Search

Key message: Presence of Phytophthora ramorum (Werres, De Cock, and Man in 't Veld) in western France was studied after the detection of this invasive pathogen in 2017 in Larix kaempferi (Lamb.) and eradication of the affected stands. P. ramorum was seldom detected in the area of the outbreak in the year following eradication. However, we confirm that P. ramorum can multiply to epidemic level on chestnuts (Castanea sativa Mill.) in the absence of larch (Larix spp.). This represents the major risk in France. Context: Phytophthora ramorum is an invasive oomycete that causes significant damage in the USA and Europe. Although the pathogen has been present in nurseries in France since 2002, the first outbreaks in forest stands were identified in 2017 in plantations of Larix kaempferi in two forests in western France (Saint-Cadou and Hanvec). In order to limit the development of the epidemic, neighboring larch stands were clear-cut. Aim: This study investigated the presence of P. ramorum in the affected area after the eradication treatment. Methods: Larch stands located within a 18-km radius of the reported outbreaks were investigated. We also monitored the native woody hosts present in infected clear-cut larch stands and in the vicinity of seven ornamental nurseries that had been infected by P. ramorum on several occasions in the past. Results: Overall, a very limited presence of P. ramorum was detected in 2018–2021. Two new stands of infected L. kaempferi were found close to the main initial outbreak, in Saint-Cadou and Saint-Rivoal. The pathogen was only detected on rhododendrons and chestnut trees (Castanea sativa Mill.) in the vicinity of the outbreaks. In the Saint-Cadou state Forest, an outbreak of the disease developed in 2019–2021 on chestnut trees even though all the mature larch trees had been felled. P. ramorum was also detected near two of the formerly infected ornamental nurseries, on Castanea sativa and on rhododendrons. Conclusion: While larches and rhododendrons are uncommon in the forests of north-western France, chestnut trees are present in 21–25% of the forest and therefore represent the major risk for the survival of P. ramorum in the region. [ABSTRACT FROM AUTHOR]

The chronicle presents the most important results of the colloquium entitled “Le bois, source de ressource durable - un acteur de la transition” and carried out as part of the exchanges started in 2019 between SCNF (Société nationale des chemins de fer français) and the Franco-Japanese Society of industrial techniques. The colloquium included the actual conference, hosted in Versailles (October 23-25), as well as two field days in the Lorraine region (north-east France) (October 26-27). The host of the colloquium was the École nationale supérieure de paysage (ENSP), a higher education institution created in 1976 and operating in the premises of the former École nationale supérieure d’horticulture, established in Versailles in 1874. The event in Versailles aimed to address the issue of ensuring and rational and sustainable use of wood resources, taking into account aspects related to biodiversity and the social functions of forests. Consequently, the colloquium proposed an exchange of ideas between the “actors” who participate in the production and transformation of “this material with exceptional qualities” and its end users. The three days of the conference took place in three directions: (i) historical and social approach to forests, (ii) reconciliation of wood resources with biodiversity and (iii) anticipation, with numerous presentations related to the mentioned themes. The colloquium continued with a field trip to the Lorraine region of France, where the host of the first day of the field visit was the Champenoux Station of the Grand Est-Nancy Research Center of INRAe, the agricultural, food and environmental research body, including forestry, of France. Here we were introduced to the activity of the station, which houses three forest research units, the laboratories in its premises, as well as the nearby Amance Arboretum. On the last day, the participants traveled to the Forêt de Haye, a forest massif of approximately 11,000 ha, of which 6,500 ha are state forests, located near Nancy. Among the most suggestive aspects of the field visit, we can mention (i) the possibility of harvesting thinning trees with the help of harvesters, after marking the trees to be extracted with paint and opening the skidding trails, (ii) the special problems with the dieback of European beech, especially on very shallow soils (only 20-30 cm of mineral soil), against the background of the long-term lack of precipitation during the growing season, (iii) the special interest given to rare and valuable tree species such as Sorbus torminalis or Sorbus domestica during the application of tending operations, species whose growth in thickness is favored by interventions from above, following the provision of free growth state (without competition) at the crown level. [ABSTRACT FROM AUTHOR]

We present a data set resulting from the first round of a national monitoring program of forest reserves. It contains 9538 permanent plots, distributed across 111 study sites in mainland France (including Corsica). Notably focusing on dead wood measurement, this protocol has primarily been applied in strict forest reserves and special nature reserves (sensu Bollmann & Braunisch 2013), with 68% (6494) of the plots being currently located in strict forest reserves (unmanaged) and 24.7% (2363 plots) in forests unmanaged for at least 50 years. Sites cover a large variety of ecological conditions, from lowland to subalpine forests, but with an underrepresentation of Mediterranean forests (Table 1). The protocol assesses all the stages of a tree's life cycle, from seedling to decomposed lying dead wood. On each plot, a combination of three sampling techniques was used: (1) fixed‐area inventory for regeneration, standing dead trees, living trees, and coarse woody debris (CWD) with diameter over 30 cm; (2) transect lines for CWD with diameter <30 cm; and (3) fixed‐angle plot method for living trees with diameter at breast height (DBH) >30 cm (using a relascopic angle of 3%). Measurements include exact tree location (azimuth, distance), species, diameter(s), tree‐related microhabitats, decay stage and bark cover, and seedling cover. With ongoing climate change, the program network can also provide important information to monitor changes in forest ecosystems. It can also be used as forest management monitoring or conservation status assessment. These data are freely available for noncommercial scientific use (Creative Commons Attribution 4.0 CC BY SA 4.0) with attribution, and this paper must be cited if this material is reused. [ABSTRACT FROM AUTHOR]

