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Forests in Europe are currently not endangered by soil erosion. However, this can change with climate change or with intensified forest management practices. Using a newly established network of plots in beech forests across Europe, the aims of this study were to (i) distinguish soil properties and erodibility indices in relation to bedrock, (ii) determine geochemical properties and organic carbon ([C.sub.org]) influencing erodibility, and (iii) assess the effect of soil depth on erodibility indices. Seventy-six soil samples from 20 beech forests were collected in 11 countries to quantify soil properties influencing erodibility indices: clay ratio, modified clay ratio, sodium adsorption ratio, and oxides ratio. The results indicate that the dominant soil properties, determined by bedrock, that correlate with forest soil erodibility indices are [C.sub.org], pH, electrical conductivity, calcium and sodium ions concentrations, total water-soluble cations, and the percentage of sand. According to the tested indices, soil susceptibility to erosion follows the order granite > andesite > sandstone > quartzite > limestone. Deeper soil horizons on granite are more susceptible to erosion than surface horizons are, but this is not the case for soils on limestones. In conclusion, forest management should consider the predisposition of different soil types to erosion. Key words: bedrock, environmental change, texture, organic matter, geochemistry, CLIMO COST Action. Les forets europeennes ne sont pas presentement menacees par l'erosion des sols. Cela pourrait cependant changer a cause des changements climatiques ou de l'intensification des pratiques d'amenagement forestier. En utilisant un reseau de parcelles echantillons etablies recemment dans des hetraies a travers l'Europe, cette etude visait les objectifs suivants : (i) distinguer les proprietes du sol et les indices d'erodabilite en relation avec la nature du substrat rocheux; (ii) determiner les proprietes geochimiques qui influencent l'erodabilite et (iii) evaluer l'effet de la profondeur du sol sur l'alternance des proprietes geochimiques et des indices d'erodabilite. Soixante- seize echantillons de sol provenant de 20 hetraies ont ete preleves dans 11 pays pour quantifier la texture et les proprietes physico-chimiques du sol. Quatre indices d'erodabilite ont ete utilises : le ratio d'argile, le ratio d'argile modifie, le ratio d'adsorption du sodium (Na) et le ratio d'oxydes. Les resultats indiquent que les proprietes du sol sont fortement influencees par le substrat rocheux et cette influence est plus grande que celle des autres facteurs abiotiques. Les plus importantes proprietes du sol qui sont correlees avec les indices d'erodabilite des sols forestiers sont : le carbone organique ([C.sub.org]), le pH, la conductivite electrique, les concentrations en ions calcium et Na, les cations hydrosolubles totaux et le pourcentage de sable. Selon les indices testes, l'erodabilite du sol suit la sequence suivante : granite > andesite > gres > quartzite > calcaire. Les indices montrent que cette sequence est accentuee en fonction de la profondeur dans le profil de sol. Les horizons les plus profonds sur les substrats rocheux granitiques sont plus erodables que les horizons de surface alors que ce n'est pas le cas des sols situes sur du calcaire. En conclusion, l'amenagement forestier devrait tenir compte des predispositions des differents types de sols a l'erosion. [Traduit par la Redaction] Mots-cles: substrat rocheux, changement environnemental, texture, matiere organique, geochimie, <>., Introduction At the forest site level, erodibility depends on the physical and chemical properties of soil, which are mainly a function of the bedrock material (Milodowski et al. 2015a, 2015b). [...]

