Why do tree species of varying sapwood thickness respire differently?
Pruyn, Michele*,1, Gartner, Barbara1, Harmon, Mark1, 1 Oregon State University, Corvallis, OR ABSTRACT- Mature and old growth tree species of varying sapwood thickness were compared with regard to stem respiration and wood chemical and cellular composition. An increment core-based, laboratory method under controlled temperature was used to measure tissue-level respiration of eleven different tree species. At breast height, species that maintained narrow sapwood thickness (< 10 cm) such as Pseudotusga menziesii, Taxus brevifolia, and Thuja plicata, showed sapwood respiration rates that were 50% higher than species of wide sapwood thickness (> 10 cm), such as Pinus monticola, Pinus ponderosa, and Tsuga heterophylla. This pattern was not shown for inner bark respiration, or for sapwood respiration within the crown. When tissue-level rates were scaled to the organ- or whole-tree level, species of lower sapwood volume had higher respiration rates. Monthly measurements revealed that stem res
