Talk, 48th Annual Symposium of the International Association of Vegetation Science (IAVS): "Marginal landscapes (and nutrient poor ecosystems) - processes and adaptations", Lisbon, Portugal: 2006-04-26
Land-use change is a major cause for biodiversity loss - especially in the Mediterranean. Quantitative and comprehensible methods to assess spatio-temporal changes in biodiversity of landscapes are still lacking. This holds even more for methods to determine the amounts of change. We develop a widely applicable method to reveal spatio-temporal changes in vegetation patterns and to relate them to ecosystem processes. We use a systematic grid of hexagonal plots in a spatially nested design (three spatial scales and levels) to investigate the impact of disturbance on spatial patterns of vegetation in North-Eastern Morocco. The investigated area is situated at the edge of the Plateau du Rekkam, hosting an ancient stone oak forest which is exposed to heavy grazing. Inside plots (120m side length) sample-plots (8m side length) are arranged and inside those we placed sub-plots (0,6m side length). We reveal patterns through the calculation of similarity- and distance-measures between adjacent plots. Results show that disturbances as well as vegetation structures (shape and extent of bushes and trees) are the major driving forces for the spatial patterns of floristic diversity. Their influence changes depending on the scale of observation and on the distance between the plots.