Evaluation of the Above-Ground Biomass of Steppe Ecosystems According to Their Stage of Degradation: Case of the Area of Ain Skhouna (Western Algeria)

Abstract

The steppe in the region of Ain Skhouna (Department of Saida) includes three major vegetation types: Stipa tenacissima , Artemisia herba alba and Lygeum spartum . They have a very important ecological and socio-economic role. Nevertheless, they are exposed to a threat of deterioration due essentially to a combination of adverse climate circumstances and human impact. In the field, we found three physiognomic stages for each type of vegetation: degraded, moderately degraded and well growing. For a better comprehension of the process of each facies, we considered that the dynamic of the above-ground biomass is an interesting indicator for quantifying the degree of degradation of the steppic ecosystems. For that, we have adopted a combined method: linear transects and vegetation harvests over a one-square meter surface. This approach allowed us to identify the chosen site taxa on the one hand and quantify the above-ground biomass of each plot on the other hand. The obtained results reveal a significant regression of the above-ground biomass when moving from one site to another. The values about the Stipa formations present an average biomass oscillating between 1024 and 271.7 kg DM/ha for perennial species and between 367 and 68.8 kg DM/ha for annuals. Those about Artemisia formations fluctuate between 3584 and 805 kg DM/ha for perennials and between 524 and 66 kg DM/ha for annuals. Those about Lygeum formations oscillate between 274.4 and 87.9 kg DM/ha for perennial species accompanying Lygeum spartum and between 162.3 and 31.6 kg DM/ha for annuals.