Assessment on the Shrinkage and Ecological Importance of Wetlands of Fogera Plain, North West Ethiopia

This study investigates the shrinkage, carbon sequestration potential and biodiversity richness of wetlands of Fogera plain, North West Ethiopia.  Landsat MSS of 1986, Landsat TM of 1994 and Landsat ETM+ 2011 were used to study the change in areas of wetlands over time. Supervised image classification through maximum likelihood classifier algorithm was used. Besides to this, interview and focused group discussion were used for the qualitative study of wetlands shrinkage. Soil sample were taken from three classes of wetlands i.e permanent wetlands (undisturbed wetlands), less disturbed wetlands and temporary wetlands. From each category of wetlands, 23 composite soil samples in three replications at a depth of 0-75 cm were collected. Sample soil organic carbon and organic matter were analyzed in soil laboratory.  The result of Landsat images analysis showed that the area of the wetland in Fogera plain is decreasing. It was 25% of the area in 1973, while it shrinked in to 19.59% in 2011. For this, sediment deposition, practice of unsustainable farming practices by local farmers and problem of land ownership are the major causes. There is a significant difference (p < 0.05) in soil OC and OM content in between different classes of wetlands. The organic carbon content of soils of permanent wetlands where there is sediment deposition is very low. In less disturbed wetlands, there is better carbon content than other state of wetlands. Totally, carbon sequestration potential of these wetlands is very low in comparison with the carbon content of the wetlands of other parts of the world. Because in these wetlands there is high deposition of sediment with high sand content transported from the upstream watersheds by Rib River.  This triggers the wetlands to lack their pristine nature.  The wetlands of Fogera plain are home for different species of birds and fish.  In these wetlands, 207 bird species during the wet and dry seasons were observed. The wetlands are rich in and nursery habitat for Labeobarbus and Clarias gariepinus fish species. This study recommends a call for wetland conservation and rehabilitation efforts through incorporating wetlands into watershed management plans, better community management system and effective land registration and certification program. Key words: wetland shrinkage, carbon sequestration, sedimentatio

Effect of Land Use and Land Cover Change on Some Soil Chemical and Physical Properties in Ameleke Watershed, South Ethiopia

This study investigates the effect of land use and land cover change on some soil chemical and physical properties. Soil samples were collected from six sample sites.  From these sample sites, composite soil samples were collected from agroforestry, crop land, grass land and shrub lands in three replications at 0-15cm and 15-30 cm depth. Soil samples’ chemical and physical properties were analyzed in soil laboratory. Laboratory result shows that there is a significant difference (p < 0.05) in soil available K, TN, OC, OM, available P, silt and sand content among land use and land covers of study watershed. There is also a difference in soil colour among land use and land covers. But there is no significant difference in soil pH and CEC among land use and land covers. The difference in soil properties among land use land covers is more significant at 0-15cm depth than at 15-30cm depth. Most soil nutrients subject to laboratory analysis are low at croplands of Cheketa sub catchment and grass lands of Debeka sub catchment. This study recommends a need to promote sustainable soil management practices and improving management of grass and shrub land uses in the watershed. Key words:land use and land cover change, changes in soil propertie

Land use and land cover change in Ameleke Watershed, South Ethiopia

This study investigated the land use and land cover change at Ameleke watershed, middle catchment of Gidabo River, South Ethiopia that occurred from 1986-2006. Landsat TM of 1986, Landsat ETM+ of 2000 and SPOT of 2006 were used to produce land use and land cover maps of the watershed. A pixel-based supervised image classification through decision rule of maximum likelihood classifier algorithm was used to map land use and land covers on ERDAS Imagine 8.6.  For land use and land cover maps of 1986, 2000 and 2006, error matrixes were produced and have an accuracy assessment of 80%, 85% and 85.71% respectively. Focused group discussions and key informant interviews were also used for land use and land cover reconstruction. The result showed from 1986 up to 2006, cropland and mixed cover increased from 23.33% to 31% and 7.26 to 15.68% of the watershed respectively. In contrast grass lands and shrub lands decreased from 25.9% to 14.96% and 30.3% and 24.25% of the watershed respectively in 1986 to 2006. There was also an increasing trend on agroforestry while there was a decreasing trend on riverine forests. This study recommends further assessment and monitoring of spatial and temporal based land use and land cover change at homestead level having high resolution satellite images. Keywords: land use and land cover change, Ameleke watershe

