Jacques Lepart

Seed size optimization theories are generally based on the assumption that seed mass increases seedling performance and decreases seed dispersal ability. In this paper, we investigated the relationship between seed mass, wing area, and seed terminal velocity in a wind-dispersed tree, Pinus sylvestris, and we asked whether these morphological seed measurements are related to seedling performance. As predicted by the isometry hypothesis, we found that seed shape remained constant as size varied. This constancy in seed shape has two major consequences: i) seed mass is negatively related to seed dispersal capacity, and ii) traits related to dispersal varied in a much narrower range than seed mass. Seed mass also had a positive effect on emergence rate and seedling growth up to 6 months; this did not result from any family effect. However, the low variation of seed terminal velocity led to no statistical relationship between seed dispersal capacity and seedling performance.

Androdioecy, the coexistence of males and hermaphrodites within a population, is a rare breeding system, often considered as unlikely to evolve because of restrictive conditions for its maintenance. Phillyrea angustifolia, a wind-pollinated shrub, is one of the handful species reported to be androdioecious. Our previous studies have shown that natural populations of this species in southern France exhibit higher male frequencies (approximately 50%) than predicted on theoretical grounds. Thus, the male functionality of hermaphrodites is still debated. To assess the functional breeding system of this species in the wild, a paternity analysis was performed with two highly polymorphic microsatellite loci on 729 seeds collected on 10 maternal shrubs in a natural population of 24 mature individuals of P. angustifolia. A large proportion of seeds were found to have been sired by pollen from outside the population. Analysis of seeds sired by individuals within the study population revealed a high male fertility of hermaphrodites resulting in a low male advantage in fertility for male plants. Intermate distances were found to have a strong impact on male reproductive success, whereas sexual morph had no effect, with males and hermaphrodites performing equivalently. This study is the first to unequivocally document the occurrence of a male function of hermaphrodites in a natural population of an androdioecious species.

Androdioecy, the coexistence of males and hermaphrodites within a population, is a rare breeding system, often considered as unlikely to evolve because of restrictive conditions for its maintenance. Phillyrea angustifolia, a wind-pollinated shrub, is one of the handful species reported to be androdioecious. Our previous studies have shown that natural populations of this species in southern France exhibit higher male frequencies (∼50%) than predicted on theoretical grounds. Thus, the male functionality of hermaphrodites is still debated. To assess the functional breeding system of this species in the wild, a paternity analysis was performed with two highly polymorphic microsatellite loci on 729 seeds collected on 10 maternal shrubs in a natural population of 24 mature individuals of P. angustifolia. A large proportion of seeds were found to have been sired by pollen from outside the population. Analysis of seeds sired by individuals within the study population revealed a high male fertility of he...

The cessation of coppicing and grazing in Quercus woodlands, with its subsequent changes in the structure, composition and functioning of vegetation communities, is becoming more frequent throughout the Mediterranean Basin. In southern France, we have studied successional changes in Quercus pubescens woodlands by visiting previously studied sites 18 yr later. Changes in vertical structure, species richness, floristic composition, life form and dispersal type were analysed and compared between woodlands that had previously been grazed or ungrazed.Both successions showed a decline in vegetation cover in the 0–25 cm height class and in the height class immediately under the canopy layer, due to oak litter accumulation and tree ageing. In post‐grazing succession, the abandonment of grazing and associated burning has allowed the vegetation cover to increase in the 0.25‐2 m height class. In both successions, grassland species decreased in frequency and forest species increased, a trend which was stronger in undisturbed succession. Species richness decreased with time in the undisturbed succession, but remained stable in the post‐grazing succession mainly because of the slow decline of plants linked to grazing. In undisturbed succession, therophytes and hemicryptophytes decreased. In contrast, therophytes and hemicryptophytes remained stable in post‐grazing succession. In both successions, endozoochorous species (notably Ruscus aculeatus) increased. Plants dispersed by non‐animal vectors decreased in undisturbed succession, but stability was observed in most of the dispersal types in post‐grazing succession. These results showed that a time‐lag existed between undisturbed succession and post‐grazing succession, the latter remaining at a younger stage of successional development due to more recent impact of grazing. However, both successions have converged suggesting that most of the traces of grazing on vegetation will disappear within a few years. The vegetation of these coppices, regardless of the previous grazing regime, will become increasingly similar to the vegetation of undisturbed woodlands. However, their floristic composition will probably never be identical to that of undisturbed woodlands, mainly because of the rarity of these undisturbed woodlands and of the short‐distance dispersal of many forest plant species.

- The example of the Grands Causses area (SE of Massif Central, France), shows that, during the twentieth century, the legitimacy granted to the woodland has strongly changed. At the beginning of XXe century, the origin of the open landscapes of the Grands Causses area is explained by the degradation of woodlands (regressive successions). Cutting, clearing and especially overgrazing are seen as the main causes of degradation. Agriculture and post-farming dynamics (progressive successions) are neglected. The planning conceptions are dominated by the projects of restoration and regeneration of woodlands. Since the Seventies, the interest of open landscapes and ovine breeding is highlighted. Main planning objective is now to preserve open landscape from reafforestation and from natural dynamics of woody plants. But it seems that grazing, in the current economic context, is not enough to stop woody plants dynamics and that landscape planning objectives will have to be redefined.