Environment rather than genetic background explains intraspecific variation in the protein-precipitating capacity of phenolic compounds in beech litter

Abstract

Background: The ecological effects of phenolic compounds in plant tissues are related to their phenolic signature, i.e. the total content and structure of the phenolic compounds. Although the spatial and temporal variation of the phenolic signature within species is well documented, it remains unclear whether intraspecific variation is due to genetic differences between individuals or to environmental conditions.

Aims: We aimed to disentangle the effects of the genetic background and environmental conditions on intraspecific variation in the phenolic signature of beech (Fagus sylvatica) leaf litter.

Methods: In a silvicultural provenance experiment, beech populations from a wide range of the natural distribution range of the species, including different phylogeographic lineages (site of origin = genetic background), were grown in two geographically distinct common gardens (site of growth = environment). The total content and the protein-precipitation capacity of phenolic leaf litter compounds and their HPLC profile were determined as a measure of the phenolic signature of leaf litter of individual beech trees.

Results: The phenolic content and the protein-precipitating capacity of methanolic litter extracts were significantly correlated. Variation in the content of phenolic compounds was largely related to genetic background and less to environment, while the reverse was true for their protein-precipitating capacity. Individuals grown in the same common garden exhibited more similar phenolic signatures than individuals from the same provenance but grown at different locations.

Conclusions: We conclude that it is environmental conditions rather than the genetic background that determines the phenolic signature of leaf litter of beech individuals. It follows from our results that environmental change may in the future lead to alteration of the phenolic signatures of present beech forest ecosystems, probably with a cascading effect on ecological processes such as decomposition.

Keywords:

• common garden
• Fagus sylvatica; leaf litter
• phenolic compounds
• phenolic signature
• protein-precipitating capacity
• total phenolic content

Acknowledgements

We are grateful to Christian Hesse, Kiel, for his thorough and reliable laboratory analyses. We thank Melanie Müller for assistance in the field and Jake Alexander for correction of the English. Martin Wahl, GEOMAR Kiel, provided access to the HPLC, and Nadja Stärck performed the HPLC analysis.

Additional information

Notes on contributors

Martin Zimmer

Martin Zimmer is a terrestrial animal ecologist focusing on the invertebrate detritivorous soil fauna and their interactions with leaf litter, microbes and predators. He has a special interest in the effects of phenolic compounds on, and their fate upon digestion by, detritivores and during decomposition processes. He analysed the phenolic signature, performed statistical analyses and wrote the manuscript.

Harald Auge

Harald Auge has a general interest in population biology and vegetation ecology, with particular focus on molecular ecology, invasion ecology, interspecific interactions, and the relevance of biodiversity for ecosystem functioning. He designed the provenance experiment and contributed to writing the manuscript.

Georg von Wühlisch

Georg von Wühlisch is interested in the genetic variability of forest tree species, including tree breeding and the conservation of the genetic resources of tree species. He contributed to the provenance experiment, provided plant material and contributed to writing the manuscript.

Silvio Schueler

Silvio Schueler has a long-standing research interest in population and quantitative genetics of forest trees and the application of this knowledge to tree breeding and the adaptation of forest ecosystems to climate change. He contributed to the provenance experiment, provided plant material and contributed to writing the manuscript.

Josephine Haase

Josephine Haase is a community ecologist motivated by a desire to understand the functional linkages between species and trophic levels, their interactions with the environment and how these processes determine large-scale ecological patterns. She designed and carried out the provenance experiment, and contributed to data analysis and in writing the manuscript.