Encroachment of shrubs into subalpine grasslands in the Pyrenees changes the plant-soil stoichiometry spectrum

Aims: shrub encroachment has been reported over a large proportion of the subalpine grasslands across Europe and is expected to have an important impact on the biogeochemical cycle of these ecosystems. We investigated the stoichiometric changes in the plant-soil system along the succession (e.g. increase in encroachment from unencroached grassland to mature shrubland) at two contrasting sites in the Pyrenees. - Methods: we analyzed the chemical composition (C, N,¹⁵N, P, K, Ca, Mg and Fe) in the soil and in the aboveground plant compartments (leaves, leaf-litter and stems) of the main herbaceous species and shrubs at three contrasting stages of the succession: unencroached grassland, young shrubland and mature shrubland. - Results: the plant-soil stoichiometry spectrum differed between the successional stages. Shrub encroachment generally increased the concentration of C and Ca and the C:N ratio and often reduced to concentrations of N, P and K in the leaves and leaf-litter, while several soil nutrient concentrations (N, P, K Ca and Mg) decreased. The stocks of C, N, P, Ca, and Mg in the total aboveground biomass increased with encroachment. - Conclusions: shrub encroachment favored the dominance of long-lived species with low concentrations of N and P in the plant-soil compartments, high C:nutrient ratios in the aboveground biomass and increase the uptake of N through ericoid or ectomycorrhizal fungi. We highlight the role of shrubs in the sequestration of C and nutrients through the allocation to the aboveground biomass. The changes in plant-soil elemental composition and stocks suggest a slowdown of the biogeochemical cycles in the subalpine mountain areas where shrub encroachment occurred

Organic wild species crops: A tool to recover traditional knowledge, and to enhance biodiversity, food security and sustainable rural development

In the context of intense ecological and socioeconomic changes on Mediterranean regions, we performed semi – structured interviews to recuperate the traditional knowledge of plants. We analyse the reported species (and those added from the literature) to evaluate their ecological appropriateness for cultivation, and their ecological and market value. We selected the 46 species (35 of them reported by the informants) that scored high for organic cultivation. These results indicate the high potential of wild species to develop new ecological and economical valuable crops, and the high value of traditional knowledge as an information source.Keywords: Agroecology, NUS (Neglected and Underutilized Species), ethnobotany, organic farming, Mediterranean landscap

Syntaxonomic conspectus of the vegetation of Catalonia and Andorra. II: Ruderal communities

This paper deals with plant communities settling on ruderalized sites, such as crop fields, edges of roads or paths, forest clearings, river banks, and other disturbed areas. We report all the phytosociological associations and subassociations recorded from Catalonia and Andorra, as the second part of a general vegetation survey, started with Ninot et al. (2000). For each community, we provide the correct name and usual synonyms, its typification (where appropriate), all the references including relevés, and the most outstanding features of its structure, species composition, ecology, distribution and diversity. Moreover, associations and subassociations are ordered in a syntaxonomic scheme. Syntaxonomic ranks are considered in a fairly broad, conservative sense. This classification established 156 associations and 6 informal community types, which correspond to the classes Oryzetea sativae, Stellarietea mediae, Sisymbrietea officinalis, Artemisietea vulgaris, Cakiletea maritimae, Saginetea maritimae, Pegano-Salsoletea vermiculatae, Bidentetea tripartitae, Polygono-Poetea annuae, Rudero-Manihotetea utilissimae and Epilobietea angustifolii. Complementarily, we propose corrections of names when appropriate, and eventually formalize the description of a few syntaxa

Syntaxonomic conspectus of the vegetation of Catalonia and Andorra. II: Ruderal communities

This paper deals with plant communities settling on ruderalized sites, such as crop fields, edges of roads or paths, forest clearings, river banks, and other disturbed areas. We report all the phytosociological associations and subassociations recorded from Catalonia and Andorra, as the second part of a general vegetation survey, started with Ninot et al. (2000). For each community, we provide the correct name and usual synonyms, its typification (where appropriate), all the references including relevés, and the most outstanding features of its structure, species composition, ecology, distribution and diversity. Moreover, associations and subassociations are ordered in a syntaxonomic scheme. Syntaxonomic ranks are considered in a fairly broad, conservative sense. This classification established 156 associations and 6 informal community types, which correspond to the classes Oryzetea sativae, Stellarietea mediae, Sisymbrietea officinalis, Artemisietea vulgaris, Cakiletea maritimae, Saginetea maritimae, Pegano-Salsoletea vermiculatae, Bidentetea tripartitae, Polygono-Poetea annuae, Rudero-Manihotetea utilissimae and Epilobietea angustifolii. Complementarily, we propose corrections of names when appropriate, and eventually formalize the description of a few syntaxa

Abrupt changes in the composition and function of fungal communities along an environmental gradient in the High Arctic

Fungi play a key role in soil-plant interactions, nutrient cycling and carbon flow and are essential for the functioning of arctic terrestrial ecosystems. Some studies have shown that the composition of fungal communities is highly sensitive to variations in environmental conditions, but little is known about how the conditions control the role of fungal communities (i.e., their ecosystem function). We used DNA metabarcoding to compare taxonomic and functional composition of fungal communities along a gradient of environmental severity in Northeast Greenland. We analysed soil samples from fell fields, heaths and snowbeds, three habitats with very contrasting abiotic conditions. We also assessed within-habitat differences by comparing three widespread microhabitats (patches with high cover of Dryas, Salix, or bare soil). The data suggest that, along the sampled mesotopographic gradient, the greatest differences in both fungal richness and community composition are observed amongst habitats, while the effect of microhabitat is weaker, although still significant. Furthermore, we found that richness and community composition of fungi are shaped primarily by abiotic factors and to a lesser, though still significant extent, by floristic composition. Along this mesotopographic gradient, environmental severity is strongly correlated with richness in all fungal functional groups: positively in saprotrophic, pathogenic and lichenised fungi, and negatively in ectomycorrhizal and root endophytic fungi. Our results suggest complex interactions amongst functional groups, possibly due to nutrient limitation or competitive exclusion, with potential implications on soil carbon stocks. These findings are important in the light of the environmental changes predicted for the Arctic

La vegetació de les serres prepirinenques compreses entre els rius Segre i Llobregat. 3 - Comunitats ruderals i arvenses

Continuant els articles dedicats - - a I'estudi fitocenolbgic de I'irea ureuirinenca L. . . comuresa entre les valls del Segre i el Llobregat, - recollim aquí les dades relatives a la vegetació segetal i a la vegetació ruderal, incloent-hi les vorades subnitrbtiles i els horts. A I'irea estudiada, aquests tipus de vegetació es troben representats sobretot a les parts baixes i perifhiques, sotmeses a una influttncia humana més forta, i són molt més rars (i menys diversos) a I'alta muntanya..