Located in southern France and bordering Spanish Catalonia, the Massane beech forest is one of the last old-growth forest of the Mediterranean basin and represents one of the southern populations of the European beech Fagus sylvatica in Western Europe. As such, it deserved special attention and a fine monitoring of its dynamics appeared especially relevant in the context of the ongoing climate change. As the team responsible for managing the Massane National Nature Reserve, we initiated a comprehensive inventory of its unmanaged forest stands in late 1998. This article aimed at presenting the methodology and monitored traits in order to shed light on this exhaustive and long-term monitoring approach. This survey encompassed all standing trees-both living and dead-as well as fallen dead wood within a 9.4 hectares area known as the integral reserve. The study extended along a 5.25 km stretch of the Massane River, covering an additional 19.4 hectares. The primary objective was to establish a detailed baseline of the forest composition, predominantly consisting of European beech (Fagus sylvatica). Collected data included dendrometric measurements, phenological stages, health assessments, and the presence and characteristics of various tree-related microhabitats (TreMs). These data were systematically stored in a Geographic Information System (GIS) and are regularly updated-semi-annually for tree decline and approximately every 12 years for dendrometric data. To date, 70,794 items have been cataloged across the 28.8 hectares study area, comprising 61,532 standing trees (alive or dead) and 9,262 pieces of fallen dead wood. This extensive data collection provides valuable insights into forest structure, dynamics (such as growth, intra-and interspecific competition, regeneration and decay), and the presence of parasitic and saprophytic fungi. It also allows for a nuanced understanding of dead wood distribution and various TreMs, including cavities and brown rot. By correlating these observations with data from the on-site weather station, we can finely assess the impacts of climatic related events, such as drought stress and phenological anomalies. The weather station, operational since 1959, has documented a nearly 2 degrees C increase in mean temperatures and a significant decline in precipitations since 2021, which may explain the changes observed in the stands, such as the decline of many trees. This ongoing monitoring initiative, underpinned by a robust cartographic database, forms the core of a unique forest observatory. The choice to conduct comprehensive inventories over substantial areas ensures a thorough representation of the forest's richness and complexity. Although initially labor-intensive, the endeavor has yielded significant results, fostering numerous scientific collaborations and encouraging continued commitment to this invaluable research.
climate change is rapidly driving species towards extinction, especially in vulnerable habitats like mountain regions such as the Pyrenees. With each degree of temperature rise, the threat accelerates, endangering diverse plant species. Due to their patrimonial importance and the susceptibility of mountainous species to climate and land-use changes, the conservation of endemic species in the Pyrenees is a crucial issue. Local populations of Pedicularis comosa in the Eastern Pyrenees provide an interesting biological model for studying climate change effects on mountain plant biodiversity. Here, an endemic pink-flowered morphotype described as Pedicularis comosa subsp. asparagoides coexists with the widely distributed, yellow-flowered Pedicularis comosa subsp. comosa. Because of its local-endemism, P. c. subsp. asparagoides is threatened as it is known to occur sporadically from a restricted number of sites in the Alb & egrave;res, the Salines Massif and the Canig & oacute; Massif. Our study highlights that climate change is a serious threat to P. c. subsp. asparagoides. Using Ecological Niche Modelling (ENM), we found that its current habitat could become unsuitable within less than two decades, outpacing the species' natural dispersal ability to newly suitable areas. Therefore, our findings suggest that conservation measures, such as assisted migration, are necessary to protect this unique morphotype.
Advancements in soil analytical techniques offer new insights into ecosystem structure, functions, and dynamics. Metabolomics has the potential to serve as a unique and efficient way to characterize the soil "chemical landscape." Thirty-three soil samples were collected from the Massane old-growth forest reserve, a UNESCO world heritage site located in the Eastern piedmont of the French Pyrenees. The study sites aimed to investigate three types of forest stands, namely beech forests, beech/oak stands, and mixed forest stands, subsets being also defined within stand types based on forest facies. We hypothesized that soil chemical heterogeneity would reflect forest spatial heterogeneity. Non-targeted metabolomics using liquid chromatography coupled with high-resolution tandem mass spectrometry (UHPLC-HRMS/ MS) and molecular network analyses were employed to map the chemical diversity across the sampled sites. This approach unveiled the presence of various compounds, including lipids (fatty acids and their derivatives, sphingolipids, prenol lipids, steroids), terpenoids (triterpenoids and sesquiterpenes), coumarins, and oligopeptides and lipopeptides. Along with the presence of a rich core metabolome, some heterogeneity was also underscored, suggesting unique chemical structures associated with specific types of sampling sites, notably mature beech stands. These results call for a deeper investigation into these specific compounds, with regards to their biological origin and the diversity and heterogeneity of soil microbial communities.
Semi-natural grasslands are threatened throughout Europe and conservation measures as well as monitoring are urgently needed. Leafhoppers (Auchenorrhyncha), a functionally important taxon with a close host plant connection and rapid reaction to changes in management, have increasingly received attention as bioindicators. We here present a case study in a Mediterranean mountain ecosystem, the R & eacute;serve Naturelle Nationale de la For & ecirc;t de la Massane, aiming to compile an inventory of its leafhopper species and to study the effects of cattle grazing on Mediterranean leafhopper communities. Leafhoppers were sampled in 2022 on 21 transects covering all of the habitats present in the reserve. A direct comparison was made between intensively grazed pastures and rocky outcrops inaccessible to cattle (12 and 4 transects respectively).The inventory increased the number of leafhopper species known in the reserve from 72 to 129. Species richness and abundance were significantly higher in the ungrazed areas. Grazed and ungrazed transects differed in their species composition with rare and in part endemic species only occurring on the ungrazed rocky outcrops. We conclude that a reduction of the grazing intensity in combination with shrub removal measures to keep the pastures open would have a positive effect of the leafhoppers and other invertebrates in the reserve and the surrounding Massif des Alb & egrave;res, where grazing pressure is similarly high.
Rivers transport a wide variety of materials, ranging from submillimeter-sized sediment particles to entire trees. The transported wood, constituting a vital component of wooded river ecosystems, constantly alters the morphology of watercourses and influences river flow. Given the inherently complex and varied nature of river systems, a thorough exploration of their diversity is justified to identify recurring trends in the dynamics of wood transport. This need becomes imperative in regions already facing prolonged episodes of drought, frequent heatwaves, and an increase in extreme precipitation events. In the specific context of the Massane River, a small Mediterranean mountain river, our study aimed to lay the groundwork for a long-term monitoring of in-stream wood transport by the watercourse. We began by inventorying the wood present in the riverbed in the upper part of the watercourse. This inventory involved measuring, identifying the species, assessing the state of degradation, and geolocating all the pieces of wood present. To estimate the transport, we introduced pieces of wood representative of the fraction of the stock that was potentially mobilizable, marked with RFID tags. The results indicate that wood was present almost throughout the considered section of the watercourse. About one-third of the total volume of the wood stock could be transported during a bankfull flood. RFID tracking revealed that a moderate rise in water level could move such pieces nearly 4 kilometers downstream. This work marks the initiation of a long-term monitoring effort to trace the movement of in-stream wood from the river's source to its estuary and examine the relationship between flood event types and the extent of wood transport.
