Comparative Study of Species Diversity in different Land Use Units of the Borana Lowlands, Southern Oromia, Ethiopia

Journal of Rangeland Science

مقاله 10، دوره 10، شماره 3، مهر 2020، صفحه 328-340   

نوع مقاله: Research and Full Length Article

نویسنده

Gemedo Dalle^*

Center for Environmental Science, Addis Ababa University

چکیده

Quantitative study of species diversity across different land use units and districts is important to document status of local plant biodiversity, to evaluate impact of management and for planning future management. This study aimed at determining impacts of land use units on species diversity and spatial distribution of species in two districts of Borana zone, Oromia, Ethiopia. Stratification and systematic random sampling techniques were used for data collection. Plot size of 500 m² for woody species and subplots of 0.25 m² for herbaceous species and soil samples were used. Data was analysed using both descriptive and inferential statistics. Shannon diversity index and Simpson index were determined. Relationships between vegetation and environmental variables were analysed using Redundancy Analysis (RDA) and Canonical Correspondence Analysis (CCA). The overall mean alpha, beta and gamma diversities were 29.2, 2.5 and 102.6, respectively. Average total number of species in enclosures and open access grazing sites was 113 and 96 species, respectively. Enclosures or relatively protected land use units (Kalos) had more species diversity than their corresponding open access grazing lands (Worras). Shannon diversity index ranged from 3.11 in the grazing land for dry livestock to 3.78 in the Web grazing land for lactating cattle. Similarly, Simpson index of dominance ranged from 0.034 in the Web Worra to 0.089 in grazing land for dry livestock (Foora). Kalos had higher Simpson diversity index than their corresponding Worras. Soil nutrients varied across land use units. Cation Exchange Capacity (CEC) was higher in enclosed than in open access grazing land use units. The study also showed that there was significant variation in P, Ca, CEC, silt and sand across the two districts (p<0.05). RDA and CCA results revealed that altitude, OM, K and N were the most important environmental variables that significantly accounted for the spatial distribution and abundance of species. It was concluded that enclosures had contributed to increased species diversity. Promoting the area enclosure as a viable strategy for biodiversity management and rehabilitation of rangelands were recommended as a result of this study.

کلیدواژه‌ها

Enclosure؛ Arid and Semi-arid؛ Diversity Indices؛ Rangeland Biodiversity

مراجع

Angassa, A. and Baars, RMT. 2000. Ecological condition of encroached and non-encroached rangelands in Borana, Ethiopia. African Journal of Ecology 38: 321-328.

Angassa, A., Oba, G. Treydte, AC. and Weladji, RB. 2010. Role of traditional enclosures on the diversity of herbaceous vegetation in a semi-arid rangeland, southern, Ethiopia. Livestock Research for Rural Development. Volume 22, Article #163. Retrieved October 8, 2019, from http://www.lrrd.org/lrrd22/9/anga22163.htm.

AOAC (Association of Official Analytical Chemists). 1990. Official methods of analysis. 15th Edn. AOAC, Arlington, VA, USA.

Arellano, L. and Halffter, G. 2003. Gamma diversity: Derived from a determinant of alpha & beta diversity. An analysis of three Tropical landscapes. Acta Zoologica Mexicana 90: 27-76.

Coppock D L. 1994. The Borana plateau of southern Ethiopia: synthesis of pastoral research, development and change, 1980-1991. International Livestock Centre for Africa (ILCA), Addis Ababa, Ethiopia. 393 pp.

Dalle, G., Maass, BL. and Isselstein, J. 2005. Plant biodiversity and ethnobotany of Borana pastoralists in southern Oromia, Ethiopia. Journal of Economic Botany59 (1): 43-65.

Dalle, G., Maass, BL. and Isselstein, J. 2006. Encroachment of woody plants and its impact on pastoral livestock production in the Borana lowlands, southern Oromia, Ethiopia. African Journal of Ecology 44: 237-246.

