In the dominantly small-scale subsistence agricultural system of Ethiopia, where most of the organic inputs are not returned to soil and land is not used based on its best suitability, the contribution of agriculture to climate change mitigation/adaptation through reduction of greenhouse gases emission is undermined. When this low-input agricultural practice is coupled with rugged topography, high population pressure, generally low soil fertility, and looming climate change, ensuring food and nutrition security of society as well as sustainable use of land resources is practically impossible. Under such circumstances, finding alternative land uses, through scientific investigation, that meet the triple mandates of climate-smart agriculture under current and future climate is imperative. In view of this, a study was conducted in Hades Sub-watershed, eastern Ethiopia, to evaluate the carbon stock of major land uses, evaluate suitability of land for rainfed production of sorghum (Sorghum bicolor L.), Maize (Zea mays L.), coffee (Coffea arabica), upland rice (Oryza sativa L.) and finger millet (Eleusine coracana L.), and project biomass production of late-maturing sorghum and maize varieties under changing climate and its contribution to carbon sequestration and reduction of greenhouse gases (GHGs) emission. Soil and vegetation samples were collected following recommended procedures. Secondary data on required crop parameters were collected for model calibration and validation in the biomass projection study made using the AquaCrop v6.0 model. Climate data of the study area was obtained from the National Meteorology Agency of Ethiopia and analyzed following standard procedures. Near-century (NC) (2017-2039) and Mid-century (MC) (2040-2069) climate was projected under two emission scenarios (RCP4.5 and RCP8.5) using four models (CNRM-CERFACS-CNRM-CM5, ICHEC-EC-Earth, MOHC-HadGEM2-ES, and MPI-M-MPI-ESM-LR) and a Multi-model Ensemble. Biomass production projection, for the climate projected under the two emission scenarios using the four models and the ensemble, was made for late-maturing sorghum (Muyira-1) and maize (BH661) varieties. From the projected biomass, organic carbon and its equivalent CO2 were estimated. Furthermore, adaptation measures, involving adjusting planting dates and irrigation, under the changing climate were evaluated for their influence on biomass production under the time slices, RCPs, and models mentioned above. The carbon stock assessment study was conducted on four major land uses (cultivated, grazing, coffee agroforestry, and forest lands) identified in the study area. The land suitability assessment, using the maximum limitation method, study was conducted on four soil mapping units identified in the sub-watershed. Results indicate that total organic carbon stock (soil, litter plus live vegetation) in the sub-watershed ranged from 138.95 ton ha-1 in the crop land to 496.26 ton ha-1 in the natural forest. The soil organic carbon stock was found to be relatively higher than that of the vegetation carbon stock in the natural forest and coffee agroforestry land uses. The results of suitability evaluation revealed that the maximum current and potential (after corrective xix measures are taken) land suitability class for production of late-maturing sorghum (180-240 days cycle), maize (180-210 days crop cycle), finger millet (120 – 150 days cycle) and coffee in the sub-watershed is marginally suitable (S3c). The maximum current and potential land suitability for upland rice (120 days) is not suitable (N2c). The major permanent limiting factor is low mean temperature (14.6 C) of the growing period in the study area as compared to the optimum temperature required for optimum growth of the selected crops. The major soil and landscape limitations include steep slope, poor drainage of low-lying areas, shallow effective root zone in the upper slopes, low organic matter and available P for sorghum and maize, high pH for maize and wetness for coffee. In all the climate models and emission scenarios, minimum and maximum temperature increment is high during June-July-August-September (JJAS) compared with the other seasons. The modest rise in minimum temperature and the slight increment of maximum temperature during the crop growing seasons (February-March-April-May (FMAM) and JJAS will benefit late-maturing sorghum and maize production in the study area. For the same model, the projected biomass yield and organic carbon sequestration of the two crop varieties varied with time slice and the type of emission scenario used. Generally, increasing biomass production and carbon sequestration were projected for Mid-century (MC) than Near-century (NC) for most of the models used. Late planting would increase sorghum biomass yield and the corresponding organic carbon as compared to early planting as projected