How Old are Tropical Trees? the Persistence of a Myth

IAWA Journal ◽  
1999 ◽  
Vol 20 (3) ◽  
pp. 255-260 ◽  
Author(s):  
Martin Worbes ◽  
Wolfgang Johannes Junk
Keyword(s):  
South America ◽  
Growth Rates ◽  
Age Determination ◽  
Tropical Trees ◽  
Pioneer Species ◽  
Annual Rings ◽  
Hollow Trees ◽  
Cariniana Legalis ◽  
Direct Counting ◽  
Age Determinations

The recent report of ancient trees in the Amazon region (Chambers et al. 1998) with a maximum radiocarbon dated age of about 1400 years for the long-living pioneer species Cariniana micrantha is discussed in the light of dendrochronological age determinations from Africa and South America together with the results of indirect age estimations from other sources. There is a tendency in the literature to considerably overestimate the maximum ages of tropical trees. Age determination by the direct counting of annual rings and making estimations for hollow trees by measuring growth rates and diameters result in ages between 400 and 500 years for the largest trunk dimensions, e.g. in Cariniana legalis.

Analysis of Bone Age Data From National Cooperative Growth Study Substudy VII

PEDIATRICS ◽  
1999 ◽  
Vol 104 (Supplement_5) ◽  
pp. 1031-1036
Author(s):  
Stephen F. Kemp ◽  
Judy P. Sy
Keyword(s):  
Age Determination ◽  
Bone Age ◽  
Strongly Correlated ◽  
Growth Study ◽  
Gh Therapy ◽  
Pubertal Stage ◽  
Significant Difference ◽  
Clinically Significant ◽  
National Cooperative ◽  
Age Determinations

National Cooperative Growth Study substudy VII was conducted 1) to compare standardized hand–wrist and knee bone age determinations in pubertal children treated with growth hormone (GH); 2) to compare local determinations of bone ages with centrally determined bone ages; 3) to relate the response to GH therapy to the bone age determinations; and 4) to ascertain the predictive value of each type of bone age determination. Eligible subjects were those in the National Cooperative Growth Study who were at Tanner pubertal stage 2 or greater for breasts (girls) or genitals (boys). Radiographs of the hand–wrist were taken annually, and radiographs of the knee were taken at the beginning and the end of the study. Separate bone age determinations were made from these radiographs. A combined hand–wrist and knee bone age determination also was derived. There were 990 patients in the study; in 925 (677 boys), there were both hand–wrist and knee bone age determinations from the baseline pubertal radiographs. There was only one radiographic assessment in 496 patients, two in 205 patients, and three to eight in the remaining patients. The strongest correlation was between the hand–wrist bone age and the hand–wrist plus knee bone age (r = .995). Also strongly correlated were knee with hand–wrist (r = .872) and knee with hand–wrist plus knee (r = .914). For none of these bone age methods was any statistically significant difference found between the methods. The locally determined bone ages correlated strongly with the centrally determined bone ages for knee (r = .850), hand–wrist (r = .928), and hand–wrist plus knee (r = .930); however, the locally determined knee and hand–wrist values were less (by ∼0.3 year) than the centrally determined values. These differences, however, do not appear to be clinically significant.

Rubidium and Strontium age determination of some Pre-Cambrian granitic rocks, S.E. Uganda

1971 ◽  
Vol 108 (5) ◽  
pp. 353-360 ◽  
Author(s):  
R. A. Old ◽  
D. C. Rex
Keyword(s):  
Age Groups ◽  
Age Determination ◽  
Granitic Rocks ◽  
Age Limit ◽  
Age Determinations

SummaryWhole rock rubidium-strontium age determinations on granitic bodies in S.E. Uganda give ages of 2930 m.y. for the Masaba Granite and 2430 m.y. for the Buteba Granite and granitic gneisses. The former age is considered to represent the upper age limit of the post-Nyanzian orogeny, and 2430 m.y. the upper age limit of the post-Kavirondian orogeny. A second isochron age of 2100 m.y. for the Masaba Granite may reflect a second intrusion, or remobilization of part of the original granite associated with the Buganda–Toro orogeny. Tentative correlations are suggested between these age groups and others within the Tanzanian Shield and beyond.

scholarly journals Routine K/Ar age determinations on rocks from Greenland carried out for GGU in 1970

1971 ◽  
Vol 35 ◽  
pp. 52-60
Author(s):  
D Bridgwater
Keyword(s):  
Analytical Data ◽  
Age Determination ◽  
Geological Significance ◽  
Reconnaissance Survey ◽  
Geological Work ◽  
The University ◽  
Age Determinations

