| dc.description.abstract | The open savannas scientist have come to regard as typical have been created by the
activities of humans, livestock, fire and wildlife. Many studies of savannas ecosystems have
concentrated on the fairly destructive effects of fire, waterholes and woodcutting. deemphasizing
the human role. Yet human activity, especially pastoralism is an important part of the savanna
ecosystem. In many parts of the world, savannas continues to expand as forest and woodland
recede due to human activities including woodcutting for fuel and clearing new kind for
cultivation.
The impact of abandoned human settlements on the savanna ecosystems is of major
importance, but is poorly understood. Construction of a settlement initiates alterations that, in
some cases, could last for centuries. In particular, the soils of settlements develop different
chemical and physical properties from the soils of undisturbed areas nearby.
During the life of a settlement, cattle, sheep and goats forage on a large area, returning
home every night. These animals continually deposit large amounts of nitrogen-loaded faeces and
urine over a small area, boosting the availability of nutrients essential for plant growth and
production, which are often in inadequate supply in savanna ecosystems. After a settlement has
been abandoned, it may act as a source of nutrients far into the future. Essentially, abandoned
settlements become eutrophic islands in a dystrophic area.
In Amboseli, ground Gover on settlements that had been abandoned for less than 40
years was higher than on the surrounding areas. The settlements that had been abandoned for
much longer periods tended ot have a canopy cover dominated by Acacia tottitis, which shades
out most of the pioneer herbs and grasses that colonize settlement soon after abandonment.
Different herbivores utilized abandoned settlements at successive vegetation stages. Soon
after abandonement, some herbivere species spent time resting in the safe open areas of former
settlements. Grazers took advantage of the abundant grass that succeeded the pioneer herbs and
eventually A. tortilis attracted browsers to the abandoned settlements | en |
