Mitarbeiter/-innen

PD Dr. Angela Hof

Land Use Change and Land Cover Assessment in the Zamfara and Runka Common Grazing Reserves in Northwest Nigeria by Angela Hof

 

Bibliographical record of the published doctoral thesis and order information:

Angela Hof (2006): Land Use Change and Land Cover Assessment in Grazing Reserves in Northwest Nigeria. Bochumer Geographische Arbeiten 74. 114 p., 37 figures (4 in colour), 32 tables. ISBN 3- 925143-75-0. Bochumer Geographische Arbeiten 74.

 


Abstract
The doctoral thesis develops a framework of integrated data analysis for the efficient use of geographic information, Geographic Information Science and Systems (GIS), and remote sensing in a Sudano-Sahelian context. This approach considers the spatial and temporal aspect of land-use and land-cover change to broaden the analytical boundaries of research on natural resources and shifts in natural resource management strategies. Because this approach uses standard remote sensor data and public access geodatasets, the method of analysis is applicable beyond the northern Nigerian case study it employs.

With regard to the identification of critical land-use/land-cover change regions, the thesis demonstrates land use and land cover assessment and change detection in the largest grazing reserves in northwest Nigeria –the Zamfara and Runka reserves. The case study illustrates the changes in savannah woodland areas, the pressures on communal grazing areas, the data requirements, data availability and the workflow of synoptic analyses in the Sudano-Sahelian zone in a nutshell.


Material and methods
Cropland expansion is documented with multisensor data for the period 1965 to 2002. Natural vegetation lands in 1999 are mapped from a land cover classification of Landsat ETM+ data. This land cover information is complemented by ground-based quantitative information on vegetation structure and plant productivity of grasslands collected in several studies from 1997 to 2001. Additional ground truth data on land cover, physiognomic vegetation units, human and livestock population and land use in the farming enclaves were collected throughout the study area from January to May 2003. Ground truth data, thematic geodatasets and land cover information are integrated in GIS for change detection and land cover analysis in the study area.


Main results
As a result of cropland expansion in the four designated farming enclaves and cropland encroachment at the fringes of the reserves, the area of land under cultivation increased from 0.7% of the total study area to 7.5% between 1965 and 2002. The rate and extent of agricultural expansion accelerated after 1988 due to land allocations, in-migration and the lack of enforcement of legal restrictions on farmland expansion in the reserves. The resulting land cover map shows that about 85.2% of the rangeland in the study area are slightly degraded and only as productive as fallows and common access rangeland in a drier northeastern Nigerian location (compare Mortimore et al., 1999). Land use profiles for the farming enclaves indicate land use intensification in the northern enclaves that contrasts with agricultural expansion at the existing technological level in the south of the study area.