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Increased summer drought will exacerbate the regeneration of many tree species at their lower latitudinal and altitudinal distribution limits. In vulnerable habitats, introduction of more drought-tolerant provenances or species is currently considered to accelerate tree species migration and facilitate forest persistence. Trade-offs between drought adaptation and growth plasticity might, however, limit the effectiveness of assisted migration, especially if introductions focus on provenances or species from different climatic regions. We tested in a common garden experiment the performance of Pinus sylvestris seedlings from the continental Central Alps under increased temperatures and extended spring and/or summer drought, and compared seedling emergence, survival and biomass allocation to that of P. sylvestris and closely related Pinus nigra from a Mediterranean seed source. Soil heating had only minor effects on seedling performance but high spring precipitation doubled the number of continental P. sylvestris seedlings present after the summer drought. At the same time, twice as many seedlings of the Mediterranean than the continental P. sylvestris provenance were present, which was due to both higher emergence and lower mortality under dry conditions. Both P. sylvestris provenances allocated similar amounts of biomass to roots when grown under low summer precipitation. Mediterranean seedlings, however, revealed lower phenotypic plasticity than continental seedlings under high precipitation, which might limit their competitive ability in continental Alpine forests in non-drought years. By contrast, high variability in the response of individual seedlings to summer drought indicates the potential of continental P. sylvestris provenances to adapt to changing environmental conditions.

Climate change is expected to significantly alter forest ecosystems, reducing the suitability of the key economic tree species Norway spruce ( Picea abies ) and European beech ( Fagus sylvatica ) in low- and mid-elevation forests of Central Europe. As these species face increasing pressures from drought, storms, and pests, it is crucial to identify alternative tree species that are economically viable and capable of maintaining primary ecosystem services. This study investigated the potential of Douglas fir ( Pseudotsuga menziesii ), a non-native conifer, to establish from seed and compete with native broadleaf and conifer species during the early regeneration stage under differing resource availabilities. We assessed the growth performance and phenotypic plasticity of Douglas fir seedlings over three years in a controlled common-garden experiment. Seedlings of Douglas fir, along with seven native species — Norway spruce, silver fir ( Abies alba ), Scots pine ( Pinus sylvestris ), European beech, pedunculate oak ( Quercus robur ), sessile oak ( Q. petraea ), and sycamore ( Acer pseudoplatanus ) — were grown for three years under factorial combinations of high and low availabilities of light, nutrients, and water. Seedling height, biomass allocation to shoots and roots and phenotypic plasticity of these traits were measured to evaluate the competitive ability of individual species and their potential to adapt to changing environmental conditions. While Douglas fir seedlings exhibited strong growth performance compared to the conifers Norway spruce and silver fir, their biomass production and height growth was considerably lower than that of the broadleaved sycamore and beech. However, Douglas fir’s height growth rate in the third year exceeded all species except sycamore. This was particularly pronounced under dry and/or nutrient-poor conditions, indicating a potential competitive advantage under expected future climatic conditions. In agreement with field studies, our results indicate that non-native Douglas fir may sustainably establish in dry, nutrient poor European lowland forests due to its superior early growth performance under these conditions and the high phenotypic plasticity, of its root system. This holds especially in situations where the species competes with other conifers, while its ability to successfully compete with broadleaves appears to be largely restricted to nutrient-poor sites.

The two storms Vivian (1990) and Lothar (1999) left an area of roughly 9000 ha of fully damaged protection forests in Swiss mountain regions. Given this huge dimension, questions arose on how to manage these areas to keep the protection gap, i.e. the time period with reduced overall protection against natural hazards, short. Quantifications are presented for the stability of lying logs left in place, the frequency of post-disturbance mass movements, and the tree regeneration in windthrow areas. The average height above ground of unsalvaged lying logs decreased from 2.1 m shortly after disturbance to 0.8 m 20 years later. In the period 1990–2014, the number of avalanches in windthrow areas was markedly small, and annual rates of shallow landslides and debris flows in windthrow areas did not differ from rates in comparable undamaged forested areas. Regeneration density rarely exceeded 4000 stems ha −1 20 years post-windthrow at elevations above 1200–1500 m a.s.l. Mean height of tallest trees reached 5.6 m in areas that were cleared and 6.5 m in those left unsalvaged. Trees planted post-windthrow were 1.0–2.4 m taller than naturally regenerated ones. Practitioners rated the protective effect to be acceptable 24 years post-disturbance in only 5 out from 16 observed windthrow areas (31%), with planting trees as the main cause of success. We conclude that in protection forests the regeneration speed after disturbance rarely meets practitioner’s expectations in terms of both stem density and stand structure. However, leaving woody debris from wind disturbance in place proved to replace protective effects for an astonishingly long time. An intensive management with salvage logging, planting and even technical constructions seems therefore only inevitable on windthrown areas where risks seem too high based on hazard, damage potential and possible spread of bark beetles to nearby protection forests. A management alternative applicable to many other cases of windthrown protection forests is to plant trees between lying stems.

