Sensibilité des milieux et impacts des activités humaines sur le massif du Ventoux

A map depicting the fragility of the environment has been drawn up (see Appendix), which distinguishes two main groups. 1) Areas of natural vegetation with low human influence. These include : a) the mature forests. These are poorly represented (only 5300 ha) due to previous overexploitation ; b) the pre-climax forest stages (mainly coniferous) covering about 1000 ha ; c) “degraded” habitats (scrub and grassland), which are mapped in terms of their value as pasture. Scrub covers about 2800 ha, and grassland about 1200 ha. These natural ecosystems make up about half of the non cultivated areas. 2) Areas with severe human pressure. This pressure may be due to one of several activities. Extensive reafforestation has been carried out since about 1860 (much of the natural forest having been destroyed by then), so that the new forests now cover the other half of the non-cultivated areas. In addition to native species, the exotics Pinus nigra ssp. austriaca and Cedrus atlantica have been widely planted. The cultivated areas are restricted to the foot of the mountain, although sheep are grazed to much higher altitudes. The type of agriculture is related to the natural vegetation series being exploited, and in most places is tending towards monoculture (mainly of vines, fruit-trees or lavender). Other human pressures include housing, roads, military activities and tourism ; industry is very limited in extent. The Mont Ventoux shows a fairly balanced relationship between man and his environment for several reasons. 1) Forest is by far the dominant vegetation type (covering about 75% of the massif). 2) The areas of non-climax and degraded vegetation are relatively restricted in extent, and have a considerable landscape value and economic importance. 3) The impact of forestry and agriculture is negligible, since these areas harmonise remarkably well with the natural landscape. 4) There has been no excessive development of other human activities, although the increasing number of holiday homes is a potential threat

Notable plant species recently observed in the Luberon Regional Natural Park

L’auteur présente des découvertes récentes de 3 espèces végétales nouvelles pour le territoire du Luberon, voire des Alpes-de-Haute-Provence et du Vaucluse.The author presents recent discoveries of 3 plant species new in the Luberon area, even in the Alpes-de-Haute-Provence and Vaucluse

Impact of river dynamics and human activities on biological evolutions of Calavon-Coulon

Les auteurs analysent les évolutions subies par la rivière au cours du demi-siècle passé, tant sous les aspects qualitatifs que quantitatifs de l’eau et des milieux aquatiques que sous ceux de la dynamique fluviale, particulièrement marquée par l’urbanisation dans la partie aval. Les évolutions sont moins marquées et les milieux mieux préservés dans la partie amont du bassin versant. Ils analysent aussi plusieurs années de gestion concertée de l’eau et des écosystèmes aquatiques visant à améliorer la qualité des eaux et de la ressource en eau, la gestion physique de la rivière et des crues, tout en assurant au mieux une gestion conservatoire des milieux naturels.The authors analyze the changes in the river during the past half-century, in both qualitative and quantitative aspects of water and aquatic environments and also in those of river dynamics, especially modified by urbanization in the downstream section. The changes are less pronounced and ecosystems best preserved in the upstream part of the watershed. They also examine several years of concerted management of water and aquatic ecosystems to improve water quality and water resources, the physical management of the river and floods, while providing the best conservation management of natural environments

Grassy areas on the crests of the Luberon, sentinels of the global warming - Evolution of the grazed ecosystems during thirty years, from 1982 to 2011

