The causes of land degradation in the African drylands have been shown to vary. Some researchers consider climate to be the major contributor to degradation, with anthropogenic factors playing a minor role. Others reverse the significance of these two factors. A third group attributes land degradation to climate and anthropogenic factors equally. This study was undertaken to establish the factors influencing land degradation in a semi-arid environment in southeastern Kenya and the rate of change in vegetation types for a period of 35 years (1973–2007). The reduction in grassland cover was used as an indicator of land degradation. Causes of land degradation were determined by a multiple regression analysis. A log-linear regression analysis was used to establish the rate of vegetation change. The multiple and log-linear regression analyses showed: (1) woody vegetation, livestock population and cultivated area to be the main contributors of reduction in grassland cover in the area, and (2) an increase in undesirable woody species, livestock population and cultivated area had a significant (P<0.05) negative effect on grassland vegetation. Increased human population, low amounts of rainfall and drought showed no significant negative effect on grassland vegetation cover. In conclusion, human and livestock population growth and increased agricultural land have contributed to intensive crop cultivation and overgrazing in the semi-arid lands. This overuse of the semi-arid rangelands has worsened the deterioration of the natural grassland vegetation.
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Adams W M, Watson E E. 2003. Soil erosion, indigenous irrigation and environmental sustainability, Marakwet, Kenya. Land Degradation & Development, 14(1): 109–122.
Angassa A. 2005. The ecological impact of bush encroachment on the yield of grasses in Borana rangeland ecosystem. African Journal of Ecology, 43(1): 14–20.
Angassa A. 2014. Effects of grazing intensity and bush encroachment on herbaceous species and rangeland condition in Southern Ethiopia. Land Degradation & Development, 25(5): 438–451.
Asner G P, Borghi C E, Ojeda R A. 2003. Desertification in central Argentina: Changes in ecosystem carbon and nitrogen from imaging spectroscopy. Ecological Applications, 13(3): 629–648.
Becerra J X. 2007. The impact of herbivore-plant coevolution on plant community structure. Proceedings of the National Academy of Sciences of the United States of America, 104(18): 7483–7488.
Bennett J E, Palmer A R, Blackett M A. 2012. Range degradation and land tenure change: insights from a ‘released’ communal area of eastern Cape Province, South Africa. Land Degradation & Development, 23(6): 557–568.
Breshears D D, Cobb N S, Rich P M, et al. 2005. Regional vegetation die-off in response to global-change-type drought. Proceedings of the National Academy of Sciences of the United States of America, 102(42): 15144–15148.
Central Bureau of Statistics (CBS). 2000. Republic of Kenya, Ministry of Economic Planning and Development report, Nairobi, Kenya.
Cerdà A. 1998. Effect of climate on surface flow along a climatological gradient in Israel. A field rainfall simulation approach. Journal of Arid Environments, 38(2): 145–159.
Cerdà A, Lavee H. 1999. The effect of grazing on soil and water losses under arid and Mediterranean climates. Implications for desertification. Pirineos, 153–154: 159–174.
Cerdà A. 2000. Aggregate stability against water forces under different climates on agriculture land and scrubland in southern Bolivia. Soil and Tillage Research, 57(3): 159–166.
Cerdà A, Flanagan D C, Le Bissonnais Y, et al. 2009. Soil erosion and agriculture. Soil and Tillage Research, 106(1): 107–108.
Coetzee B W T, Tincani L, Wodu Z, et al. 2008. Overgrazing and bush encroachment by Tarchonanthus camphoratus in a semi-arid savanna. African Journal of Ecology, 46(3): 449–451.
Conant R T, Paustian K. 2002. Potential soil carbon sequestration in overgrazed grassland ecosystems. Global Biogeochemical Cycles, 16(4): 90–1–90-9.
Darkoh M B K. 2003. Regional perspectives on agriculture and biodiversity in the drylands of Africa. Journal of Arid Environments, 54(2): 261–279.
de Souza R G, da Silva D K A, de Mello C M A, et al. 2013. Arbuscular mycorrhizal fungi in revegetated mined dunes. Land Degradation & Development, 24(2): 147–155.
Geist H J, Lambin E F. 2004. Dynamic causal patterns of desertification. Bioscience, 54(9): 817–829.
