Where Does Desertification Occur? Mapping Dryland Degradation at Regional to Global Scales

Chapter
Part of the Springer Earth System Sciences book series (SPRINGEREARTH)

Abstract

To make sense of the controversies about Sahelian desertification, we must be able to assess objectively the processes, their location and level of threat to drylands and those who inhabit them. Surprisingly, after the United Nations Conference on Desertification (UNCOD) was set up in 1977, there still are no reliable maps or means of monitoring desertification at the sub-national to global scales, even in the iconic Sahel region. These are the scales needed to formulate institutional policies for prevention and remediation and for Earth system science. While there are a few maps that do extend to larger areas, they mostly have serious shortcomings. This void is partly because suitable metrics have not been available and those that have been proposed can be difficult or impossible to apply over large areas. One of the most basic problems is the lack of comparison with non-desertified sites and an absence of validation, without which statements about more or less desertification are misleading. Furthermore, existing maps are mostly based on subjective assessments by experts, and therefore cannot be applied elsewhere or by different observers, nor can they be used in future for monitoring. Consequently, unsupported statements about the extent and severity of desertification abound. This chapter reviews the existing global maps and sets out principles for more rigorous mapping and proposes methods that adhere to these. Decades of work have improved our understanding of individual components of the desertification processes, but have not answered the three fundamental questions at the regional to global scales: What is degraded? Where does it occur? Howsevere is the degradation?

Keywords

Methods for mapping desertification Drylands Global GLASOD GLADA USDA NRCS 

References

  1. Abella, S. R., Chiquoine, L. P., Newton, A. C., & Vanier, C. H. (2015). Restoring a desert ecosystem using soil salvage, revegetation, and irrigation. Journal of Arid Environments, 115, 44–52.CrossRefGoogle Scholar
  2. Adeel, Z., Safriel, U., Niemeijer, D., & White, R. (Eds.). (2005). Millennium ecosystem assessment. Ecosystems and human well-being: Desertification synthesis. Washington, D.C.: World Resources Institute.Google Scholar
  3. Al-Bakri, J. T., Taylor, J. C., & Brewer, T. R. (2001). Monitoring land use change in the Badia transition zone in Jordan using aerial photography and satellite imagery. The Geographical Journal, 167, 248–262.CrossRefGoogle Scholar
  4. Asner, G. P., & Heidebrecht, K. B. (2002). Spectral unmixing of vegetation, soil and dry carbon cover in arid regions: Comparing multispectral and hyperspectral observations. International Journal of Remote Sensing, 23, 3939–3958.CrossRefGoogle Scholar
  5. Bai, Z. G., Conijn, J. G., Bindraban, P. S., & Rutgers, B. (2012). Global changes of remotely sensed greenness and simulated biomass production since 1981. Towards mapping global soil degradation Report 2012/02. Wageningen: ISRIC.Google Scholar
  6. Bai, Z. G., Dent, D. L., Olsson, L., & Schaepman, M. E. (2008). Proxy global assessment of land degradation. Soil Use and Management, 24, 223–234.CrossRefGoogle Scholar
  7. Bastin, G., Pickup, G., Chewings, V., & Pearce, G. (1993). Land degradation assessment in central Australia using a grazing gradient method. Rangeland Journal, 15, 190–216.CrossRefGoogle Scholar
  8. Batjes, N. H. (1996). Global assessment of land vulnerability to water erosion on a 1/2 by 1/2 grid. Land Degradation and Development, 7, 353–365.CrossRefGoogle Scholar