Changes that occur on the local level can explain the processes on the population level and, at the same time, are the driving force of species adaptation. This manuscript reports data about genetic diversities of the fungus Schizophyllum commune on the level of a local population. Objects of the study were dicarious cultures of S. commune collected from 38 basidiocarps grown on the territory of Holosiivskyi National Nature Park, Lysa Hora Regional Landscape Park and Feofaniya forest parcel (Ukraine). Results showed similarity of genetic variability of S. commune in different local populations. The heterozygote deficiency of some loci that was discovered might have resulted from new forms of allozymes that have not become widespread or due to small population sizes. The degree of differentiation of genes between local studied populations was moderate due to the high flow of genes. The absence of spatial structuration of genotypes is established, and the Mantel test showed a lack of interconnection between the genetic component and the geographical coordinates of the samples. It has been suggested that wind direction and terrain are the factors that influence the genetic structure of local populations. [ABSTRACT FROM AUTHOR]

The sampling intensity of a national forest inventory is usually low. Forest dynamics models can be used to update plots from past inventory campaigns to enhance the precision of the estimate on smaller areas. By doing this, however, the inference relies not only on the sampling design, but also on the model. In this study, the contribution of model predictions to the variance of enhanced small-area estimates was assessed through a case study. The French national forest inventory provided different annual campaigns for a particular region and department of France. Three past campaigns were updated using a forest dynamics model, and estimates of the standing volumes were obtained through two methods: a modified multiple imputation and the Bayesian method. The update greatly increased the precision of the estimate, and the gain was similar between the two methods. The sampling-related variance represented the largest share of the total variance in all cases. This study suggests that plot updating provides more precise estimates as long as (i) the forest dynamics model exhibits no systematic lack of fit and was fitted to a large data set and (ii) the sampling-related variance clearly outweighs the model-related variance. [ABSTRACT FROM AUTHOR]

Abstract Soil thickness (ST) is a crucial factor in earth surface modelling and soil storage capacity calculations (e.g., available water capacity and carbon stocks). However, the observed depths recorded in soil information systems for some profiles are often less than the actual ST (i.e., right censored data). The use of such data will negatively affect model and map accuracy, yet few studies have been done to resolve this issue or propose methods to correct for right censored data. Therefore, this work demonstrates how right censored data can be accounted for in the ST modelling of mainland France. We propose the use of Random Survival Forest (RSF) for ST probability mapping within a Digital Soil Mapping framework. Among 2109 sites of the French Soil Monitoring Network, 1089 observed STs were defined as being right censored. Using RSF, the probability of exceeding a given depth was modelled using freely available spatial data representing the main soil-forming factors. Subsequently, the models were extrapolated to the full spatial extent of mainland France. As examples, we produced maps showing the probability of exceeding the thickness of each GlobalSoilMap standard depth: 5, 15, 30, 60, 100, and 200 cm. In addition, a bootstrapping approach was used to assess the 90% confidence intervals. Our results showed that RSF was able to correct for right censored data entries occurring within a given dataset. RSF was more reliable for thin (0.3 m) and thick soils (1 to 2 m), as they performed better (overall accuracy from 0.793 to 0.989) than soils with a thickness between 0.3 and 1 m. This study provides a new approach for modelling right censored soil information. Moreover, RSF can produce probability maps at any depth less than the maximum depth of the calibration data, which is of great value for designing additional sampling campaigns and decision making in geotechnical engineering. Highlights • We present a new approach for modelling right censored soil information • The probability of exceeding a given thickness was mapped using random survival forest • This approach avoided underestimating soil thickness at censored positions • This probability was well predicted, especially for thin and very thick soils • The new approach can be adopted into the Digital Soil Mapping framework [ABSTRACT FROM AUTHOR]

