Pruyn, Michele L.; Gartner, Barbara L.; Harmon, Mark E. 2002. Respiratory potential in sapwood of old versus young Ponderosa pine trees in the Pacific Northwest. Tree Physiology. 22: 105-116.
Our primary objective was to present and test a new technique for in vitro estimation of respiration of cores taken from old trees to determine respiratory trends in sapwood. Our secondary objective was to quantify effects of tree age and stem position on respiratory potential (rate of CO2 production of woody tissue under standardized laboratory conditions). We extracted cores from one to four vertical positions in boles of +200-, +50- and +15-year-old Pinus ponderosa Dougl. ex Laws. trees. Cores were divided into five segments corresponding to radial depths of inner bark; outer, middle and inner sapwood; and heartwood. Data suggested that core segment CO2 production was an indicator of its respiratory activity, and that potential artifacts caused by wounding and extraction were minimal. On a dry mass basis, respiratory potential ofinner bark was 3-15 times greater than that of sapwood at all heights for all ages (P
Keywords: cambium, phloem, stem respiration, tree age, tree size.