LADA Degradation Index

Land degradation is a complex set of processes of impoverishment of terrestrial ecosystems mainly under the impact of human activities. Land degradation can be understood as the gradual or permanent loss of productivity of the land to produce ecosystem goods and services. During the Land Degradation Assessment in Drylands (LADA) project, the South African National Assessment of Land Degradation and Conservation was done between 2008 and 2011. 728 Contributing specialists throughout the country contribute their knowledge and experience on land degradation and sustainable land management during a series of 34 Participatory Expert Assessment Workshops. It is important to notice that the results of these national assessments are qualitative in nature and based on the perceptions of contributing specialists based on the assumption that they all know their respective assessment areas well enough to report on land degradation and conservation attributes. Variables on the state of land degradation (the extend, degree and rate of degradation processes) were combined with the level of impact of these degradation processes on ecosystem services to provide an unique Degradation Index (DI) for each type of degradation identified by the contributing specialist for each mapping unit as defined by the LADA Land Use Map for South Africa. The DI values range from 0 to 100, for all degradation types identified. The higher the DI value, the more degraded the area are.

土地退化是一系列主要受人类活动驱动的陆地生态系统衰退过程的集合。土地退化可被定义为陆地生产生态产品与提供生态服务的能力逐步丧失或永久丧失的过程。在旱地土地退化评估（Land Degradation Assessment in Drylands, LADA）项目框架下，南非于2008年至2011年间开展了全国土地退化与保护状况评估工作。来自南非全国的728名特邀专家，通过共计34场参与式专家评估研讨会，贡献了其在土地退化与可持续土地管理领域的专业知识与实践经验。需特别说明的是，本次全国评估的结果本质上为定性结果，基于特邀专家的主观判断，其前提假设为所有专家均充分熟悉各自负责的评估区域，足以准确汇报土地退化与保护相关属性。研究人员将土地退化状态相关变量（即退化过程的范围、程度与速率）与这些退化过程对生态系统服务造成的影响程度相结合，为特邀专家依据南非LADA土地利用图划定的每个制图单元所识别的每一类退化类型，生成了专属的退化指数（Degradation Index, DI）。所有已识别的退化类型对应的退化指数取值范围为0至100，指数值越高，则对应区域的退化程度越严重。