Alpine shrubs have benefited more than trees from 20th century warming at a treeline ecotone site in the French Pyrenees

Mountain ecosystems are particularly sensitive to climate change, which in part causes encroachment of woody plants at the treeline ecotone, with repercussions on advance and ecosystem carbon balance. Yet, studies investigating long-term trends radial growth as well year-to-year response several tree shrub species change scarce, especially Pyrenees where dendroecological hitherto critically lacking. Here, we estimate compare two (Rhododendron ferrugineum Juniperus communis) one (Pinus uncinata) species, investigate their changing climatic conditions advancing snow melt-out timings. We used Age-Class Isolation method (ACI) derive from ring width series trees shrubs. Climate-growth relationships were evaluated using fixed- moving-window bootstrap correlation functions aim determine effects snowpack growth. Overall, our results show that all site, shrubs, have grown increasingly over least last century, probably increasing temperatures during growing season earlier dates. Nevertheless, differ quite strongly climate. Whereas signal J. communis has been relatively stable recent decades despite persistent significant warming trend, R. shows a strong shift sensitivity is affected negatively by change. Altogether, address different most common shrubs Pyrenees. They also contribute better understanding vegetation dynamics Pyrenean ecotone context global