Over the past centuries in Western Europe, the long history of forest management has shaped both landscape- and local-scale forest structures. In France, a network of strict forest reserves was created in the 1950s to serve as a reference for nature conservation and forest dynamics. However, few studies to date have quantitatively compared the structural characteristics between managed stands and the reserves, where management has been (more or less recently) abandoned. In addition, the time needed for old-growth characteristics to restore themselves in strict forest reserves remains poorly known. We analysed the differences in stand characteristics between managed and unmanaged stands in 17 French forests (233 plots) located in both lowland and in mountainous regions. We quantitatively showed that overall basal area, very large trees and deadwood features were significantly higher in unmanaged forests, though this pattern was mainly found in the lowland forests while in mountainous regions, managed and unmanaged forests showed far fewer differences. In addition, most structural characteristics that were higher in unmanaged forests also increased with the time since last harvesting. Compared to the remaining old-growth forests elsewhere in Europe, the strict forest reserves in France often appear less mature, since they are still recovering from centuries of intensive management. Our results also show lower levels than those observed in other European studies on the restoration of old-growth characteristics over time; this indicates that it will take French reserves a very long time to reach values comparable to old-growth references in Europe. Our study constitutes one of the first references on unmanaged forests in France and may serve practitioners in their everyday management. [ABSTRACT FROM AUTHOR]

Ancient forests are known to host a biodiversity of high ecological distinctiveness and are likely to provide habitat for red-listed species. Yet, few studies have investigated the role of forest continuity for the conservation of threatened species. We used species-presence data on red-listed species from 12 taxonomic groups (Spermatophyta, Pteridophyta, Bryophyta, Lichens, Chiroptera, Aves, Squamata, Amphibia, Coleoptera, Lepidoptera, Odonata and Orthoptera) to ascertain if ancient forests are an important habitat for threatened species in five mountain and subalpine protected areas in France. We compared the effect of the amount of historical forest (1853–1860) with the effect of the amount of current forest on the distribution of red-listed species in six circular landscape buffers ranging in radius from 100 to 1500 m. We showed that the amount of historical forest in the landscape had a positive effect on forest Spermatophyta, Bryophyta, Coleoptera and edge forest Pteridophyta with a better predictive power than current forest area, highlighting a colonization credit in recent forests. Conversely, edge-forest lepidopterans were more negatively affected by historical than by current forest area, highlighting an extinction debt in recent forests. Our findings underline that implementing protective measures of ancient forests would be a better strategy than afforestation to preserve threatened forest species in mountain and subalpine forest landscapes. [ABSTRACT FROM AUTHOR]

Abstract: Changes in forest growth have been found in European forests and worldwide. However most observations have been derived from samples of restricted size, whose representativeness at a regional forest scale is questionable. National forest inventories provide an interesting perspective for both regional scale assessment of these trends and the investigation of their variations over environmental gradients, but have been little used. The aim of our work was to carry out an exploratory modelling analysis of productivity changes, based on the French national forest inventory data. The objectives were: (i) to assess recent trends in forest productivity and to investigate a possible recent decline as found in previous studies; and (ii) to investigate trend variations relative to site fertility factors. We focused on pure and even-aged stands of common beech (Fagus sylvatica L.) in north-eastern France, already documented from previous studies based on retrospective data. The dataset consisted of 925 temporary plots inventoried between 1979 and 2007. We developed two regression models of stand basal area increment (BAI) against stand developmental stage (dominant height), site fertility (site index in the SI model, environmental indicators in the EI model) and stand density (relative density index). The effect of calendar date was tested in order to investigate possible historical trends. Site fertility–date interactions were also tested to investigate the site-dependence of trends. The fitted models showed a high goodness of fit (adj. R 2 over 0.69). We showed an increase in stand BAI of 27.8% between 1977 and 1987, (10.4% between 1979 and 1987). Stand BAI then decreased by approximately 5% between 1987 and 2004. We thus confirmed the hypothesis of a recent decline in common beech vitality in its temperate range. The chronologies clearly depicted the effect of severe drought events (1976 and 2003), pointing out the predominant role of water availability in the changes observed. No significant site-dependence of the trend was identified. [Copyright &y& Elsevier]

This article discusses the ecological and cultural criteria underlying the management practices for protected areas in France. It examines the evolution of French conservation from its roots in the 19th century, when it focused on the protection of scenic landscapes, to current times when the focus is on the protection of biodiversity. However, biodiversity is often socially defined and may not represent an ecologically sound objective for conservation. In particular, we question the current approach to protecting a specific type of biodiversity that is at the basis of traditional landscape but does not value systems that are left to develop naturally (i.e., without significant human intervention). We present several examples of current attempts in France and Europe to managing traditional ecosystems and then discuss the values that exist in systems that develop naturally. We feel the latter systems often have much to offer in terms of biodiversity as well as providing important sites for the study of dynamic ecological communities in an ever-changing world. [ABSTRACT FROM AUTHOR]

Investigates fallen dead wood levels in the near-natural beech forest at La Tillaie reserve in Fontainebleau, France. Domination of old-growth beech-ash or beech-oak; Abundance of fallen dead wood despite rapid decay of beech.

Details travel-related information on Paris, France. Description of Versailles, France; Accommodations; Features of the Forest of Rambouillet.

The article offers information on the Forest of Rambouillet, one of the loveliest forests in France, and Château of Rambouillet. It says that forests stretch from the valley of the Eure to the high valley of Chevreuse with lakes, copses of deer and wild boar. It mentions that the château has been surrounded by a park with woodwork throughout the château and tapestries on the wall. It adds that the La Poste restaurant has provided meals for tourists.