Main Anthropogenic Factors Research Articles

Landscape change in the lower Omo valley, southwestern Ethiopia: burning patterns and woody encroachment in the savanna

In this article we examine bush encroachment in a savanna ecosystem of the lower Omo Valley occupied by Mursi agro-pastoralists. Focusing on the role of fire and grazing, the main anthropogenic disturbance factors in the savanna, we compare the results of our ecological surveys with Mursi perceptions and understandings of environmental change. The main change described by Mursi is the loss of grassland over the last 30 to 40 years. Their explanations centre on three complementary factors: a growth in human and livestock numbers, leading to a reduction in grass availability; a tendency towards more permanent settlement, leading to heavy year-round pressure on certain grazing areas; and the loss of traditional burning practices, leading to frequent small fires rather than infrequent large blazes, capable of clearing the savanna of trees. In addition, state encroachment in general and the establishment of the Omo and Mago National Parks in particular have restricted mobility and reduced the actual and potential grazing area available to Mursi livestock. Our ecological surveys did not, however, show a causal relationship between fire, grazing and encroachment pattern. We therefore suggest that grazing and burning practices should be considered relevant, but not necessarily the most important, factors explaining bush encroachment in this case.

Естественные и антропогенные изменения русла реки Аргуни (в свете ее пограничного положения)

The paper gives outcomes of the analysis of channel reformations that occurred within the Argun River border reach during the second half of ХХ – early ХХI century; negative consequences associated with the state border position change have been noted, the role of the main anthropogenic factors that influence the channel natural regime has been assessed.

THE ROLE OF LAND USE CHANGES ON DESERTIFICATION IN IMAM KHOMEINI AIRPORT REGION-IRAN FROM 1956 TO 2003

The kind of land use and intensity of its change is considered as important desertification indices in different models. Land use change is one of the main anthropogenic factors in the desertification. The current research was carried out around Imam Khomeini airport, with an area of 32000 km2, in order to evaluate mentioned area's land use changes effects during 1955-2003 on desertification. To study the changes, aerial photos of 1955 (1:55000) and 2003 (1:40000), in addition to IRS (Pan and LISS III) and ETM images of 2003 were used. Boundaries of different land uses were determined based on aerial photos and satellite images. In the next stage, boundaries were controlled in the field. Five kinds of land uses including agricultural land, abandoned agricultural lands, rangelands, industrial regions and complex, were distinguished in the study area. The extent of land uses areas, except to complex, has been changed during the 48 years. Rangeland has least change (1.5%), while 14% of agricultural areas have been changed into abandoned and industrial areas. This research showed that biomass has been decreased to 24355.6 ton during the last 48 years. This leads to the decrease of organic matter and decline of soil quality, which in turn causes a 32.9% increase of area regions with severe and very severe desertification intensities.