Environmental and anthropogenic drivers of coniferous species distribution in Mediterranean drylands from North West Algeria

Abstract

Understanding the influence of environmental and anthropogenic factors on the distribution of species is essential for developing management in endangered ecosystems. We studied the current abundance and distribution patterns of vegetation along environmental and anthropogenic gradients in North West Algeria. We focused on the four dominant coniferous species (Pinus halepensis, Tetraclinis articulata, Juniperus oxycedrus and Juniperus phoenicea). We compiled inventories of species composition, together with 12 environmental variables in 177 sampling plots throughout the study area. Multivariate (detrended correspondence analysis) and univariate (Huisman–Olf–Fresco models) analyses were applied to predict the presence of coniferous species and to explore species-environment relationships with ecological and anthropogenic variables. We found that species segregated along environmental gradients, mainly altitude and related climatic variables (temperatures). Anthropogenic variables, like fire frequency and overgrazing, were secondary, but also significant. Juniperus phoenicea was located exclusively in coastal areas. Tetraclinis articulata had a wide distribution and was linked to coastal and inland areas, but did not arrive at more continental areas (colder and drier), where it was replaced with J. oxycedrus. P. halepensis displayed the widest distribution and was practically present throughout the study area, but its maximum abundance was in continental areas. These results indicate a possible shift of species’ potential distribution in future climatic change. Species like J. oxycedrus would be seriously threatened by niche narrowing, while Pinus halepensis and T. articulata could expand to a certain extent. Our results provide important inputs for optimizing the management plans of coniferous species by considering environmental factors key modulators of vegetation distribution.