by most of the models under both RCPs. Most models predicted an increase in maize biomass yield and organic carbon sequestration if supplementary irrigation is used. The results of this study indicate that the current land uses are not enhancing carbon sequestration because of their exploitative nature and the soil/landscape and climate are not optimum for production of the crops studied. The rise in temperature in the coming 50 years is expected to create a more favorable condition for production of late-maturing sorghum and maize varieties. In order to enhance carbon sequestration, soil productivity and crop yield, and reduce greenhouse gas emissions, the current land uses and their management require re-visiting. / College of Agriculture and Environmental Sciences / Ph. D. (Environmental Sciences)

The daunting tasks of responding to climate change and ensuring sustainable development (SD) are high on the political agenda among world leaders. From the onset, the clean development mechanisms (CDM) outlined in Article 12 of the Kyoto Protocol (KP), state that CDM activities should contribute to SD in the host country while reducing greenhouse gas (GHG) emission. Nevertheless, many scholars have criticized CDM for failing to deliver on its twin objectives. In Ethiopia in particular, there was lack of afforestation/reforestation (A/R) CDM research specific to the nation; specifically, research as to whether A/R-CDM met the stipulated twin objectives of SD and mitigation (reducing GHG). This study was conducted in the Humbo district of Wolyaita Zone, Southern Nations - Nationality and People Regional (SNNPR) state of Ethiopia, where A/R-CDM was implemented in pursuit of these twin objectives. Humbo is located between 6°46’48.47 and 6°41’04.28N; and between 37°48’35.44 and 37° 55’14.51E, between altitudinal gradients 1200 and 1900 m.a.s.l. The climate of the study area is characterized by annual temperatures between 25°C and 28°C, and by total annual rainfall between 800 to 1000 mm. The objectives of the study were to quantify the change of above ground and below ground carbon pools of native tree species; to assess the attractiveness of FMNR forestry practices; to examine A/R-CDM contributions to community level SD; and to assess the effectiveness of climate change mitigation policy founded on native tree species-based A/R-CDM. Data regarding above ground biomass (AGB) and below ground biomass (BGB) carbon pools of native tree species was collected through non-destructive techniques to quantify the change in carbon sequestration and associated carbon trading. A multi-stage random cluster household (HH) sampling approach was used to assess the attractiveness of farmer managed natural regeneration (FMNR) forestry practice. To examine the contribution of A/R-CDM to community level SD, three dimensions of SD were evaluated, namely; (local) environmental, social, and economic. Two indicators were considered per each dimension. With regard to local environmental SD, community access to natural resources, as well as changes to the local climate were considered. With regard to the social dimension, job creation and changes to social support structures were considered. With regard to the economic dimension, economic activities of the area and local skill development were considered. Focus group discussions and key informant interviews were used to triangulate the survey as well as to assess policy perspectives. Results revealed that the Humbo native tree species based A/R-CDM, which employed FMNR forestry practices, sequestered a net total of 73,138; 84,848; 103,769 and 111,657 tCO2e along 2011, 2014, 2015 and 2016 years, respectively, across 2,728 ha. In terms of carbon leakage due to fuel wood collection activity displacement, a net zero was found since the average volume of fuelwood collected from the project area, after the area was closed off, was found to be 5.1 - 6.1 M3, while before the area was closed off, that number was 4.3 M3. This was due to the project employing FMNR forestry practices. Similarly, the leakage due to livestock grazing activity displacement also was found to be a net zero, since the number of animals grazing on land adjacent to the project area after four years of the area’s being closed off reached 11,383 cattle, 429 donkeys and 4,108 goats, unlike 8,684 cattle and 2,288 goats before the project. In other words, the number of livestock owned by farmers on the land adjacent to the project site was not adversely affected by the closing off of the site, which prevented grazing on the area allocated to A/R-CDM. The livestock management training provided by project developer improved the farmers’ rearing efficiency. Another expected leakage due to soil pitting for A/R was also found to be nil since soil disturbance did not take place because of FMNR practices. These results indicated that