Effects of canopy history and climate on radial growth patterns of Fagus sylvatica L. and Quercus robur L.

Abstract

Radial growth patterns and the effects of canopy history and climate on the growth of beech (Fagus sylvatica L.) and oak (Quercus robur L.) in a mature forest in the Cantabrian lowlands, were studied. Tree ages ranged between 150 to 270 years, and their diameters were of up to 86 cm in beech and 129 cm in oak. The most frequent growth pattern in beech showed a conspicuous rising trend since 1900 to nowadays. This pattern was a consequence of disturbances that occurred in 1929, 1956 y 1978, which accounted for a significant increment in beech growth rates above those expected from random observations. On the other hand, oak growth was only slightly affected by canopy history. The most abundant growth patterns were negative exponential or monotonic descendent, which could be expected for oak in the absence of disturbances. Also, only 26% of the radial growth patterns of oak showed disturbance signals. The climate variability accounted for 28.4% of beech’s ring-width variation and 26.7% of oak’s one. Precipitation in July showed a positive effect on oak radial growth, while beech growth was negatively related to temperature in June-July. These results suggested the feasible effects of climate warming on the productivity of natural forests.