et al. 2002; Freckleton and Watkinson 2002; Ehrlen and Eriksson 2003). The criticism of the metapopulation concept for plants is mostly associated with methodological problems such as difficulties in assessing colonization and extinction events. Perennial plants react to changes in the number and area of available habitats with delay, and the current distribution of populations in landscapes may represent merely the historical pattern, some years or even decades ago. Because of that, the traditional vegetation monitoring approach, relying on the periodical inspection of species and communities, suffers from the problem that gradual changes may be recognized too late (Bühler and Schmid 2001).