Effects of Land Use/Land Cover Change on Some Soil Physical and Chemical Properties in Ameleke micro-Watershed, Gedeo and Borena Zones, South Ethiopia

This study investigates effect of land use and land cover change (LUCC) on some soil physical and chemical properties at Ameleke micro-watershed, South Ethiopia. Satellite images of 1986, 2000 and 2006 were used to analyze LUCCs of the watershed. For the purpose of soil sampling, the watershed was divided in to three altitudinal belts, from each of which two sample sites were taken. From each sample site, composite soil samples were collected from agroforestry, crop land, grass land and shrub lands in three replications at 0-15cm and 15-30 cm depth and selected soil physical and chemical properties were analyzed. The result of the land use/cover analyses showed that agroforestry and crop lands occupy larger part of the upland while grass and shrub lands occupy larger part of the middle and lower altitude of the watershed. The change detection study revealed that from 1986 to 2006, crop land  area increased from 23.3% to 31.0%; grass lands decreased from 25.9% to 14.96% and shrub lands  decreased from 30.3% to 24.25%. Analyses of soil properties reveal that significant differences (p <  0.05) in soil available K, TN, OC, OM, available P and soil texture and insignificant differences in soil  pH and CEC among land use and land cover types. The difference in soil properties among land use and land covers is highly significant at 0-15 cm depth than at 15-30 cm depth.  This study recommends assessment of land use and land covers at homestead level and sharing experiences for expansion of agro forestry type of land use between Gedeo and Guji Oromo people are central for sustainable management of natural resources of the watershed. Keywords:land use and land cover change, soil chemical properties, soil physical properties, Ameleke micro-watershed, South Ethiopi

Shrinkage and Carbon Stock in Wetlands of Fogera Plain, North West Ethiopia

This study investigates the shrinkage and carbon sequestrationin wetlands of Fogera plain,North West Ethiopia. Landsat MSS of 1973, Landsat TM of 1994 and Landsat ETM+ 2011 were used for change detection. Supervised image classification through maximum likelihood classifier algorithm and qualitative data collection methods wereused. Composite soil samples in three replications at a depth of 0-75 cm were collected and samples organic carbon and organic matter was analyzed in soil laboratory. The result of Landsat images analysis showed that the area of the wetland was 25% of the area in1973 while it shrinkedin to 19.59% in 2011.There is a significant difference (p < 0.05) in soil OC and OM content in between different classes of wetlands. The organic carbon content of soils in wetlands where there is sediment deposition is very low. In less disturbed wetlands, there is better carbon content than other state of wetlands. Totally, carbon sequestration potential of these wetlands is very low in comparison with the carbon content of the wetlands of other parts of the world. This study recommends further upstreamwatershed conservation efforts and payment for the ecosystem services and benefits for such like ecosystems is to be started. Key words; carbon sequestration, sediment depositio

Woody Plant Inventory and Diversity in Traditional Agroforestry of Selected Peasant Association of South Gonder Zone, North West Ethiopia

