Des problèmes dans la classification des chênes, taxonomie en Europe et région méditerranéenne

Le genre Quercus présente de grandes difficultés taxonomiques car son polymorphisme élevé, a suscité, pour de très nombreux taxons, des descriptions qui souvent résultent de méthodes incertaines. En comparant, dans les principaux traités existants, la distribution et la classification des taxons du genre Quercus en Europe et dans la région méditerranéenne, on met en évidence une notable incertitude taxonomique : ceux qui, pour certains auteurs, sont des espèces à propement parler, ne sont pour d'autres que des sous-espèces ou variétés. Dans le présent travail, nous avons réalisés une compilation bibliographique en cherchant à regrouper les taxons, tels qu'ils sont décrits par divers auteurs, en un nombre limité d'espèces principales

Forest ecosystem monitoring in Tuscany (Italy): past activities, present status and future perspectives

Since 1987 the Region of Tuscany has been actively monitoring crown status in its forests, in order to protect them from atmospheric pollution, biotic factors and environmental change. Over this period the Region has performed periodical inventories on crown condition in publicly-owned forests (Level I network) and established a network of permanent plots (MON.I.TO., Level II – III) to study long-term changes occurring in forest ecosystems. Some of these permanent plots were later included in the national programme CONECOFOR, managed by the Ministry for Policy in Agriculture and Forest. Currently a further development of MON.I.TO. is being implemented, called MONITO III – TOpModel, the aim of which is to broaden the information potential of the monitoring system to include carbon stocks and biodiversity evaluation. This paper provides an up-to-date report on the status of the various surveys and recommends a closer connection between MON.I.TO. and the other regional information systems, especially the Regional Forest Inventory, in order to produce information that may be useful in forest planning and in Sustainable Forest Management

The role of marine salt and surfactants in the decline of Tyrrhenian coastal vegetation in Italy

The decline of coastal vegetation is a phenomenon affecting some areas of the Mediterranean region and Australia; it is due to the presence of surfactants in marine aerosols, a consequence of sea pollution by detergents. This paper gives some observations made at various sites along the Tyrrhenian coast in Italy. The authors show that the presence of surfactants in the environment correlates with the presence of sea salt, and that the impact of surfactants on vegetation is local and occurs only in association with strong sea winds. The study of the synergistic effect of surfactants and sea salt on the crowns of trees exposed to aerosols suggests that the surfactant can cause direct damage, while the absorption of sea salt is enhanced by the presence of the surfactant only when exposure to aerosol is prolonged, or if it is administered in very high concentrations.Le rôle du sel marin et des agents tensio-actifs dans le dépérissement de la végétation côtière tyrrhénienne en Italie. Le dépérissement de la végétation côtière est un phénomène qui concerne un certain nombre de zones de la Méditerranée et de l'Australie; il est dû à la présence d'agents tensio-actifs, engendrés par la pollution hydrique de détergents dans les aérosols marins. Notre recherche fait le point de 10 années d'observations d'un certain nombre de localités italiennes du littoral tyrrhénien. II en ressort que la présence d'agents tensio-actifs dans l'environnement dépend de la présence de sel marin ; leur impact sur la végétation est local et il est limité aux périodes de vent de mer fort. L'étude de l'action synergique des agents tensio-actifs et du sel marin sur les houppiers des plantes exposées aux aérosols suggère l'existence d'un dommage direct dû à l'agent tensio-actif en question, tandis que l'absorption de sel marin n'est favorisée par la présence de l'agent tensio-actif que dans des conditions d'exposition prolongée à l'aérosol ou s'il est administré en fortes concentrations

Does spontaneous respiration alter pulmonary artery input impedance?

The aim of this study was to determine whether spontaneous respiration influences pulmonary artery input impedance, a question that has received little attention in the literature. Impedance values were assessed during three different phases of the respiratory cycle, namely inspiration, expiration and postexpiration (i.e. the null respiratory flow period between expiration and the next inspiration) in five anaesthetized spontaneously breathing dogs, Firstly, impedance values during postexpiration were taken as the reference baseline, and compared with values obtained during inspiration and expiration, Then, differences between values in inspiration and in expiration were tested, taking impedance during inspiration as the baseline, Differences with respect to postexpiration were found for three parameters of input impedance: input resistance, characteristic impedance, and the frequency at the first zero-crossing of the impedance phase from negative to positive values (fcross), Input resistance was significantly lower in inspiration (85% of the baseline), characteristic impedance was significantly greater in inspiration and in expiration (112 and 119% respectively), and fcross was significantly lower in expiration (89%), By contrast, only input resistance differed significantly when inspiration was compared to expiration. Therefore, spontaneous respiration was shown to influence input impedance significantly, The observed changes in characteristic impedance and fcross might be explained by a stiffening of the pulmonary artery wall, due to neural and/or mechanical factors, during inspiration and expiration

Anatomical and ultrastructural alterations in Pinus pinea L. needles treted with simulated sea aerosols

The effects of sea pollution by surfactants on coastal vegetation have been studied for several decades now in a number of European and non European regions. The damage is normally attributed to an excessive absorption of salts as a result of the action of the surfactants which lower the surface tension of the droplets of aerosol and make it easier for them to penetrate the stomata. Yet researchers have also discussed the possibility that surfactants may have a direct phytotoxic effect. This paper illustrates an anatomical and ultrastructural study of Pinus pinea L. needles treated with simulated sea aerosol for brief exposure periods. The results of this study confirm that anionic and non-ionic surfactants are directly toxic and affect mainly the stomatal apparatus, including both the epistomatal network and the guard cells and substomatal cells

Monitoring of air pollutants in Florence (Italy) with erbaceous and woody bioindicators

An integrated biomonitoring activity was carried out during 1996 in Florence. Ten fully equipped stands of bioindicators were set up in the city; observations were performed between May and October 1996. Ozone was monitored with the sensitive cultivar Nicotiana tabacum Bel W3, by means of the usual Leaf Injury Index (LII). The unsensitive cultivar Nicotiana tabacum Bel B was used as a control. Heavy metals (Pb, Cd, Cr, Cu, Fe, Ni), chlorine and sulphur were detected with the bioaccumulator Lolium multiflorum L., harvesting and analyzing micro-cultivations of this species once a month. Further, some potted plants of Pinus halepensis Mill, were placed in five of these stands in order to test their sensitivity to ozone and verify their possible use as bioindicators. Results show that the LII of the sensitive tobacco cultivar increases as one moves from the centre towards the peripheral and suburban areas of Florence; this finding correlates perfectly with the air ozone concentrations measured using traditional automatic methods. Heavy metals, on the contrary, show an opposite trend, with concentrations decreasing as one moves from the centre to the suburbs. No trends were detected for chlorine and sulphur. As far as Pinus halepensis is concerned the characteristic chlorotic mottles, described in the literature as ozone-like symptoms, were observed on the needles. These symptoms were detected in areas with high ozone concentration, but not in the control stand. Despite its sensitivity to ozone, the use of Pinus halepensis as a biomonitor appears doubtful because no proportionality was observed between injury and ozone concentration