Introduction
Location Map
Base Map
Database Schema
Conventions
GIS Analyses
Flowchart
GIS Concepts
Results
Conclusion
References

Introduction

Changes in Ethiopian Vegetation

The country of Ethiopia faces substantial environmental problems in part because of the demands of a growing population and the cost of development.

In the seventeen year period between 1990 and 2007 Ethiopia experienced a loss of 15% of its national forest cover (UN 2008).  The loss can mainly be attributed to human use of forest timber for fuel and the clearing of land for agricultural purposes.   As the population of Ethiopia continues to grow the remaining forests will be at risk to further losses.  The role forests play in short and long term environmental cycles is crucial for the country of Ethiopia as well as nations on its borders that depend on the waters originating in the Ethiopian highlands (ETFF 2009).    

In the case of the Ethiopian highlands, deforestation is a direct cause of desertification (Reusing et al. 2000).  Arable land is lost during the conversion from forest cover to agriculture.  It is estimated that two billion tons of fertile soil is lost in Ethiopia every year because of land degradation (IFAD 2009). 

Efforts to protect wildlife in Ethiopia are primarily limited to Ethiopia’s national parks. In 2004 the International Union for Conservation of Nature estimated that conservation areas in Ethiopia amounted to 11.86% of total land (IUCN 2004).

Bale Mountains National Park is a protected area which is home to wildlife species endemic to Ethiopia.  The park and protected forests are crucial for the continued survival of species like the Ethiopian wolf (Canis simensis) which are restricted to a severely limited habitat (Sillero-Zubiri 1995). 

Bale Mountain national park and the habitats formed by the park are only protected if the park boundary restrictions are enforced and timber extraction is excluded.  To better protect wildlife in the park conservation efforts should be extended beyond the park boundaries to buffer for future extraction and degradation.   Finally to successfully protect species in the park it will be important to monitor conditions in and around these protected areas to assess the effectiveness of any program.  

The Presence of Vegetation 

A survey for the presence and change in vegetation cover can be accomplished with the combination of remote sensing and Geographic Information Systems.  Remote sensing is a favorable survey tool due to the efficiency intrinsic to this kind of sampling and the variability associated with vegetation cover from year to year (Schott 1997).  Identifying vegetation in remote sensing images may be achieved through a number of calculations in combination with multiple formats of remotely sensed images (Bolstad 2005). 

For this baseline analysis we used satellite imagery from landsat5 and landsat7 from the years 1987 and 2000.  In order to compare these images we used the normalized difference vegetation index.  Normalized Difference Vegetation Index or NDVI is a method of image analysis, which identifies the presence of vegetation based on the normalized difference between different reflectance values in the image (NASA 2009).  In a GIS analysis NDVI can explain for the presence or total area of vegetation in an image based on the difference in the reflectance of individual pixels between two images.  The two images used to calculate NDVI relate to reflected wavelengths of the red and near infrared bands.
With these two bands an assessment for the presence of vegetation can be derived using the following NDVI equation:

NDVI= (NIR-red)/ (NIR +red) where NIR is the near infrared corresponding to band 4 on landsat images. Red is the color red in the visible spectrum corresponding to band 3 on landsat images.

NASA image of global NDVI values. NDVI for a given pixel will be displayed in a range of values from -1 to 1 with vegetation values corresponding with valued between 0 and 1 as pictured above (Remer 2009).