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New silvicultural proposals based on long-term trials are needed to develop forest management strategies. Radial growth response was the preferred proxy for managers to define thinning levels and best years for intervention. We analyzed long-term thinning strategies in secondary Nothofagus pumilio forests (55 years old) in Tierra del Fuego (Argentina) to determine and quantify the effect on radial growth. Samplings were conducted in a trial area established in 1965 where three interventions (17, 33 and 44 years after harvesting) with different thinning strategies were applied. We employed dendrochronological techniques to measure and co-date ring widths, comparing 19 different thinning strategies (n = 100 slices x 2 reading sections). Average ring width (RW), basal area increment (BAI), and periodic annual increment every five years (PAI5) were calculated and compared through univariate comparisons. Radial growth responses were directly related to thinning intensity; however, a differential response was found according to thinning strategy (e.g. selective and systematic cuttings) and always significantly higher than the control (3 vs. 1 mm year-1). The maximum growth occurred between 2 and 4 years after thinning (YAT), and progressively decreased until reaching pre-cutting levels (5 to 8 YAT). The analyses of the thinning strategies showed that initial systematic thinning followed by at least light thinning when growth rates recover their pre-intervention values is the most convenient combination of intermediate treatments for Nothofagus pumilio forests. These results can contribute to better silvicultural decision-making in secondary forests and provide information to analyze the feasibility of their implementation., Las propuestas silvícolas basadas en ensayos a largo plazo son necesarias para desarrollar estrategias de manejo forestal. La respuesta de crecimiento radial ha sido el proxy preferido por los gestores para definir los niveles de raleo y los años de intervención. Analizamos estrategias de raleo a largo plazo en bosques secundarios de Nothofagus pumilio (55 años) en Tierra del Fuego (Argentina) para determinar y cuantificar el efecto sobre el crecimiento radial. Los muestreos se realizaron en un área de ensayo establecido en 1965 donde se aplicaron tres intervenciones (17, 33 y 44 años después de la cosecha) con diferentes estrategias de raleo. Se emplearon técnicas dendrocronológicas, donde se midieron y co-fecharon anchos de anillos definiendo 19 estrategias de raleos diferentes (n = 100 rodajas x 2 secciones de lectura). Se calculó el ancho medio de los anillos (RW), el incremento del área basal (IAB) y el incremento periódico anual cada cinco años (PAI5), comparando valores mediante pruebas univariadas. Las respuestas de RW estuvieron relacionadas con la intensidad del raleo y se encontró una respuesta diferencial según la estrategia aplicada (por ejemplo, cortas selectivas y sistemáticas), siendo siempre significativamente mayor que el control (3 vs 1 mm año-1). El crecimiento máximo ocurrió entre 2 y 4 años después del raleo (ADR), y disminuyó hasta alcanzar los niveles previos a los raleos (5 a 8 ADR). Los análisis mostraron que una primera intervención sistemática seguida de al menos un raleo suave cuando las tasas de crecimiento recuperan los valores previos a la intervención, es la combinación de tratamientos intermedios más conveniente para los bosques de Nothofagus pumilio. Estos resultados pueden contribuir a una mejor toma de decisiones silvícolas en los bosques secundarios, proporcionando herramientas para analizar la viabilidad de su aplicación.

Climate change is expected to cause major changes in forest ecosystems during the 21st century and beyond. To assess forest impacts from climate change, the existing empirical information must be structured, harmonised and assimilated into a form suitable to develop and test state-of-the-art forest and ecosystem models. The combination of empirical data collected at large spatial and long temporal scales with suitable modelling approaches is key to understand forest dynamics under climate change. To facilitate data and model integration, we identified major climate change impacts observed on European forest functioning and summarised the data available for monitoring and predicting such impacts. Our analysis of c. 120 forest-related databases (including information from remote sensing, vegetation inventories, dendroecology, palaeoecology, eddy-flux sites, common garden experiments and genetic techniques) and 50 databases of environmental drivers highlights a substantial degree of data availability and accessibility. However, some critical variables relevant to predicting European forest responses to climate change are only available at relatively short time frames (up to 10-20 years), including intra-specific trait variability, defoliation patterns, tree mortality and recruitment. Moreover, we identified data gaps or lack of data integration particularly in variables related to local adaptation and phenotypic plasticity, dispersal capabilities and physiological responses. Overall, we conclude that forest data availability across Europe is improving, but further efforts are needed to integrate, harmonise and interpret this data (i.e. making data useable for non-experts). Continuation of existing monitoring and networks schemes together with the establishments of new networks to address data gaps is crucial to rigorously predict climate change impacts on European forests.

Climate change is expected to cause major changes in forest ecosystems during the 21st century and beyond. To assess forest impacts from climate change, the existing empirical information must be structured, harmonised and assimilated into a form suitable to develop and test state-of-the-art forest and ecosystem models. The combination of empirical data collected at large spatial and long temporal scales with suitable modelling approaches is key to understand forest dynamics under climate change. To facilitate data and model integration, we identified major climate change impacts observed on European forest functioning and summarised the data available for monitoring and predicting such impacts. Our analysis of c. 120 forest-related databases (including information from remote sensing, vegetation inventories, dendroecology, palaeoecology, eddy-flux sites, common garden experiments and genetic techniques) and 50 databases of environmental drivers highlights a substantial degree of data availability and accessibility. However, some critical variables relevant to predicting European forest responses to climate change are only available at relatively short time frames (up to 10-20 years), including intra-specific trait variability, defoliation patterns, tree mortality and recruitment. Moreover, we identified data gaps or lack of data integration particularly in variables related to local adaptation and phenotypic plasticity, dispersal capabilities and physiological responses. Overall, we conclude that forest data availability across Europe is improving, but further efforts are needed to integrate, harmonise and interpret this data (i.e. making data useable for non-experts). Continuation of existing monitoring and networks schemes together with the establishments of new networks to address data gaps is crucial to rigorously predict climate change impacts on European forests.