Dalle, G., Maass, BL. and Isselstein, J. 2014. Relationships between Vegetation Composition and Environmental Variables in the Borana Rangelands, Southern Oromia, Ethiopia. SINET: Ethiopia, J. Sci. 37(1):1–12.

Edwards, S., Mensfin, T. and Hedberg, I. 1995. Flora of Ethiopia and Eritrea. Vol. 2 part 2. Addis Ababa, Ethiopia.

Edwards, S., Sebsebe, D. and Hedberg, I. 1997. Flora of Ethiopia and Eritrea. Vol. 6. Addis Ababa, Ethiopia.

Gharmakher, HN., Foutami, IJ. and Sharifi, A. 2015. Effects of Grazing Exclusion on Plant Productivity and Carbon Sequestration (Case Study: Gomishan Rangelands, Golestan Province, Iran). Journal of Rangeland Science 5(2): 122-132.

Haugen, T. 1992. Woody vegetation of Borana, south Ethiopia. A study on the main community types of the area. SINET: Ethiopian Journal of Science 15(2): 117-130.

Hedberg, I. and Edwards, S. 1995. Flora of Ethiopia and Eritrea. Vol. 7. Addis Ababa, Ethiopia.

Heikkinen, R., Birks, HJB. and Kalliola, R. 1998. A numerical analysis of the mesoscale distribution patterns of vascular plants in the subarctic Kevo Nature Reserve, northern Finland. Journal of Biogeography 25(1): 123-146.

Korvenpää T., von Numers, M. and Hinneri, S. 2003. A mesoscale analysis of floristic patterns in the south-west Finnish Archipelago. Journal of Biogeography 30(7):1019-1031.

Mekuria, W., Wondie, M., Amare, T., Wubet, A., Feyisa T. and Yitaferu. B. 2018. Restoration of degraded landscapes for ecosystem services in North-Western Ethiopia. Heliyon 4 e00764.doi: 10.1016/j.heliyon.2018.e00764.

Mengistu, A. 1998. The Borana and the 1991-92 drought. A rangeland and livestock resource study. Institute for Sustainable Development and French Catholic Committee against Hunger and for Development, Addis Ababa, Ethiopia. 90 pp.

Oba, G. and Kotile, DG. 2001. Assessment of landscape level degradation in southern Ethiopia: Pastoralists versus ecologists. Land Degradation and Development 12: 461-475.

Oba, G., Post, E., Syvertsen, PO. and Stenseth, NC. 2000. Bush cover and range condition assessments in relation to landscape and grazing in southern Ethiopia. Landscape Ecology 15: 535-546.

Ohmann, JL. and Spies, TA. 1998. Regional gradient analysis and spatial pattern of woody plant communities of Oregon Forests. Ecological Monographs 68(2): 151-182.

SCBD. (Secretariat of the Convention on Biological Diversity). 2003. Handbook of the convention on biological diversity. 2^nd ed. 937 pp.

ter Braak, CJF. and Šmilauer P. 1998. CANOCO reference manual and user’s guide to CANOCO for Windows: software for canonical community ordination (version 4.0). Microcomputer Power, Ithaca, NY, USA. 352 pp.

UN (United Nations). 1992. Convention on Biological Diversity.

Verdoodt, A., Mureithi, SM. and Van Ranst, E. 2010. Impacts of management and enclosure age on recovery of the herbaceous rangeland vegetation in semi-arid Kenya. Journal of Arid Environments 74: 1066-1073.

Vogiatzakis, IN., Griffiths, GH. and Mannion, AM. 2003. Environmental factors and vegetation composition, Lefka Ori massif, Crete, S. Aegean. Global Ecology and Biogeography 12(2): 131–146.

Wiegleb, G. and Felinks, B. 2001. Primary succession in post-mining landscapes of Lower Lusatia – chance or necessity. Ecological Engineering 17: 199-217.

Woldu, Z. and Nemomissa, S. 1998. Vegetation change in the central Borana plateau region of southern Ethiopia. Coenoses 13(3): 137-148.