Aim: Woodlands make up a third of European territory and carry out important ecosystem functions, yet a comprehensive overview of their invasion by alien plants has never been undertaken across this continent. Location: Europe. Methods: We extracted data from 251,740 vegetation plots stored in the recently compiled European Vegetation Archive. After filtering (resulting in 83,396 plots; 39 regions; 1970–2015 time period), we analysed the species pool and frequency of alien vascular plants with respect to geographic origin and life-forms, and the levels of invasion across the European Nature Information System (EUNIS) woodland habitats. Results: We found a total of 386 alien plant species (comprising 7% of all recorded vascular plants). Aliens originating from outside of and from within Europe were almost equally represented in the species pool (192 vs. 181 species) but relative frequency was skewed towards the former group (77% vs. 22%) due, to some extent, to the frequent occurrence of Impatiens parviflora (21% frequency among alien plants). Phanerophytes were the most species-rich life-form (148 species) and had the highest representation in terms of relative frequency (39%) among aliens in the dataset. Apart from Europe (181 species), North America was the most important source of alien plants (109 species). At the local scale, temperate and boreal softwood riparian woodland (5%) and mire and mountain coniferous woodland (<1%) had the highest and lowest mean relative alien species richness (percentage of alien species per plot), respectively. Main conclusions: Our results indicate that European woodlands are prone to alien plant invasions especially when exposed to disturbance, fragmentation, alien propagule pressure and high soil nutrient levels. Given the persistence of these factors in the landscape, competitive alien plant species with a broad niche, including alien trees and shrubs, are likely to persist and spread further into European woodlands.

In the context of global change, the integration of non-native tree (NNT) species into European forestry is increasingly being discussed. The ecological consequences of increasing use or spread of NNTs in European forests are highly uncertain, as the scientific evidence is either constraint to results from case studies with limited spatial extent, or concerns global assessments that lack focus on European NNTs. For either case, generalisations on European NNTs are challenging to draw. Here we compile data on the impacts of seven important NNTs ( Acacia dealbata , Ailanthus altissima , Eucalyptus globulus , Prunus serotina , Pseudotsuga menziesii , Quercus rubra , Robinia pseudoacacia ) on physical and chemical soil properties and diversity attributes in Europe, and summarise commonalities and differences. From a total of 103 publications considered, studies on diversity attributes were overall more frequent than studies on soil properties. The effects on soil properties varied greatly among tree species and depended on the respective soil property. Overall, increasing (45%) and decreasing (45%) impacts on soil occurred with similar frequency. In contrast, decreasing impacts on biodiversity were much more frequent (66%) than increasing ones (24%). Species phylogenetically distant from European tree species, such as Acacia dealbata , Eucalyptus globulus and Ailanthus altissima , showed the strongest decreasing impacts on biodiversity. Our results suggest that forest managers should be cautious in using NNTs, as a majority of NNT stands host fewer species when compared with native tree species or ecosystems, likely reflected in changes in biotic interactions and ecosystem functions. The high variability of impacts suggests that individual NNTs should be assessed separately, but NNTs that lack European relatives should be used with particular caution.

Fires shape fundamental properties of many forest ecosystems and climate change will increase their relevance in regions where fires occur infrequently today. In ecosystems that are not adapted to fire, post-fire tree recruitment is often sparse, a fact that might be attributed to a transient lack of mycorrhizae. Ectomycorrhizal (EcM) fungi play an important role for recruitment by enhancing nutrient and water uptake of their hosts. The questions arise whether and for how long the EcM community is transformed by fire. We investigated the resistance and resilience of EcM fungal communities on a chronosequence of 12 Pinus sylvestris stands in Valais (Switzerland) and Val d'Aosta (Italy) affected by fire between 1990 and 2006. Soil samples from burnt and non-burnt forests were analyzed with respect to EcM fungi by means of a bioassay. The number of EcM species was significantly lower in samples from recently (2-5 years) burnt sites than nonburnt forest, and increased with time since fire reaching levels of adjacent forests after 15-18 years. Community composition changed after fire but did not converge to that of non-burnt sites over the 18 year period. Only Rhizopogon roseolus and Cenococcum geophilum were abundant in both burnt sites and adjacent forest. Our data indicate fire resistance of some EcM fungal species as well as rapid resilience in terms of species number, but not in species composition. As long as the function of different EcM species for seedling establishment is unknown, the consequences of long-term shifts in EcM community composition for tree recruitment remain unclear.

