Conversion of savanna rangelands to bush dominated landscape in Borana, Southern Ethiopia
Tóm tắt
Analyzing trends of land use systems and the changes occurred overtime is an effective way of assessing the impacts of land use/land cover (LULC) changes on ecosystem function. It provides important insights for understanding the spatial patterns of land use processes. The rangelands of southern Ethiopia are adversely affected by increased human population pressure, encroachment of crop cultivation, and bush encroachment. Hence, it is vital to understand the trends of rangeland vegetation cover dynamics. This paper evaluates land use/land cover changes and spatial patterns between 1987 and 2003 in Yabelo (5426 km2), Borena rangelands of southern Ethiopia. We used a combination of three Landsat Thematic Mapper (TM) 1987, Landsat TM 1995 and Enhanced Thematic Mapper Plus (ETM+) 2003, and local perceptions. A pixel-based supervised classification with maximum likelihood classifier was used to classify images. The accuracy of classification was assessed for 1987 (81.8 %), 1995 (84.6 %), and 2003 (81.3 %). The results showed that the Borana rangelands had undergone substantial changes during the last 16 years. Between 1987 and 2003, we observed a considerable increase in woodland cover (11.7 %), bushland cover (17 %), cultivated land (72.5 %), and settlements (79.8 %). The results showed a rapid decline in grassland cover (7.7 %), shrubby grassland cover (86 %), and bareland (0.7 %). The spatial pattern analysis indicate that the Borana rangeland was fragmented and characterized by the proliferation of large numbers of patches with a decline in patch index, increased patch density, and irregular shape of patches within a landscape. Local communities’ perceptions indicate that recurrent drought, increased human population size, and expansion of cultivation were largely responsible for the observed LULC changes in the study area. LULC changes contribute to rangeland degradation and weaken the traditional practices of rangeland management. We suggest appropriate management measures to halt the impact of disturbances on LULC dynamics and its implication on the livelihoods of the Borana pastoralists.
Tài liệu tham khảo
Addis GY (2010) Spatio-temporal land use/land cover changes analysis and monitoring in Valencia municipality, Spain. An MSc Thesis in Geospatial Technologies at the University of ISEGI, New Lisbon (Portugal), Muenster, IFGI (Germany), University Jaume I Castellon (Spain). p. 69.
Angassa A (2011) Effects of drought on cattle herd dynamics and its implication on local livelihood systems in Borana, Ethiopia. Food Security Center, Universität Hohenheim, Wollgrasweg 43, 70599 Stuttgart, Germany.
Angassa A, Oba G (2007) Relating long-term rainfall variability to cattle population dynamics in communal rangelands and a government ranch in southern Ethiopia. Agr Syst 94:715–725
Angassa A, Oba G (2008a) Effects of management and time on mechanisms of bush encroachment in southern Ethiopia. Afr J Ecol 46:186–196
Angassa A, Oba G (2008b) Herder perceptions on impacts of range enclosures, crop farming, fire ban and bush encroachment on the rangelands of Borana, southern Ethiopia. Hum Ecol 36:201–215
Angassa A, Oba G, Tolera A (2012a) Bush encroachment control demonstrations and management implications on herbaceous species in savannas of southern Ethiopia. Trop Subtrop Agroecosyst 15:173–185
Angassa A, Sheleme B, Oba G, Treydte AC, Linstaedter A, Sauerborn J (2012b) Savanna land use and its effect on soil characteristics in southern Ethiopia. J Arid Environ 81:67–76
Assefa E, Bille JC, Corra M (1986) Ecological map of Southern Sidamo. JEPSS (Joint Ethiopian Pastoral System Study). Research report 19. ILCA (International Livestock Centre for Africa), Addis Ababa
Aynekulu E, Kassawmar T, Tamene L (2008) Applicability of ASTER imagery in mapping land use/cover as a basis for biodiversity studies in drylands of northern Ethiopia. Afr J Ecol 46(1):19–23
Bender DJ, Contreras TA, Fahrig L (1998) Habitat loss and population decline: a meta-analysis of patch size effect. Ecology 1998(79):517–533
Bloesch U (1999) Fire as a tool in the management of a savanna/dry forest reserve in Madagascar. Appl Veg Sci 2:117–124
Borghesio L, Giannetti F (2005) Habitat degradation threatens the survival of the Ethiopian bush crow (Zavattariornis stresemanni). Oryx 39:44–49
Braimoh AK (2006) Random and systematic land-cover transitions in northern Ghana. Agric Ecosyst Environ 113:254–263
Congalton R, Green K (1999) Assessing the accuracy of remotely sensed data. Principles and practices. Lewis Publishers, Boca Raton, p 137
Coppock DL (1994) The Borana plateau of southern Ethiopia: synthesis of pastoral research, development and change, 1980-1991. International Livestock Center for Africa (ILCA), Addis Ababa, p 299
Cossins NJ, Upton M (1988) The impact of climatic variation on the Borana pastoral system. Agr Syst 27:117–135
Dalle G, Brigitte LM, Isselstein J (2006) Encroachment of woody plants and its impact on pastoral livestock production in the Borana lowlands, southern Oromia, Ethiopia. Afr J Ecol 44:113–299
Desta S, Coppock DL (2002) Cattle population dynamics in the southern Ethiopian rangelands, 1980–97. J Range Manage 55:439–451
DiBari JN (2007) Evaluation of five landscape-level metrics for measuring the effects of urbanization on landscape structure: the case of Tucson, Arizona, USA. Landsc Urban Plan 79:308–313
Duadze SEK (2004) Land use and land cover study of the savannah ecosystem in the Upper West Region (Ghana) using remote sensing. Ecology and Development Series No. 16. Cuvillier Verlag, Gottingen, p 241
Elias M, Hensel O, Richter U, Hulsebusch C, Kaufmann B, Wasonga O (2015) Land conversion dynamics in the Borana rangelands of Southern Ethiopia: an integrated assessment using remote sensing techniques and field survey data. Environments 2:1–31
Ellis JE, Swift DM (1988) Stability of African pastoral ecosystems: alternate paradigms and implications for development. J Range Manage 41:450–459
ERDAS (1999) Field guide. Fifth edition. ERDAS Inc. Buford High was, NE, Atlanta, Georgia,USA.ERDAS IMAGINE Tour Guides. (2003). ERDAS IMAGINE V 9.0, ERDAS, Inc. Atlanta, Georgia, and USA.
