- Comparison of old-field and forest revegetation dynamics - 295 Journal of Vegetation Science 5: 295-302, 1994 © IAVS; Opulus Press Uppsala. Printed in Sweden Comparison of old-field and forest revegetation dynamics in Provence Tatoni, Thierry 1* & Roche, Philip 2 1 Institut Mediterranéen d’Ecologie et de Paléoécologie (URA CNRS 1152), Case 461, and 2 Laboratoire de Biosystematique et Ecologie Mediterranéenne, Case 421 bis, Faculté des Sciences et Techniques de St-Jérôme, 13397 Marseille Cedex 20, France; * Tel. +33 91288426; Fax +33 288051 Abstract. This paper describes vegetation changes on cultiva- tion terraces after abandonment, considered as secondary suc- cession, and vegetation responses after clear-cutting, consid- ered as regeneration. Species were grouped in life form and dynamic categories in order to infer dynamic patterns. By applying the Shannon diversity index to these characteristics, an index of functional diversity is obtained. Regenerative succession is considered here as a particular case of secondary succession, characterized by a fast vegetative regeneration of the dominant woody species, which controls the succession of the understorey species. Post-agricultural succession and for- est regeneration succession show a similar relation between the diversity index and a forest index, indicating the relative amount of forest species. It appeared that the old-field dynam- ics resemble the deciduous oak-forest regeneration after the woody species have established. The species diversity at the end of the post-agricultural succession and in the forest is controlled by the nature of the dominant tree species. Keywords: Clear-cutting; Cultivation terrace; Diversity; Life form; Oak coppice; Quercus; Regeneration; Vegetation dy- namics. Introduction The concept of succession is one of the oldest con- cepts of ecology (Whittaker & Levin 1977), but it is still one of the most debated (e.g. McIntosh 1980; Miles 1987). In particular, the notions of secondary succession and regeneration are subject to many ambiguities and contradictions. Indeed, revegetation processes can be perceived either as different from or similar to second- ary succession (Grubb 1977; Miles 1987; van der Maarel 1988); most definitions of succession would correspond to both phenomena (Braun-Blanquet 1932; Drury & Nisbet 1973; van der Maarel & Werger 1978; Escarré et al. 1983; Huston & Smith 1987; Vitousek & Walker 1987), and van der Maarel (1993) even suggested regen- eration succession as a better synonym for secondary succession. Mediterranean France is particularly suitable for the study of revegetation processes, because the present vegetation is a complex of dynamic stages resulting from human disturbance: fire, forest cutting, cultivation and urbanization. Our objective is to compare patterns of two kinds of vegetation dynamics: old-field succes- sion and forest regeneration after clear-cutting. Through the study of concrete cases, it should be possible to determine whether the two succession patterns con- verge or differentiate. Methods Study sites The study sites are situated on calcareous substrate in Provence. The old-field succession studies were carried out near Auriol, 20 km east of Marseilles, and Maubec in the Luberon massif, 100 km north of Marseilles, and the forest regeneration studies in the state forest of ‘la Gardiole de Rians’, Var, 80 km north-east of Marseilles. The climate is mild-mediterranean and the vegetation belongs to the meso- and supra-mediterranean series. The potential natural vegetation is generally considered to be a mesophyllous oak forest with Quercus pubescens (pubescent oak) on deep soil (Quézel & Barbero 1982; Pons & Quézel 1985) and a sclerophyllous oak forest with Quercus ilex (holly oak) on dry and rocky substrate (Bacilieri et al. 1993). Human impact has reduced the extension of the mesophyllous oak forest and promoted the extension of an impoverished sclerophyllous oak forest, because Q. ilex is better adapted to recurrent disturbance than Q. pubescens . At present, much arable land has been abandoned in Provence; it is important to know which type of vegetation will develop here. Cultivation ter- races have been abandoned at different times, some of them hundreds of years ago. Consequently, they are very suitable for revegetation studies (Tatoni 1992).