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Energy is an essential factor regarding the economic development and for providing a high standard of living to the population of any country. Because energy is produced mainly using classic fuels (coal, oil and gas) for a few decades there are signals regarding their exhaustion. Therefore, mankind should concern more about finding viable alternatives to replace the classical fuels. This way the use of nuclear fuels appeared, then the force of the wind, of the tides and of the photovoltaic cells. However, there are still enough energy resources for further growth of the global energy production. The great consumers are both the major energy producers, only their hierarchy has changed and changes over time. The paper presents all these countries, and also Romania, including its specific developments in recent years.

Les grandes caractéristiques hydrobiologiques du bassin de Marennes-Oléron sont définies par quatre campagnes saisonnières de 120 prélèvements chacune effectuée-, en 15 stations en demi-cycle de marée. Les salinités y fluctuent de 10 '/rr. et ce secteur peut donc être assimilé à un vaste estuaire contrôlé principalement par les apports fluviaux de la Charente. La turbidité reste élevée souvent supérieure à 100 mg.I"', les teneurs en oxygène dissous montrent un déficit en amont de la Charente et de la Seudre de 4 mg.L1 tandis que les sels nutritifs sont apportés par la Charente pour les nitrates, phosphates et silicates. Ces derniers suivent les courbes de dilution théorique excepté lors des poussées phytoplanctoniques et lors des crues hivernales. Lors de ces crues, les nitrates semblent soit apportés par la Gironde, soit dus à une minéralisation organique. Au même moment, les phosphates pourraient être absorbés sur les particules et être piégés dans les sédiments. Les biomasses phytoplanctoniques exprimées par les teneurs en chlorophylle a sont supésieures à 30 f^-g.1 ' en amont des estuaires au printemps avec des teneurs en phéopigmenls pouvants dépasser 200 IUJ.1 . par contre, dans le bassin, les teneurs ne dépassent guère 10 fig.l ''. Les concentrations en ATP montrent que peu de phytoplancton est physiologiquement actif en particulier dans les estuaires, tandis que les dosages de protéines permettent de quantifier la part des apports allochtone - par rapport à la production autochtone des estuaires. Line analyse factorielle des correspondances définit le schéma général hydrobiologique du bassin estuarien en précisant que 'e rôle de la Charente ne se limite pas à l'apport en sels minéraux azotés et phosphatés, mais aussi à l'apport d'une biomasse phytoplanctonique d'eau douce en voie de dégénérescence. Les auteurs proposent qu'une nouvelle stratégie d'échantillonnage, mieux adaptée aux objectifs recherchés, soit suivie ultérieurement en assurant des prélèvements en cycle de marée mais avec une périodicité la plus élevée possible. Four seasonal compaigns providing a sampling of 15 stations each followed during half a tide cycle, i.e. 120 water samples permit the definition of the main hydrobiological features of Marennes-Oleron Bay: salinity and turbidity, phytoplanktonic biomasses, ATP concentrations. The authors suggest that a new way of adapted sampling to their objectives, will work out in the future by sampling during tidal cycles but as frequently as possible.

[Paper in French] The European public policy in favor of the biodiesel consumption is highly debated. Available estimates of the induced land use changes conclude that this policy is inefficient to reduce emissions of GreenHouse Gas. We show that the crop yield evolutions in these estimates are significantly lower than the observed and expected evolutions. This difference is directly related to biased calibration choice of behavioral parameters. We show using the GTAP-BIO framework that a consistent calibration of these parameters leads to a strong reduction (by around 80% in the long run) of the land use changes and induced emissions.

Climate change will affect agricultural production conditions, which will translate in impacts on yield and cost of production for Quebec farmers. This would likely affect the relative competitive position of Quebec in North America. Using the Delphi technique and partial budgets, climate change scenarios for the 2050 period were elaborated and their impact on relative competitiveness assessed for Quebec and its competitors in North America. Results indicate that Quebec competitive position would improve due to more favorable conditions for corn and apple production and due to worsen conditions for the competitors in maple syrup production.

