Utilisation of wild growing yams as supplementary nutrition and its impact on the dry forest ecosystem in north-western Madagascar
2004
Ackermann, K.,Leipzig (Germany)
In the dry forests of north-western Madagascar, wild yams (Dioscorea antalyDioscorea maciba) are appreciated by the local inhabitants as a supplementary diet. The harvest period of yams coincides with the period of rice shortage. Although rice stocks in the households of Mariarano are much lower than in Tsilakanina, more than 70% of the population of both study areas harvest yams in the forests. The harvested yams provide households with staple food for periods of 11 to 28 days. Dioscorea spp. is a light-demanding species. A high frequency of these plants can be found in recently burned forests that usually are well penetrated by light. About 65% of the yams collected by the local people stems from such open forest formations. The corollary of this is an incentive to burn the forests intentionally. However, stimulating the growth of yams by means of forest fires is only viable in the short term. In the long run, the ecosystem will be degraded and finally transformed into savannah formations. In turn, this naturally leads to the destruction of the habitat of the preferred species of yams. Steps to a sustainable utilisation of wild growing yams are land-use planning, cultivation of yam species and fire management. A precondition for the sustainable management of dry forests in north-western Madagascar is the improvement of low and unstable rice yields.
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