Fagus sylvatica L. is widely distributed across Europe thanks to its high adaptability in a wide variety of soils and climate. Microbial communities are essential for maintaining forest soil quality and are responsible for forest ecosystem functioning; the ability of soil microorganisms to respond to abiotic stressors (e.g., organic carbon losses, water scarcity, temperature changes) is crucial under ongoing environmental changes and also supports tree health. In this study, soil samples were collected from pure beech plots as part of the COST Action project CLIMO to find differences in microbial community characteristics and evaluate the effects of soil properties on microbial communities across gradients of elevation, latitude, and longitude. Positive relationships were found between organic carbon content and both microbial abundance and dehydrogenase activity. Dehydrogenase and catalase activities were elevation-correlated and microbial activities were longitude-correlated. In the most southern beech plot, the microbial community was abundant and displayed high activities. This shows that microbial communities could help tree populations to better adapt to predicted changes in environmental conditions in the future. We suggest that research into forest health and beech performance should also test soil microbial enzymatic activity, particularly under changing climate conditions, to assist in identifying adaptation strategies. Key words: Fagus sylvatica, soil quality, soil enzyme activities, elevational, latitudinal, and longitudinal transects, soil microbial structure. Fagus sylvatica L. est largement present a travers l'Europe grace a sa capacite elevee d'adaptation a une grande variete de sols et de climats. Les communautes microbiennes sont essentielles au maintien de la qualite des sols forestiers et responsables du fonctionnement des ecosystemes forestiers; la capacite des microorganismes du sol de reagir aux stress abiotiques (p. ex. la perte de carbone organique, la penurie d'eau, les changements de temperature) est cruciale face aux changements environnementaux en cours et assure egalement la sante des arbres. Dans cette etude, des echantillons de sol ont ete preleves dans des parcelles de hetre en peuplement pur dans le cadre du projet CLIMO, une Action COST visant a trouver des differences entre les caracteristiques des communautes microbiennes et a evaluer les effets des proprietes du sol sur les communautes microbiennes le long de gradients elevational, latitudinal et longitudinal. Des relations positives ont ete observees entre d'une part la teneur en carbone organique et d'autre part l'activite de la deshydrogenase et l'abondance microbienne. L'activite de la deshydrogenase et de la catalase etait correlee avec l'elevation et l'activite microbienne etait correlee avec la longitude. Dans les parcelles de hetre les plus meridionales, la communaute microbienne etait abondante et tres active. Cela indique que les communautes microbiennes pourraient aider les populations d'arbres a mieux s'adapter aux changements prevus dans les conditions environnementales futures. Nous croyons que la recherche sur l'etat de sante des forets et la performance du hetre devrait egalement s'interesser a l'activite enzymatique microbienne dans le sol, particulierement dans le contexte des changements climatiques, pour aider a identifier des strategies d'adaptation. [Traduit par la Redaction] Mots-cles : Fagus sylvatica, qualite du sol, activite enzymatique dans le sol, transects elevational, latitudinal et longitudinal, structure microbienne su sol., Introduction Fagus sylvatica L. (European beech) is widely distributed in temperate regions in Europe, because it is sensitive to drought and high temperatures (Colin et al. 2017) and less sensitive [...]

Accurate measurement of forest growing stock is a prerequisite for implementing climate-smart forestry strategies. This study deals with the use of airborne laser scanning data to assess carbon stock at the tree level. It aims to demonstrate that the combined use of two unsupervised techniques will improve the accuracy of estimation supporting sustainable forest management. Based on the heterogeneity of tree height and point cloud density, we classified 31 forest stands into four complexity categories. The point cloud of each stand was further divided into three horizontal layers, improving the accuracy of tree detection at tree level for which we calculated volume and carbon stock. The average accuracy of tree detection was 0.48. The accuracy was higher for forest stands with lower tree density and higher frequency of large trees, as well as a dense point cloud (0.65). The prediction of carbon stock was higher with a bias ranging from -0.3% to 1.5% and a root mean square error ranging from 0.14% to 1.48%. Key words: tree detection, airborne laser scanning (ALS), forest structure, carbon stock, climate-smart forestry. La mesure precise du capital forestier en croissance est un prerequis a l'implantation de strategies forestieres intelligentes face au climat. Cette etude porte sur l'utilisation de donnees de balayage laser aeroporte pour evaluer le stock de carbone a l'echelle de l'arbre. Elle vise a demontrer que l'utilisation combinee de deux techniques non supervisees va ameliorer la precision de l'estimation sur laquelle s'appuie un amenagement forestier durable. Sur la base de l'heterogeneite de la hauteur des arbres et de la densite du nuage de points, nous avons classe 31 peuplements forestiers dans quatre categories de complexite. Le nuage de points de chaque peuplement a par la suite ete divise en trois couches horizontales, ce qui ameliore la precision de la detection de chacun des arbres pour lesquels nous avons calcule le volume et le stock de carbone. La precision moyenne de la detection des arbres etait de 0,48. La precision etait plus elevee pour les peuplements forestiers qui avaient une plus faible densite et une frequence plus elevee de gros arbres, ainsi qu'un nuage de points dense (0,65). La prediction du stock de carbone etait plus elevee avec un biais allant de -0,3 a 1,5 % et un ecart moyen quadratique (EMQ) entre 0,14 et 1,48 %. [Traduit par la Redaction] Mots-cles: detection des arbres, balayage laser aeroporte (BLA), structure de la foret, stock de carbone, foresterie intelligente face au climat., 1. Introduction In Europe, forests cover about 35% of the total land area (SoEF 2020) and play a significant role in climate change mitigation thanks to their capacity to remove [...]

