Use of Sensitivity analysis to evaluate key factors for improving slash-and-burn cultivation systems on the eastern escarpment of Madagascar

Slash-and-burn for pluvial rice cultivation (Tavy) is a predominant component in the land use system on the Eastern Escarpment of Madagascar. It causes ecological degradation and subsequent aggravation of rural poverty. After conducting multidisciplinary research resulting in an in-depth diagnosis of the area's agroecological system, the BEMA (Bilans écologiques à Madagascar) project now aims to propose improvements and alternatives to the land use system. The objective of contributing relevant knowledge to stakeholder discussions and enhancing the choice of development priorities has called for a method allowing aggregation of existing knowledge, in order to constitute an integrated overall picture of the local level. The present article illustrates the application of a sensitivity analysis. This method allows exploitation of existing knowledge with a view to setting priorities among key factors with regard to a postulated development objective and discussion of possible strategies for development activities. For this study, intensification and stabilisation, which are common concerns among the region's stakeholders, were chosen as development objectives to be analysed by example. Analysis of the local land use system has revealed that actions aiming to retard degradation caused by the slash-and-burn technique, as well as to promote self-sufficiency of Tavy, have hindered intensification and stabilisation. This paper concludes that the key factors in promoting more sustainable development are the intensification and the spatial concentration of permanent crops (irrigated rice and home gardens), cash cropping, and animal husbandry on the valley floors. Interventions at the socio-organisational level (collective conventions, improved access to land, etc.) and efforts to improve the dynamics of the local market are the most important factors in inducing and perpetuating such changes.