  9. Batjes, N., Dijkshoorn, K., van Engelen, V., Fischer, G., Jones, A., Montanarella, L., et al. (2012). Harmonized world soil database: Version 1.2. FAO, Rome, Italy and IIASA, Laxenburg, Austria: FAO/IIASA/ISRIC/ISSCAS/JRC.Google Scholar
  10. Beinroth, F. H., Eswaran, H., & Reich, P. F. (2001). Global assessment of land quality. In D. E. Stott, R. H. Mohtar & G. C. Steinhardt (Eds.), Sustaining the global farm: Selected papers from the 10th international soil conservation organization meeting (pp. 569–574). Purdue University and the USDA-ARS National Soil Erosion Research Laboratory.Google Scholar
  11. Berry, L., Abraham, E., & Essahli, W. (2009). UNCCD recommended minimum set of impact indicators. UNCCD.Google Scholar
  12. Boer, M. M., & Puigdefábregas, J. (2003). Predicting potential vegetation index values as a reference for the assessment and monitoring of dryland condition. International Journal of Remote Sensing, 24, 1135–1141.CrossRefGoogle Scholar
  13. Bossio, D., Geheb, K., & Critchley, W. (2010). Managing water by managing land: Addressing land degradation to improve water productivity and rural livelihoods. Agricultural Water Management, 97, 536–542.CrossRefGoogle Scholar
  14. Bowker, M. A., Belnap, J., & Miller, M. E. (2006). Spatial modeling of biological soil crusts to support rangeland assessment and monitoring. Rangeland Ecology and Management, 59, 519–529.CrossRefGoogle Scholar
  15. Bridges, E. M., & Oldeman, L. R. (1999). Global assessment of human-induced soil degradation. Arid Soil Research and Rehabilitation, 13, 319–325.CrossRefGoogle Scholar
  16. Brown, M. E. (2008). Famine early warning systems and remote sensing data. Berlin: Springer.Google Scholar
  17. Brown, M. E., Grace, K., Shively, G., Johnson, K. B., & Carroll, M. (2014). Using satellite remote sensing and household survey data to assess human health and nutrition response to environmental change. Population and Environment, 36, 48–72.CrossRefGoogle Scholar
  18. Cai, X., Zhang, X., & Wang, D. (2010). Land availability for biofuel production. Environmental Science and Technology, 45, 334–339.CrossRefGoogle Scholar
  19. Castro, J. M., Salomone, J. M., & Reichart, R. N. (1980). Estudio de los focos de erosión en el SO de la Provincia de Chubut. In Informe Técnico (p. 68). Trelew, Argentina: Instituto Nacional de Tecnología Agropecuaria.Google Scholar
  20. Cerdan, O., Govers, G., Le Bissonnais, Y., Van Oost, K., Poesen, J., Saby, N., et al. (2010). Rates and spatial variations of soil erosion in Europe: A study based on erosion plot data. Geomorphology, 122, 167–177.CrossRefGoogle Scholar
  21. CIESIN. (2005). Gridded Population of the World (GPW), v3. Socioeconomic Data and Applications Center (SEDAC), http://sedac.ciesin.columbia.edu/. Accessed February 7, 2015.
  22. Cohen, J. (1960). A coefficient of agreement for nominal scales. Educational and Psychological Measurement, 20, 37–46.CrossRefGoogle Scholar
  23. Conant, R. T., & Paustian, K. (2002). Potential soil carbon sequestration in overgrazed grassland ecosystems. Global Biogeochemical Cycles, 16, 1143.CrossRefGoogle Scholar
  24. Cook, B., & Pau, S. (2013). A global assessment of long-term greening and browning trends in pasture lands using the GIMMS LAI3 g dataset. Remote Sensing, 5, 2492–2512.CrossRefGoogle Scholar
  25. Coppin, P., Jonckheere, I., Nackaerts, K., Muys, B., & Lambin, E. (2004). Digital change detection methods in ecosystem monitoring: A review. International Journal of Remote Sensing, 25, 1565–1596.CrossRefGoogle Scholar
  26. CSE. (2015). Centre de Suivi Ecologique (Ecological Monitoring Center), http://www.cse.sn. Accessed February 6, 2015.