Les crêtes du Luberon sont occupées par des pelouses méditerranéo- montagnardes à forte biodiversité. Ces écosystèmes soumis à des conditions climatiques difficiles sont façonnés depuis des siècles par l’action de troupeaux ovins conduits en gardiennage. Depuis quelques décennies, ces pelouses sont menacées par la déprise pastorale, l’érosion causée par la fréquentation motorisée, les dégâts croissants de sangliers, enfin les accidents climatiques répétés de cette dernière décennie. Le PNRL, avec le CERPAM, l’ONF et l’appui de la recherche (INRA d’Avignon, Université d’Aix-Marseille) a animé depuis plus de trente ans des actions de conservation de ces habitats en confortant l’élevage pastoral (réouverture des milieux, équipements pastoraux, mesures agri-environnementales). Un bilan est dressé de l’évolution des pelouses sommitales du Luberon en mobilisant divers suivis mis en place depuis 1982 pour les plus anciens, permettant de comparer pelouses pâturées et non pâturées. Cette synthèse concerne principalement le Grand Luberon, dans une moindre mesure le Petit Luberon. Durant cette période, les chargements ont fortement baissé sur le Grand Luberon alors que le niveau de ressource pastorale est resté stable. Cette baisse s’explique dans le cadre d’un moindre besoin de la part des éleveurs du piémont utilisateurs des crêtes, d’une moindre incitation agri-environnementale dans le cadre des MAET Natura 2000, enfin de pratiques de garde qui ont évolué vers un pâturage moins « serré ». Les suivis pastoraux confirment un maintien de la ressource pastorale, mais avec l’apparition de trouées colonisées par des graminées opportunistes, résultant sans doute de la canicule de 2003 et des sécheresses des années suivantes. Les suivis de biodiversité effectués dans les deux massifs montrent une évolution contrastée d’un certain nombre d’espèces floristiques phares. Mais les baisses dominent, notamment pour Genista pulchella subsp. villarsii, Anthyllis montana, Plantago argentea, Sempervivum calcareum, Valeriana tuberosa, Ephedra nebrodensis ; les résultats sont comparables avec et sans pâturage, ce qui suggère fortement une cause climatique: répétition des canicules et sécheresses entre 2003 et 2006, et/ou début du réchauffement climatique documenté dans notre région depuis la fin des années 1970.Luberon’s crests are occupied by mediterraneo-mountain grassy areas with strong biodiversity. These ecosystems affected by difficult climatic conditions have been shaped for centuries by the action of guarded ovine herds. Since a few decades, these areas are threatened by the decrease of pasture, the erosion caused by motorized circulation, increasing damages of wild boars, and the repeated climatic incidents of the last decade. For more than thirty years, the PNRL, with the CERPAM and the ONF, and with the support of research centers (INRA of Avignon, University of Aix-Marseille), has developed actions to preserve these natural ecosystems by consolidating the pastoral breeding (reopening of the environment, pastoral equipments, agri-environmental measures). A balance sheet of the evolution of sommitals grassland of Luberon is drawn up by mobilizing some follow-ups set up since 1982, allowing to compare grazed and non-grazed grasslands. This synthesis concerns mainly the Grand Luberon, and to a lesser extent the Petit Luberon. During this period, loads strongly decreased on Grand Luberon, while the level of pastoral resource remained stable. This decline can be explained by a lesser need of the breeders from piedmont, using crests, by a lesser agri-environmental incitement within Natura 2000, and by practices of guarding which evolved towards a « less tight » pasture. The follow-ups confirm a preservation of the pastoral resource, but with the appearance of places colonized by opportunist grasses, resulting from the heat wave of 2003 and from the droughts of the next years. The follow-ups of biodiversity made in both massifs show a contrasted evolution for a certain number of key floral species. But many species decline, in particular Genista pulchella ssp. villarsii, Anthyllis montana, Plantago argentea, Sempervivum calcareum, Valeriana tuberosa, Ephedra nebrodensis. The results are comparable with and without pasture, and this strongly suggests a climatic cause : repetition of the heat waves and the droughts between 2003 and 2006, and\or at the beginning of the global warming informed in our region since the end of 1970s

