Determinants of vegetation patterns and land cover dynamics in Nech Sar National Park, southern Ethiopian Rift Valley
DETERMINANTS OF LAND COVER DYNAMICS IN NECHISAR NATIONAL PARK SOUTH ETHIOPIA RIFT VALLEY
Ethiopia with its broad latitudinal rangeand great altitudinal variation encompasses a variety of habitats that harbor a unique collection of fauna and flora with a high level of endemism. To safeguard the losses of biodiversity protectedareas were established in different part of the country. Most of these protected areas including the gazetted National parks (Semien Mountain and Awash National parks) are not well protected from settlements, agricultural activities, human and livestock pressure. Anthropogenic activities and other environmental factors affect the biodiversity of both terrestrial and aquatic ecosystems by increasing fragmentation and edge of boundaries and reducing the natural habitats ( Sala et al., 2010). These effects has been shown in reducing level of biodiversity and abundance of rare and endemic species ( Yihune et al., 2008; Clark, 2010; Bartunkova, 2011). Nechisar National park(NSNP), one of the protected areas in Ethiopia, located between 5051’-6010’N latitude and 37032’-37048’E longitude in the rift valley. NSNP was established in 1974 to conserve Swayne’s Hartebeest (endemic to Ethiopia) and for its scenic beauty but latter because of its biodiversity richness other objectives like generation of revenues from tourism was included. Currently, NSNP is oneof the most threatened protected area in Ethiopia (Negussie, 2008; Clark, 2010, Fetene et al., 2012). Vegetation and land degradation of NSNP due to high human and livestock pressure were reported by different studies (Andargie, 2001, Aregu and Demeke, 2006, Fetene 2012). New settlements in and around the park, agricultural expansion, grazing and browsing competition, and encroachment of woody species were mentionedas reasons for the overall change of the park. Expansion of non-native species and woody species encroachment are negatively affect the abundance and distribution of wildlife and indigenous plant species ( Svialek, 2008; Negussie, 2008; Yusuf et al., 2011). Change in qualities and quantities of native plants might be reason for local extinction of some wildlife.
Though the above studies clearly pointed out that changes have been occurred in NSNP, there are gaps of knowledge in quantifying changes and underlined causes. Moreover, the distribution of vegetation in NSNP showed distinct variations in habitat structure and composition.Human influence was reported as major factor for the changes and variations (Aregu and Demeke, 2006; Clark, 2010), and environmental factors were given less emphasis.
The main objective of this study is to describe the major driving factors of habitat changes/land cover changes and environmental factors responsible for the pattern of variation. The study will have the following specific objectives.(I). Identify the types of vegetation and the most important soil parameters that influence the pattern of vegetation distribution across the landscape;(ii) quantify the land cover changes and habitat losses in NSNP; (iii). Produces soil map of the area and describe the major soil types
(IV). Describe the vegetation dynamics in response to livestock and human influences