systematic regeneration of native tree species through FMNR forestry practices is an effective method to develop carbon sinks. From the point of view of FMNR attractiveness, the results revealed that the practice improved land cover change. The use of FMNR avoided the projected eight years reforestation investment cost of US$ 2,751,312.00 which could have been used if plantation forestry was undertaken. This showed that Humbo A/R-CDM might not have happened if FMNR is had not been introduced, as CDM has no pre-finance mechanism. With regard to community level SD contributions, the establishment of forest protection and development farmers’ cooperatives, as well as the granting of communal land-user rights certification, resulted in legal ownership of the land to the community, whereas before, the land was considered “no man’s land,” and subject to open access. The land-user rights and carbon ownership in turn empowered the community to sign a contract with an international carbon credit buyer. In terms of the local microclimate, the regeneration of native tree species was correlated with increased rainfall in the area in June, July, August and September (JJAS) and March, April and May (MAM). This suggested that the native tree species based A/R-CDM project played a role in improving the local microclimate. In terms of sociological SD, the study showed that new employment opportunities were created including tree pruning, thinning, forest guarding, and jobs at the community warehouse and community flourmill. The availability of employment opportunities was significantly higher for those who participated in the Humbo A/R-CDM, when compared to those who didn’t. In terms of social support structures, in less than ten years, seven Humbo A/R-CDM project owner farmers’ cooperatives, initially established as owners of the project, evolved into one forest protection and development Union. This enabled the institutionalization of grassroots organizations towards a common communal and international agenda of care for the environment. In terms of economic effects, the project enabled a carbon credit contract worth a total of US$ 3,873,298.00, signed at the sell rate of US$ 4.4 per tCO2e, for a total of 880,295 tCO2e across a 30 year crediting period. This is a new business model for the community, the country, and global businesses, all doing their part in climate change mitigation - CDM. As of the first A/R-CDM verification, the community received a total of US$ 321,807.2 in 2011. Consequently, the community received 373,331.2 in 2014, 456,583.6 in 2015 and 491,290.8 in 2016. In terms of revenue from logging, selective harvesting is planned to take place in years 12, 24 and 36. The community is projected to earn at least US$ 15,150.00 per ha1 (a total of US$ 3.9 million) from the first forest harvest in year 12 alone. These benefits in emission reduction (ER) and SD suggest that massive cross-dimensional benefits were foregone due to the country’s refusal to welcome A/R-CDM in its first commitment period, despite having 36,434,400 ha of land eligible for A/R. The research results in the area of policy perspectives indicated that the Humbo A/R-CDM project, the only one of its kind in Ethiopia, was made possible by environment related constitutional provisions, especially those pertaining to land-user rights, and the existence of a nationally standardized definition of forest that complies with international range. Additionally, the timely ratification of the Kyoto Protocol (KP), the establishment of a designated national authority (DNA) and a letter of approval by the DNA to the project developer were found to be enablers. Yet, defining land use, clarifying carbon ownership rights and bringing an inclusive benefit sharing mechanism for forest carbon are among the key instruments the country has yet to put in place to prove local readiness for such development opportunities. The Humbo A/R-CDM also undertook voluntary assessments to obtain additional certification in the form of the Climate Community Biodiversity (CCB) certification, and was certified to be of gold standard for its premium. However, there were no benefits to the host community and project developer from the CCB gold standard certification. Such ambiguity could have been cleared from the onset. This implied whenever going for market and/or result based climate change mitigation, it is necessary to understand the provisions. This study revealed that the Humbo native tree species-based A/R-CDM via FMNR forestry practices met the CDM twin objectives as specified in Article 12 of the KP in 1997, namely the double aims of achieving mitigations of GHG emissions and assisting developing countries inSD. Yet, more research is needed to understand all eligible A/R carbon pools sequestered at Humbo A/R-CDM site. / Environmental Sciences / Ph. D. (Environmental Management)