荒漠化分类分级理论的初步探讨

简要回顾了二十多年来联合国荒漠化代表性分类分级理论的发展,评价了1977年、1984年、1992年和1997年提出的最有代表性分类分级理论,归纳出目前三种分类分级理论的评价思想:以指标体系为基础的绝对退化评价,生产力与经营水平相结合的相对退化评价和以生态系统中植被土壤地形差异退化为依据的多样性评价。在对比分析的基础上,针对各体系存在的问题,指出通过荒漠化退化生态基准的恢复和确定可提高分类分级理论的科学性与权威性,并提出确定时间尺度和空间类型的初步建议。

An approach to classification and assessment of desertification

Since the United Nations Conference on Desertification held in 1977 in Nairobi, much progress has been made abroad on classification and assessment of desertification. Three major steps accompanied with three new definitions of desertification are discussed respectively,which are UNCOD in 1977,“provisional methodology for the assessment and mapping of desertification” in 1984 and the first edition of the World Atlas of Desertification in 1992. Fully representation on type, severity, degree, hazard, indicator of desertification is in the newly released world atlas. Three of them are important, including the global assessment of human-induced soil degradation(GLASOD), the assessment of the status of human-induced soil degradation in South and South-East Asia(ASSOD), and the theory put forward by Moscow State University and Russia Academy of Science. Great differences on the classification and assessment focus chiefly on the evaluation concerning method and indicators. In the GLASOD, severity=degradation degree·extent per polygon, in the ASSOD, severity=productivity change·management level·extent per polygon and RUSSIA=diversity degree·number of main degradation factor. To improve the level of classification and assessment in science and authority, efforts should be taken in establishment of theoretical base of degradation which including determination of temporal and spatial scale.