La végétation du mont Ventoux

The vegetation map (see Appendix) is based on the concept of the vegetation series, within which different stages (mature forest, pre-climax forest, scrub, grassland and reafforested areas) are recognised. The most important native trees are Quercus ilex, Q. pubescens, Fagus sglvatica, Pinus halepensis, P. sglvestris, P. uncinata and Abies alba. The vegetation contains elements of both the Mediterranean and the Central European phyto-geogra- phical regions. The former is more typical of the southern slope and the lower part of the northern slope ; the latter occurs on the upper part of the northern slope (extending over to the summit of the southern slope) and part of the eastern ridge. Each of the vegetation series is restricted to one subgroup of these two broad divisions. The Mont Ventoux contains most of the vege tation series known from the limestone regions of southern France ; and the combination of a Mediterranean vegetation on the southern slopes with a Central European type on the northern slopes make it a typical example of the southern prealpine mountains

The « rare and sensitive biotopes » agro-environmental measure in the Luberon regional natural park : assesment for the territory and for breeding practices

Dans le massif du Luberon, une Mesure agri-environnementale (MAE) a été promue pour favoriser une gestion pastorale visant à préserver les « biotopes rares et sensibles ». Dans ce cadre, un suivi scientifique et technique a été mis en place et cet article vise à établir un bilan de son impact sur l’élevage et sur le territoire. Ainsi, un lien a été mis en évidence entre le type d’espaces ciblés par la mesure (grands espaces « sauvages » et écartés), et les types de systèmes d’élevage en mesure de s’engager (gros effectifs en phase de redéploiement). La MAE n’a pas mobilisé les petits élevages diversifiés ni les espaces qu’ils exploitent. Les pratiques pastorales engagés dans des milieux complexes ont souvent été novatrices. La logique contractuelle imposait la recherche d’indicateurs de réussite. Or le suivi a montré que les éleveurs s’appuient sur l’hétérogénéité du territoire pour mieux s’adapter aux contraintes posées par le climat méditerranéen sur des surfaces pastorales peu artificialisées. La contradiction entre la définition de mesures contractuelles à la surface, forcément standardisées, et des pratiques pastorales extensives comporte un risque de rigidification. En définitive, l’hypothèse est posée selon laquelle la diversité des systèmes d’élevage est le meilleur gage du maintien de milieux naturels diversifiés.Within the Luberon massif, an Agro-environmental Measure (AEM) was adopted to favor a pastoral management, which aims at preserving « rare and sensitive biotopes ». Within this scope, a scientific and technical follow-up was implemented ; this article aims at assessing its impact on breeding and on the territory. In this way, a link between the type of spaces targetted by the measure (vast « wild » and spread spaces) and the breeding practice modes able to suit the measure (great numbers in phase of redeployment) was brought to the fore. The AEM has not mobilized small diversified breeders and the spaces they exploit. Pastoral practices engaged in complex environments have often been innovative. A search for success indicators was imposed by the contractual logic. The follow-up showed that breeders rest on the territory’s heterogeneity to better adapt to the constraints of the Mediterranean climate on hardly man-shaped pasture surfaces. The contradiction between the definition of standardized contractual measures for the surface and extensive pastoral practices leads to the risk of becoming too rigid. As a conclusion, it would seem that the diversity of breeding systems is the best guarantee for the maintaining of diversified natural environments

Distribution and ecology of Garidella nigellastrum L. : application to its conservation

