CR 56:197-207 (2013)  -  DOI: https://doi.org/10.3354/cr01158

ABSTRACT: Tree-ring growth of Pinus canariensis at high elevation on Tenerife, Canary Islands, is thought to be principally controlled by drought-induced stress. Aspect of mountain slopes on this oceanic island strongly influences local water input, with trade winds maintaining humid weather conditions on windward slopes, while leeward slopes remain much more arid. We tested whether P. canariensis tree-ring growth is controlled by local water availability and the large-scale climatic pattern of the North Atlantic Oscillation (NAO) along its elevation range on windward and leeward slopes on Tenerife. Wood cores were taken from 6 stands on windward and 6 on leeward slopes at elevations of 1120 to 1930 m. We found outstanding differences between windward and leeward slopes with regard to tree growth responses to local climate and NAO. Responsiveness to winter temperature was greater in windward stands, while tree growth in leeward stands was mainly controlled by total annual rainfall, which was strongly linked to NAO variation. Tree-ring growth was dependent on water input throughout the whole leeward slope, but elevation gradients were not relevant for tree growth dynamics. The unique exception was the lowest windward stand, located within the most humid environment on Tenerife, which experienced detrimental effects both of rainfall in late winter-spring and heat in summer. We conclude that slope aspect and exposure to trade winds are mostly driving P. canariensis growth. Prospects of growth of this species should consider that NAO-driven drought stress may affect populations on leeward slopes, where drier conditions could become limiting in the future.

KEY WORDS: Canary Islands pine · Dendrochronology · Drought stress · Elevation gradient · North Atlantic Oscillation · Subtropical mountain