Assessing farmers’ income vulnerability to vanilla and clove export economies in northeastern Madagascar using land-use change modelling

Using a participatory Bayesian network-based land-use decision model, we simulate future land-use patterns under various scenarios, including changes in vanilla and clove market prices as well as changes in irrigation water availability and potential harvest failures. Findings indicate that specifically the vanilla value chain (compared to the clove value chain) has a major influence on farmers income vulnerability. Abandoning vanilla cultivation may lead to poverty once income from vanilla reaches a certain threshold. By comparing farmer’s income gains from cash crop production with costs for buying rice to cover basic needs, we show that while focusing on cash crop production is more lucrative, it is, however, highly risky with regard to climate change, price volatility and possible crop thefts. Such lock-in-effects in cash crops, like the vanilla ones in northeastern Madagascar, are essential to be considered, when designing policies for a more sustainable development of resource-rich but poverty-prone regions.

本研究采用基于参与式贝叶斯网络（participatory Bayesian network）的土地利用决策模型，模拟多情景下的未来土地利用格局，涵盖香草与丁香的市场价格波动、灌溉水可获得性变化以及潜在的作物歉收等情景。研究结果显示，相较于丁香价值链（value chain），香草价值链对农户收入脆弱性的影响尤为显著。一旦香草种植收益降至某一临界值，放弃香草种植可能会使农户陷入贫困。本研究通过对比农户种植经济作物（cash crop）的收益与购置口粮大米所需的成本后发现，尽管专注经济作物种植收益更为可观，但该模式在气候变化、价格波动及作物被盗风险面前极具风险性。在为资源丰富但易致贫区域（poverty-prone regions）设计可持续发展政策时，马达加斯加东北部香草种植这类经济作物所存在的锁定效应（lock-in effects），是必须纳入考量的关键因素。