  27. Dawelbait, M., & Morari, F. (2012). Monitoring desertification in a Savannah region in Sudan using landsat images and spectral mixture analysis. Journal of Arid Environments, 80, 45–55.CrossRefGoogle Scholar
  28. Deichmann, U. (1994). A medium resolution population database for Africa: Technical paper and digital database. Santa Barbara: National Center for Geographic Information and Analysis.Google Scholar
  29. del Valle, H. F., Blanco, P. D., Metternicht, G. I., & Zinck, J. A. (2010). Radar remote sensing of wind-driven land degradation processes in Northeastern Patagonia. Journal of Environmental Quality, 39, 62–75.CrossRefGoogle Scholar
  30. den Biggelaar, C., Lal, R., Wiebe, K., Eswaran, H., Breneman, V., & Reich, P. (2004). The global impact of soil erosion on productivity II: Effects on crop yields and production over time. Advances in Agronomy, 81, 1–48.CrossRefGoogle Scholar
  31. DESIRE. (2008). Manual for describing land degradation indicators. Athens: Agricultural University of Athens.Google Scholar
  32. Dewitte, O., Jones, A., Elbelrhiti, H., Horion, S., & Montanarella, L. (2012). Satellite remote sensing for soil mapping in Africa: An overview. Progress in Physical Geography, 36, 514–538.CrossRefGoogle Scholar
  33. Dijkshoorn, J. A., van Engelen, W. W. P., & Huting, J. R. M. (2008). Global Assessment of Land Degradation Soil and landform properties for LADA partner countries (Argentina, China, Cuba, Senegal and The Gambia, South Africa and Tunisia). ISRIC report 2008/06 and GLADA report 2008/0. Wageningen: ISRIC—World Soil Information Center and FAO.Google Scholar
  34. Dregne, H. E. (1983). Desertification of arid lands. In F. El-Baz & M. H. A. Hassan (Eds.), Physics of desertification (p. 242). Chur, Switzerland; New York: Harwood Academic Publishers.Google Scholar
  35. Dregne, H. E., & Chou, N. T. (1992). Global desertification dimensions and costs. In H. E. Dregne (Ed.), Degradation and restoration of arid lands. Lubbock, Texas: International Center for Arid and Semiarid Land Studies, Texas Tech. University.Google Scholar
  36. Ellis, E. C., & Ramankutty, N. (2008). Putting people in the map: Anthropogenic biomes of the world. Frontiers in Ecology and the Environment, 6, 439–447.CrossRefGoogle Scholar
  37. Eswaran, H., Almaraz, R., van den Berg, E., & Reich, P. (1997). An assessment of soil resources of Africa in relation to productivity. Geoderma, 77, 1–18.CrossRefGoogle Scholar
  38. Eswaran, H., Lal, R., & Reich, P. F. (2001). Land degradation: an Overview. In E. M. Bridges, I. D. Hannam, L. R. Oldeman, F. W. T. Pening de Vries, S. J. Scherr, & S. Sompatpanit (Eds.), Responses to land degradation. Khon Kaen, Thailand: Oxford Press.Google Scholar
  39. FAO/UNESCO. (1991). The digitized soil map of the world. In World Soil Resources Report, Rome.Google Scholar
  40. FAOSTAT. (2015). Food and agriculture organization of the United Nations, statistics division. http://faostat.fao.org. Accessed February 7, 2015.
  41. Feddema, J. J. (1999). Future African water resources: Interactions between soil degradation and global warming. Climatic Change, 42, 561–596.CrossRefGoogle Scholar
  42. FEWS Net. (2015). Famine early warning network. http://www.fews.net. Accessed February 7, 2015.
  43. Furby, S., Caccetta, P., & Wallace, J. (2010). Salinity monitoring in Western Australia using remotely sensed and other spatial data. Journal of Environmental Quality, 39, 16–25.CrossRefGoogle Scholar
  44. Gao, J., & Liu, Y. (2010). Determination of land degradation causes in Tongyu County, Northeast China via land cover change detection. International Journal of Applied Earth Observation and Geoinformation, 12, 9–16.CrossRefGoogle Scholar
