Is the upper timberline in subtropical mountains induced by drought? - A case study of Pinus canariensis along its elevation range in Tenerife, Canary Islands

• Main Authors: Pérez de Lis, Gonzalo, Rozas Ortiz, Vicente Fernando, García-González, Ignacio, Arévalo, José Ramón
• Other Authors: Association for Tree-Ring Research (ATR)
• Format: Conference Object
• Language: unknown
• Published: 2012
• Subjects: Burgess; Morales; North Atlantic; North Atlantic oscillation
• Online Access: http://hdl.handle.net/10261/99146

Comunicación presentada en Postdam y Eberswalde (Alemania) del 9 al 12 de mayo de 2012. Tree growth of Pinus canariensis forests on Tenerife, Canary Islands, has been suggested as being mainly controlled by physiological limitations due to drought-induced stress (Jonsson et al. 2002), in agreement with the general pattern for subtropical mountains (Morales et al. 2004). Aspect of mountain slopes harshly influences local water input and controls vegetation distribution (Fernández-Palacios & de Nicolás 1995). Trade winds maintain humid weather conditions on windward slopes, while leeward slopes remain much more arid (Aboal et al. 2000). In this study, we assessed the effects of local climate and the North Atlantic Oscillation (NAO) on the radial growth of P. canariensis along its elevation range on both windward and leeward slopes in Tenerife. Wood cores were taken from six stands on windward, and six on leeward in even-aged afforestations between 1000 and 2000 m a.s.l. Total tree-ring widths were used to explore common patterns of growth behaviour, using principal component analysis in the common period 1967¿2006. Tree-ring growth responses to climate were evaluated by correlation analysis. We used monthly gridded time series of mean (T) and maximum (Tmax) temperatures, precipitation (P), sea level pressure (SLP), vapour pressure (VP), and the NAO index. Great differences in climate-driven growth patterns and their responses to local and large-scale climate variation were noted between slopes, with greater responsiveness to winter Tmax and VP on windward, but to annual P, autumn-winter SLP and NAO on leeward. This is probably due to the contrasting physiological effects of water inputs and radiation on both slopes caused by fog drip (Burgess & Dawson 2004). By contrast, altitudinal gradients showed to be irrelevant on tree growth, with the only exception of the lowest stand on windward. We conclude that physiological limitations due to slope aspect, but not to increasing elevation, are mostly driving P. ...