Monitoring the magnitude of land-cover change around the southern limits of the Sahara

Studies of land-cover change using satellite remote sensing are often constrained to depict land-cover conversions only, with the equally important modifications undetected or misrepresented, resulting in significant error. Desert fluctuations within the Sahel were examined using an approach that indicated the magnitude of land-cover changes. This showed that the conventional post-classification comparison method of change detection appeared to underestimate the area of land-cover change and, where a change was detected, typically overestimate its magnitude. At the regional scale, the land-cover changes detected were strongly related to rainfall variability. This relationship did not, however, explain changes at a finer spatial scale and indicated that dryland degradation, and its causes, may remain far from understood.

[1]  J. Townshend,et al.  African Land-Cover Classification Using Satellite Data , 1985, Science.

[2]  Ashbindu Singh,et al.  Review Article Digital change detection techniques using remotely-sensed data , 1989 .

[3]  Ulf Helldén,et al.  Desertification - time for an assessment? , 1991 .

[4]  C. Tucker,et al.  Expansion and Contraction of the Sahara Desert from 1980 to 1990 , 1991, Science.

[5]  S. Nicholson,et al.  A re‐evaluation of rainfall variability in the sahel. Part I. Characteristics of rainfall fluctuations , 1993 .

[6]  D. Skole.  Data on global land-cover change: acquisition, assessment, and analysis , 1994 .

[7]  P. Vitousek.  Beyond Global Warming: Ecology and Global Change , 1994 .

[8]  Samuel N. Goward,et al.  Transient Effects of Climate on Vegetation Dynamics: Satellite Observations , 1995 .

[9]  G. Daily,et al.  Restoring Value to the World's Degraded Lands , 1995, Science.

[10]  C. Hutchinson.  The Sahelian desertification debate: a view from the American south-west , 1996 .

[11]  C. Woodcock,et al.  An assessment of several linear change detection techniques for mapping forest mortality using multitemporal landsat TM data , 1996 .

[12]  S. Gopal,et al.  Remote sensing of forest change using artificial neural networks , 1996, IEEE Trans. Geosci. Remote. Sens..

[13]  C. Agnew,et al.  A framework for tackling drought and land degradation , 1996 .

[14]  Ruth S. DeFries,et al.  The NOAA/NASA pathfinder AVHRR 8-Km land data set , 1997 .

[15]  Eric F. Lambin,et al.  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 , 1997 .

[16]  David S. G. Thomas,et al.  Science and the desertification debate , 1997 .

[17]  Eric F. Lambin,et al.  Modelling and monitoring land-cover change processes in tropical regions , 1997 .

[18]  C. Tucker,et al.  Desertification, Drought, and Surface Vegetation: An Example from the West African Sahel , 1998 .

[19]  Rasim Latifovic,et al.  Can interannual land surface signal be discerned in composite AVHRR data , 1998 .

[20]  Stephen D. Prince,et al.  Evidence from rain‐use efficiencies does not indicate extensive Sahelian desertification , 1998 .

[21]  J. Townshend,et al.  Global land cover classifications at 8 km spatial resolution: The use of training data derived from Landsat imagery in decision tree classifiers , 1998 .

[22]  M. Ridd,et al.  A Comparison of Four Algorithms for Change Detection in an Urban Environment , 1998 .

[23]  T. Häme,et al.  An unsupervised change detection and recognition system for forestry , 1998 .

[24]  D. Fuller,et al.  Trends in NDVI time series and their relation to rangeland and crop production in Senegal, 1987-1993 , 1998 .

[25]  C. Elvidge,et al.  NALC Land Cover Change Detection Pilot Study , 1998 .

[26]  Giles M. Foody,et al.  Detection of partial land cover change associated with the migration of inter-class transitional zones , 1999 .

[27]  P. Jones,et al.  Representing Twentieth-Century Space–Time Climate Variability. Part I: Development of a 1961–90 Mean Monthly Terrestrial Climatology , 1999 .

[28]  G. M. Foody.  The Continuum of Classification Fuzziness in Thematic Mapping , 1999 .

[29]  C. Potter,et al.  Large-scale impoverishment of Amazonian forests by logging and fire , 1999, Nature.

[30]  S. Khorram,et al.  Remotely Sensed Change Detection Based on Artificial Neural Networks , 1999 .

[31]  David A. Landgrebe,et al.  Partially supervised classification using weighted unsupervised clustering , 1999, IEEE Trans. Geosci. Remote. Sens..

[32]  Klaus Steinnocher,et al.  Detecting land cover changes from NOAA-AVHRR data by using spectral mixture analysis , 1999 .

[33]  J. Mas.  Monitoring land-cover changes: A comparison of change detection techniques , 1999 .

[34]  D. Nepstad,et al.  Positive feedbacks in the fire dynamic of closed canopy tropical forests , 1999, Science.