  45. GCMD. (2015). Global change master directory. http://gcmd.nasa.gov. Accessed February 6, 2015.
  46. Geist, H. (2005). The causes and progression of desertification. Abingdon Oxon, UK: Ashgate Publishing.Google Scholar
  47. Gibbs, H. K., & Salmon, J. M. (2015). Mapping the world’s degraded lands. Applied Geography, 57, 12–21.CrossRefGoogle Scholar
  48. GIEWS. (2015). Global information and early warning system. http://www.fao.org/giews/english/index.htm. Accessed February 15, 2015.
  49. GLADIS. (2015). Global land data information system. http://www.fao.org/nr/lada. Accessed February 8, 2015.
  50. Hagen-Zanker, A., Engelen, G., Hurkens, J., Vanhout, R., & Uljee, I. (2006). Map Comparison Kit (MCK). 3.0. Maastricht, The Netherlands: Research Institute for Knowledge Systems (RIKS bv).Google Scholar
  51. Harris, I., Jones, P. D., Osborn, T. J., & Lister, D. H. (2014). Updated high-resolution grids of monthly climatic observations—the CRU TS3.10 dataset. International Journal of Climatology, 34, 623–642. doi:10.1002/joc.3711.CrossRefGoogle Scholar
  52. Herrick, J. E., Lessard, V. C., Spaeth, K. E., Shaver, P. L., Dayton, R. S., Pyke, D. A., et al. (2010). National ecosystem assessments supported by scientific and local knowledge. Frontiers in Ecology and the Environment, 8, 403–408.CrossRefGoogle Scholar
  53. Hill, J. (2001). Remote sensing of surface properties. In S.-W. Breckle, M. Veste & W. Wucherer (Eds.), The key to land degradation and desertification assessments. Sustainable land use in deserts (pp. 243–254). Springer, Berlin.Google Scholar
  54. Holm, A. M., Cridland, S. W., & Roderick, M. L. (2003). The use of time-integrated NOAA NDVI data and rainfall to assess landscape degradation in the arid shrubland of Western Australia. Remote Sensing of Environment, 85, 145–158.CrossRefGoogle Scholar
  55. Ibáñez, J., Martínez Valderrama, J., & Puigdefabregas, J. (2008). Assessing desertification risk using system stability condition analysis. Ecological Modelling, 213, 180–190.CrossRefGoogle Scholar
  56. IPBES. (2015). Intergovernmental panel on biodiversity and ecosystem services. http://www.ipbes.net/. Accessed June 9, 2015.
  57. IPCC. (2015). Intergovernmental panel on climate change. http://ipcc.ch/. Accessed February 7, 2015.
  58. Izaurralde, R. C., Williams, J. R., Post, W. M., Thomson, A. M., McGill, W. B., Owens, L. B., & Lal, R. (2007). Long-term modeling of soil C erosion and sequestration at the small watershed scale. Climatic Change, 80, 73–90.CrossRefGoogle Scholar
  59. Kirkby, M. J., Irvine, B. J., Jones, R. J. A., & Govers, G. (2008). The PESERA coarse scale erosion model for Europe. I.—Model rationale and implementation. European Journal of Soil Science, 59, 1293–1306.CrossRefGoogle Scholar
  60. Kosmas, C., Karavitis, C., Kairis, O., Kounalaki, A., Fasouli, V., & Tsesmelis, D. (2012). Using indicators for identifying best land management practices for combating desertification. DESIRE Scientific reports. Deliverable 2.2.3. Agricultural University of Athens.Google Scholar
  61. Lambin, E. F., & Ehrlich, D. (1997). Land-cover changes in sub-saharan Africa (1982–1991): Application of a change index based on remotely sensed surface temperature and vegetation indices at a continental scale. Remote Sensing of Environment, 61, 181–200.CrossRefGoogle Scholar
  62. Liniger, H., Schwilch, G., Gurtner, M., Studer, R.M., Hauert, C., van Lynden, G., et al. (2008). WOCAT degradation categorization system. WOCAT—World Overview of Conservation Approaches and Technologies.Google Scholar
