Activities and Disciplines

 Projects: Mount Oku and Ijim Ridge (Cameroon)

Introduction Project description Study Area Data and Methods Imagery used Digital Elevation Model (DEM) Methodology detailed Results Kilum-Ijim Forest Project Animation 3d Model Acknowledgements Contacts Links

 Introduction

This project was initially a collaboration between the Royal Botanic Gardens, Kew, and the Department of Geomatic Engineering, at University College London. Susana Baena, working towards her MSc dissertation for a degree in Geographical Information Science, 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. The GIS Unit at RBG Kew with Birdlife International have further developed this study.

Mount Oku and the Ijim Ridge is the largest remaining patch of montane forest in West Africa. It has exceptional levels of endemism amongst flora (for example, Kniphofia reflexa shown in the photograph) and fauna – especially amongst birds. For this reason, since 1987 an important conservation project managed by Birdlife International has been working in the area, aiming to reduce forest loss and to improve agricultural practices. The conservation project is currently known as the "Kilum-Ijim Forest Project". The aim of this study is to assess the reserve performance by monitoring the vegetation cover, comparing the forest extent before and after the conservation project started.

Project description

The Kilum-Ijim forest lies at the centre of the Bamenda Highlands in north-western Cameroon (Location of the study area). This region includes the mountains and highland areas of the border region between Nigeria and Cameroon; Mount Oku is the highest point within this region at 3,011m above the sea level.

The majority of the area enclosed by the Kilum-Ijim boundary is at an altitude of over 2000 metres. The vegetation is highly influenced by this altitude: above 2000m, where the study area is mainly located, it consists of montane forest mixed with montane grassland and subalpine communities. Below this, most of the submontane forest has already disappeared due to clearance for agriculture.

Data and Methods

The project, studying the changes in vegetation cover over time, was carried out using remote sensing imagery (satellite images and aerial photographs). The methodology involved different processing techniques for both satellite images and aerial photography in order to create a time-series of images (1958-2001). Each of the satellite images in the data set was classified to delimit the forest boundaries. In the case of aerial photographs, before any analysis could be performed they had to be orthorectified using a DEM derived from a Radarsat stereo pair. The forest boundaries for these photographs were then defined by on-screen digitising and converted to raster format. All the images showing the forest extension for the different dates studied were combined in a GIS environment to perform subsequent analysis.

False Colour Landsat ETM+ composite of the region (Vegetation is Bright red)

Results

The results show strong spatial patterns of deforestation between 1958 and 1988 (more than 50 % of the montane forest was lost in this period) followed by a regeneration period starting in 1988, just after the Conservation Project was created. In this last 1988-2001 period, 7.8 % of the 1988 extent of montane forest has been recovered, mainly on the eastern side of the mountain. The forest vegetation boundary in the north-east has been held at the 1988 level, while in the east it has recovered and extended by 800 metres (until 1995). From 1995 the forest boundary has remained static and marks the limits of the reserve. In the western boundary, the reserve limits have also been held at the 1995 level; regeneration is still taking place inside these limits. Also see the animation.

Click for larger image

• Kilum-Ijim Forest Project

Reserve boundary

The "Kilum-Ijim Forest Project" started in 1987, when the most dramatic deforestation in the area occurred. Its establishment has been followed by a regeneration period. After 1995 the rate of regeneration (3.9%) significantly exceeded the deforestation, and the forest area has increased by 10.6%. These results, showing the excellent reserve performance, are of major importance to the Kilum-Ijim communities, since the reserve is under their direct management.

Acknowledgements

We are especially indebted to Helen Papadaki (UCL) for her help in the processing of aerial photography and digital elevation models, and to Jeremy Morley (UCL) for his suggestions during the course of this study. Thanks are also due to Dr. Martin Cheek (RBG Kew) for contributing field knowledge and valuable information on the vegetation of the area. Help from Russell Fox (Ordnance Survey) and Ben Pollard (RBG Kew) is also gratefully acknowledged. We are grateful to Rob Freeman (QINETIQ) and EROS Data Center (USGS) who supplied the satellite data, also to Norman Lamont of the MOD for supplying the aerial photographs.

Contacts

Please contact the GIS unit gisunit@rbgkew.org.uk

Links

• Birdlife international

• Wet Tropics Africa

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