In order to run a localization filter for parking systems in real time, the directional information must be directly available when a distance measurement of the wheel speed sensor is detected. When the vehicle is launching, the wheel speed sensors may already detect distance measurement in the form of Delta-Wheel-Pulse-Counts (DWPCs) without having defined a rolling direction. This phenomenon is particularly problematic during parking maneuvers, where many small correction strokes are made. If a localization filter is used for positioning, the restrained DWPCs cannot process in real time. Without directional information in the form of a rolling direction signal, the filter has to ignore the DWPCs or artificially stop until a rolling direction signal is present. For this reason, methods for earlier estimation of the rolling direction based on the pattern of the incoming DWPCs and based on the force equilibrium have been presented. Since the new methods still have their weaknesses and a wrong estimation of the rolling direction can occur, an extension of a so-called Dual-Localization filter approach is presented. The Dual-Localization filter uses two localization filters and an intelligent initialization logic that ensures that both filters move in opposite directions at launching. The primary localization filter uses the estimated and the secondary one the opposite direction. As soon as a valid rolling direction signal is present, an initialization logic is used to decide which localization filter has previously moved in the true direction. The localization filter that has moved in the wrong direction is initialized with the states and covariances of the other localization filter. This extension allows for a fast and real-time capability to be achieved, and the accumulated velocity error can be dramatically reduced.

Temperature manipulation experiments are an effective way for testing plant responses to future climate conditions, especially for predicting shifts in plant phenological events. While passive warming techniques are widely used to elevate temperature in low stature plant communities, active warming has been applied less frequently due to the associated resource requirements. In forest ecosystems, however, active warming is crucial to simulate projected air temperature rises of 3–5 K, especially at the warm (i.e., southern and low elevation) range edges of tree species. Moreover, the warming treatment should be applied to the complete height of the experimental plants, e.g., regenerating trees in the understory. Here, we combined open top chambers (OTCs) with active heat sources, an electric heater (OTC-EH) and warming cables (OTC-WC), and tested the effectiveness of these set-ups to maintain constant temperature differences compared to ambient temperature across 18 m 2 plots. This chamber size is needed to grow tree saplings in mixture in forest gaps for 3 to 10 years. With passive warming only, an average temperature increase of approx. 0.4 K as compared to ambient conditions was achieved depending on time of the day and weather conditions. In the actively warmed chambers, average warming exceeded ambient temperatures by 2.5 to 2.8 K and was less variable over time. However, active warming also reduced air humidity by about 15%. These results underline the need to complement passive warming with active warming in order to achieve constant temperature differences appropriate for climate change simulations under all weather conditions in large OTCs. Since we observed considerable horizontal and vertical temperature variation within OTCs with temperature differences of up to 16.9 K, it is essential to measure and report within-plot temperature distribution as well as temporal temperature variation. If temperature distributions within large OTCs are well characterized, they may be incorporated in the experimental design helping to identify non-linear or threshold responses to warming.

AIM: Formalized classifications synthesizing vegetation data at the continental scale are being attempted only now, although they are of key importance for nature conservation planning. Therefore, we aim to provide a vegetation classification and to describe the main biogeographical patterns of floodplain forests and alder carrs in Europe. LOCATION: Europe. METHODS: A database of more than 40 000 vegetation plots of floodplain forests and alder carrs across Europe was compiled. After geographic stratification, 16 392 plots were available for classification, which was performed using the supervised method Cocktail. We also searched for new associations using semi‐supervised K‐means classification. The main biogeographic patterns and climate‐related gradients in species composition were determined using detrended correspondence analysis and cluster analysis. RESULTS: Thirty associations of floodplain forests and alder carrs were distinguished, which belong to five alliances. The Alnion incanae includes riparian, seepage and hardwood floodplain forests in the nemoral and hemiboreal zones (dominated by Alnus glutinosa and Fraxinus excelsior) and in the boreal zone (dominated by A. incana). The Osmundo‐Alnion represents oceanic vegetation dominated by Alnus glutinosa, Fraxinus angustifolia and F. excelsior distributed mostly on the Iberian Peninsula and composed of species with Atlantic distribution and Iberian endemics. The Populion albae comprises floodplain forests frequently dominated by Fraxinus angustifolia, Populus alba and P. nigra that are widespread in floodplains of large rivers under summer‐dry climates in the Mediterranean region. The Platanion orientalis represents eastern Mediterranean floodplain forests dominated by Platanus orientalis. The Alnion glutinosae includes forest swamps dominated by Alnus glutinosa distributed mostly in the nemoral and hemiboreal zones. The main biogeographic patterns within European floodplain forests and alder carrs reflect the climatic contrasts between the Mediterranean, nemoral, boreal and mountain regions. Oceanic floodplain forests differ from those in the rest of Europe. The hydrological regime appears to be the most important factor influencing species composition within regions. CONCLUSIONS: This study is the first applying a formalized classification at the association level for a broad vegetation type at the continental scale. The proposed classification provides the scientific basis for the necessary improvement of the habitat classification systems used in European nature conservation.