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We analysed the chemistry of solutions collected from soil by zero-tension plate lysimeters and cup lysimeters connected to a constant suction (600 hPa) under Douglas fir in the Beaujolais mountains (France). The chemistry of zero-tension lysimeters' (ZTL) and tension lysimeters' (TL) solutions differed enormously: TL solutions were most concentrated in Si, NHi-N, NO;-N, Cl-, Mg2+ and A13+ and TOC, whereas Ca2+ and K+ concentrations were greater in ZTL solutions. Organic matter (OM) greatly influenced the solution chemistry in both ZTL and TL. The chemistry of ZTL solutions was affected mainly by OM mineralization in the forest floor and upper soil horizon, and that of TL solution seemed to be related to destabilization of humified compounds under the new vegetation. Nitrification was important: residual nitrification led to excess protons neutralized in weathering or ion exchange reactions, mobilized cations, mainly A13+. Selectivity coefficients calculated both for ZTL and TL solutions formalized the differences between the two types of solutions. Nevertheless, these coefficients remained most often within the same order of magnitude indicating relations between them. Solutions from the two devices provided different information and should not be used for the same objectives. Solutions from ZTL are suited for ecosystem input-output budgets, whereas TL solutions are more useful when equilibrium between the solution and solid phase or when plant nutrition are considered.

-Litterfall is a major component of the carbon and nutrient cycles in forest ecosystems. Results of the present study are from a chronosequence of Douglas-fir stands monitored continuously for seven years. Aboveground litterfall was measured every three months, sorted by components, and analysed for major nutrients. Results make it possible to characterize the dynamics of organic matter and nutrient returns to the forest floor during stand development. Simple extrapolation was used to estimate the total return in litter, cumulated over a 70-yearrotation length. Already published data were collected in order to try to identify simple relationships capable of predicting the litterfall return from structural stand characteristics. These models failed to be predictive, due on the one hand to insufficient data, and, on the other hand, to data not always perfectly comparable. Litterfall is a quantitative ecological measurement necessary to validate the models of ecosystem function. Douglas-fir / litterfall / nutrient cycling / chronosequence / litter trapsRésumé -Dynamique des retombées de litière dans une chronoséquence de Douglas (Pseudotsuga menziesii Franco) située dans les Monts du Beaujolais (France). Les retombées de litières représentent un paramètre écologique fonctionnel important des écosystèmes forestiers, apportant des informations-clés sur le cycle du carbone et des éléments nutritifs. Les résultats présentés dans cette étude proviennent d'une chronoséquence de trois peuplements de Douglas situés dans les Monts du Beaujolais, étudiée pendant sept années. La litière a été collectée tous les trimestres, séparée en compartiments et analysée pour son contenu en éléments nutritifs. Les résultats permettent d'analyser en détail la dynamique des restitutions de carbone et d'éléments nutritifs au cours du développement du peuplement. Une extrapolation simple permet de calculer les retombées cumulées pour la révolution forestière complète. Une analyse bibliographique a permis de sélectionner une vingtaine de peuplements de Douglas pour lesquels les restitutions de litière ont été mesurées. L'objectif était de mettre en évidence des relations statistiques simples permettant d'estimer les restitutions de litière à partir de données de structure des peuplements, existant plus couramment dans la littérature. L'analyse des données montre que ces modèles généraux ne peuvent pas encore être élaborés, d'une part faute de données suffisamment nombreuses, et d'autre part faute de données parfaitement comparables. Les mesures écologiques quantitatives telles que les retombées de litière, doivent être poursuivies de façon à pouvoir valider des modèles de fonctionnement d'écosystèmes. Douglas / retombées de litière / cycle des éléments / chronoséquence / pièges à litière

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Norway spruce (NS) and Douglas-fir (DF) are among the main species used for production forestry in France. In low-elevation mountains and under-acidic conditions, they often occupy the same ecological situations. It is therefore of paramount interest to have a good understanding of how the two species behave under similar conditions and how they react to site improvement by fertilisation. The study stands are part of an experimental stand located in the estate forest of Breuil-Chenue in the Morvan (east central part of France). Its aim is to compare the impact of change in species on ecosystem functions. Destructive sampling of 10 trees per stand, distributed over the whole spectrum of inventoried classes of circumference at breast height (c 1.30 ), was carried out within four stands, e.g., fertilised and control (non-fertilised) NS; fertilised and control (non-fertilised) DF. Allometric relationships between c 1.30 and biomass or nutrient content per tree compartment were calculated. These equations were applied to the stand inventory for quantifying stand biomass and nutrient content on a hectare basis. The standard deviations of results were estimated using Monte-Carlo simulations. Specific emphasis was given to explain the origin of differences observed between species and treatments, i.e., changes in carbon allocation leading to specific allometric relationships, changes in stand structure (tree size distributions) and changes in stand density due to mortality.DF was more productive than NS (+28% for total tree biomass, +50% for ligneous biomass and +53% for stem wood). Both NS and DF were affected by fertilisation but in Communicated by R. Hampp