Contrasting effects of wildfire and climate on radial growth of Pinus canariensis on windward and leeward slopes on Tenerife, Canary Islands

Abstract

Little is known concerning the effects of wildfires on tree radial growth and their climatic response under contrasting regimes of fog water inputs on oceanic islands. On Tenerife, Canary Islands, windward slopes are humid with high-fog frequency due to influence of wet trade winds, while climate on leeward slopes is more arid. We used tree-ring records of Pinus canariensis Sweet ex Spreng. to quantify the effects of a fire of known date on radial growth and determine the main limiting climatic factors for growth. Radial growth patterns and their responsiveness to fire severity and climatic variation differed between windward and leeward slopes. Surface fire did not significantly impact growth, while crown fire caused short-term growth reduction, and even cessation, more pronounced on the windward slope. Growth rates, tree-ring common signal, and climate sensitivity were smaller on the windward slope, with cold winters, and summer water stress limiting growth. On the leeward slope, climate explained a greater amount of growth variation mainly due to negative effects of high October–December sea-level pressures causing dry winter conditions. Contrasting growth dynamics on both slopes may result from diverging physiological effects of water inputs and reduced radiation caused by fog drip. Our findings suggest that dating growth suppressions and absent rings are useful to date past high-severity crown fires in P. canariensis forests, in addition to ordinary fire scars dating indicative of low-severity surface fires.