Key message: Climate change is posing a considerable challenge to foresters. The intensity of required adaptive measures and the relevance of old-growth forests as benchmark for managed forests are debated. Forest managers need to make decisions on stand treatment that are based on climatological and biological parameters with high uncertainties. We provided the conceptual basis for adaptive forest management and provide a number of case studies that reflect the options and limitations of ways of coping with climate change. The examples are derived from the experience of the authors. We conclude that only few forest types are either not strongly affected by climate change or do not require immediate adaptations of forest management. Many productive forests have stand properties that are decisively shaped by past management decisions, such as tree species composition, age distribution, rotation period, and stand structure. Maintaining these properties under the influence of climate change requires continuous and even increasing efforts of forest managers.

International audienceA technique to date branch mortality was used to estimate crown recession of Norway spruce and Silver fir in uneven-aged mixed forests on temporary plots of the Black Forest (Germany). In a preliminary study accurate and efficient sampling methods were developed. Results of the main study indicate that unthinned trees show a high crown recession rate, contrarily to thinned trees, which reveal more balanced crowns. Height increment and Hegyi's competition index were the only significant variables left in the final regression model. Trees of equal competition status but with higher height increment exhibit higher crown recession rates. This tendency is even more pronounced with Norway spruce than with Silver fir. Norway spruce, however, shows a higher crown recession rate with increasing competition compared with Silver fir of similar height increment. This seems to indicate a lower shade tolerance of Norway spruce.Évolution en hauteur des houppiers d'épicéa (Picea abies (L.) Karst.) et de sapin pectiné (Abies alba Mill.) - technique, mise en œuvre de méthodes d'échantillonnage, application à l'analyse de la croissance des forêts. On a utilisé une technique permettant de dater la mortalité des branches pour estimer la régression par le bas des houppiers de l'épicéa et du sapin pectiné, dans des placettes temporaires installées dans des forêts mélangées et inéquiennes de la Forêt Noire (Allemagne). Les résultats démontrent qu'en l'absence d'éclaircie les arbres présentent un taux de régression des houppiers plus élevé, au contraire des arbres ayant bénéficié d'éclaircies dont les houppiers apparaissent mieux équilibrés. L'accroissement en hauteur et l'indice de compétition de Hegyi sont les seules variables significatives qui subsistent dans le modèle de régression final. Les arbres soumis à un niveau de compétition équivalent, mais dont l'accroissement en hauteur est plus élevé, présentent un taux de régression du houppier plus important. Cette tendance est même plus prononcée pour l'épicéa que pour le sapin pectiné. Lorsque le niveau de compétition s'accroît, l'épicéa accuse un taux de réduction plus élevé que le sapin pectiné à accroissement en hauteur équivalent. Ceci semble indiquer une moindre tolérance à l'ombre de l'épicéa

The objective of the present work was to analyse diameter growth and the relationship of natural pruning and various morphological characteristics of Parana pine (Araucaria angustifolia (Bert.) O Ktze.) growing on different sites in southern Brazil and to formulate silvicultural strategies for producing high quality timber for this species. Data on four hundreds trees in both natural and planted forests were collected on temporary sample plots each containing 25 Parana pines. The size of the knotty core within Parana pine stems was modeled with the predictor variables height of the lowest dead branch, height to crown base and maximum radial increment of stem at 1.3 m. The results of our study show that crown width is a good estimator of diameter growth and is closely related to stem diameter at 1.3 m above ground. Restricting crown expansion such that average annual radial increment is 4 mm/year at 1.3 m for a stem grown for 63 years compared to one grown for 36 years with less crown restriction such that the average annual radial increment is about 75% greater (7 mm/year) results in a knotty core volume that is about 75% less for the slower growing tree. Managers can use this model to guide silvicultural decisions needed to achieve the production goal of high quality wood of Parana pine.