The growth of juvenile populations of Ulva rigida C. Agardh was measured by means of immersion in in situ cages against environmental parameters (temperature, incident light, salinity, dissolved inorganic nitrogen and dissolved reactive phosphorus) in four different eutrophicated southern sites: Channel of the Thau lagoon (France), Lido, Sacca Sessola and Fusina stations (Venice lagoon, Italy). The growth curves as a function of temperature showed that, in all cases, the maximal temperature for Ulva growth was 17 degrees C (limitation in growth below 7 degrees C and above around 25 degrees C). The growth analysis of these four sites showed seasonal differences. In the least eutrophicated and calmest Lido station, grazing and dissolved reactive phosphorus (seven times lower at Lido than at Thau) played a key role. At Thau and Fusina, which are eutrophicated and turbid environments, the incident light had a strong impact on growth. Sacca Sessola, with an intermediate position between the above two mentioned situations, showed the highest growth rate. The values and relative growth rate (RGR) curves of the Mediterranean and open-sea northern sites are discussed. In particular, the temperature defines the type of growth curve (unimodal or bimodal) and the incident light is responsible for the low Mediterranean RGR values (<10% day(-1)).

Deux stations a Ulva rigida C. Agarth, l'une dans l'etang de Thau (Sete, France), l'autre dans la lagune de Venise (Lido, Italie), sont suivies durant une annee sur le plan des facteurs environnementaux: salinite, temperature, lumiere incidente, azote (DIN) et phosphore dissous (DRP), et sur le plan des facteurs biotiques: biomasse in situ et taux de croissance (RGR) des Ulves en cages. L'A.C.P. relative aux variables environnementales met en avant la liaison « salinite-temperature de l'eau » a Thau, et la liaison « salinite-lumiere incidente » au Lido de Venise. Contrairement au shema classique, la courbe du RGR annuel, prioritairement sous la dependance de l'evolution thermique, est bimodale (pics printannier et automnal). Les A.C.P. des facteurs biotiques et abiotiques ajoutent la certitude qu'a Venise le taux faible de phosphates limite le pic printannier du RGR, tandis qu'a Thau le pic automnal est fortement reduit par une lumiere incidente faible (consequence des processus de degradation estivaux). Les valeurs relativement basses du RGR (< 10 %d -1 ) sont discutees.

Environmental factors: water salinity, temperature, incident light, dissolved inorganic nitrogen (DIN), dissolved reactive phosphorus (DRP), and biotic factors: Ulva rigida biomass in field and relative growth rates (RGR) in cages of the two Mediterranean stations (Chanel of the Thau lagoon, France and Venice Lido, Italy) were compared. Principal Componant Analysis of environmental variables shows the linkage " salinity-temperature " in the eutrophicated Thau lagoon, and the linkage " salinity-incident light " in Venice Lido. Due to the water temperature the annual Ulva rigida RGR curve is bimodal (spring and autumn peaks) in contrast to the unimodal classical sheme. The PCA of biological and environmental variables underlines the DRP as the most limiting factor in spring at Venice Lido station and the incident light as a strigent limiting factor for autumn growth in the Thau lagoon.

The European project Waves and Storms in the North Atlantic (WASA) has been set up to prove, or to disprove, hypotheses of a worsening storm and wave climate in the Northeast Atlantic and adjacent seas in the present century. A major obstacle for assessing changes in storm and wave conditions are inhomogeneities in the observational records, both in the local observations and in the analysed products, which usually produce an artificial increase of extreme winds and waves. Therefore, changes in the wave climate were assessed with a state-of-the-art wave model using wind analyses. Within the scope of the WASA project, a 40 year reconstruction (1955-1994) of the wave climate in the North Atlantic was completed using the WAM wave model. The input wind fields were assumed to be reasonably homogeneous with time in the area south of 70°N and east of 20°W, and it was expected that the hindcast wave data would reliably describe the space-time evolution of wave conditions in this area. The results of the hindcast experiment are presented in this article. The main conclusion was that the wave climate in most of the Northeast Atlantic and in the North Sea has undergone significant variations on time scales of decades. Part of variability was found to be related to the North Atlantic Oscillation. As a general result we noted an increase of the maximum annual significant wave height over the last 40 years of about 5 to 10 cm/year for large parts of the Northeast Atlantic, north of the North Sea. There was also a slight increase of probabilities of high waves derived from conventional extreme value statistics in northwest approaches to the North Sea. Similar trends of the extreme waves were found in a scenario of future wave climate at a time of doubled CO 2 concentration in the atmosphere.

The European project WASA (Waves and Storms in the North Atlantic) has been set up to verify or disprove hypotheses of a worsening storm and wave climate in the northeast Atlantic and its adjacent seas in the present century. Its main conclusion is that the storm and wave climate in most of the northeast Atlantic and in the North Sea has undergone significant variations on timescales of decades; it has indeed roughened in recent decades, but the present intensity of the storm and wave climate seems to be comparable with that at the beginning of this century. Part of this variability is found to be related to the North Atlantic oscillation.An analysis of a high-resolution climate change experiment, mimicking global warming due to increased greenhouse gas concentrations, results in a weak increase of storm activity and (extreme) wave heights in the Bay of Biscay and in the North Sea, while storm action and waves slightly decrease along the Norwegian coast and in most of the remaining North Atlantic area. A weak increase in storm surges in the southern and eastern part of the North Sea is expected. These projected anthropogenic changes at the time of CO2 doubling fall well within the limits of variability observed in the past.A major methodical obstacle for the assessment of changes in the intensity of storm and wave events are inhomogeneities in the observational record, both in terms of local observations and of analyzed products (such as weather maps), which usually produce an artificial increase of extreme winds. This occurs because older analyses were based on fewer observations and with more limited conceptual and numerical models of the dynamical processes than more recent analyses. Therefore the assessment of changes in storminess is based on local observations of air pressure and high-frequency variance at tide gauges. Data of this sort is available for 100 yr and sometimes more. The assessment of changes in the wave climate is achieved using a two-step procedure; first a state-of-the-art wave model is integrated with 40 yr of wind analysis; the results are assumed to be reasonably homogeneous in the area south of 70 degrees N and east of 20 degrees W; then a regression is built that relates monthly mean air pressure distributions to intramonthly percentiles of wave heights at selected locations with the help of the 40-yr simulated data; finally, observed monthly mean air pressure fields from the beginning of this century are fed into the regression model to derive best guesses of wave statistics throughout the century.

Goods and services from forests can contribute in various forms to sustainable development, such as through provision of subsistence for rural communities living in or around the forests, through generating employment and income in rural and urban areas, and through direct contributions to the GDP in the form of industrialised wood, fuelwood and non - wood forest products production and trade. This paper analyses the role, opportunities and challenges of wood and non-wood forest products utilisation in sustainable development. It addresses wood and non- wood forest products' contribution to poverty alleviation, trends in wood utilisation and trade, as well as possible socio-economic and environmental impacts of wood products' substitution. A brief overview of recent wood products industry trends affecting sustainable development is provided. Environmentally friendly forest harvesting practices (reduced impact logging) and efficient processing technologies are mentioned as steps taken by an increasing number of forest enterprises world-wide. The document also highlights some key aspects related to the role of forest products utilisation and climate change, as potential sinks of one of the major green house gases, as substitutes for energy intensive materials and as substitutes for fossil fuels. Finally, this presentation points out steps taken by the international community to better incorporate the sustainable use of forest resources into national and international development objectives.