Environmental Engineering Reference
In-Depth Information
designated and used for dry or wet season grazing, or only used in years
of drought. Fire was often used to clear woody vegetation and encourage
grass growth in grazing areas, reducing woody biomass and maintaining
a more open savanna system. Agricultural groups also used i re to clear
areas for growing crops, and brought in new plant species such as banana,
sorghum, millet and maize, which they grew in dif erent areas depending
on soil quality and rainfall. As a result, settlement patterns depended on
soil quality and water availability. Only in the highlands where soils were
generally more fertile, rainfall higher and competition for land greater did
communities settle for long periods and invest in their i elds. In semi-arid
regions agricultural communities moved regularly to clear new areas for
cultivation in response to declining soil fertility or inadequate rainfall. It is
likely that both pastoral and agricultural groups were responsible for clear-
ing woody vegetation in many areas, creating open savanna or secondary
miombo woodlands and reducing dry tropical forest cover (White, 1983).
Today some 110 tribes are recognized in Tanzania (Gulliver, 1972).
Although they can be grouped according to their linguistic and historical
traditions they show divergent patterns in livelihood systems and social
organization (Gulliver, 1972). Tribal identii cation has been l uid and
was often related to location; many tribal names can be translated to
mean 'highlanders', 'northerners' or 'from the waterless country' (Ilif e,
1979). Therefore, it was possible to change tribal ai liation by moving
and changing livelihood strategies. As a result, linguistic origin is not
always useful in delineating livelihood strategies. Although Cushitic and
Nilotic tribes were generally pastoralists and Bantu, cultivators, in fact
many tribes adapted their livelihood strategies according to the ecology
and environment in which they lived. The diversity of soils and variability
in climate that created ecological heterogeneity in semi-arid regions were
also responsible for the heterogeneity found in tribal identity and liveli-
hoods. Both Cushitic and Bantu tribes cultivated crops as well as owning
livestock and the relative importance of these strategies varied with loca-
tion and especially rainfall. Tribal identity was inextricably linked to the
local ecology.
Sociopolitical change has had a huge impact on livelihoods and ecology
in Tanzania. The inl ux of pastoral and agricultural groups changed the
way that people interacted with the environment and as a result the ecology
of semi-arid regions. In the past there was a close link between livelihoods
and ecological conditions. More recently, however, a process of decou-
pling of people and environment has occurred. This process began with
the spread of livestock and human diseases into East Africa in the early
1800s. The spread of rinderpest is recognized as being particularly impor-
tant in its impact on people and environment and the relationship between
