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Stem mechanics, functional anatomy and ecology of Alnus viridis and Alnus glutinosa
Author(s) -
Brüchert F.,
Gallenmüller F.,
Bogenrieder A.,
Speck T.
Publication year - 2003
Publication title -
feddes repertorium
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.24
H-Index - 25
eISSN - 1522-239X
pISSN - 0014-8962
DOI - 10.1002/fedr.200390021
Subject(s) - alnus glutinosa , interspecific competition , intraspecific competition , biology , herbivore , alder , botany , flexural rigidity , ecology , composite material , materials science
Mechanical properties, the internal stem structure and the wood anatomy of stems of Alnus glutinosa from the Black Forest and of two populations of Alnus viridis from the Black Forest and from the Swiss Alps are compared as to their ecological significance. The mechanical bending properties are characterised by the parameters “flexural stiffness” ( E struct · I ax ) and “structural modulus of elasticity” ( E struct ). The structural modulus of elasticity increases significantly for all three populations during the first years of growth and becomes approximately constant in stems being five years old and older. These ontogenetic variations of the bending mechanical properties are affected by changes of the internal stem structure, i.e. by changes of the amount and distribution of plant tissues with different mechanical properties within the cross section, described by the axial second moment of area ( I ax ) which weights the position of the tissues by their distance to the neutral plane. The contribution of bending‐stiff wood towards the axial second moment of area increases during the first years of growth whereas the contribution of the more bending flexible bark decreases. With further increasing age, i.e. in five years old and older stems, the distribution of tissues remains approximately constant as do the mechanical properties. Comparing the different species or populations, respectively, the interspecific difference between A . glutinosa and A . viridis from the same regional origin (Black Forest) are much smaller than the intraspecific differences between the two A . viridis populations from the Black Forest and from the Alps. Significant differences between the two species from the Black Forest are only found in the structural modulus of elasticity of 5–7 year old stems. In contrary, in most ontogenetic stages significant differences are found in all tested mechanical and anatomical parameters between A . viridis from the Black Forest and A . viridis from the Alps. The differences may be due to the different environmental conditions in high elevated sites in the Alps compared to lower sites in the Black Forest. However, the observed differences may also originate from a genetic differentiation into two different ecotypes in A. viridis .