7 research outputs found
Tropolone Content of Increment Cores as an Indicator of Decay Resistance in Western Redcedar
The high decay resistance of western redeedar (Thuja plicata Donn) is due to the presence of toxic extractives, called tropolones, in the heartwood. Therefore, tropolone content may be used as an indicator of decay resistance. With increment core-sized samples of western redcedar heartwood, we used gas chromatography to measure tropolone content and soil block tests to assess decay resistance. Results showed that decay resistance was extremely variable at low tropolone levels, but was uniformly high at tropolone levels of 0.25% or greater. Analyzing tropolone content of western redeedar increment cores is a useful way to assess decay resistance of standing trees
Recommended from our members
Branch diameter and wood density of young western hemlock (Tsuga heterophylla (Raf.) Sarg.) grown at several spacings
Recommended from our members
Wood quality studies in second-growth western redcedar (Thuja plicata Donn.)
Western redcedar (Thuja plicata Donn.) is a valuable commercial species found in
the northwestern United States and southwestern Canada. This dissertation includes four
papers focused on wood and stem characteristics of second-growth western redcedar, and
how those characteristics vary within the stem or how they are influenced by cultural
practices. Trees from three study sites were used these studies: 1) approximately 90-year-old
trees from a naturally regenerated, unmanaged stand in northwest Oregon, 2) a 35-
year-old planted western redcedar spacing trial near Vancouver, British Columbia, and 3)
an approximately 30-year-old, naturally regenerated western redcedar stand that had
received thinning and fertilization treatments on the Olympic Peninsula in Washington.
Characteristics studied at one or more sites include stem taper, branch diameter,
incidence and severity of stem fluting, sapwood width and area, heartwood radius and
area, heartwood percentage, content of tropolones (toxic extractives) in the heartwood,
and decay resistance of heartwood in soil block tests.
Stem morphological characteristics such as branch size, taper and fluting increased
with tree spacing. Tropolone content and decay resistance varied substantially within the
stem, with the lowest levels of each usually found in wood near the pith or the top of the
tree; this pattern indicates a "juvenile wood" with respect to tropolone content exists in
western redcedar. Wood with high tropolone content had high decay resistance in soil
block tests, while wood with low tropolone content was extremely variable in decay
resistance. Heartwood and sapwood relationships varied both within the stem and
between trees subjected to different cultural treatments. Within the stem, the quantity and
proportion of heartwood increased from the top of the tree downward. Trees that grew
faster as a result of cultural treatments had more sapwood and heartwood, and tended to
have a higher proportion of heartwood compared to their slower-growing counterparts. It
appears that cultural treatments can be used to exert a significant influence on wood and
stem characteristics in western redcedar
Recommended from our members
Fiber length in young hybrid Populus stems grown at extremely different rates
Length of libriform fibers was measured in rings 2 7 at breast height in 7-year-old hybrid poplar stems from two clones (11-11, a Populus trichocarpa Torr. & Gray ´ P. deltoides Bartr. ex Marsh. hybrid; and D-01, of unknown taxonomic identity) grown in a controlled test of three spacings (0.5, 1.0, and 2.0 m) on an irrigated and fertilized site in western Washington. In each clone, samples included a very wide range of cambial growth rates, with ring widths from 1 to 19 mm. Growth rate, expressed in several ways, had no consistent effect on fiber length within rings of the same age for rings 2 6. For ring 7, however, there were positive correlations between most growth rate measures and fiber length. Whole-disk fiber length increased with overall growth rate as measured by stem diameter; this apparent anomaly is caused by the fact that fast-growing trees have more of their basal area concentrated in rings further from the pith than do slower growing trees, and these rings have longer fibers compared with rings closer to the pith
Recommended from our members
Tropolone content of increment cores as an indicator of decay resistance in western redcedar
The high decay resistance of western redcedar (Thuja plicata Donn) is due to the presence of toxic extractives, called tropolones, in the heartwood. Therefore, tropolone content may be used as an indicator of decay resistance. With increment core-sized samples of western redcedar heartwood, we used gas chromatography to measure tropolone content and soil block tests to assess decay resistance. Results showed that decay resistance was extremely variable at low tropolone levels, but was uniformly high at tropolone levels of 0.25% or greater. Analyzing tropolone content of western redcedar increment cores is a useful way to assess decay resistance of standing trees.Keywords: decay resistance, thujaplicins, tropolones, Thuja plicat