Year: 2020
Type: other
Abstract: Degradation of natural vegetation has been a serious concern in northern highland areas of Ethiopia for a long time.It is believed that the country was originally 40% forested, which drastically decreased in extent throughout the 20 th century.Major reasons for the forest decrease have been intensive uses of forest resources by people and livestock.The loss of woody vegetation has resulted primarily in soil erosion and fuelwood shortage.Therefore, there is urgent need to restore vegetation cover in the highland areas of Ethiopia.Against this background, this project (i) determined important factors influencing on current distribution pattern of forests and other land cover types by using a Geographic Information System (GIS) and several thematic maps, (ii) estimated the trajectory of forest cover change through literature review and comparison of land cover maps in different years, and (iii) found practical modeling methods to identify suitable locations for common useful tree species in the Amhara Region, one of the National Regional States 1 located in the northern highland of Ethiopia.Analysis of a land cover map in 1995 showed that cropland cover was 38.5% in the Amhara Region, indicating that at least 38.5% of the original vegetation was converted to the cropland.Conversely, forest and woodland cover was low, 1.6% and 5.7%, respectively.Cropland cover was higher in the weyna dega (1,500-2,300 m), dega (2,300-3,200 m), and wurch (3,200-3,700 m) zones than in the other zones.1 Ethiopia is the federate state that consists of nine national regional states and two chartered cities.The Amhara National Regional State (ANRS) is commonly known as the Amhara Region.Cropland cover was also higher in high rainfall areas than low rainfall areas.These results suggest that population pressure was higher in these areas than the other areas.However, forest cover was also higher in high rainfall areas, even though cropland cover was high.This may be due to favorable conditions for forest growth in high rainfall areas.Analysis of four land cover maps in 1972-1978, 1995, 1999-2000, and 2003 indicated that forest cover in the Amhara Region fluctuated from 0.4% to 1.6% during this period.However, this may be due to variation in spatial resolution of satellite imagery rather than actual land cover changes.It can be inferred that areas of most forests were so small that they should be identified by high resolution satellite imagery only.Woodland, shrubland, grassland, and cropland covers also fluctuated greatly.This may be because of difference in the classification method of satellite imagery rather than actual land cover change.Current land cover, slope gradient range, elevation range, and annual rainfall range were used as criteria for suitability analysis of six useful tree species.The suitable slope gradient ranges for agroforestry and forestry species were set at 0-50% and 30-50%, respectively.This had large influence on the results because the area percentages of the two slope gradient ranges were largely different.However, the criteria of suitability classification by slope gradient range was provisional, which needs to be reexamined based on reliable scientific methods and ground-truthing.The suitable elevation and annual rainfall ranges for each tree species were estimated by reference to information from several sources.The criteria of suitability classification by elevation and annual rainfall ranges also needs to be reexamined since the information varied by literature source.Using slope gradient, elevation, and annual rainfall ranges for suitability assessment of tree species in the Amhara Region seemed practical because these factors significantly vary by location.The method was easy to understand and implement.Necessary maps can be obtained on the web for free.The same suitability analysis method is applicable at smaller units of administration for afforestation planning.
Source: eCommons (Cornell University)
Author: Shintani, Akira
Institution: Mie University
Language: English
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDGs: Life on land, Climate action
Open Access status: green
OpenAlex ID: W6991222452