Gisladottir G, Stocking M. 2005. Land degradation control and its global environmental benefits. Land Degradation & Development, 16(2): 99–112.
GoK (Government of Kenya). 2002. Makueni District Development Plan for the period 2002–2008.
Nairobi: Kenya Government Printers. GoK (Government of Kenya). 2009. Ministry of Planning and Development. Nairobi: National population census.
GoK/NAP. 2002. National Action Programme: Framework for combating desertification in Kenya, in the context of the United Nations Convention to Combat Desertification (UNCCD). Nairobi: National Environment Secretariat.
Haddad N M, Tilman D, Knops J M H. 2002. Long-term oscillations in grassland productivity induced by drought. Ecology Letters, 5(1): 110–120.
Hall D O, Scurlock J M O. 1991. Climate change and productivity of natural grasslands. Annals of Botany, 67(Suppl.): 49–55.
Hibbard K A, Archer S, Schimel D S, et al. 2001. Biogeochemical changes accompanying woody plant encroachment in a subtropical savanna. Ecology, 82(7): 1999–2011.
Holdo R M. 2013. Revisiting the two-layer hypothesis: coexistence of alternative functional rooting strategies in savannas. PLoS ONE, 8(8): e69625.
Izzo M, Araujo N, Aucelli P P C, et al. 2013. Land sensitivity to desertification in the Dominican Republic: an adaptation of the ESA methodology. Land Degradation & Development, 24(5): 486–498.
Kassahun A, Snyman HA, Smit GN. 2008. Livestock grazing behaviour along a degradation gradient in the Somali region of eastern Ethiopia. African Journal of Range & Forage Science, 25(1): 1–9.
Lal R. 2004. Carbon sequestration in dryland ecosystems. Environmental Management, 33(4): 528–544.
Lal R. 2009. Sequestering carbon in soils of arid ecosystems. Land Degradation & Development, 20(4): 441–454.
Lázaro R, Rodrigo F S, Gutiérrez L, et al. 2001. Analysis of a 30-year rainfall record (1967–1997) in semi-arid SE Spain for implications on vegetation. Journal of Arid Environments, 48(3): 373–395.
Li X L, Gao J, Brierley G, et al. 2013. Rangeland degradation on the Qinghai-Tibet Plateau: Implications for rehabilitation. Land Degradation & Development, 24(1): 72–80.
Mataix-Solera J, Cerdà A, Arcenegui V, et al. 2011. Fire effects on soil aggregation: a review. Earth-Science Reviews, 109(1–2): 44–60.
Mganga K Z, Musimba N K R, Nyangito M M, et al. 2010. Improving hydrological responses of degraded soils in semi arid Kenya. Journal of Environmental Science and Technology, 3(4): 217–225.
Mganga K Z, Musimba N K R, Nyariki D M, et al. 2011. Different land use types in the semi-arid rangelands of Kenya influence soil properties. Journal of Soil Science and Environmental Management, 2(11): 370–374.
Mganga K Z, Kuzyakov Y. 2014. Glucose decomposition and its incorporation into soil microbial biomass depending on land use in Mt. Kilimanjaro ecosystems. European Journal of Soil Biology, 62: 74–82.
Mureithi S M, Verdoodt A, Njoka J T, et al. 2016. Impact of community conservation management on herbaceous layer and soil nutrients in a Kenyan semi-arid savannah. Land Degradation & Development, 27(8): 1820–1830.
Mwang’ombe A W, Ekaya W N, Muiru W M, et al. 2011. Livelihoods under climate variability and change: an analysis of the adaptive capacity of rural poor to water scarcity in Kenya’s drylands. Journal of Environmental Science and Technology, 4(4): 403–410.
Ngugi R K, Nyariki D M. 2005. Rural livelihoods in the arid and semi-arid environments of Kenya: sustainable alternatives and challenges. Agriculture and Human Values, 22(1): 65–71.
Nyangito M M, Musimba N K R, Nyariki D M. 2008. Range use and dynamics in the agropastoral system of southeastern Kenya. African Journal of Environmental Science and Technology, 2(8): 222–230.
Nyangito M M, Musimba N K R, Nyariki D M. 2009. Hydrologic properties of grazed perennial swards in semiarid southeastern Kenya. African Journal of Environmental Science and Technology, 3(2): 26–33.
