Morphogenetic trends in the morphological, optical and biochemical features of phyllodes in Acacia mangium Willd (Mimosaceae)

Abstract

International audienceEndogenous variations in the annual growth of trees suggest that similar trends would occur in phyllodes. In comparison to leaves, the characteristics of phyllodes are less well known, hence this study examines the effects of architectural position and age of tree on the phyllodes of Acacia mangium. Phyllodes were investigated on 1-, 2-, and 3-year-old trees from three axis positions within the crown. We focused on the morphological, optical and biochemical traits of the phyllodes. The increase in phyllode area and lamina thickness is more pronounced in the older trees. Leaf mass area (LMA), stomatal density, nitrogen and chlorophyll content increase with tree age. The values of these characteristics decrease from the main stem to the lower branches for the older trees. Phyllode light absorptance increased with tree age whereas reflectance was higher for the upper position compared to the lower position within the crown. Carotenoid content and chlorophyll a/b ratio were higher for the younger phyllodes of younger trees. Increasing tree size induced modifications in the phyllode characteristics which are influenced by both morphogenetic and light gradients within the crown. This study demonstrated pronounced changes in terms of morphological and functional indicators of photosynthetic capacity in relation to phyllode position within the crown and to tree age. These morphogenetic effects on the phyllode characteristics should be taken into account in studies on phenotypic plasticity

Non-destructive measurement of leaf area and dry biomass in Tectona grandis

“…For our study, the leaf mass area of the main stem (average of 0.019 g/cm 2 with a standard deviation of 0.002 g/cm 2 ) was higher than that of the branches (average of 0.014 g/cm 2 with a standard deviation of 0.003 g/cm 2 ). Our results back the results on the variability in leaf mass area linked to the architectural position and the axis category of the parent shoots (Leroy et al 2008).…”

Gravel pits support waterbird diversity in an urban landscape

“…The occurrence probabilities of each species were visualized on the SOM map in grey scale, and allowed us to analyse the effect of each species on the patterning input dataset (sites). The SOM was clustered using Ward's algorithm (Leroy et al, 2009). In order to bring out relationships between biological and environmental variables, we introduced the environmental variables into the SOM previously trained with bird occurrences (see Park et al, 2003).…”

Gravel pits support waterbird diversity in an urban landscape

“…The occurrence probabilities of each species were visualized on the SOM map in grey scale, and allowed us to analyse the effect of each species on the patterning input dataset (sites). The SOM was clustered using Ward's algorithm (Leroy et al, 2009). In arder to bring out relationships between biological and environmental variables, we introduced the environmental variables into the SOM previously trained with bird occurrences + + The 39 species recorded in our 11 gravel pits (Toulouse suburbs) appear in bold, + = presence.…”