Riparian vegetation is one of the biotic communities living close to the river banks, which is sustained by and interacts with the stream to a great extent [Naiman and Decamps, 1997; Hughes, 1997]. Several definitions of the riparian zone can be found in literature. Malanson  defined the riparian ecosystem as a very complex zone that usually occurs as an ecotone between aquatic and upland ecosystems, but with distinct vegetation and soil characteristics. Naiman and Decamps  characterized the riparian zone as an area which encompasses the stream channel between the low and high water marks, where vegetation may be influenced by elevated water tables or flooding and the ability of the soils to hold water. More recently, Mitsch and Gosselink  defined the riparian zone as the land adjacent to water that is, at least periodically, influenced by flooding.
 This paper focuses on riparian vegetation along meandering rivers and investigates whether morphological river dynamics are able to significantly affect the formation of spatial vegetation patterns. It is well known that the morphodynamics and hydrology of meandering rivers affect several riparian processes to a great extent [e.g., Salo et al., 1986; Bendix and Hupp, 2000; Hupp, 2000]. For example, spatial patterns of plant succession along river transects depend on river migration, which erodes the concave bank and deposits sediments on the opposite point bar. Interactions among river movements, sedimentation processes, and vegetation cause the formation of arcuate tree bands parallel to the river axis [Everitt, 1968; Salo et al., 1986; McKenney et al., 1995; Robertson and Augspurger, 1999]. Fluvial migration also controls the texture of riparian soils, influencing the soil moisture balance [Rodriguez-Iturbe et al., 1999; Rodriguez-Iturbe and Porporato, 2005] and thereby affecting the establishment of riparian plants [Nanson and Beach, 1977; Robertson and Augspurger, 1999; Piegay et al., 2000]. Oxbow lakes, due to meander cutoffs, also contribute to the mosaicism of riparian landscapes. River hydrology, i.e., the variation of river flow, induces oscillations in water levels in the stream and in the groundwater table, thus influencing the transport of water, sediments, seeds, and nutrients. Floods and discharge recessions affect the survival of seedlings after germination [Rood and Mahoney, 1990; Johnson, 2000; Scott et al., 2000; Hughes et al., 2001]. Floods can also disturb riparian vegetation, by causing uprooting, anoxia or burial [Friedman and Auble, 1999; Bendix and Hupp, 2000]. As riparian floodplains of meandering rivers usually have a ridge and swale topography, vegetation patches differ, depending on the adaptation of the species to the hydroperiod.
 The result of these processes by the river is that vegetation can have “a predictable development based on the distance from the river” [Kalliola et al., 1992, p. 78], namely the river can induce riparian vegetation patterns [Nanson and Beach, 1977]. Figure 1a shows an example: Sediment deposition is visible close to the internal bank of the meanders, where the density of vegetation increases moving away from the river. Other well-known examples of river-induced patterns are the regular zonation of the communities in the Peruvian Amazonia [Kalliola et al., 1992; Puhakka and Kalliola, 1995] and the cottonwoods in boreal climates, where forests along meandering rivers usually take the form of arcuate, parallel bands of even aged trees [Everitt, 1968; Nanson and Beach, 1977] (see Figure 1b).
 In general, several other factors, such as climate conditions, the presence of animals, harvesting, fire, grazing, diseases, large wood debris, and human actions, are able to influence the formation of riparian vegetation patterns, and the patterns observable in nature are often the result of the concurrent action of many processes, both fluvial and river independent [Naiman and Decamps, 1997; Nilsson et al., 1997; Timoney et al., 1997; Seagle and Liang, 2001; Menard et al., 2002]. In this work, attention is focused on the morphological river evolution in order to isolate its contribution to pattern formation and to the type of patterns that are likely to emerge. Owing to the complexity of the problem, the role of meander evolution before cutoff occurrence has been investigated, without considering the formation of oxbow lakes.
 Several conceptual-qualitative models regarding riparian vegetation evolution were proposed in the past [e.g., Bradley and Smith, 1986; McKenney et al., 1995; Hupp, 2000; Gurnell et al., 2001]; however, to our knowledge, only a few quantitative models have been formulated. For instance, Phipps  and Pearlstine et al.  modeled the influence of floods and water table fluctuations on vegetation growth. More recently, in the context of ecosystem restoration, Mahoney and Rood  proposed a predictive model for poplars in western Canadian rivers, and Richter and Richter  developed a model that is able to show the importance of flooding on riparian vegetation along meandering rivers. These models are important steps in the process of understanding the interactions between river and riparian vegetation, but they do not focus on morphological dynamics. The novelty of our approach is that it couples a fluid dynamic model, providing a realistic process based simulation of river evolution, with a model of riparian vegetation along a river transect. In particular, we modeled the growth and enlargement of the meanders and the consequent response of vegetation to river migration. The former aspect was carried out by simulating shallow water equations on an erodible bed [Ikeda and Parker, 1989]. The riparian vegetation dynamics are modeled taking into account (1) some of the key effects of hydrological and geomorphological processes on riparian vegetation (water table oscillations, flooding, and sedimentation [Hughes et al., 2001]), and (2) the increase or decrease in vegetation biomass, which depends on the distance of the vegetation sites from the river bank. As a river migrates, the riparian system continuously evolves through transitory states where characteristic patterns emerge, provided the typical timescales of the vegetation and the river evolution are comparable. In this model, we have considered only the one-way influence of the river on riparian vegetation, while the feedback of vegetation on river morphology has been neglected.
 The approach followed in our modeling was to retain some key processes, both in river morphodynamics and vegetation dynamics, while keeping the model as simple as possible. In this way, we believe that the obtained results describe the fundamental morphodynamic-induced components that exist in several real riparian patterns, as some qualitative comparisons with real data seem to confirm. To this end, and in accordance with recent results by Van De Wiel and Darby , we referred to vegetation biomass without taking the diversity of species into account.