-1 Research article Multiscale control of vegetation patterns: the case of Don ˜ ana (SW Spain) Jose ´ Carlos Mun ˜ oz-Reinoso * and Francisco Garcı ´a Novo Department of Organism Biology and Ecology, University of Sevilla; *Author for correspondence (e-mail: reinoso@us.es) Received 16 October 2003; Accepted in revised form 27 May 2004 Key words: Don ˜ana, Hydrology, Sand dunes, Scale, Split Moving Window, Vegetation pattern, Water availability Abstract The early studies about the plant ecology of Don ˜ana carried out at a small scale showed that the main process controlling vegetation composition of the stabilized dunes was soil water availability. However, the extrapolation of this model to larger spatial scales failed to explain observed vegetation patterns. In this work, the vegetation patterns and the processes causing them are studied at a larger scale. Data of topography, soil pH, electrical conductivity, and available iron allowed to distinguish three large geomorphologic zones on the stabilized dunes of the Don ˜ana Biological Reserve which correspond to different dune building episodes. Different dune episodes showed differences in both water table depth and dynamics, which are due to groundwater flow systems of different scale. It is further manifested by differences in shrub composition. The results show that geomorphology controls the vegetation pattern at different scales mediated through water availability. Differences in water availability are due to the connection to groundwater flow systems of contrasted scale. On a small scale (10À10 2 m), along dune slopes, there is a gradient from dune ridges to slacks, from xerophyte to hygrophyte vegetation types. On a mesoscale (10 2 À10 3 m), there are several dune episodes with variable topographic altitude, dominated by different types of xerophytes. On a regional scale (>10 3 m), the discharges of the regional aquifer produce strong environmental and biotic stresses resulting in a mixed community. Introduction In spatially heterogeneous landscapes it is first nec- essary to detect its patterns and processes, and obtain information at a detailed level (Wiens et al. 1985). Later, the study of interactions between landscape pattern and ecological processes can be undertaken (Turner 1989). However, if different ecological pro- cesses are dominant at different spatial scales, the results obtained at a single scale of observation will be specific of that scale and will lose generality (Allen and Starr 1982; Wiens 1989). Then, it is important to know whether the processes that determine the com- munity structure at different scales are similar, because if the processes are scale-dependent they will manifest quantitative changes with a shift in the scale used to observe them (Allen and Hoekstra 1992). Coastal dunes have long been recognised as an appropriate environment to study the relationships between vegetation patterns and controlling processes (van Leeuwen and van der Maarel 1971; Gonza ´lez Berna ´ldez et al. 1975a; Crawford 1989), and both, pattern and processes, have been studied at several scales (Ranwell 1972; Dickinson and Mark 1994; van der Maarel and Leertouwer 1967; Sykes and Wilson 1987; Grootjans et al. 1991). The early studies about the plant ecology of the stabilized dunes of the Don ˜ana National Park were carried out at a small scale. They showed that the main controlling factor for the composition of plant Landscape Ecology (2005) 20: 51–61 Ó Springer 2005 DOI 10.1007/s10980-004-0466-x