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

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.

Evaluation of Characteristics Floristico-Edaphic of the Steppes at Alfa (<i>Stipa tenacissima</i>L.) in the Saida Region (Western Algeria)

To establish an assessment of floristic and edaphic characteristics of steppe formations we conducted a phytoecological study on a local scale by comparing the current plant diversity and soil in three (3) stations representative of the vegetation to alfa (Stipa tenacissima L.) located south of Saida (western Algeria). The relations between the station, the vegetation and the characteristics of soils in the steppe are very imperfectly known. This study intends to analyze the relationship between floristic composition and edaphic parameters of the steppe at alfa. Anthropogenic pressures on plant structure are different imbalance resulting in one ecological. The floristic and edaphic data have been the subject of a factorial correspondence analysis (A.F.C). The floristic inventory denotes a regressive dynamics of the formations at alfa passing from one site to another. Thus 39 plant species have been inventoried in the site in good condition, against 26 species for the moderately degraded site and 16 species only for the damaged site. The coupled results between species and edaphic parameters show the relations between the plant diversity and the physico-chemical characteristics of the soils. The statistical analyses do appear a strong correlation between floristic composition, the state of vegetation and the edaphic parameters.

Contribution of Chamaerops humilis L. (Arecaceae) in Conservation in Situ of Soil Resources in the Tlemcen Region (Western Algeria)

In recent years, the anthropic action on scrubs in the region of Tlemcen (a province in western Algeria) has represented a threat to the groups of Chamaerops humilis L. (Arecaceae). The main purpose of the present investigation is to highlight the relationship between Chamaerops humilis and its biotope. Taking advantage of the refurbishment works in the study area, clumps of Chamaerops humilis, freshly dug by machinery, were collected and used to conduct some measurements. A total of 34 clusters were considered. The main parameters to be studied are: 1. The height of the tangle of roots and the number of roots in each cluster;2. The weight of soil trapped between roots;3. Physico-chemical properties of soil in which taxa grow. The results obtained showed that the average weight of soil retained by the clumps was important (70.3 kg);the average height of the tangle was 68.4 cm and the average number of roots was 382. The tangle of roots, of various stocks of Chamaerops humilis, creates a root network, very tangled in its upper part, thereby trapping a significant amount of soil. The statistical analyses of pairs of parameters, considered in the present work (height of the tangle, mass of soil trapped by roots and number of roots), were found to be highly correlated. These analyses allowed identifying the relationships existing between the studied parameters. They also helped to deduce the role of the taxon in the in situ conservation of edaphic potential.

Study of Halophytes Dispersion in the North-West Region of Algeria

To know the mode of distribution of halophytes species in the western region of Algeria, it was considered useful to undertake a study based on the achievement of identified linear. Two areas were considered, Northern Tlemcen (Beni Saf and Rachgoun) and Northwest Oran (Sabkha). The trend of climate aridity which is more pronounced in the study area may have influences on floristic halophytes. The study of the floristic composition showed the importance of indicator halophitisation species such as Atriplex halimus, Tamarix gallica, Salicornia fruticosa, Arthrocnemum glaucum and was accompanied by various therophytes such as Sinapis arvensis, Erodium moschatum, Malva sylvestris and Plantago lagopus. ANOVA (analysis of variance) has highlighted the factors that influence the spatial distribution of some halophytes species at five stations studied;some are dispersed aggregates (Tamarix gallica, Suaeda fruticosa) with a coefficient of variation (Cv) greater than 10%;others are regularly dispersed (Atriplex halimus) with a coefficient of variation (Cv) less than 10%.

Anthropogenic effects on plant cover in the Tlemcen region (western Algeria)

The present work is devoted to the study of broad physiological and ecological characteris- tics of anthropophytic species on the high step- pe lands of the Tlemcen region. The bioclimatic analysis confirms the development of drought in this region with a dominance of spiny and/or toxic asylvatic: plant species of shrub and her- baceous size species. We used correspondence factor analysis (CFA) of the various factors causing degradation to better understand the complexity of this ecosystem, whose floristic composition was complemented by means of soil measurements (spectrum green/ecological spectrum). This analysis allowed us to identify five groups of anthropophytic species with in this highly degraded matorral. We show that this ecosystem is already showing symptoms of de-gradation, and propose a preservation policy for protecting ensuring the survival of native species under threat from human activities.