Climate-smart forestry (CSF) is an emerging branch of sustainable adaptive forest management aimed at enhancing the potential of forests to adapt to and mitigate climate change. It relies on much higher data requirements than traditional forestry. These data requirements can be met by new devices that support continuous, in situ monitoring of forest conditions in real time. We propose a comprehensive network of sensors, i.e., a wireless sensor network (WSN), that can be part of a worldwide network of interconnected uniquely addressable objects, an Internet of Things (IoT), which can make data available in near real time to multiple stakeholders, including scientists, foresters, and forest managers, and may partially motivate citizens to participate in big data collection. The use of in situ sources of monitoring data as ground-truthed training data for remotely sensed data can boost forest monitoring by increasing the spatial and temporal scales of the monitoring, leading to a better understanding of forest processes and potential threats. Here, some of the key developments and applications of these sensors are outlined, together with guidelines for data management. Examples are given of their deployment to detect early warning signals (EWS) of ecosystem regime shifts in terms of forest productivity, health, and biodiversity. Analysis of the strategic use of these tools highlights the opportunities for engaging citizens and forest managers in this new generation of forest monitoring. Key words: climate change, early warning signals, ecosystem regime shifts, wireless sensor network, Internet of Things, citizen science, green technologies. La foresterie intelligente face au climat est une branche emergente de la gestion forestiere adaptative et durable dont l'objectif est d'accroitre la capacite des forets de s'adapter au changement climatique et d'en attenuer les effets. Cela comporte beaucoup plus d'exigences en termes de donnees que la foresterie traditionnelle. Ces exigences en matiere de donnees peuvent etre satisfaites grace a de nouveaux appareils qui permettent de surveiller la foret in situ en continu et en temps reel. Nous proposons un reseau complet de capteurs, c.-a-d. un reseau de capteurs sans fil, qui peut faire partie d'un reseau mondial d'objets interconnectes individuellement adressables, un Internet des objets (IdO) qui peut rendre les donnees disponibles presque en temps reel a de nombreux interesses, incluant des scientifiques, des forestiers et des gestionnaires forestiers, et qui peut en partie motiver les citoyens a participer a une importante collecte de donnees. L'utilisation de sources in situ de donnees de suivi comme donnees d'entrainement validees sur le terrain pour des donnees de teledetection peut favoriser la surveillance des forets en augmentant les echelles spatiale et temporelle, permettant ainsi une meilleure comprehension des processus forestiers et des menaces potentielles. Certains des developpements et applications cles de ces capteurs sont presentes dans cet article avec des directives pour la gestion des donnees. Des exemples de leur deploiement pour detecter les signaux d'alerte rapide des changements de regime des ecosystemes en ce qui a trait a la productivite, l'etat de sante et la biodiversite de la foret sont presentes. L'analyse de l'utilisation strategique de ces outils met en evidence les occasions d'interesser les citoyens et les gestionnaires forestiers a cette nouvelle generation de suivi des forets. [Traduit par la Redaction] Mots-cles : changement climatique, signaux d'alerte rapide, changement de regime des ecosystemes, reseau de capteurs sans fil, Internet des objets, science participative, technologies vertes., 1. Introduction Forests have traditionally been managed as large blocks with uniform treatments. This approach simplifies management but may miss shifts in forest dynamics over time; however, new technology permits [...]

