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