  63. Lobell, D. B. (2010). Remote sensing of soil degradation: Introduction. Journal of Environmental Quality, 39, 1–4.CrossRefGoogle Scholar
  64. Martín-Fernández, L., & Martínez-Núñez, M. (2011). An empirical approach to estimate soil erosion risk in Spain. Science of the Total Environment, 409, 3114–3123.CrossRefGoogle Scholar
  65. Mbow, C., Fensholt, R., Rasmussen, K., & Diop, D. (2013). Can vegetation productivity be derived from greenness in a semi-arid environment? Evidence from ground-based measurements. Journal of Arid Environments, 97, 56–65.CrossRefGoogle Scholar
  66. Millennium Ecosystem Assessment. (2005). Millennium ecosystem assessment synthesis report. Ecosystems and human well-being: A framework for assessment. Concepts of ecosystem value and validation approaches. Washington, DC: Island Press and World Resources Institute.Google Scholar
  67. Milton, S. J., Dean, W. R. J., du Plessis, M., & Siegfried, W. R. (1994). A conceptual model of arid rangeland degradation. Bioscience, 44, 70–76.CrossRefGoogle Scholar
  68. Mortimore, M. J., & Adams, W. M. (2001). Farmer adaptation, change and ‘crisis’ in the Sahel. Global Environmental Change-Human and Policy Dimensions, 11, 49–57.CrossRefGoogle Scholar
  69. Mulligan, M. (2015). Computational policy support systems for understanding land degradation effects on water and food security for and from Africa. Land restoration: Reclaiming landscapes for a sustainable future, Elsevier (p. 400). ILLP Publication.Google Scholar
  70. Mulligan, M., Burke, S., & Ogilvie, A. (2015). Much more than simply “desertification”: understanding agricultural sustainability and change in the Mediterranean. In R. Benkhe (Ed.), (pp. x–xx). doi:10.1007/978-3-642-16014-1_8. Berlin: Springer.
  71. Nachtergaele, F. O. F., & Licona-Manzur, C. (2008). The land degradation assessment in drylands (LADA) project: Reflections on indicators for land degradation assessment. In C. C. Lee & T. Schaaf (Eds.), The future of drylands (pp. 327–348). Rome, Italy: UNESCO, Food and Agriculture Organization of the United Nations (FAO).Google Scholar
  72. Nachtergaele, F. O., Petri, M., Biancalani, R., van Lynden, G., van Velthuizen, H., & Bloise, M. (2011). An Information database for land degradation assessment at global level. In Global land degradation information system (GLADIS).Google Scholar
  73. Oldeman, L. R., Hakkeling, R. T. A., & Sombroek, W. G. (1991). World map of the status of human-induced soil degradation: An explanatory note. Global Assessment of Soil Degradation (GLASOD) (2nd ed.). Wageningen Winand Staring Center, International Society for Soil Science, FAO, International Institute for Aerospace Survey and Earth Science.Google Scholar
  74. Oldeman, L. R., & van Lynden, G. W. J. (1996). Revisiting the GLASOD methodology. ISRIC report 1996/03. Wageningen: ISRIC World Soil Information.Google Scholar
  75. Olson, D. M., Dinerstein, E., Wikramanayake, E. D., Burgess, N. D., Powell, G. V. N., Underwood, E. C., et al. (2001). Terrestrial ecoregions of the world: A new map of life on earth. Bioscience, 51, 933.CrossRefGoogle Scholar
  76. Olsson, L., Eklundh, L., & Ardö, J. (2005). A recent greening of the Sahel—trends, patterns and potential causes. Journal of Arid Environments, 63, 556–566.CrossRefGoogle Scholar
  77. ORNL DAAC. (2015). Oak Ridge National Laboratory Distributed Active Archive Center, http://daac.ornl.gov/index.shtml. Accessed February 15, 2015.
