Browsing Tree-Ring Research, Volume 66, Issue 1 (Jan 2010) by Subjects
Now showing items 1-2 of 2
The Meteorological Significance Of False Rings In Eastern Redcedar (Juniperus Virginiana L.) From The Southern Great Plains, U.S.A.The growth rings of eastern redcedar (Juniperus virginiana L.) often contain a high frequency of false intra-annual growth bands, which complicates the dendrochronology of this species. However, exactly dated false rings replicated among many trees can reflect major weather changes during the growing season. Sixty-one trees from two sites (Oklahoma and Kansas) were dated and used to compile replicated chronologies of false rings at both locations extending from AD 1700–2000. False-ring events during the modern instrumental era were compared with the daily weather data from nearby stations. Significant false-ring events occurred at both locations during years that experienced a dramatic late-growing season weather reversal, when an extended period of high temperatures and drought was followed by prolonged cool and wet conditions. Synoptic weather maps for these events indicate that all ten replicated false-ring events in the instrumental era occurred during the highly unseasonable penetration of a cold front into the region. However, none of the significant false-ring events occurred in the same year at both sites. These separate false-ring chronologies indicate that there may be phenological differences in the timing of radial growth in redcedar between Kansas and Oklahoma, and that the weather conditions responsible for false-ring formation often occur at the mesoscale and do not often impact central Kansas and northcentral Oklahoma simultaneously.
Technique To Improve Visualization Of Elusive Tree-Ring Boundaries In Aspen (Populus tremuloides)A simple, quick, and inexpensive technique to improve visualization of aspen (Populus tremuloides) tree rings under the microscope, the ‘shadow technique’, is described. The technique assumes appropriate preparation of increment cores or cross-sections and works well on the lighter portions of the sample with fungus- and bacteria-free wood. The shadow technique was used successfully to elucidate tree-ring boundaries in small diameter (<5 cm DBH) aspen from northern Utah that commonly had >100 annual rings. Crossdating verified whether the elusive rings were missing or false rings. Aspen tree-ring measurement will be greatly enhanced with the shadow technique and preliminary investigation suggests it could be used on other species such as curlleaf mountain mahogany (Cercocarpus ledifolius).