The study is aimed to assess the traditional agroforestry practice and tree composition in six selected peasant association of South Gonder Zone, Northern Ethiopia. In addition, variation of woody plant species on major niches of agroforestry was also assessed. Peasant association were selected based agro ecology, two peasant associations from Dega agro ecology, two peasant associations from Woinadega agro ecology and two peasant associations from Kolla agroecology were selected. Accordingly, 96 household heads were selected randomly from the peasant association for the study. The study was also supported by key informant interview to triangulate the data. Woody species inventory was conducted on the farmlands of the 96 selected farmers and quadrant was also laid on major agroforestry niches home garden, crop land and grazing land which were analyzed using Shannon diversity index to compare their variation.The results of this study have shown that home gardens, farm boundary, crop land, grazing lands and degraded lands are the common traditional agroforestry practices in the study area. On home garden the common tree species are Acacia nilotica,Capparis tomentosa, Persea Americana and Rhamnus prinoides while on crop land the common tree species are Cordia Africana Croton macrostachyus Adansonia digitata and Syzygium guineense. Similarly, the common trees species on boundary are Eucalyptus spp, Rosa abyssinica, Carissa spinarum and Sesbaina sesban while the common tree species on degraded land are Eucalyptus spp, Justicia schimperiana, Vernonia amygdalina and Rosa abyssinica. And the common tree species on trees on grazing land are Ficus vasta, Ficus sur, Albizia gummifera and Acacia nilotica. In comparison of major agroforestry niche, grazing land is more diversified followed by crop land and grazing land as their mean Shannon diversity index value is 1.52, 1.44 and 1.24 respectively. The study recommends that conservation of the existing indigenous trees and the importance of each potential tree species for soil fertility improvement, animal feed, biological soil conservation, and ecological importance should be studied further. Keywords: agroforestry practice, woody species inventory and diversit

Statistical bias correction of regional climate model simulations for climate change projection in the Jemma sub-basin, upper Blue Nile Basin of Ethiopia

This study evaluates bias correction methods and develops future climate scenarios using the output of a better bias correctiontechnique at the Jemma sub-basin. The performance of different bias correction techniques was evaluated using several statisticalmetrics. The bias correction methods performance under climate condition different from the current climate was also evaluatedusing the differential split sample testing (DSST) and reveals that the distribution mapping technique is valid under climatecondition different from the current climate. All bias correction methods were effective in adjusting mean monthly and annualRCM simulations of rainfall and temperature to the observed rainfall and temperature values. However, distribution mappingmethod was better in capturing the 90th percentile of observed rainfall and temperature and wet day probability of observedrainfall than other methods. As a result, we use the future (2021–2100) simulation of RCMs which are bias corrected usingdistribution mapping technique. The output of bias-adjusted RCMs unfolds a decline of rainfall, a persistent increase of temperature and an increase of extremes of rainfall and temperature in the future climate under emission scenarios of RepresentativeConcentration Pathways 4.5, 8.5 and 2.6 (RCP4.5, RCP8.5 and RCP2.6). Thus, climate adaptation strategies that can provideoptimal benefits under different climate scenarios should be developed to reduce the impact of future climate change

Observed changes in extremes of daily rainfall and temperature in Jemma Sub-Basin, Upper Blue Nile Basin, Ethiopia

Climate variability has been a threat to the socio-economic development of Ethiopia. This paper examined the changes in rainfall, minimum, and maximum temperature extremes of Jemma Sub-Basin of the Upper Blue Nile Basin for the period of 1981 to 2014. The nonparametric Mann-Kendall, seasonal Mann-Kendall, and Sen’s slope estimator were used to estimate annual trends. Ten rainfall and 12 temperature indices were used to study changes in rainfall and temperature extremes. The results showed an increasing trend of annual and summer rainfall in more than 78% of the stations and a decreasing trend of spring rainfall in most of the stations. An increase in rainfall extreme events was detected in the majority of the stations. Several rainfall extreme indices showed wetting trends in the sub-basin, whereas limited indices indicated dryness in most of the stations. Annual maximum and minimum temperature and extreme temperature indices showed warming trend in the sub-basin. Presence of extreme rainfall and a warming trend of extreme temperature indices may suggest signs of climate change in the Jemma Sub-Basin. This study, therefore, recommended the need for exploring climate induced risks and implementing appropriate climate change adaptation and mitigation strategies

Nutrient Utilization and Yield Response of Lentil (Lens culinaris Medikus) to Rhizobium Inoculant and Sulphur Fertilization