  78. Petschel-Held, G., Block, A., Cassel-Gintz, M., Kropp, J., Lüdeke, M. K. B., Moldenhauer, O., et al. (1999). Syndromes of global change: A qualitative modelling approach to assist global environmental management. Environmental Modeling and Assessment, 4, 295–314.CrossRefGoogle Scholar
  79. Pickup, G., & Chewings, V. (1994). A grazing gradient approach to land degradation assessment in arid areas from remotely-sensed data. International Journal of Remote Sensing, 15, 597–617.CrossRefGoogle Scholar
  80. Prince, S. D. (1991). Satellite remote sensing of primary production: Comparison of results for Sahelian grasslands 1981–1988. International Journal of Remote Sensing, 12, 1301–1311.CrossRefGoogle Scholar
  81. Prince, S. D. (2002). Spatial and temporal scales of measurement of desertification. In M. Stafford-Smith & J. F. Reynolds (Eds.), Global desertification: Do humans create deserts? (pp. 23–40). Berlin: Dahlem University Press.Google Scholar
  82. Prince, S. D., Becker-Reshef, I., & Rishmawi, K. (2009). Detection and mapping of long-term land degradation using local net production scaling: Application to Zimbabwe. Remote Sensing of Environment, 113, 1046–1057.CrossRefGoogle Scholar
  83. Prince, S. D., De Colstoun, E. B., & Kravitz, L. L. (1998). Evidence from rain-use efficiencies does not indicate extensive Sahelian desertification. Global Change Biology, 4, 359–374.CrossRefGoogle Scholar
  84. Reeves, M. C., & Baggett, L. S. (2014). A remote sensing protocol for identifying rangelands with degraded productive capacity. Ecological Indicators, 43, 172–182.CrossRefGoogle Scholar
  85. Reich, P. F., Numbem, S. T., Almaraz, R. A., & Eswaran, H. (2001). Land resource stresses and desertification in Africa. Responses to Land Degradation. Proceedings of the 2nd International Conference on Land Degradation and Desertification, Khon Kaen, Thailand. New Delhi, India: Oxford Press.Google Scholar
  86. Reynolds, J. F., Grainger, A., Stafford Smith, D. M., Bastin, G., Garcia-Barrios, L., Fernández, R. J., et al. (2011). Scientific concepts for an integrated analysis of desertification. Land Degradation and Development, 22, 166–183.CrossRefGoogle Scholar
  87. Reynolds, J. F., & Stafford Smith, M. (Eds.). (2002). Global desertification: Do humans create deserts? Berlin: Dahlem University Press.Google Scholar
  88. Reynolds, J. F., Stafford-Smith, D. M., Lambin, E. F., Turner, B. L, I. I., Mortimore, M., Batterbury, S. P. J., et al. (2007). Global desertification: Building a science for dryland development. Science, 316, 847–851.CrossRefGoogle Scholar
  89. Rishmawi, K. (2013). Spatial patterns and potential mechanisms of land degradation in the Sahel. Unpublished PhD, University of Maryland.Google Scholar
  90. Robinson, T. P., Francescini, G., & Wint, W. (2007). The Food and Agriculture Organization’s gridded livestock of the world. Veterinaria Italiana, 43, 745–751.Google Scholar
  91. Romm, J. (2011). The next dustbowl. Nature, 478, 450–451.CrossRefGoogle Scholar
  92. Safriel, U. (2007). The assessment of global trends in land degradation. In M. V. K. Sivakumar & N. Ndiang’ui (Eds.), Climate and land degradation (pp. 1–38). New York: Springer.CrossRefGoogle Scholar
  93. Safriel, U. (2009). Deserts and desertification: Challenges but also opportunities. Land Degradation and Development, 20, 353–366.CrossRefGoogle Scholar
  94. Scherr, S. J., & Yadav, S. (1996). Land degradation in the developing world: Implications for food, agriculture, and the environment to 2020. In Food, agriculture, and the environment. International Food Policy Research Institute.Google Scholar
  95. Seaquist, J. W., Hickler, T., Eklundh, L., Ardo, J., & Heumann, B. W. (2009). Disentangling the effects of climate and people on Sahel vegetation dynamics. Biogeosciences, 6(3), 469–477.CrossRefGoogle Scholar
  96. SEDAC. (2015). Socioeconomic Data and Applications Center, http://sedac.ciesin.columbia.edu/about. Accessed February 15, 2015.
