34

PETER STR0MGAARD



Mambwe area

-international border
- road

0 100 200 300_400 km

- railroad

Fig. 1. The lands of the Aisa-Mambwe.

Die Landereien der Aisa-Mambwe.

from shifting cultivation to mound cultiva-
tion, is a function of population pressure or
the opposite is debatable. A larger population
might be the result of changed cultivation
strategy: the agricultural response of the
Mambwe to deforestation enabled them to
support a larger population: Whiteley (1950)
quotes population density in colonial Mamb-
we-land at around 19 persons per square kilo-
metre as compared to neighbouring Bemba-
land where the density was recorded at
roughly 6 persons per square kilometre (Al-
lan 1949).

Nutrient cycling in grassland systems
The early over-utilization in Mambwe terri-
tory by excess cutting and cultivation led to
further deforestation where the miombo
woodland was replaced by secondary grass,
Hyparrhenia filipendula. In such a treeless
grassland area the above-ground biomass was
found by clear-cutting some 20x20 m plots:
less than 1 metric tonne wet weight per hec-
tare was found, compared to the 105 metric
tonnes wet-weight per hectare under undis-
turbed miombo and the 26 metric tonnes
wet-weight per hectare in miombo chopped 16