Lentil (Lens culinaris Medikus) is a major food crop in Ethiopian. It is affordable protein source and important in sustaining soil fertility through nitrogen fixation. However, its current national productivity of 1.46 t ha-1 is lower than its potential due to inadequate agronomic management practices, nutrient imbalance and lack of indigenous or commercial Rhizobium strains of lentil. Therefore, the field experiment was conducted at Ada’a district under rain-fed condition during 2016/17 main cropping season to assess the role of S and Rhizobium inoculant on nodulation, nutrient utilization and yield response of lentil. The experiment consisted of three levels of S (0, 20 and 40 kg ha-1) and Rhizobium inoculant (un-inoculated and inoculated) in a factorial combination using Alemaya lentil variety as a test crop. The experiment was conducted using randomized complete block design with three replications. The result showed the interaction of sulphur fertilization and Rhizobium inoculant were significant on days to flowering, number of nodules plant-1, nodule dry weight plant-1, number of seeds pod-1, aboveground dry biomass, seed yield, seed S uptake, haulm S uptake, total S uptake, sulphur agronomic and recovery efficiency as well as sulphur harvest index. Application of 40 kg S ha-1 without Rhizobium inoculant led to produce the highest seed yield (2.27 t ha-1) and delayed days to flowering (46 days) of lentil whereas, the highest nodule dry weight plant-1 (1.1mg) and sulphur harvest index (17.68%) were obtained at the rate of 40 kg S ha-1under Rhizobium inoculations. On the other hand the maximum number of nodule plant-1 (15.60), number of seed pod-1 (1.99), total aboveground dry biomass (8.22 t ha-1), Sulphur agronomic efficiency (32.11kg ha-1), sulphur recovery efficiency (66.00 kg ha-1) were obtained in response to sulphur application at 20 kg ha-1 under Rhizobium inoculations. Moreover, Rhizobium inoculation without S fertilization gave the highest seed (3.88kg ha-1), haulm (23.33kg ha-1) and total S uptake (24.89 kg ha-1). Rhizobium inoculation without S application had high net benefit, relatively low variable cost with an acceptable and maximum MRR for lentil production in Ada'a district. However, since the experiment was conducted only for one season and one site, repeating the trial at different sites as well as in the same trial site would be important in order to draw sound recommendation

Evaluation of regional climate models performance in simulating rainfall climatology of Jemma sub-basin, Upper Blue Nile Basin, Ethiopia

This study examines the performance of 10 Regional Climate Model (RCM) outputs which are dynamically downscaled from the fifth phase of Coupled Model Inter-comparison Project (CMIP5) GCMs using different RCMs parameterization approaches. The RCMs are evaluated based on their ability to reproduce the magnitude and pattern of monthly and annual rainfall, characteristics of rainfall events and variability related to Sea Surface Temperature (SST) for the period 1981–2005. The outputs of all RCMs showed wet bias, particularly in the higher elevation areas of the sub-basin. Wet bias of annual rainfall ranges from 9.60% in CCLM4 (HadGEM2-ES) model to 110.9% in RCA4 (EC-EARTH) model. JJAS (June-September) rainfall is also characterized by wet bias ranges from 0.76% in REMO (MPI-ESM-LR) model to 100.7% in RCA4 (HadGEM2-ES) model. GCMs that were dynamically downscaled through REMO (Max Planck Institute) and CCLM4 (Climate Limited-Area Modeling) performed better in capturing the rainfall climatology and distribution of rainfall events. However, GCMs dynamically downscaled using RCA4 (SMHI Rossby Center Regional Atmospheric Model) were characterized by overestimation and there are more extreme rainfall events in the cumulative distribution. Most of the RCMs’ rainfall over the sub-basin showed a teleconnection with Sea Surface Temperature (SST) of CMIP5 GCMs in the Pacific and Indian Oceans, but weak. The ensemble mean of all 10 RCMs simulations was superior in capturing the seasonal pattern of the rainfall and had better correlation with observed annual (Correl = 0.6) and JJAS season rainfall (Correl = 0.5) than any single model (S-RCM). We recommend using GCMs downscaled using REMO and CCLM4 RCMs and stations based statistical bias correction to manage elevation based biases of RCMs in the Upper Blue Nile Basin, specifically in the Jemma sub-basin