Flintan F (2011) Broken lands: broken lives? Causes, processes and impacts of land fragmentation in the rangelands of Ethiopia, Kenya and Uganda. For REGLAP (Regional Learning and Advocacy Programm e). Save the Children USA, Nairobi
Flintan F, Tache B, Eid A (2011) Rangeland fragmentation in traditional grazing areas and its impact on drought resilience of pastoral communities: lessons from Borana, Oromia and Harshin, Somali Regional States, Ethiopia. Regional Learning and Advocacy Programme
Food and Agricultural Organization (FAO)/UNESCO/ISRIC (1986) Soil map of the world. Revised Legend. Technical Paper 20. ISRIC, Wageningen, The Netherlands.
Forman RTT, Godron M (1986) Landscape ecology. John Wiley and Sons, New York
Haile G, Assen M, Ebro A (2010) Land use/cover dynamics and its implications since the 1960s in the Borana rangelands of Southern Ethiopia. Livestock Research for Rural Development, Volume. http://www.lrrd.org/lrrd22/7/hail22132.htm
Helland J (1997) Development intervention and pastoral dynamics in Southern Ethiopia. In: Hogg R (ed) Pastoralists, ethnicity and the state in Ethiopia. HAAN publishing, London, pp 105–122
Herold M, Goldstein N, Clarke K (2003) The spatio-temporal form of urban growth: measurement, analysis and modeling. Remote Sens Environ 86(3):286–302
Hogg R (1997) Introduction. In: Hogg R (ed) Pastoralists, ethnicity and the state in Ethiopia. Haan Publishing, London, pp 1–22
Homann SB, Rischkowsky J, Steinbach Kirk M (2005) Towards endogenous development: Borana pastoralists’ response to environmental and institutional changes. Conference on international Agricultural Research for Development. Deutscher Tropentag 2005, Stuttgart-Hohenheim, October 11-13: 2003.
ILRI, International Livestock Research Institutes. GIS data Services http://data.ilri.org/geoportal/catalog/main/home.page. Accessed Nov 2011
Kamusoko C, Aniya M (2006) Land use/cover change and landscape fragmentation analysis in the Bindura district, Zimbabwe. Land Degrad Dev 18(2):221–233
Krummel JR, Gardner RH, Sugihara G, O’Neill RV, Coleman PR (1987) Landscape patterns in a disturbed environment. Oikos 48:321–324
Lafortezza R, Coomes D, Kapos V, Ewers RM (2010) Assessing the impacts of fragmentation on plant communities in New Zealand: scaling from survey plots to landscapes. Glob Ecol Biogeogr 19:741–754
Laris P (2002) Burning the seasonal mosaic: preventative burning strategies in the wooded savanna of Southern Mali. Hum Ecol 30(2):155–186
Leitao AB, Ahern J (2002) Applying landscape ecological concepts and metrics in sustainable landscape planning. Landsc Urban Plan 59:65–93
Li X, Lu L, Cheng G, Xiao H (2001) Quantifying landscape structure of the Heihe River Basin, north-west China using FRAGSTATS. J Arid Environ 48:521–535
Long J, Nelson T, Wulder M (2010) Characterizing forest fragmentation: distinguishing change in composition from configuration. Appl Geogr 30(3):426–435
Lu D, Weng Q (2007) A survey of image classification methods and techniques for improving classification performance. Int J Remote Sens 28(5):823–870
Lu D, Mausel P, Brondizio E, Moran E (2004) Change detection techniques. Int J Remote Sens 25(12):2365–2407
Mcgarigal K, Marks BJ (1994) FRAGSTATS: spatial pattern analysis program for quantifying landscape structure (Version 2.0). Forest Science Department, Oregon State University, Corvallis
Mcgarigal K, Cushman S, Neel M, Ene E (2002) FRAGSTATS: spatial pattern analysis program for categorical maps. www.umass.edu/landeco/research/fragstats/fragstats.html. Accessed 15 Nov 2011
Mesele S, Gebrekidan H, Gizachew L, Coppock DL (2006) Changes in land cover and soil conditions for the Yabelo District of the Borana Plateau, 1973-2003. Research Brief 06-06-PARIMA. Global Livestock Collaborative Research Support Program. University of California, Davis. p.4.
