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

Urbina Ifigenia, Grau Oriol, Sardans Jordi, Ninot Josep M., Peñuelas Josep. 2020. Encroachment of shrubs into subalpine grasslands in the Pyrenees changes the plant-soil stoichiometry spectrum. Plant and Soil, 448 (1-2) : 37-53.

Quartile : Q1, Sujet : AGRONOMY / Quartile : Q1, Sujet : PLANT SCIENCES / Quartile : Q2, Sujet : SOIL SCIENCE

Résumé : 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.

Mots-clés Agrovoc : arbuste, composition chimique, plante herbacée, brousse

Mots-clés géographiques Agrovoc : Pyrénées

Mots-clés libres : Shrub encroachment, Plant-soil stoichiometry, Nutrient stocks, Subalpine grassland succession, Plant strategy

Agences de financement européennes : European Research Council

Agences de financement hors UE : Gobierno de España, Generalitat de Catalunya, Organismo Autónomo de Parques Nacionales

Projets sur financement : (EU) Effects of phosphorus limitations on Life, Earth system and Society, (ESP) Arbustos de alta montaña: entender su biología nos permite prever los cambios de paisaje

Auteurs et affiliations

• Urbina Ifigenia, CREAF (ESP) - auteur correspondant
• Grau Oriol, CIRAD-ES-UMR Ecofog (GUF)
• Sardans Jordi, CREAF (ESP)
• Ninot Josep M., UB (ESP)
• Peñuelas Josep, CREAF (ESP)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/614864/)

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