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Studying intra-annual growth dynamics through a modelling approach has proved useful for characterizing differences in wood phenology between species and deviations from the expected tree growth due to climate change.The aim of this paper was to determine the climatic factors and the inter-and intra-specific competition traits that drive intra-annual secondary growth dynamics in three Mediterranean tree species that naturally co-exist in the Spanish Northern Plateau (Pinus pinea L., Juniperus thurifera L., and Quercus ilex subsp. ballota (Desf.) Samp.). For this purpose, we obtained girth increment data from band dendrometers installed on 58 trees from May 2012 to April 2015. Half of them were located in a high-density plot and half were in a low-density plot. These data were analysed through a nonlinear multifactorial model considering daily and cumulative climatic effects together with inter-and intra-specific competition indices.Our results provide evidence of a spatiotemporal niche separation between species. Compared with other species, Q. ilex subsp. ballota showed a wider thermal amplitude, a higher mean optimum temperature for growth, and a milder effect of drought on its secondary growth.Under current climate change projections, simulations based on our model predict a secondary growth reduction for P. pinea and a growth enhancement for Q. ilex subsp. ballota in these Mediterranean mixtures.

16 Pág. Centro de Investigación Forestal (CIFOR), Key message: Our modelling approach shows the predominance of the facilitative over the competition effects in controlling the regeneration of the studied species, thus pointing out to intra- and inter-specific coexistence mechanisms. Abstract: Natural regeneration is a main issue in the management of continental Mediterranean forests. Ensuring natural forest regeneration is therefore vital for preserving ecosystem function under climate warming and increased frequency and intensity of extreme droughts. In this study, we evaluated intraspecific and inter-specific relationships between saplings and adult trees in mixed Pinus pinea-Quercus ilex-Juniperus stands in the Spanish Northern Plateau. Data were gathered from five 50 m × 60 m plots that covered different stand densities. Adult trees, saplings, and stumps were positioned, and height and diameter were measured. We developed a patch model to predict the probability of occurrence and abundance of saplings of the three species in 2.5 m × 2.5 m patches using a zero-inflated model. We considered as predictive variables abundance of adult trees, stumps, and saplings of each species, both in a patch and in its adjacent patches. Saplings of the three species showed a cluster pattern. The abundance of saplings of the three species was positively related with the current or past presence of their conspecific adult trees. The presence of adult trees of Pinus pinea plays a main role in both Quercus ilex and Juniperus dissemination. Our modelling approach shows the predominance of the facilitative effects over the competition effects in controlling the regeneration of the three species, pointing out to intra- and inter-specific coexistence mechanisms. The simulations suggested that to perpetuate the mixture, it is necessary to apply intense release cuttings in Pinus pinea trees once seedlings have been successfully established., The authors thank the Forest Service at Valladolid for their support in the installation and maintenance of the plots. The study was supported by the national project AGL2017-83828.