Mhangara P, Kakembo V (2012) An object-based classification and fragmentation analysis of land use and cover change in the Keiskamma catchment, Eastern Cape, South Africa. World Appl Sci J 19(7):1018–1029
Morris RJ (2010) Anthropogenic impacts on tropical forest biodiversity: a network structure and ecosystem functioning perspective. Philosophical transactions of the Royal Society of London. Ser Biol Sci 365(1558):3709–3718
Oba G (1998) Assessments of indigenous range management knowledge of the Borana pastoralists in southern Ethiopia. Borana Lowland Pastoral Development Program/GTZ, Consultancy paper, Negelle/Borana May 1998. p. 97.
Oba G, Kotile DG (2001) Assessment of landscape level degradation in southern Ethiopia: pastoralists versus ecologists. Land Degrad Dev 12:461–475
Oba G, Post E, Syvertsen PO, Stenseth NC (2000) Bush cover and range condition assessments in relation to landscape and grazing in southern Ethiopia. Landsc Ecol 15:535–546
Opdam P, Luque S, Jones KB (2009) Changing landscapes to accommodate for climate change impacts: a call for landscape ecology. Landsc Ecol 24:715–721
Pontius RGJR, Shusas E, McEachern M (2004) Detecting important categorical land changes while accounting for persistence. Agric Ecosyst Environ 101:251–268
Reid RS, Thornton PK, Kruska RL (2004) Loss and fragmentation of habitat for pastoral people and wildlife in East Africa: concepts and issues. Afr J Range Forage Sci 21:171–184
Ricca N, Guagliardi I (2015) Multi-temporal dynamics of land use patterns in a site of community importance in southern Italy. Applied Ecological. Environ Res 13:677–691
Rosenqvist A, Milne A, Lucas R, Imhoff M, Dobson C (2003) A review of remote sensing technology in support of the Kyoto Protocol. Environ Sci Pol 6:441–455
Sidiropoulou A, Karatassiou M, Galidaki G, Sklavou P (2015) Landscape pattern changes in response to transhumance abandonment on Mountain Vermio (North Greece). Sustainability 7:15652–15673
Solomon T, Snyman HA, Smit GN (2006a) Rangeland dynamics of southern Ethiopia: (2). Assessment of woody vegetation structure in relation to land use and distance from water in semi-arid Borana rangelands. J Environ Manage 85(2):443–452
Solomon T, Snyman HA, Smit GN (2006b) Cattle-rangeland management practices and perceptions of pastoralists towards rangeland degradation in the Borana zone of southern Ethiopia. J Environ Manage 82:481–494
Tache B, Oba G (2010) Is poverty driving Borana herders in southern Ethiopia to crop cultivation? Hum Ecol 38:639–649
Teixido AL, Quintanilla LG, Carreño F, Gutiérrez D (2010) Impacts of changes in land use and fragmentation patterns on Atlantic coastal forests in northern Spain. J Environ Manage 91(4):879–886
Teshome A (2011) Land cover dynamics in savanna ecosystem of Borana, Ethiopia. An MSc Thesis in Geospatial Technologies at the University of ISEGI, New Lisbon (Portugal), Muenster, IFGI (Germany), University Jaume I Castellon (Spain). p. 82.
Thapa RB, Murayama Y (2009) Examining spatiotemporal urbanization patterns in Kathmandu Valley, Nepal: remote sensing and spatial metrics approaches. Remote Sens 1(3):534–556
Tiki W, Oba G, Tvedt T (2011) Human stewardship or ruining cultural landscapes of the ancient Tula wells, southern Ethiopia. Geogr J 177:62–78
Tsegaye D, Moe SR, Vedeld P, Aynekulu E (2010) Land-use/cover dynamics in Northern Afar rangelands, Ethiopia. Agric Ecosyst Environ 139:174–180
Turan SO, Kadrogullari A, Gunlu A (2010) Spatial and temporal dynamics of land use pattern response to urbanization in Kastamonu. Afr J Biotechnol 9(5):640–647
USGS (United States Geological Survey) (2009) Global Land Survey, 1995, Landsat TM, 30m scene L5168057_05719950130. USGS, Sioux Falls, SD 57198-0001
Wu J, Jenerette GD, Buyantuyev A, Redman CL (2011) Quantifying spatiotemporal patterns of urbanization: the case of the two fastest growing metropolitan regions in the United States. Ecol Complex 1(1):1–8