  97. Sietz, D., Untied, B., Walkenhorst, O., Ludeke, M. K. B., Mertins, G., Petschel-Held, G., & Schellnhuber, H. J. (2006). Smallholder agriculture in Northeast Brazil: Assessing heterogeneous human-environmental dynamics. Regional Environmental Change, 6, 132–146.CrossRefGoogle Scholar
  98. Singh, G., Bundela, D. S., Sethi, M., Lal, K., & Kamra, S. K. (2010). Remote sensing and geographic information system for appraisal of salt-affected soils in India. Journal of Environmental Quality, 39, 5–15.CrossRefGoogle Scholar
  99. Sonneveld, B. G., & Dent, D. L. (2009). How good is GLASOD? Journal of Environmental Management, 90, 274–283.CrossRefGoogle Scholar
  100. Symeonakis, E., & Drake, N. (2004). Monitoring desertification and land degradation over sub-Saharan Africa. International Journal of Remote Sensing, 25, 573–592.CrossRefGoogle Scholar
  101. Tamene, L., & Le, Q. B. (2015). Estimating soil erosion in sub-Saharan Africa based on landscape similarity mapping and using the revised universal soil loss equation (RUSLE). Nutrient Cycling in Agroecosystems, 101, 1–15. doi:10.1007/s10705-10015-19674-10709.CrossRefGoogle Scholar
  102. Thomas, D. S. G., & Middleton, N. J. (1993). Salinization: new perspectives on a major desertification issue. Journal of Arid Environments, 24, 95–105.CrossRefGoogle Scholar
  103. Trabucco, A., & Zomer, R. J. (2009). Global Aridity Index (Global-Aridity) and Global Potential Evapo-Transpiration (Global-PET) Geospatial Database. Published online, available from the CGIAR-CSI GeoPortal at: http://www.csi.cgiar.org
  104. Tucker, C. J., Dregne, H. E., & Newcomb, W. W. (1991). Expansion and contraction of the Sahara desert from 1980 to 1990. Science, 253, 299–301.CrossRefGoogle Scholar
  105. Tucker, C. J., Justice, C. O., & Prince, S. D. (1986). Monitoring the grasslands of the Sahel 1984–1985. International Journal of Remote Sensing, 7, 1571–1581.CrossRefGoogle Scholar
  106. Tucker, C. J., Pinzon, J. E., Brown, M. E., Slayback, D. A., Pak, E. W., Mahoney, R., et al. (2005). An extended AVHRR 8-km NDVI dataset compatible with MODIS and SPOT vegetation NDVI data. International Journal of Remote Sensing, 26, 4485–4498.CrossRefGoogle Scholar
  107. UNCCD. (1994). Elaboration of an international convention to combat desertification in countries experiencing serious drought and/or desertification, particularly in Africa (p. 58). United Nations General Assembly, 93rd plenary meeting, New York.Google Scholar
  108. UNCED. (1992). Managing fragile ecosystems: combating desertification and drought. In Agenda 21: Earth summit. Rio de Janerio: United Nations Conference on Environment and Development.Google Scholar
  109. UNEP. (1997). World Atlas of Desertification. (2nd ed.). London, New York: Arnold & Wiley, on behalf of UNEP.Google Scholar
  110. UNEP. (2015). United Nations Environment Programme, http://www.unep.org/. Accessed February 7, 2015.
  111. United Nations General Assembly. (2013). Future we want—Outcome document. In Resolution adopted by the General Assembly. United Nations Department of Economic and Social Affairs (DESA).Google Scholar
  112. USGS. (2015). The Land Processes Distributed Active Archive Center (LP DAAC), https://lpdaac.usgs.gov/. Accessed February 7, 2015.