On Mt. Etna (Italy), an enhanced Normalized Difference in Vegetation Index (NDVI) signature was detected in the summers of 2001 and 2002 along a distinct line where, in November 2002, a flank eruption subsequently occurred. These observations suggest that pre-eruptive volcanic activity may have enhanced photosynthesis along the future eruptive fissure. If a direct relation between NDVI and future volcanic eruptions could be established, it would provide a straightforward and low-cost method for early detection of upcoming eruptions. However, it is unclear if, or to what extent, the observed enhancement of NDVI can be attributed to volcanic activity prior to the subsequent eruption. We consequently aimed at determining whether an increase in ambient temperature or additional water availability owing to the rise of magma and degassing of water vapour prior to the eruption could have increased photosynthesis of Mt. Etnas trees. Using dendro-climatic analyses we quantified the sensitivity of tree ring widths to temperature and precipitation at high elevation stands on Mt. Etna. Our findings suggest that tree growth at high elevation on Mt. Etna is weakly influenced by climate, and that neither an increase in water availability nor an increase in temperature induced by pre-eruptive activity is a plausible mechanism for enhanced photosynthesis before the 2002/2003 flank eruption. Our findings thus imply that other, yet unknown, factors must be sought as causes of the pre-eruption enhancement of NDVI on Mt. Etna.

In Europe, mixed mountain forests, primarily comprised of Norway spruce (Picea abies (L.) Karst.), silver fir (Abies alba Mill.), and European beech (Fagus sylvatica L.), cover about 10 x [10.sup.6] ha at elevations between ~600 and 1600 m a.s.l. These forests provide invaluable ecosystem services. However, the growth of these forests and the competition among their main species are expected to be strongly affected by climate warming. In this study, we analyzed the growth development of spruce, fir, and beech in moist mixed mountain forests in Europe over the last 300 years. Based on tree-ring analyses on long-term observational plots, we found for all three species (i) a nondecelerating, linear diameter growth trend spanning more than 300 years; (ii) increased growth levels and trends, the latter being particularly pronounced for fir and beech; and (iii) an elevation-dependent change of fir and beech growth. Whereas in the past, the growth was highest at lower elevations, today's growth is superior at higher elevations. This spatiotemporal pattern indicates significant changes in the growth and interspecific competition at the expense of spruce in mixed mountain forests. We discuss possible causes, consequences, and silvicultural implications of these distinct growth changes in mixed mountain forests. Key words: climate change, competition shift, dominance of beech, growth trends, relative loss of Norway spruce. En Europe, les forets mixtes de montagne, surtout composees d'epicea commun (Picea abies (L.) Karst.), de sapin blanc (Abies alba Mill.) et de hetre commun (Fagus sylvatica L.), couvrent 10 x [10.sup.6] ha a des altitudes de ~600 a 1600 m ASL. Ces forets fournissent de precieux services ecosystemiques. Cependant, on s'attend a ce que la croissance de ces forets et la competition entre leurs principales especes soient fortement perturbees par le rechauffement climatique. Dans cette etude, nous avons analyse l'evolution de la croissance de l'epicea, du sapin et du hetre dans les forets mixtes humides de montagne en Europe au cours des 300 dernieres annees. Sur la base des analyses des cernes annuels des arbres dans des parcelles d'observation a long terme, nous avons note chez les trois especes (i) une croissance lineaire en diametre qui ne ralentit pas s'etendant sur plus de 300 ans; (ii) une croissance plus elevee, particulierement chez le sapin et le hetre et (iii) un changement dans la croissance du sapin et du hetre relie a l'altitude. Alors que dans le passe la croissance etait plus forte a basse altitude, elle est maintenant plus forte a haute altitude. Cette configuration spatio-temporelle temoigne de changements dans la croissance et la competition interspecifique aux depens de l'epicea dans les forets mixtes de montagne. Nous discutons des causes possibles, des consequences et des implications sylvicoles de ces changements marques dans la croissance des forets mixtes de montagne. [Traduit par la Redaction] Mots-cles : changement climatique, changement dans la competition, dominance du hetre, tendances de la croissance, perte relative d'epicea commun., 1. Introduction Intemperate Europe, mixed mountain forests of Norway spruce (Picea abies (L.) Karst.), silver fir (Abies alba Mill.), and European beech (Fagus sylvatica L.) connect the lowland beech forest [...]