The Kilum-Ijim Forest is located at the center of the Bamenda Highlands in northwestern Cameroon in western Africa. This region includes the mountains and highland areas of the border region between Nigeria and Cameroon. Mount Oku, the second highest mountain in central and west Africa standing 9,880 feet (3,011 meters) above sea level, is home to the largest remaining patch of montane forest in west Africa and one of the biologically richest areas in Africa.

According to BirdLife International, a global alliance of conservation organizations based in Cambridge, United Kingdom, the montane forest in the Bamenda Highlands was at risk of disappearance due to years of clearance for farming and grazing. In addition to its biodiversity, the forest is important to the local people of the region as a source of water, firewood, medicine, food, and cultural traditions. For these reasons, BirdLife International created the Kilum-Ijim Forest Project in 1987. Working with local communities, traditional authorities, and governments, the intent of BirdLife International was to reduce forest loss and improve agricultural practices in the area.

In 2002, Susana Baena, a student sponsored by the Royal Botanic Gardens, Kew, United Kingdom, was working on her master of science dissertation for a geographical information science degree at University College London (UCL). Baena began studying the magnitude, rates of change, and temporal/spatial distribution of forest cover in the area of Mount Oku and the adjoining Ijim Ridge. Her study was further developed by the Royal Botanic Gardens, Kew, GIS Unit.

The Royal Botanic Gardens, Kew, study examines changes in the vegetation cover and assesses the performance of BirdLife International's Kilum-Ijim Forest conservation project by comparing the forest extents before and after it was initiated through an analysis of satellite images and aerial photography between 1958 and 2001. The Royal Botanic Gardens, Kew, used ERDAS IMAGINE from Esri Business Partner Leica Geosystems and Esri's ArcGIS software on PCs running Microsoft Windows 2000 to carry out the study.

The vegetation cover change study was performed by analyzing remotely sensed data, including 16 aerial photos taken in 1958 and a set of satellite images (Landsat multispectral scanner [MSS], Thematic Mapper [TM], Enhanced Thematic Mapper [ETM], and SPOT multispectral) taken in 1984, 1988, 1995, and 2001, to create a time series of images that represents changes in the forest.

Image processing techniques were employed to extract relevant vegetation cover data from the satellite imagery and aerial photography. Satellite image processing, which included image display, rectification, classification, and Normalized Difference Variation Index (NDVI) analysis, was carried out using ERDAS IMAGINE. For example, the satellite images were classified into different vegetation types to extract the forest boundaries at the different dates.

The digital elevation model (DEM) was generated using SOCET SET, a digital photogrammetric software distributed by Leica Geosystems. DEM was used in ERDAS IMAGINE to orthorectify the aerial photography. Heads-up digitizing delineating the 1958 forest boundaries was performed using ArcView. The resulting thematic layers were imported into ArcGIS for further analysis.

The ArcScene viewing functions within ArcGIS 3D Analyst software were used for 3D data display. Additional processes such as image reclassification, vector to raster conversion, and data merging were performed using ArcGIS. For example, ArcGIS Spatial Analyst was used to reclassify raster layers. Successive combinations of dates were then used to obtain information on change trajectories, analyze the spatial pattern of changes, and estimate the amount of deforestation or regeneration in the period considered. The final map compositions and visual displays of all data, including original images, processing steps, and final outputs, were carried out using ArcGIS. The final geographic output was a series of maps showing patterns of deforestation or regeneration in the different periods studied.

"We found ERDAS IMAGINE to be very easy to use with Esri's software products," says Justin Moat, head of the Royal Botanical Gardens, Kew, GIS Unit. "Data format conversion was not needed to use the ERDAS IMAGINE-generated images within ArcGIS. ArcGIS includes the tools we needed for spatial and 3D analysis, visual display, and map composition, all together in one software package."

The results of the study showed strong spatial patterns of deforestation between 1958 and 1988. In fact, more than 50 percent of the montane forest was lost in this period. A regeneration progression began in 1988 after the Kilum-Ijim Forest Project was created and just after the most dramatic deforestation process in the area was taking place. In the period from 1988-2001, 10.6 percent of the 1988 montane forest inventory had been recovered.

The northeastern boundary has remained at the 1988 extent. The eastern boundary increased by approximately 2,600 feet (800 meters) until 1995, where it has since remained stable. The forest reserve limits have also been held at the 1995 level at the western boundary.

After 1995, the study showed the rate of regeneration (3.9 percent) significantly exceeded deforestation. "Since the Kilum-Ijim Forest Project began, the forest boundaries have remained and regeneration continues to appear inside the forest limits, suggesting that the vegetation is firmly established and will continue to grow," states Baena. "These results clearly prove the good performance of the Kilum-Ijim Forest Project in this area. The rate at which deforestation was occurring before the Kilum-Ijim Forest Project began was 890.4 hectares per year. Without the project, it is predicted that the forest would have been completely lost by 2001."

For more information on this study, contact Justin Moat, head of the GIS Unit, Royal Botanic Gardens, Kew (e-mail: J.Moat@rbgkew.org.uk), or Susana Baena, spatial information scientist, GIS Unit, Royal Botanic Gardens, Kew (e-mail: S.Baena@rbgkew.org.uk), or visit www.rbgkew.org.uk/gis.

For more information on the Kilum-Ijim Forest Project, visit BirdLife International at www.birdlife.org, Earthwatch at www.earthwatch.org/europe/limbe/communmgmt.html, and the World Wildlife Fund at www.worldwildlife.org/wildworld/profiles/terrestrial/at/at0103_full.html.

For more information on spatial solutions, contact Leica Geosystems GIS & Mapping (toll free in the United States at 1-877-463-7327 or outside the United States at 1-404-248-9000), or visit gis.leica-geosystems.com.