Relationship between topography and the distribution of matorral plant species in the Saharan Atlas: Case of Djebel Amour, Algeria

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One of the primary goals in community ecology is to determine the relative importance of processes and mechanisms that control biodiversity. The reduced coverage of vegetation and the severe losses of biodiversity in semiarid matorrals have recently become serious concerns in the Saharan Atlas in southern Algeria. In terms of research, the control of the spatial distribution of vegetation by the topographic factors has not received the attention it merits in Djebel Amour's region. This study combined several multivariate analyses to assess quantitatively the extent and nature of the topographic influence on the distribution of matorral plant species. Thirty plots (20 m × 20 m) were selected according to their physiognomy for the field survey of vegetation and topography in a semiarid mountainous region. The distributions of vegetation differed significantly amongst topographies, indicating different environmental conditions and determine a turnover of important species. Most species colonize downslopes, and only some persist on steep-slopes and summits. The low coverage of vegetation (36.98%) on steep-slopes was due to the serious soil erosion and rockiness 66.5–83.1%. The low average richness in summits (39.67) was due to elevation and negative effect of trees. Elevation, then rockiness and slope were respectively the main topographic factors influencing the distribution of matorral plants. The relationship between topography and distribution could be described by a linear model. Seventeen linear models were built for eleven floristic variables with three topographic factors, elevation, rockiness and slope explained 26–83% of the variance in distribution, also four groups of plant species were listed according to topographic positions. The suitability of plant species to the topographic factors should be considered in the restoration of matorrals in the study area. The results of this study will be useful for selecting the appropriate species and the potential sites for seeding to improving damaged matorral ecosystems in this area. However, additional investigations on soils, water availability and microclimate are required to clarify the mechanism of distribution of plant species in these ecosystems.