Land Use Change
Land Use Change
Land is a finite natural resource that sustains diverse ecosystems in Sub Saharan Africa. To date, there have been significant land use and cover changes throughout this region. Land use and land cover changes are key indicators of anthropogenic changes to the environment and are a critical contributor to loss of biodiversity and land degradation (Lambin, Geist and Lepers 2003). In Africa, forest land occupies 23 percent of land, yet between 1990 and 2010, approximately 75 million hectares of forest land (10 percent of total forest area) had been converted to other uses such as subsistence and commercial agricultural production (FAO 2012, 2016, Cotula et al., 2009). Additionally, Africa has the second highest rate of net land cover change per year at 0.36% after Southeast Asia’s 0.71% (Lambin, Geist and Lepers 2003). Malawi’s aggregated land cover percentage between 1990 and the 2000s revealed a 1.4 % decrease in trees, 0.06% decrease in tree plantations and a 1.4% increase in agriculture (Latham et al., 2014, FAO GLC-SHARE). Between 2000 and 2010, trees decreased by 0.16% and there was a 0.3% increase in agriculture (FAO GLC-SHARE).
Studies on land cover changes in Sub Saharan Africa point to interconnected influences including rural population growth, increased subsistence and commercial agriculture, climate change, and shifting economic and socio-political factors (Lambin et al., 2001). In particular, land use change to crop production has increased in Sub Sahara Africa primarily through smallholder farm agricultural intensification and extensification (Lambin et al., 2001). Smallholder farmers are the predominant land users in Sub Saharan African and their farming systems are typically rain-fed and characterized by highly variable environmental conditions and diverse socio-economic factors (Cooper et al., 2008). Food production in the region is often hindered by input (fertilizer and seed) availability and cost, marginal soil preparation, and an inability to allocate sufficient resources and labor during peak times in the agricultural cycle (Chikowo et al., 2014). Nonetheless, smallholder farmers in these tropical regions depend on their small landholdings to sustain their livelihoods due to lack of other employment and livelihood opportunities.
Anthropogenic land use change has been linked to multiple potentially negative consequences including decreased plant and animal habitat, soil erosion and degradation, and anthropogenic climate change. Deforestation, in particular, impacts climate change by modifying the latent heat flux, or earth’s energy budget based on evaporation into and/or condensation within the atmosphere (Myhre et al., 2013). Additionally, forests act as natural pools (or sinks) for carbon (C), and release significant amounts of C and nitrogen into the atmosphere when converted into agricultural lands (Murty et al., 2002). Land use changes also contribute to habitat loss for diverse species such as small mammals, birds, and plants. Many wild plant species that act as habitats for birds and bees (important pollinators) are at risk of extinction in the near future (Perrings and Halkos 2015). Additionally, continuous agricultural cropping that does not replenish soil nutrients by fallowing land, or supplementing with organic or inorganic inputs, causes soil fertility depletion, leading to marginalized fields and decreased yields. As a result, smallholders often seek to expand agricultural holdings, further exacerbating land conversion rates.
Cotula, L., Vermuelen, S., Leonard, R. & Keeley, J. 2009. Land grab or development opportunity? Agricultural investment and international land deals in Africa. London and Rome, IIED/FAO/IFAD. www.ifad.org/pub/land/land_grab.pdf.
FAO Global Land Cover. 2017. Land Cover Mapping of Malawi. Available at http://www.glcn.org/activities/mwi_lc_en.jsp <accessed February 7 2017>.
FAO. 2016. State of the World’s Forests 2016. Forests and agriculture: land-use challenges and opportunities. Rome. State of the World’s Forests 2012 (FAO, Rome, 2012).
Foley, J. A., DeFries, R., Asner, G. P., Barford, C., Bonan, G., Carpenter, S. R., … & Helkowski, J. H. 2005. Global consequences of land use. science, 309(5734), 570-574.
Lambin, E. F., Geist, H. J., & Lepers, E. 2003. Dynamics of land-use and land-cover change in tropical regions. Annual review of environment and resources, 28(1), 205-241.
Lambin, E. F., Turner, B. L., Geist, H. J., Agbola, S. B., Angelsen, A., Bruce, J. W., … & George, P. 2001. The causes of land-use and land-cover change: moving beyond the myths. Global environmental change, 11(4), 261-269.
Latham, J., Cumani, R., Rosati, I., & Bloise, M. 2014. Global land cover share (GLC-SHARE) database beta-release version 1.0-2014. FAO: Rome, Italy.
Perrings, C., & Halkos, G. 2015. Agriculture and the threat to biodiversity in sub-saharan africa. Environmental Research Letters, 10(9), 095015
Murty, D., Kirschbaum, M. U., Mcmurtrie, R. E., & Mcgilvray, H. 2002. Does conversion of forest to agricultural land change soil carbon and nitrogen? A review of the literature. Global Change Biology, 8(2), 105-123.
Myhre, G., D. Shindell, F.-M. Bréon, W. Collins, J. Fuglestvedt, J. Huang, D. Koch, J.-F. Lamarque, D. Lee, B. Mendoza, T. Nakajima, A. Robock, G. Stephens, T. Takemura and H. Zhang. 2013: Anthropogenic and Natural Radiative Forcing. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
The Snapp Lab is investigating the following promising options: