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Quercus ilex L. (holm oak) coppices, widespread around the Mediterranean basin, are probably the result of 5 000 years of prolonged human disturbance of the original Quercus pubescens Willd. (downy oak) forests. Since disturbance has almost ceased in recent years, a question arises as to the development of these coppices: will the Q. pubescens forests return, or will Q. ilex remain the dominant species? To investigate the phenomenon, we analyzed the first stages, i.e. germination of the two species in holm oak coppices. Our experiments show that both species germinated better in coppices than in clearings or clear-cuts. Moreover, Q. pubescens appears to be slightly favored above Q. ilex and it is suggested auto-allelopathy is involved, at least partially inhibiting the germination of Q. ilex.

Growth forms are considered from two viewpoints: a descriptive and a functional one. Mono-character growth forms and their biological spectra were used to test whether they can characterize certain underlying processes in Quercus ilex coppice in southern France. Correspondence analysis of 35 mono-character growth forms of 203 described taxa shows that location of renewal buds is a good integrating indicator of plant adaptations to the environment. Two of these characters (renewal bud location, i.e. Raunkiaer's main life forms, and leaf consistency) appear to vary significantly along a gradient of increasing environmental constraints, especially climatic ones.

In 1969, several experiments were carried out in a Quercus coccifera garrigue, in order to clear up the role of man's action. Two of these experiments are described here: The experimental results presented here are those obtained from 1969 to 1974, by observation along lines. They concern the species number and the behaviour of certain species; it appears from these results: The stability of the original flora is noteworthy but the species frequency is modified. A few species appear, these ones are rare in the Quercus coccifera garrigue or come from the surrounding vegetation. The experiment ‘fire’ has not yet allowed to obtain by succession, the Brachypodium ramosum sward-hypothesis currently supported — the experiment ‘cutting’ has led towards a formation in which the grasses predominate. These experiments are now in progress.

This study is an attempt to interpret a mediterranean climatic gradient. It is based on 5-year observations of the dynamics of young plant communities dominated by Pinus pinaster in the hills of Provence, on permanent plots set up after the destruction of the pine forest by the introduction of Matsucoccus feytaudi. After a short description of the transect, including a classification of the plant communities and their relationship with environmental factors, we discuss the diversity pattern in relation to the niche concept. It is useful to explain diversity with the concept of resource distribution in order to construct models for the productivity of the communities and possible changes in the process of dominance. However, the acquisition of dominance by some species, the variation of habitat-niche breadth and the level of productivity of an environment are inferences from the models rather than the result of a process. As an alternative, we interpret the diversity gradient on the basis of the morphological and demographic characteristics of the species. We here consider Raunkiaer's life forms, including vegetative or offspring regeneration, leaf size and morphology as type of adaptive resistance to limiting factors such as frost, drought, competition, and as strategies used by the species to colonize or to survive.

The data processing for 202 phyto-ecological releves from the Liptov valley (Czecho-Slovakia) proceeded in two ways. The groups of indicator species formed with the ecological profiles are plotted for each species in the plane of axes 1 and 2 of the factor analysis. Comparison of the two types of results shows good agreement. The center of the plotted points (axes 1 and 2) is very crowded for our data (which is often so with factor analysis). With the help of the indicator groups (derived from ecological profiles) it is possible to discern a good organization of the indicator groups in this center. This comparison is helpful for the interpretation of the results furnished by the factor analysis. It also makes it easier to analyse the relationship between the indicator groups; these relationships are often difficult to find only with the ecological profiles. Die Daten von 202 phyto-okologischen Aufnahmen aus dem Liptov-Tal (Tschecoslovakei) werden mit zwei Methoden verarbeitet: Die von den okologischen Profilen abgeleitenen Indikatorartengruppen werden auf die Ebene der Koordinaten 1 und 2 der Faktorenanalyse eingetragen. Dieser Vergleich zeigt eine befriedigende Ubereinstimmung zwischen den Ergebnissen der beiden Methoden. Er ermoglicht insbesondere festzustellen, dass der mittlere Teil der durch die Faktorenanalyse erhaltenen Punktenwolke — der zunachst ziemlich verworren erscheint — eine klare Organisation aufweist, die die relative Anordnung der Indikator-artengruppen deutlich macht. Dieser Vergleich erleichtert die Erklarung der Diagramme der Faktorenanalyse und ermoglicht Beziehungen zwischen den verschiedenen Faktoren zu erkennen, die durch Anwendung von analytischen Methoden nur schlecht deutlich werden.