Oxygen in tree stems and its role in tree-parasite interactions
Abstract
Oxygen can decrease to very low levels also in above-ground parts of plants, particularly in tree stems. In many trees, a major proportion of the oxygen supplied to the live sapwood appears to be transported with the transpiration stream rather than diffuse through the nearly impenetrable cambium. Short-time dynamics of oxygen concentrations in the wood are however not known at all. A main reason why relatively little attention has been paid to stem oxygen is that it is very difficult and cumbersome to measure with traditional methods. An oxygen electrode based on fluorescence quenching makes instantaneous, prolonged and small-scale measurements of O2 concentrations possible and promises to be a most important tool for a better understanding of oxygen relations in plants. The first part of our work should lead to an overview of diurnal and seasonal variations in oxygen content of tree stems of diverse species. We hypothesise that the oxygen courses will have a connection to tree anatomy and habitat requirements, especially to the flooding tolerance of the species. Furthermore we hypothesise here that oxygen is a major factor in tree stress and particularly in tree - pathogen interactions. Wood-infecting fungi may lower oxygen concentrations through increased respiration or by additionally clogging xylem vessels and tracheids and thus preventing transport via sapflow. If oxygen is supplied via the sapflow, several types of stress may result in decreasing wood oxygen concentrations or even anoxia: waterlogging, which reduces soil oxygen content, severe drought, which reduces sapflow, and infections, which increase respiration and may decrease sapflow. Anoxia frequently results in the production of ethanol, which is an important attractant for bark beetles. The hypothesis to be tested is that various forms of stress decrease oxygen content, which increases ethanol and attracts bark beetles. However, transpiration, stem respiration and oxygen solubility in water are strongly affected by climatic factors even without stress, which makes predictions in this poorly understood system difficult.
keywords tree physiology oxygen host-parasite interaction stress spruce
Publikationen
Gas diffusion through wood: implications for oxygen supply
Autoren: Sorz, J., Hietz, P. Jahr: 2006
Journal articles
Sauerstoff in Baumstämmen – Mögliche Zusammenhänge mit Stress, Pathogenen und Kernholzbildung
Autoren: Sorz, J., Hietz, P., Richter, H. Jahr: 2006
Conference & Workshop proceedings, paper, abstract
Is oxygen involved in beech (Fagus sylvatica) red heartwood formation
Autoren: Sorz J., Hietz P. Jahr: 2008
Journal articles
Project staff
Hanno Richter
Em.O.Univ.Prof. Dr.phil. Hanno Richter
hanno.richter@boku.ac.at
Project Leader
20.12.2002 - 31.10.2006
Peter Hietz
Univ.Prof. Mag.rer.nat. Dr.rer.nat. Peter Hietz
peter.hietz@boku.ac.at
Tel: +43 1 47654-83110
Sub Projectleader
20.12.2002 - 31.10.2006