Grasslands of the World.pdf - Disasters and Conflicts - UNEP

J.M. SUTTIE
Other grasslands 425
savannahs (62 percent) are in the west and the south, and 76 percent are below
800 m. The grasses of Madagascar were the subject of an in-depth study by
Bosser (1969). The grasslands are floristically poor and there are no wild ungulates,
but nor is there tseste fly, and many of the serious livestock diseases of
mainland Africa are also absent.
The main extensive grazing areas are in the northwest, mid-west and south.
Bush fires occur all over the pastoral areas every year. Land tenure in the pastoral
land is essentially traditional; its management depends, grosso modo, on
whomsoever uses it. Insecurity of tenure favours the continued extensive use
of the grasslands. The grazing lands are grasslands with few trees or shrubs,
except in the extreme south. Poor soils and frequent fire maintain a grassy
vegetation under rainfalls that should support savannah or forest .
In northern savannahs, Heteropogon contortus is dominant on the plateaux,
but replaced by Aristida spp. on severely eroded areas (Plate 11.7). At
the foot of slopes and on colluvions, the commonest grasses are Hyparrhenia
rufa and Hyperthelia dissoluta . Bottom lands are covered by Echinochloa
spp. and a retinue of secondary grasses. The relief is dominated by vast plains
at altitudes below 300 m. Annual rainfall is 1 000 mm and the dry season lasts
from mid-March to the end of November.
In the mid-west, plateaus and the gentle slopes are covered by Heteropogon
contortus and Hyparrhenia rufa , but in many places serious erosion has
allowed Aristida spp. and Loudetia spp. to establish. The soil cover of
Plate 11.7
Madagascar plateau area with a dry season cover of Themeda triandra on
disturbed soil in the foreground and Aristida rufescens and Hyparrhenia spp. on
the main area.