plantations significantly increased crop yields, livestock holdings, and the household incomes of all beneficiaries. In addition, tree planting on degraded hillsides had a positive impact on the livelihoods of formerly landless farmers. However, moisture stress and free-ranging livestock were crucial problems. The findings are highly relevant in a conservation context because many existing or planned hillside allocations to landless farmers are located on degraded steep slopes that are unsuitable for crop production. Thus, replicating the practice to other areas with similar environment and problems would be worthwhile, although the management should focus on careful planning to avoid conflicts of interest between beneficiaries and non-beneficiaries.

Behavioral Interference Between Sympatric Reindeer and Domesticated Sheep in Norway

Abstract Interspecific interaction among sympatric ungulates is important in management and conservation. We investigated behavioral interference between sympatric wild or semidomestic reindeer (Rangifer tarandus tarandus) and sheep (Ovis aries) in two field studies and one enclosure experiment. For free-ranging wild and semidomestic reindeer, interference between the two species increased with decreasing distances, occurring only at less than 200 m and 30 m, for wild and semidomestic reindeer, respectively, and neither species consistently dominated the other. In a controlled, duplicated experiment we tested interference and confrontations at the feeding patch level among semidomestic reindeer and sheep within 40 × 50 m enclosures. When new reindeer or sheep were introduced into enclosures already occupied by reindeer, new reindeer resulted in significantly more interference and confrontations among individuals compared to new sheep; i.e., intraspecific interference was more prevalent than interspecific interference at equal densities. For all study areas, confrontations decreased with time after “first encounter,” indicating cohabituation. A sympatric use of pastures was not visually disruptive for recorded grazing behavior for either species.

Bird Abundance, Diversity and Habitat Preferences in the Riparian Zone of a Disturbed Wetland Ecosystem - the Kilombero Valley, Tanzania

Wetlands provide important habitats to many bird species but are also under threat from human-caused degradation. The Kilombero Valley Floodplain Ramsar site in Tanzania has been subject to an increasing level of disturbance, but harbors the endemic Kilombero Weaver, Kilombero Cisticola and White-tailed Cisticola, as well as several other species of local, national and global importance. Using point counts over a year, we studied seasonal patterns in bird species richness, diversity and abundance, as related to habitat types in the riparian zone along the Kilombero River. Particular focus was on Important Bird and Biodiversity Area (IBA) ‘trigger’ species. Richness, abundance and diversity were highest in July, just after the wet season, and lowest in March when the water level started rising. The endemic Kilombero Weaver (Ploceus burnieri) was by far the most common species. Reeds and grass-bush habitats had the highest bird diversity throughout, and all three endemic taxa showed a preference for these vegetation types. After decades of increasing human disturbance, Kilombero still qualify as an IBA. Large numbers of livestock have recently been evicted from the area, and this study could serve as a benchmark on how this change will affect bird populations in the future.

Competition between sympatric wolf taxa: an example involving African and Ethiopian wolves

Carnivore populations are declining globally due to range contraction, persecution and prey depletion. One consequence of these patterns is increased range and niche overlap with other carnivores, and thus an elevated potential for competitive exclusion. Here, we document competition between an endangered canid, the Ethiopian wolf (EW), and the newly discovered African wolf (AW) in central Ethiopia. The diet of the ecological specialist EW was dominated by rodents, whereas the AW consumed a more diverse diet also including insects and non-rodent mammals. EWs used predominantly intact habitat, whereas AWs used mostly areas disturbed by humans and their livestock. We observed 82 encounters between the two species, of which 94% were agonistic. The outcomes of agonistic encounters followed a territory-specific dominance pattern, with EWs dominating in intact habitat and AWs in human-disturbed areas. For AWs, the likelihood of winning encounters also increased with group size. Rodent species consumed by EWs were also available in the human-disturbed areas, suggesting that these areas could be suitable habitat for EWs if AWs were not present. Increasing human encroachment not only affects the prey base of EWs, but also may impact their survival by intensifying competition with sympatric AWs.