Centro de Investigación Forestal (CIFOR), Recent studies show that several tree species are spreading to higher latitudes and elevations due to climate change. European beech, presently dominating from the colline to the subalpine vegetation belt, is already present in upper montane subalpine forests and has a high potential to further advance to higher elevations in European mountain forests, where the temperature is predicted to further increase in the near future. Although essential for adaptive silviculture, it remains unknown whether the upward shift of beech could be assisted when it is mixed with Norway spruce or silver fir compared with mono-specific stands, as the species interactions under such conditions are hardly known. In this study, we posed the general hypotheses that the growth depending on age of European beech in mountain forests was similar in mono-specific and mixed-species stands and remained stable over time and space in the last two centuries. The scrutiny of these hypotheses was based on increment coring of 1240 dominant beech trees in 45 plots in mono-specific stands of beech and in 46 mixed mountain forests. We found that (i) on average, mean tree diameter increased linearly with age. The age trend was linear in both forest types, but the slope of the age–growth relationship was higher in mono-specific than in mixed mountain forests. (ii) Beech growth in mono-specific stands was stronger reduced with increasing elevation than that in mixed-species stands. (iii) Beech growth in mono-specific stands was on average higher than beech growth in mixed stands. However, at elevations > 1200 m, growth of beech in mixed stands was higher than that in mono-specific stands. Differences in the growth patterns among elevation zones are less pronounced now than in the past, in both mono-specific and mixed stands. As the higher and longer persisting growth rates extend the flexibility of suitable ages or size for tree harvest and removal, the longer-lasting growth may be of special relevance for multi-aged silviculture concepts. On top of their function for structure and habitat improvement, the remaining old trees may grow more in mass and value than assumed so far., Open Access funding enabled and organized by Projekt DEAL.The authors would like to acknowledge networking support by the COST (European Cooperation in Science and Technology) Action CLIMO (Climate-Smart Forestry in Mountain Regions—CA15226) financially supported by the EU Framework Programme for Research and Innovation HORIZON 2020. This publication is part of a project that has received funding from the European Union’s HORIZON 2020 research and innovation programme under the Marie Skłodowska-Curie Grant Agreement No 778322. Thanks are also due to the European Union for funding the project ‘Mixed species forest management. Lowering risk, increasing resilience (REFORM)’ (# 2816ERA02S under the framework of Sumforest ERA-Net). Further, we would like to thank the Bayerische Staatsforsten (BaySF) for providing the observational plots and to the Bavarian State Ministry of Food, Agriculture, and Forestry for permanent support of the Project W 07 ‘Long-term experimental plots for forest growth and yield research’ (#7831-26625-2017). We also thank the Forest Research Institute, ERTI Sárvár, Hungary, for assistance and for providing observational plots. Furthermore, our work was partially supported by the SRDA via Project No. APVV-16-0325 and APVV-15-0265, the Ministry of Science and Higher Education of the Republic of Poland, the Project “EVA4.0” No. CZ.02.1.01/0.0/0.0/16_019/0000803 funded by OP RDE and the Project J4-1765 funded by the Slovenian Research Agency and also by the Bulgarian National Science Fund (BNSF) and the Project No. DCOST 01/3/19.10.2018., 19 Pág.

15 Pág. Instituto de Ciencias Forestales (ICIFOR), Forecasted scenarios of climate change are expected to result in a dramatic reduction in the provision of Ecosystem Services (ES) from forests. Increasing tree species diversity has been proposed as a measure for adapting forests and warrantee the provision of services, since mixed forests, if compared with monospecific forests, are expected to be more productive, resilient and stable facing disturbances. In the present work we use a modelling approach in order to quantify the provision of different ES under expected climate scenarios, comparing pure forests of Pinus pinea L. with mixed forests where the species grows accompanied by different Quercus and Juniperus species. To this aim we first adapted the existing individual tree level model PINEA2, originally constructed for pure even-aged stands of P. pinea, in order to consider the interspecific interactions acting in mixed forests. In a second step we used the so adapted model for forecasting and comparing the provision of different ES – focusing on stocking, growth, yield, CO2 fixation, economic income and structural diversity – under current climate and expected scenarios RCP 4.5 & 8.5. Our results indicate that although growth and allometry in P. pinea trees is enhanced in mixtures, this effect is currently counterbalanced by the expected reduction in growth in the species occupying the understorey, thus under current climate conditions little differences due to composition are observed in the provision of ES. On the other hand, our simulations point to a generalized decrease in the ES supply under more severe climate change scenarios, being this reduction mitigated – at least in part - in mixed P. pinea forests, which are more competitive under the most restrictive environmental conditions. As a consequence, the promotion of mixtures by under-planting and/or releasing of pre-existing advanced regeneration of complementary species may be postulated as a management concept for adapting these forests to climate change., this work was supported by the Spanish Ministry of Science (ERA-Net SUMFOREST project REFORM PCIN-2017-026; projects OLDPINE ALG-2017-83828-C2.1-R, RTA2013-00011-C2.1), H2020 Marie Sklodowska Curie Actions-RISE (grant 778322-CARE4C) and agreement PROPINEA CC16-095 between INIA-ITACYL-Diputación Valladolid.