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Drought is the major limiting factor for tree-ring growth of high-altitude Canary Island pines on Tenerife |
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| Authors: | Stig Jonsson Björn Gunnarson & Constantino Criado |
| Institution: | Department of Physical Geography and Quaternary Geology, Stockholm University, Stockholm, Sweden,;Department of Geography, University of La Laguna, La Laguna, Tenerife, Spain |
| Abstract: | This is a detailed study of 50 wood cores sampled from 25 Canary Island pines ( Pinus canariensis ) growing in a subtropical climate close to the tree limit (at Lomo de Retamar, 2000–2100 m a.s.l.) on the southern, leeward side of Tenerife. The Canary Island pines form tree-rings and, similarly to temperate pines, earlywood is formed during spring. But many pines fail to form tree-rings every year and one purpose for this paper has been to find a way to overcome this problem. Another purpose has been to see what correlations, if any, exist between the ring widths and meteorological data. Meteorological data have been collected since 1916 at the nearby Izaña meteorological observatory. It was also important to find the limiting factor for growth of Canary Island pines close to the tree limit. Through cross-dating, missing rings were found to be typical for younger parts of older trees; in the same years younger trees instead had low growth. Some trees lacked more than 20 rings in a century. This study shows that it is possible to compensate for missing rings, at least when the number of missing rings is less than 10%. Correlation studies showed that the growth of the tree rings was mainly due to the precipitation factor, particularly the annual precipitation one year before the ring formation, but also due to temperature. Strangely enough, multiple linear regression gave the highest correlation coefficient (0.50) for a combination of annual precipitation one year earlier and temperature four years earlier. |
| Keywords: | Pinus canariensis tree-rings missing tree-rings tree limit trade wind inversion polar front Mediterranean climate Tenerife Canary Islands |