Bark Photosynthesis
Abstract
The research in plant physiology and anatomy of woody plants has focused mainly on the wood of stems, primary roots, and leaves, while the bark has received far less attention until now. Small pores in the outer bark, called lenticels, allow continuous gas exchange between the atmosphere and the underlying living tissues of the bark and wood. One important aspect of the bark is the multi-functional role it plays in the carbon budget of the entire plant. Immediately beneath the dead outer bark lies a “green sleeve” of living cells that surrounds the stem and contains abundant chloroplasts. The main function of this green sleeve is thought to be related to the refixation of respiratory carbon dioxide, but it may also serve other functions vital to the tree's survival, such as supplying oxygen, maintaining water transport, defending against pathogens, and healing mechanical injuries. As trunks age, rhytidome formation reduces the light penetration through the outer bark, making the inner bark incapable of photosynthesis. This represents a trade-off between the protective function of the outer bark and the physiological function of the underlying living tissues. Objectives: The main objective is to investigate the multi-functionality of the living green layers of the bark in terms of: carbon balance, plant hydraulics, gas exchange, light transmission, and biomechanical functions. The project aims to establish a new research discipline called "phytodermatology" that incorporates functional, structural, and physiological approaches to the study of bark in order to fill gaps in our current knowledge. Approach: Histological and physiological studies will be conducted on ten different tree species that differ in bark structure, lenticel type, and bark and wood anatomy, with the aim of determining the net carbon gain of the whole plant, the distribution of the green sleeve within and between species, and the photosynthetic capacity of the bark. Originality and innovation: the role of the green sleeve in carbon balance, oxygenation, and hydraulics of woody plants remains largely unexplored. Combining classical methods of anatomy with state-of-the-art technologies such as microCT to measure structural changes in lenticels, chlorophyll fluorescence techniques to measure light transmission, 13C labeling, and isotope ratio mass spectrometry (IRMS) to track the various carbon fluxes in the stem should allow us to gain new insights into bark structure and function.
keywords bark photosynthesis lenticells periderm rhytidome gas-exchange
Publikationen
Project staff
Daniel Tholen
Ass.Prof. Dr. Daniel Tholen
daniel.tholen@boku.ac.at
Tel: +43 1 47654-83112
Project Leader
01.06.2023 - 31.05.2026
Anne-Charlott Fitzky
Dr. Anne-Charlott Fitzky MSc.
anne.fitzky@boku.ac.at
Project Staff
01.06.2023 - 31.05.2026