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

The changing face of pastoral systems in grass-dominated ecosystems of eastern Africa 61
Africa , analogous to that observed in southern Africa (Ringrose et al., 1990).
Sometimes this conversion forms a monospecific stand of persistent woody
species, which greatly reduces biodiversity (de Queiroz, 1993).
Rehabilitation of grasslands
Rehabilitation of grasslands usually involves use of exclosures and restricted
access to allow the vegetation to recover and natural species to re-establish
from the seed bank in the soil or from spread of plants by vegetative means.
Grime (1979) recognized a variety of mechanisms of regeneration, with
different types of revegetative strategies based on disturbance, vegetative
cover and management , and proposed a model of vegetative succession and
vegetation dynamics . Vegetative expansion is associated with undisturbed
habitats with few seedlings and relies on rhizomes and stolons of perennial
grasses. Seasonal regeneration of gaps involves synchronous germination of
seeds from abundant seeders. Regeneration from persistent seed banks and
wind dispersed seeds is associated with spatially unpredictable disturbances.
Woody species also have persistent seed and seedling banks but opportunities
for recruitment are infrequent. Disturbances alter ecosystem processes and
may alter the equilibrium balance of the system (Chapin, 2003). Disturbances
are usually revegetated by species of the original community and return to the
previous species composition within a few years (Belsky, 1986). Introduction
of new species through colonization and recruitment following disturbances
may result in system change, and plant traits may be important indicators to
predict the consequences of global change (Chapin, 2003).
Many previous attempts at rehabilitation have not been successful due to
lack of consultation and involvement of local communities and their customs,
and a perception that traditional systems need changes. Many technological
interventions have been tested in the rangelands of southern Ethiopia but lack
of development impact is linked to unrealistic expectations of development
planners and poor appreciation of social values and production rationale of
pastoralists (Coppock, 1994). Community participation in rehabilitation of
degraded rangelands is an important step in promoting the success of current
projects. A system in Samburu District in Kenya built on local knowledge and
traditions to work in partnership with local people on local problems is having
some success (Herlocker, 1999).
Rehabilitation offers an opportunity to sequester carbon through forestation,
grass and shrub establishment. This is particularly important because pastoral
lands are so extensive and they sequester large amounts of carbon. Rangelands
are only second to tropical forests in the amount of carbon they sequester,
although most of this sequestration is unseen below ground in rangelands, in
contrast to carbon above ground in rain forests (IPCC, 2000). Poor use of rangelands
can cause up to a 50 percent loss in soil carbon, so the potential gains from
rehabilitation are substantial (Cole et al., 1989; IPCC, 2000; Reid et al., 2003).