Nyariki D M. 2009. Price response of herd off-take under market liberalization in a developing cattle sector: panel analysis applied to Kenya’s ranching. Environment and Development Economics, 14(2): 263–280.
Oba G, Post E, Syvertsen P O, et al. 2000. Bush cover and range condition assessments in relation to landscape and grazing in Southern Ethiopia. Landscape Ecology, 15(6): 535–546.
Olukoye G A, Kinyamario J I. 2009. Community participation in the rehabilitation of a sand dune environment in Kenya. Land Degradation & Development, 20(4): 397–409.
Omuto C T, Vargas R R, Alim M S, et al. 2010. Mixed-effects modelling of time series NDVI-rainfall relationship for detecting human-induced loss of vegetation cover in drylands. Journal of Arid Environments, 74(11): 1552–1563.
Opiyo FEO, Ekaya W N, Nyariki D M, et al. 2011. Seedbed preparation influence on morphometric characteristics of perennial grasses of a semi-arid rangeland in Kenya. African Journal of Plant Science, 5(8): 460–468.
Pei S F, Fu H, Wan C G. 2008. Changes in soil properties and vegetation following exclosure and grazing in degraded Alxa desert steppe of Inner Mongolia, China. Agriculture, Ecosystems & Environment, 124(1–2): 33–39.
Qadir M, Noble A D, Chartres C. 2013. Adapting to climate change by improving water productivity of soils in dry areas. Land Degradation & Development, 24(1): 12–21.
Roques K G, O’Conner T G, Watkinson A R. 2001. Dynamics of shrub encroachment in an African savanna: relative influences of fire, herbivory, rainfall and density dependence. Journal of Applied Ecology, 38(2): 268–280.
Serneels S, Lambin E F. 2001. Proximate causes of land-use change in Narok District, Kenya: a spatial statistical model. Agriculture, Ecosystems & Environment, 85(1–3): 65–81.
Speranza C I, Kiteme B, Ambenje P, et al. 2010. Indigenous knowledge related to climate variability and change: insights from droughts in semi-arid areas of former Makueni District, Kenya. Climate Change, 100(2): 295–315.
Van der Wal R. 2006. Do herbivores cause habitat degradation or vegetation state transition? Evidence from the tundra. Oikos, 114(1): 177–186.
Visser N, Morris C, Hardy M B, et al. 2007. Restoring bare patches in the Nama-Karoo of South Africa. African Journal of Range & Forage Science, 24(2): 87–96.
Vohland K, Barry B. 2009. A review of in situ rainwater harvesting (RWH) practices modifying landscape functions in African drylands. Agriculture, Ecosystems & Environment, 131(3–4): 119–127.
Wang Q X, Batkhishig O. 2014. Impact of overgrazing on semiarid ecosystem soil properties: a case study of the eastern Hovsgol Lake Area, Mongolia. Journal of Ecosystem & Ecography, 4(1): 140, doi: 10.4172/2157-7625.1000140.
Wang T, Yan C Z, Song X, et al. 2013. Landsat images reveal trends in the Aeolian desertification in a source area for sand and dust storms in China’s Alashan Plateau (1975–2007). Land Degradation & Development, 24(5): 422–429.
Wessels K J, Prince S D, Frost P E, et al. 2004. Assessing the effects of human-induced land degradation in the former homelands of northern South Africa with a 1 km AVHRR NDVI time-series. Remote Sensing of Environment, 91(1): 47–67.
Wessels K J, Prince S D, Malherbe J, et al. 2007. Can human-induced land degradation be distinguished from the effects of rainfall variability? A case study in South Africa. Journal of Arid Environments, 68(2): 271–297.
This research was funded by the European Commission under the Agricultural Innovations for Drylands Africa (AIDA), Grant Number 043863-SSA Africa (2006). We are also grateful to the Kamba Agropastoral Community in Kibwezi sub-County, Makueni County, Kenya for their support and cooperation throughout the research period.
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Mganga, K.Z., Nyariki, D.M., Musimba, N.K.R. et al. Determinants and rates of land degradation: Application of stationary time-series model to data from a semi-arid environment in Kenya. J. Arid Land 10, 1–11 (2018). https://doi.org/10.1007/s40333-017-0036-0
- regression analysis
- land degradation
- grassland cover
- semi-arid Kenya
- Sub-Saharan Africa