Wood anatomical changes in roots of European ash (Fraxinus excelsior L.) after exposure

Abstract

Global changes have distinct influence on fluvial processes in torrents causing erosion on slopes and riverbanks even in forested areas. Continuous as well as discontinuous erosion of riverbanks covered by trees frequently results in destabilisation and finally cause the trees affected to tip over. These uprooted trees may lead to a blockage of the river and, in the case of a collapse of the resulting dam, resulting in severe flooding or even debris-flow surges. Dating the time of root exposure along riverbanks allows the reconstruction of erosion dynamics. In the previous studies, roots of coniferous trees have shown anatomical changes (cell size reduction in earlywood) after exposure. This anatomical feature in the xylem of exposed roots has helped to determine the time of exposure at an annual resolution. In the current study, this methodology is now applied for the first time to European ash (Fraxinus excelsior L.) to determine its specific reactions to root exposure.First results show different reactions in vessel and fibre dimensions. Fibres show a distinct decrease in lumen area due to exposure, whereas vessel lumen area displays more variability ranging from 50% size reduction to no changes. It is discussed that vessel size characteristics are also related to ecophysiological and climatic patterns.

Biological Flora of the British Isles:Fraxinus excelsior

“…The morphology of wood in roots changes when exposed to the air (probably a mechanical response) with new wood usually having smaller vessels (Hitz et al . ). Leaf area to root biomass ratio increases with decreasing irradiance (36% down to 4% full sunlight), but more so in Acer pseudoplatanus than ash (Barigah et al .…”

The interactions between vegetation and erosion: new directions for research at the interface of ecology and geomorphology

“…Abrupt suppression of growth as well as tangential rows of traumatic resin ducts are now being used to recognize anomalies that reflect erosion in the root zone. As a further result of the loss of edaphic cover, that is, the uppermost soil horizons, roots produce earlywood tracheid cells and vessels with lumina of significantly reduced width (Gärtner et al , ; Bodoque et al , ; Hitz et al , ). Corona et al () recently demonstrated that the reduction of cell lumina starts to occur before the root is exposed and as soon as the soil mantle covering the uppermost segment of the root is reduced to about 30 mm.…”

Effects of experimental stem burial on radial growth and wood anatomy of pedunculate oak

“…diffuse-porous species drastically increase vessel size after stem burial (Beakbane, 1941;Sigafoos, 1964;Fayle, 1968;Friedman et al, 2005), ring-porous species exhibit decreases in earlywood-vessel size (Knowlson, 1939;Cournoyer and Bégin, 1992;Friedman et al, 2005;Den Ouden et al, 2007). In addition, ring-porous species show the tendency to appear diffuse porous, or root like, after burial and shift back to ring-porous after exposure (Fayle, 1968;Cournoyer and Bégin, 1992;Den Ouden et al, 2007;Hitz et al, 2008).…”