Abstract：
The Algerian Saharan rangelands are an arid ecosystem characterized by limited soil, water, and vegetation resources, which make it very susceptible to degradation. This research focuses on the diachronic assessment and multi-temporal mapping of the degradation of steppe vegetation in the south of Biskra during the period 1987-2019, using remote sensing data (MSAVI index), for extracting spatiotemporal data to monitor the rangeland vegetation dynamics. We examined demographic evolution, number of livestock, and land use from quantitative data. The results show that during this period, the landscape of the region changed considerably. The area of rangelands decreased from 19,939 ha (1987) to 3605 ha (2019), where 58% of the pre-existing vegetation was transformed into bare soil. This study confirmed that the rangeland vegetation health is closely related to climate, and its degradation is mainly due to the recurrence, duration, severity, and magnitude of drought events. Manmade activities were also a determinant factor of long-term degradation of the rangeland, such as the expansion of new land development areas that increased from 3754 ha (1987) to 24,410 ha (2019). This trend was found throughout the region, including predominantly pastoral regions such as Oumache and El Haouch, leading to overgrazing with a loss of about 2% of vegetation cover. All these factors have led to a severe and continuous degradation of pastoral resources in a vulnerable environment. The preservation of these limited resources requires appropriate management of the ecosystem and a rational exploitation of its vegetation, soil, and water resources.
摘要：
阿尔及利亚撒哈拉牧场是一个干旱的生态系统，其特征是土壤有限，水,和植被资源，这使得它很容易退化。本研究主要利用遥感数据（MSAVI指数），对1987-2019年期间比斯克拉南部草原植被退化的历时评估和多时态制图，提取时空数据，监测草地植被动态。我们研究了人口结构的演变,牲畜数量,和土地利用来自定量数据。结果表明,在此期间,该地区的景观发生了很大变化。牧场面积从19,939公顷（1987年）减少到3605公顷（2019年），其中58％的先前存在的植被转化为裸露的土壤。本研究证实,草地植被健康与气候密切相关,它的退化主要是由于复发，持续时间,严重程度,以及干旱事件的严重程度。人造活动也是牧场长期退化的决定因素，例如扩大新的土地开发面积，从3754公顷(1987年)增加到24,410公顷(2019年)。这种趋势在整个地区都有，包括Oumache和ElHaouch等主要牧区，导致过度放牧，损失约2%的植被覆盖。所有这些因素导致了在脆弱环境中牧区资源的严重和持续退化。保护这些有限的资源需要对生态系统进行适当的管理和对其植被进行合理的开发,土壤,和水资源。
