• Cedrela Angustifolia and Juglans Australis: Two New Tropical Species Useful in Dendrochronology

      Villalba R.; Boninsegna, Jose A.; Holmes, Richard L.; Laboratory of Dendrochronology, Instituto Argentino de Nivologia y Glaciologia, Mendoza, Argentina; Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona (Tree-Ring Society, 1985)
      Dendrochronological problems in dating tropical tree species are responsible for a large gap in global dendroclimatic reconstructions. Study of Cedrela and Juglans in the low-latitude forests of northern Argentina and Bolivia has resulted in development of four chronologies. These genera have good tree-ring characteristics, and statistics indicate that they have good potential for dendroclimatology. Longer series should be obtained from older stands.
    • Fitzroya Cupressoides Yields 1534-Year Long South American Chronology

      Boninsegna, José A.; Holmes, Richard L.; Instituto Argentino de Nivolo gia y Glaciología, Mendoza, Argentina; Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona (Tree-Ring Society, 1985)
      The longest tree-ring chronologies for the Southern Hemisphere published to date go back to A.D. 1011 in central Chile; 1028 in Tasmania, Australia; 1140 in western Argentina; and 1256 on the North Island, New Zealand. For paleoclimatic and other studies longer time series would be very desirable. Here we report on the first successful crossdating and chronology development for Fitzroya cupressoides, a redwood-like conifer in western Argentina, which goes back to 441 and exhibits desirable statistical characteristics.
    • Intra-Annual Variation in Wood Density in Gmelina Arborea from X-Ray Densitometry and its Relationship with Rainfall

      Akachuku, A. E.; Department of Forest Resources Management, University of Ibadan, Ibadan, Nigeria (Tree-Ring Society, 1985)
      The variation in wood density within growth rings was determined from X-ray negative images of wood samples of Gmelina arborea. The within-tree and between-tree comparisons showed that no two growth rings had exactly similar patterns of variation in the radial direction. The proportions of wood in four within-ring density classes were estimated. The variations in the proportions of wood in the four classes with age were nonlinear. On the average, the proportion of low density wood decreased with increasing age, while the proportion of high density wood increased with age. Regression analysis testing different curvilinear models showed that 37 to 99 per cent of the variations in the proportions of wood were associated with variations in age. Maximum and minimum ring density were negatively correlated with dry season rainfall. Variations in the proportion of high density wood and mean ring density were not associated with corresponding variation in dry season rainfall. The proportions of low and high density wood, mean ring density, maximum ring density and minimum ring density were not determined by annual rainfall.
    • Modern New Zealand Tree-Ring Chronologies III. Agathis australis (Salisb.) - Kauri

      Ahmed, Moinuddin; Ogden, John; Department of Botany, University of Baluchistan, Quetta, Pakistan; Department of Botany, Auckland University, Auckland, New Zealand (Tree-Ring Society, 1985)
      Dendrochronological sampling of sixteen stands of kauri (Agathis australis) covering almost the whole range of the species in northern New Zealand is described. Eight new chronologies were obtained and compared to previous results from the same species. It is concluded that north-facing slopes are most suitable for tree-ring studies in this species. The chronologies cover a maximum period from A.D. 1580 to 1981 and show from 20 to 35 percent common chronology variance over the sample period 1790 to 1976. All the chronologies are significantly correlated with all others, and the degree of correlation appears unrelated to the spatial separation between the sites. Some longer-term (15 to 30 year) trends are also shared by most chronologies; narrow rings and high between-tree and between-site correlations were a feature of the first two decades of the Twentieth Century. Similar tree ring patterns, and similar site characteristics suggest that the chronology network described here is suitable for palaeoclimatic reconstruction back to at least 1750.
    • Tree-Ring Bulletin, Volume 45 (1985)

      Unknown author (Tree-Ring Society, 1985)
    • Tree-Ring Dating Through Pattern-Matching of Stable-Carbon Isotope Time Series

      Leavitt, Steven W.; Long, Austin; Dean, Jeffrey S.; Division of Science, University of Wisconsin-Parkside, Kenosha, Washington; Department of Geosciences, University of Arizona, Tucson, Arizona; Laboratory of Tree-Ring Research, University of Arizona, Tucson, Arizona (Tree-Ring Society, 1985)