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Abstract:
Tree architecture has important consequences
for tree performance as it determines resource
capture, mechanical stability and dominance over
competitors. We analyzed architectural relationships
between stem and crown dimensions for 13 dominant
Iberian canopy tree species belonging to the Pinaceae
(six Pinus species) and Fagaceae (six Quercus species
and Fagus sylvatica) and related these architectural
traits to wood density, shade tolerance and climatic
factors. Fagaceae had, compared with Pinaceae,
denser wood, saplings with wider crowns and adults
with larger maximal crown size but smaller maximal
height. In combination, these traits enhance light
acquisition and persistence in shaded environments;
thus, contributing to their shade tolerance. Pinaceae
species, in contrast, had low-density wood, allocate
more resources to the formation of the central trunk
rather than to branches and attained taller maximal
heights, allowing them to grow rapidly in height and
compete for light following disturbances; thus, contributing
to their high light requirements. Wood
density had a strong relationship with tree architecture,
with dense-wooded species having smaller maximum
height and wider crowns, probably because of cheaper
expansion costs for producing biomechanically stable
branches. Species from arid environments had shorter
stems and shallower crowns for a given stem diameter,
probably to reduce hydraulic path length and assure water transport. Wood density is an important correlate
of variation in tree architecture between species
and the two dominant families, with potentially large implications for their resource foraging strategies and successional dynamics.
