"Desertification" or "Greening"? Human-Environment Relationships in the Face of Climate Variability: Case Studies in Mauritania and Senegal

从1960年代后期开始，西非萨赫勒地区由于土地覆盖变化所表现出的一些环境和经济问题而一再成为头条新闻。 虽然这些变化通常被称为“荒漠化”，但科学家们并没有就这一概念的确切含义、控制机制以及萨赫勒地区问题的严重程度达成共识。 最近的遥感研究表明，萨赫勒部分地区总体上呈绿化趋势，这可能表明正在发生积极的事态发展，但“绿化”的含义与“荒漠化”一样模糊，其在实地的影响远不明确。 这一研究项目将发展经验证据，为基本了解在毛里塔尼亚和塞内加尔这两个萨赫勒国家的对比研究地点，面对可变和不可预测的降雨量，土地利用、土地覆盖和人民生计之间的相互作用提供信息。 研究人员将采用跨学科的视角，并借用自然科学和社会科学的方法来解决这个复杂的研究问题。 他们将利用遥感技术测量和绘制当前和过去的土地覆盖变化图，将其与降雨量数据联系起来，进行各种重点小组讨论，以重建当前和过去的土地使用和管理做法，对研究地点的不同土地使用单位进行地理参考，并调查不同资源使用者群体在土地使用和管理方面的决策如何考虑到环境制约因素和机会。 他们还将评估土地使用和管理如何影响遥感测量的土地覆盖。 界定一系列资源使用者群体，梳理并量化这些群体与其生物物理环境之间的联系，将为今后将土地使用决策与空间上明确的环境变化模型结合起来奠定基础。特别是人类行为和气候变化对土地利用和土地覆盖变化的相对贡献。 该项目的成果可能有助于打破荒漠化辩论中的僵局，加深对影响荒漠化和绿化的驱动力的理解。 此外，在气候多变的情况下确定经济上可行和环境上可持续的土地使用战略，可用来帮助社区和援助机构作出更知情的资源管理决定。

Beginning in the late 1960s, the West African Sahel zone repeatedly made headlines because of a number of environmental and economic problems that manifest themselves in changes in land cover. While these changes often were referred to as "desertification," scientists did not develop consensus regarding the exact meaning of this notion, the mechanisms governing it, and the extent of the problem in the Sahel. Recent remote sensing-based studies have shown an overall greening trend in parts of the Sahel, which might indicate that positive developments have been going on. The meaning of "greening" is as vague as that of "desertification," however, and its implications on the ground are far from clear and unambiguous. This research project will develop empirical evidence that will inform basic understanding of the interactions among land use, land cover, and people's livelihoods in the face of variable and unpredictable rainfall in contrasting study sites in two Sahelian countries, Mauritania and Senegal. The investigators will adopt a cross-disciplinary perspective and borrow methods from the natural and social sciences in order to approach this complex research problem. They will use remote sensing techniques to measure and map current and past land-cover changes, relate them to rainfall data, conduct a variety of focus group discussions to reconstruct current and past land-use and management practices, georeference different land-use units in the study sites, and investigate how decision making on land use and management by different resource user groups takes into account environmental constraints and opportunities. They also will assess how land use and management affects land cover measured by remote sensing. Defining a range of resource user groups and teasing out and quantifying linkages between them and their biophysical environment will lay the ground work for future integration of land-use decision making with spatially explicit models of environmental change.This project will help enhance basic understanding of human and natural systems in dryland environments, particularly the relative contributions of human behavior and climate variability to land- use and land-cover change. The project results may help break the gridlock in the desertification debate by deepening understanding of the driving forces influencing desertification and greening. Moreover, identifying economically viable and environmentally sustainable land-use strategies under climate variability might be used to help communities and aid agencies to make more informed resource management decisions.