  113. Ustin, S. L., Palacios-Orueta, A., Whiting, M. L., Jacquemoud, S., & Li, L. (2009). Remote sensing based assessment of biophysical indicators for land degradation and deserlification. In R. Hill (Ed.), Recent advances in remote sensing and geoinformation processing for land degradation assessment (pp. 15–44). London: Taylor & Francis Group.Google Scholar
  114. Verón, S. R., Paruelo, J. M., & Oesterheld, M. (2006). Assessing desertification. Journal of Arid Environments, 66, 751–763.CrossRefGoogle Scholar
  115. Vogt, J. V., Safriel, U., Von Maltitz, G., Sokona, Y., Zougmore, R., Bastin, G., & Hill, J. (2011). Monitoring and assessment of land degradation and desertification: Towards new conceptual and integrated approaches. Land Degradation and Development, 22, 150–165.CrossRefGoogle Scholar
  116. Warren, A. (2002). Land degradation is contextual. Land Degradation and Development, 13, 449–459.CrossRefGoogle Scholar
  117. Wessels, K. J. (2009). Comments on ‘Proxy global assessment of land degradation’ by Bai et al. (2008). Soil Use and Management, 25, 91–92.Google Scholar
  118. Wessels, K. J., Prince, S. D., Carroll, M., & Malherbe, J. (2007a). Relevance of rangeland degradation in semiarid northeastern South Africa to the nonequilibrium theory. Ecological Applications, 17, 815–827.CrossRefGoogle Scholar
  119. Wessels, K. J., Prince, S. D., Malherbe, J., Small, J., Frost, P. E., & VanZyl, D. (2007b). Can human-induced land degradation be distinguished from the effects of rainfall variability? A case study in South Africa. Journal of Arid Environments, 68, 271–297.CrossRefGoogle Scholar
  120. Wessels, K. J., Prince, S. D., & Reshef, I. (2008). Mapping land degradation by comparison of vegetation production to spatially derived estimates of potential production. Journal of Arid Environments, 72, 1940–1949.CrossRefGoogle Scholar
  121. Wessels, K. J., van den Bergh, F., & Scholes, R. J. (2012). Limits to detectability of land degradation by trend analysis of vegetation index data. Remote Sensing of Environment, 125, 10–22.CrossRefGoogle Scholar
  122. Whitlow, R. (1988). Land degradation in Zimbabwe. Harare: Department of Natural Resources, Government of Zimbabwe/Department of Geography, University of Zimbabwe.Google Scholar
  123. Wildlife Conservation Society (WCS) and Center for International Earth Science Information Network (CIESIN). (2005). Last of the Wild Project, (LWP-2): Global Human Influence Index (HII) Dataset. Palisades, NY: NASA Socioeconomic Data and Applications Center (SEDAC), Columbia University.Google Scholar
  124. Zika, M., & Erb, K. H. (2009). The global loss of net primary production resulting from human-induced soil degradation in drylands. Ecological Economics, 69(2), 310–318.CrossRefGoogle Scholar
  125. Zucca, C., & Biancalani, R. (2011). Guidelines for the use of the LADA QM DB in the frame of the “National Piloting of provisional UNCCD impact indicators” (p. 24), LADA FAO.Google Scholar
  126. Zucca, C., Della Peruta, R., Salvia, R., Sommer, S., & Cherlet, M. (2012). Towards a world desertification atlas. Relating and selecting indicators and data sets to represent complex issues. Ecological Indicators, 2012, 157–170.CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  1. 1.University of MarylandCollege ParkUSA

Personalised recommendations