Land degradation assessment in an African dryland context based on the Composite Land Degradation Index and mapping method

Increasing environmental and socioeconomic transformations in African drylands are driving land degradation. Using the Composite Land Degradation Index, this study assessed physical, chemical and biological degradation by determining their extent and severity. Palapye, an agro-pastoral region in eastern Botswana was used as a case study. Land degradation maps (status and indicators) were created with data from the field, soil chemical properties and image interpretation. Areas in the vicinity of settlements with Luvisols at elevations between 773 and 893 m were most degraded, implying impacts from human activities. This study developed a comprehensive list of of land degradation indicators for Botswana and created additional symbols for mapping indicators. Creation of these reference data for 2015 will facilitate the monitoring of land degradation in Palapye. The integrative and spatially explicit procedure utilized in this study can be adapted for assessing and validating local-level land degradation baseline and estimates towards operationalizing Land Degradation Neutrality in all countries.

非洲干旱地区日益加剧的环境与社会经济转型进程，正加剧土地退化问题。本研究采用综合土地退化指数（Composite Land Degradation Index），通过测算各类退化的范围与严重程度，对土地的物理、化学与生物退化开展评估。本研究选取博茨瓦纳东部农牧交错区帕拉皮耶（Palapye）作为案例研究区域。土地退化图（涵盖现状与指标两类）基于野外实测数据、土壤化学属性数据与影像解译结果绘制完成。海拔773米至893米范围内分布淋溶土（Luvisols）的定居点周边区域退化程度最高，这表明人类活动对土地退化存在显著影响。本研究为博茨瓦纳梳理出一套完整的土地退化指标清单，并为指标制图新增了专属符号体系。这套2015年的参考数据集将为帕拉皮耶地区的土地退化监测工作提供便利。本研究采用的整合式空间显性评估流程，可被推广应用于各地的地方级土地退化基线评估与验证工作，助力全球各国推进土地退化中性（Land Degradation Neutrality）目标的落地实施。