The n-alkane concentrations in buds and leaves of browsed broadleaf trees

Abstract

The concentration of n-alkanes in the cuticular wax of plants can be used to estimate the composition of the diet selected by free-ranging animals. The aims of this study were to characterize the n-alkane profiles of developing leaves and evaluate the degree of chemical discrimination between six browsed broadleaf tree species: European ash (Fraxinus excelsior L.), flowering ash (Fraxinus ornus L.), hornbeam (Carpinus betulus L.), hazel (Corylus avellana L.), mountain ash (Sorbus aucuparia L.) and beech (Fagus sylvatica L). The effect of the stage of development was examined by considering five different vegetative stages: dormant bud (DB), late bud (LB), young leaf (YL), mature leaf (ML) and senescing leaf (SL). Five samples per each vegetative stage and species, gathered in a mixed woodland of the Italian Eastern Alps between February and October, were analysed for their n-alkane concentrations (C23-C36). The residual coefficient of variation was 15.5% on average for the individual n-alkanes considered. There were noticeable differences in individual and total n-alkanes content between species. In particular, C27 was the predominant n-alkane in beech and C33 was found in high proportions in the two species of Fraxinus; hazel and flowering ash had a higher total n-alkanes content than the overall mean, while the lowest values were found in hornbeam and beech. The n-alkane profile also underwent important changes during the vegetative development, with different extent and direction according to the species. In the three successive leaf stages, a tendency for a progressive increase in the longest chain homologues was observed. In any case, the young leaf stage differed most from the contiguous stages. Canonical discriminant analysis indicated that the n-alkane profile of buds and leaves were mathematically distinguishable and the chemical differences between species were persistent over the plant vegetative development

Predicting leaf wax n‐alkane 2H/1H ratios: controlled water source and humidity experiments with hydroponically grown trees confirm predictions of Craig–Gordon model

“…We compiled peak areas of high-molecular weight n-alkanes in order to quantify variations in distributions of n-alkanes. Strong odd-over-even predominance in modern leaf wax n-alkanes is consistent with previous observations (Eglinton & Hamilton 1967;Lockheart et al 1997;Piasentier et al 2000). Carbon preference indices (CPIs) were used to assess the odd-over-even predominance and calculated following Marzi et al (1993):…”

“…; Piasentier et al . ). Carbon preference indices (CPIs) were used to assess the odd‐over‐even predominance and calculated following Marzi et al .…”

Hydrogen isotope ratios of recent lacustrine sedimentary n-alkanes record modern climate variability

“…n-Alkanes originate from the epicuticular waxes of leaves, developed shortly after the unfolding of the leaf in spring (Gulz, 1994), when evapotranspiration is not yet very strong. However, the n-alkane composition of the wax is changing throughout the year, differing from tree species (Piasentier et al, 2000). If most of the n-alkanes are produced in spring, we would not see a stronger enrichment relative to the aquatic n-alkanes for sites with higher evapotranspiration in summer.…”

Production of n-alkyl lipids in living plants and implications for the geologic past

“…Leaf wax composition and abundance can vary with ontogeny (Lockheart et al, 1997;Jetter and Schaffer, 2001;Sachse et al, 2009), environmental variables and stresses (Jetter and Schaffer, 2001;Dodd and Poveda, 2003;Shepherd and Griffiths, 2006), and among plant families (Eglinton and Hamilton, 1967;Baker, 1982;Piasentier et al, 2000;Dodd and Poveda, 2003). Most alkane abundance data are reported relative to the most abundant component, and to our knowledge, no one has quantified variation in n-alkyl lipid concentrations among plants at the same site that differ in their leaf phenology and phylogenetic group.…”