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

从20世纪60年代末开始，西非萨赫勒地区多次成为头条新闻，因为一些环境和经济问题表现在土地覆盖的变化上。虽然这些变化经常被称为“沙漠化”，但科学家们并没有就这一概念的确切含义、控制它的机制以及萨赫勒地区问题的严重程度达成共识。最近基于遥感的研究表明，萨赫勒部分地区出现了全面绿化的趋势，这可能表明积极的发展正在进行。然而，“绿化”的含义和“荒漠化”一样模糊，其在地面上的含义也远非清晰和明确。该研究项目将开发经验证据，在毛里塔尼亚和塞内加尔两个萨赫勒国家的对比研究地点，为了解面对可变和不可预测的降雨时土地利用、土地覆盖和人民生计之间的相互作用提供基础知识。研究者将采用跨学科的视角，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。他们将使用遥感技术测量和绘制当前和过去的土地覆盖变化，将其与降雨数据联系起来，进行各种焦点小组讨论，以重建当前和过去的土地利用和管理做法，参考研究地点的不同土地利用单位，并调查不同资源用户群体在土地利用和管理方面的决策如何考虑到环境限制和机会。他们还将评估土地利用和管理如何影响遥感测量的土地覆盖。确定一系列资源用户群体，梳理和量化他们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。这个项目将有助于提高对旱地环境中人类和自然系统的基本认识，特别是人类行为和气候变率对土地利用和土地覆盖变化的相对贡献。通过加深对荒漠化和绿化驱动因素的理解，项目成果可能有助于打破荒漠化辩论中的僵局。此外，确定气候变化下经济上可行和环境上可持续的土地利用战略可用于帮助社区和援助机构作出更明智的资源管理决定。

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.