BackgroundDespite empirical support for an increase in ecosystem productivity with species diversity in synthetic systems, there is ample evidence that this relationship is dependent on environmental characteristics, especially in structurally more complex natural systems. Empirical support for this relationship in forests is urgently needed, as these ecosystems play an important role in carbon sequestration.Methodology/Principal FindingsWe tested whether tree wood production is positively related to tree species richness while controlling for climatic factors, by analyzing 55265 forest inventory plots in 11 forest types across five European countries. On average, wood production was 24% higher in mixed than in monospecific forests. Taken alone, wood production was enhanced with increasing tree species richness in almost all forest types. In some forests, wood production was also greater with increasing numbers of tree types. Structural Equation Modeling indicated that the increase in wood production with tree species richness was largely mediated by a positive association between stand basal area and tree species richness. Mean annual temperature and mean annual precipitation affected wood production and species richness directly. However, the direction and magnitude of the influence of climatic variables on wood production and species richness was not consistent, and vary dependent on forest type.ConclusionsOur analysis is the first to find a local scale positive relationship between tree species richness and tree wood production occurring across a continent. Our results strongly support incorporating the role of biodiversity in management and policy plans for forest carbon sequestration.

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-A distance-independent diameter growth model, a static height model, an ingrowth model and a survival model for uneven-aged mixtures of Pinus sylvestris L. and Pinus nigra Arn. in Catalonia (north-east Spain) were developed. Separate models were developed for P. sylvestris and P. nigra. These models enable stand development to be simulated on an individual tree basis. The models are based on 922 permanent sample plots established in 1989 and 1990 and remeasured in 2000 and 2001 by the Spanish National Forest Inventory. The diameter growth models are based on 8058 and 5695 observations, the height models on 8173 and 5721 observations, the ingrowth models on 716 and 618 observations, and the survival models on 7823 and 5244 observations, respectively, for P. sylvestris and P. nigra. The relative biases for the height models are 6.7% for P. sylvestris and 3.3% for P. nigra. The biases for the diameter growth models are zero due to the applied Snowdon correction. The biases of the ingrowth models are zero due to the applied fitting method. The relative RMSE values for the P. sylvestris and P. nigra models, respectively, are 56.4% and 48.6% for diameter growth, 24.0% and 21.7% for height, and 224.3% and 257.3% for ingrowth.

-The study developed models for predicting the post-fire tree survival in Catalonia. The models are appropriate for forest planning purposes. Two types of models were developed: a stand-level model to predict the degree of damage caused by a forest fire, and tree-level models to predict the probability of a tree to survive a forest fire. The models were based on forest inventory and fire data. The inventory data on forest stands were obtained from the second (1989-1990) and third (2000-2001) Spanish national forest inventories, and the fire data consisted of the perimeters of forest fires larger than 20 ha that occurred in Catalonia between the 2nd and 3rd measurement of the inventory plots. The models were based on easily measurable forest characteristics, and they permit the forest manager to predict the effect of stand structure and species composition on the expected damage. According to the stand level fire damage model, the relative damage decreases when the stand basal area or mean tree diameter increases. Conversely, the relative stand damage increases when there is a large variation in tree size, when the stand is located on a steep slope, and when it is dominated by pine. According to the tree level survival models, trees in stands with a high basal area, a large mean tree size and a small variability in tree diameters have a high survival probability. Large trees in dominant positions have the highest probability of surviving a fire. Another result of the study is the exceptionally good post-fire survival ability of Pinus pinea and Quercus suber. damage model / fire management / logistic function / tree mortality / survival model Résumé -Prédiction des dommages au peuplement et de la survie des arbres dans les forêts brûlées en Catalogne. L'étude développe des modèles pour prédire la survie des arbres après feu en Catalogne. Les modèles sont appropriés à des objectifs de planification en forêt. Deux types de modèles ont été développés : un modèle au niveau des peuplements pour prédire le niveau des dommages causés par les feux de forêts, et des modèles arbre-centrés pour prédire la probabilité de survie à un feu de forêt. Les modèles sont basés sur les données de l'inventaire des forêts et des feux. Les données de l'inventaire des peuplements forestiers ont été obtenues à partir du deuxième (1989-1990) et du troisième (2000-2001) inventaire forestier espagnol, et les données sur les feux proviennent de périmètres de feux de forêts supérieurs à 20 ha qui se sont produits en Catalogne entre les deuxièmes et troisièmes mesures dans les placettes d'inventaire. Les modèles sont basés sur des caractéristiques facilement mesurables, et permettent au praticien forestier de prédire l'effet de la structure du peuplement et de la composition en espèces sur les dégâts. D'après le modèle de dommage au niveau peuplement, les dégâts diminuent lorsque la surface terrière ou le diamètre moyen des arbres augmente. Inversement, les dégâts augmentent en cas de forte variabilité de dimension des arbres, quand l...