Nutrient analyses were done in melted ice, frazil and sea water of the upper part of the water column, where as major constitutive elements of micro-algae were analysed. Measurements of nutrient uptake were carried out with frazil algae incubated at -1.5 degree C in a field incubator. Differential-enrichment bioassays and mean N/P ratio (5.9) demonstrated that actual growth of the cultures was nutrient-limited. Nitrogen governed the algal yield when illumination and grazing allowed the microalgae to grow. It concluded that the epontic dynamics is not only controlled from above, by the seasonal (climatic) changes in light intensity as generally assumed, but also from below, by the short-term (hydrodynamic) events of vertical mixing that replenish the ice-water interface in nutrients.

A model of plant succession has been built for simulating the growth of six species, based on physiological processes such as photosynthesis, growth and maintenance respiration, carbon allocation, nitrogen absorption, fixation and remobilisation, organ mortality, seed dispersal and germination. The simulated global plant productivity decreases in response to an increase in soil nitrogen availability. The reason is a replacement of the rapidly-growing legume species by slow-growing shrub species that are higher than the legume and thus shade it. This paradoxical result could have a wide application field.

The study of two pollen sequences from El-Kala marshes allowed the reconstruction of the regional vegetation history supported by eight radiocarbon dates. Pollen assemblages from Bourdim site were dominated by local input of Alnus and Salix, while regional vegetation was characterized by scattered Quercus suber forests with a well-developed Erica arborea matorral. While the vegetation dynamics recorded at Bourdim is recent (Late Holocene), the majority of the pollen diagram from Garaat El-Ouez is contemporaneous to the Late Pleniglacial and is characterized by open woodlands with Pinus, Poaceae and several heliophilous herbs. The significant values of Cedrus pollen identified in this period indicate that the region of El-Kala most probably played the role of a refugium for this tree.

Metadata only record This document presents an analysis of Fulani pastoral farming systems that focuses on how pastoralists use silvopastoral land. It aims to provide the missing knowledge needed to implement the resource management ('gestion des terroirs') approach at village level. In this region the influence of pastoral land use on the environment appears to be less pronounced than that of crop cultivation, even though levels of animal production are reasonable. The carrying capacity of the region has not yet been attained. Current constraints to pastoral land use in the region arise from the encroachment of cropland at the expense of pastoral land, and the increase in animal numbers. To develop sustainable natural resource management at village level that includes Fulani pastoral land use, the key factors appear to be the integration of livestock husbandry and cropland cultivation at household level, agreements between pastoralists and cropland farmers on land tenure and resource management, and support targeting of Fulani households (which have so far been neglected). Specific recommendations are given. (CAB Abstract)

L’objectif principal de ce travail est d’analyser l’impact du changement climatique sur la productivité des cultures céréalières dans la région de Béja, située au nord-ouest de la Tunisie. Pour ce faire, des modèles de régression multiple ont été estimés pour trois cultures céréalières (blé dur, blé tendre et orge). Les variables explicatives du rendement utilisées dans l’analyse sont celles d’ordre climatique (précipitations et températures) et le progrès technique. La période d’analyse est de 1980 à 2009. Les estimations des modèles de régression semi-logarithmiques ont montré que les rendements des différentes cultures céréalières dépendaient des variables climatiques et du progrès technique. L’analyse de la projection des effets du changement climatique sur les rendements céréaliers dans la zone d’étude, en utilisant les scénarios du modèle HadCM3, a montré que l’impact est important à l’horizon de 2030. Cet impact sera plus accentué pour le blé tendre. Ainsi, l’encouragement de la recherche en matière d’identification de nouvelles techniques agricoles, la diffusion de variétés tolérantes à la diminution des précipitations, dans les périodes critiques de croissance, et de variétés précoces, font partie des stratégies d’adaptation pour la réduction des effets du changement climatique sur le rendement céréalier à long terme...... This article analyzes the potential impact of climate change on cereal productivity in the Béja region of northwestern Tunisia. Multiple regression models were estimated for the cereal crops durum wheat, bread wheat and barley, using annual data from 1980 to 2009. The yield of each crop was used as the dependent variable, while the explanatory variables were mainly related to the climate (precipitation and temperature) and technological progress. The results show that yield variability is affected by climate and technological progress variables. The projected climate change scenarios predicted by the HadCM3 model will have a significant effect on crop yields by 2030, particularly for bread wheat. Some adaptation strategies that could alleviate climate change effects on cereal crops yields in the long run are the identification of new agricultural practices in this area, the widespread diffusion of varieties that can tolerate rainfall shortage during the critical periods, and the adoption of early maturing varieties.