Cloud Forest Tree Growth Responses to Climate and Drought Vary by Island and Species in the Macaronesian Region

Abstract

Aim: Macaronesian cloud forests are insular ecosystems subjected to local environmental variability, but the responses of theirtree species to climate variations have never been studied. Our aim was to assess how the variation in environmental conditionsassociated with the geographical location of several islands in three Macaronesian archipelagos affects the growth patterns anddrought-resistance of the dominant cloud forests trees. Location: Azores, Madeira and Canary archipelagos. Portugal and Spain.Taxon: Lauraceae, Aquifoliaceae, Clethraceae, Oleaceae, Rosaceae and Cupressaceae. Methods: We assessed variations in the radial growth response of 10 cloud forest tree species from 18 populations on 5 is-lands along a geographical gradient in Macaronesia. We quantified the influence of local climatic variables and North AtlanticOscillation (NAO) and East Atlantic Pattern (EA) circulation patterns on tree growth and how drought events affected to theresistance, recovery and resilience indices estimated for these species. Results: Trees from the same island showed similar growth patterns, particularly in islands with marked hydric stress. InMadeira and the Canary Islands, radial growth was mainly determined by water availability, winter NAO negatively affected