Respuesta de los bosques mixtos de Quercíneas a los cambios en el clima.

Abstract

Recent changes in climate have induced mortality episodes affecting many oak forests worldwide. However, and despite the ecological importance of these ecosystems, there is scarce information regarding the current health status of oak forests and their response to extreme climate events over time. Quercus canariensis is a deciduous oak, sensitive to summer drought characteristic of Mediterranean climate, currently showing growth decline and defoliation or mortality episodes. Here, we investigated how radial growth respond to climate and the changes in resilience to extreme drought events over time in five sites in “Los Alcornocales” Natural Park (Spain) using a dendrochronological approach. This study shows how the microclimate and latitudinal gradient affect to growth and determine the health status of the different populations using the resilience index. Our results show that although the temperature is steadily increasing since 1950, the growth in Q. canariensis is mainly limited by low temperatures and, surprisingly, there is only a weak effect of precipitation at some sites. Q.canariensis resilience to extreme droughts is overall decreasing since 1970, resulting in a reduced capacity to recover pre-drought growth. These conditions preceded growth declines in some populations, indicating that trees are vulnerable to the observed aridification trend. By the use of growth analyses, we have detected early-warning signals of decline for this Mediterranean oak highlighting the most sensitive populations to further changes in climate.