Garidella nigellastrum L., espèce messicole rare et protégée des champs de céréales est confrontée à un déclin récent et à un isolement des populations spontanées. Le Parc du Luberon et le Conservatoire d’espaces naturels de PACA (CEN PACA, ex-CEEP), en partenariat avec l’Institut méditerranéen de biodiversité et d’écologie marine et continentale (IMBE, ex-IMEP), veulent agir sur sa conservation en multipliant les populations in situ. Le succès de l’introduction dépend de la diversité génétique potentiellement contenue dans la banque de graines et des traits de vie de l’espèce, mais également de la prise en compte de sa dynamique spatiale. Une carte de distribution a été réalisée à partir de la littérature et des herbiers pour la région Provence-Alpes-Côte d’Azur (PACA). L’utilisation d’une technique de modélisation bioclimatique montre que la majeure partie du territoire du Parc du Luberon et plus généralement l’ouest de la Provence, apparaît favorable à sa présence ou à sa réinstallation. G. nigellastrum ne forme pas de banque de graines persistante. Dans un échantillonnage systématique de 29 kg de sol, seules 4 graines ont été retrouvées. Ceci peut être relié à une instabilité au niveau de la population et à de nombreuses extinctions en France. L’étude du cortège associé à cette espèce, à l’échelle intrapopulationnelle, n’a pas révélé de différences floristiques fortes reliées à son abondance. Nos résultats permettent de favoriser le transfert de graines comme technique de (re-)introduction. Cependant, les prélèvements doivent être limités afin de ne pas mettre en péril les deux dernières populations françaises,Garidella nigellastrum L., a rare and protected annual plant of cereal fields is faced with a recent decline and isolation of large spontaneous populations. The Parc du Luberon and the CEN PACA, in partnership with the IMBE, want to act on its conservation by multiplying in situ populations. Since the successful introduction of an annual plants depends on many factors such as genetic diversity, existence of a persistent seed bank, reproductive and vegetative traits of the species and our knowledge about its history and distribution. A distribution map was compiled from literature and herbarium accounts for the PACA region, France. We used bioclimatic modeling techniques to produce a map of suitable areas for G. nigellastrum populations. It appears that the majority of the Parc du Luberon as well as large parts of Western Provence, are suitable for the presence or its relocation. G. nigellastrum does not form a persistent seed bank in the soil. In a systematic sample of 29 kg of soil, only four dead seeds have been found. This may be related to its instability on the population level and the high number of recent extinction events for populations in France. The study of the flora associated with this species at the intra-population scale has not revealed significant floristic differences related to its abundance. Our findings suggest that the transfer of wheat seeding material can be a promising tool for (re-)introductions. However, seed sampling must be limited in order not to jeopardize the last two populations in the wild

Sensibilité des milieux et impacts des activités humaines sur le massif du Ventoux

A map depicting the fragility of the environment has been drawn up (see Appendix), which distinguishes two main groups. 1) Areas of natural vegetation with low human influence. These include : a) the mature forests. These are poorly represented (only 5300 ha) due to previous overexploitation ; b) the pre-climax forest stages (mainly coniferous) covering about 1000 ha ; c) “degraded” habitats (scrub and grassland), which are mapped in terms of their value as pasture. Scrub covers about 2800 ha, and grassland about 1200 ha. These natural ecosystems make up about half of the non-cultivated areas. 2) Areas with severe human pressure. This pressure may be due to one of several activities. Extensive reafforestation has been carried out since about 1860 (much of the natural forest having been destroyed by then), so that the new forests now cover the other half of the non-cultivated areas. In addition to native species, the exotics Pinus nigra ssp. austriaca and Cedrus atlantica have been widely planted. The cultivated areas are restricted to the foot of the mountain, although sheep are grazed to much higher altitudes. The type of agriculture is related to the natural vegetation series being exploited, and in most places is tending towards monoculture (mainly of vines, fruit-trees or lavender). Other human pressures include housing, roads, military activities and tourism ; industry is very limited in extent. The Mont Ventoux shows a fairly balanced relationship between man and his environment for several reasons. 1) Forest is by far the dominant vegetation type (covering about 75% of the massif). 2) The areas of non-climax and degraded vegetation are relatively restricted in extent, and have a considerable landscape value and economic importance. 3) The impact of forestry and agriculture is negligible, since these areas harmonise remarkably well with the natural landscape. 4) There has been no excessive development of other human activities, although the increasing number of holiday homes is a potential threat.Guende Georges. Sensibilité des milieux et impacts des activités humaines sur le massif du Ventoux. In: La Terre et La Vie. Supplément n°1, 1978. Écologie du Mont Ventoux, sud de la France. pp. 39-65