The programme of commercial age determinations started in 1969 (Bridgwater, 1970) was continued to supplement the work carried out by the University of Copenhagen (Larsen, this report). The material dated represents a rather heterogeneous collection of rocks from many parts of Greenland about which information was required for current geological work but which were not included in existing age determination projects. All the results obtained are listed whether or not the "ages", have a clear geological significance, since a major reason for carrying out this form of reconnaissance survey is to test the suitability of K/Ar methods for making more detailed studies. Full analytical data is available on request from GGU. Unless otherwise stated the results given are means of three determinations.

scholarly journals Bomb dating, age validation and quality control of age determinations of monodontids and other marine mammals

2014 ◽  
Vol 8 ◽  
Author(s):  
Steven E Campana ◽  
Robert EA Stewart
Keyword(s):  
Quality Control ◽  
Marine Mammals ◽  
Age Determination ◽  
Age Validation ◽  
Age Bias ◽  
Bomb Radiocarbon ◽  
Control Protocols ◽  
The 1960S ◽  
Age Determinations

Methods for confirming the accuracy of age determination methods are reasonably well established in fishes, but the millions of routine age determinations which take place every year require their own quality control protocols. In contrast, methods for ensuring accuracy in age determination of monodontids and other marine mammals are still being developed. Here we review the basis and application of bomb radiocarbon to marine mammal age validation, highlighting its value for providing unambiguous estimates of age for belugas and other long-lived animals which form growth bands. Bomb radiocarbon is particularly useful for marine mammals, given that the age of an individual animal can be determined to within ±1-3 years, as long as it was alive during the 1960s. However, ongoing age determinations require careful monitoring to ensure that age interpretations remain consistent across ages and through time. Quality control protocols using reference collections of ageing material, in conjunction with age bias plots and measures of precision, are capable of detecting virtually all of the systematic ageing errors that often occur once age determinations of an animal become routine.

scholarly journals Oxygen isotopes as a valuable tool for measuring annual growth in tropical trees that lack distinct annual rings

2014 ◽  
Vol 48 (4) ◽  
pp. 371-378 ◽  
Author(s):  
CHENXI XU ◽  
MASAKI SANO ◽  
KEI YOSHIMURA ◽  
TAKESHI NAKATSUKA
Keyword(s):  
Oxygen Isotopes ◽  
Tropical Trees ◽  
Annual Growth ◽  
Annual Rings

Age Determination of Sockeye (Oncorhynchus nerka) and Chum (O. keta) Salmon from Examination of Pectoral Fin Rays

1969 ◽  
Vol 26 (5) ◽  
pp. 1199-1203 ◽  
Author(s):  
H. T. Bilton ◽  
D. W. Jenkinson
Keyword(s):  
Chum Salmon ◽  
Oncorhynchus Nerka ◽  
Age Determination ◽  
Annual Rings ◽  
Pectoral Fin ◽  
Fin Ray ◽  
Fin Rays ◽  
Ray Methods ◽  
Pectoral Fin Rays

Ages of adult sockeye and chum salmon were estimated from examination of the second anterior pectoral fin ray, and were compared with estimates from their scales or otoliths. For sockeye, only the ocean age could be estimated. Freshwater annual rings could not be distinguished on their fin rays even though they were present on their scales or otoliths. In general, the three methods provided the same estimates of ocean age. Agreement of estimates of ocean age by one to five readers ranged from 78.9 to 98.8%. For chum salmon, the scale and fin ray methods generally provided the same estimates of total age. Agreement of estimates of total age by one or two readers ranged from 73.8 to 99.3%.

Population dynamics of pioneer (Macaranga) trees and understorey (Mallotus) trees (Euphorbiaceae) in primary and selectively logged Bornean rain forests

1991 ◽  
Vol 7 (4) ◽  
pp. 439-457 ◽  
Author(s):  
Richard B. Primack ◽  
H. S. Lee
Keyword(s):  
Growth Rates ◽  
Total Population ◽  
Size Class ◽  
Primary Forest ◽  
Pioneer Species ◽  
Morphological Comparison ◽  
Size Class Distribution ◽  
Forest Sites ◽  
East Malaysia ◽  
Using Data

ABSTRACTUsing data from forest sites in Sarawak, East Malaysia, a demographic comparison is made of pioneer species in the genus Macaranga with understorey trees of the primary forest in the closely related genus Mallotus. In primary forest, saplings and trees of these genera arc uncommon and have low growth rates. For the six years following disturbance by logging, a Macaranga population was characterized by high rates of diameter growth and recruitment. Eleven years after disturbance, seedling and sapling abundance had declined sharply. In contrast, the Mallotus population was stable in size class distribution and increased slightly in total population size during the 11 years after logging. Growth rates of Mallotus trees increased after logging but were still much less than Macaranga trees.A morphological comparison shows that most Macaranga species, in contrast with Mallotus species, have large hollow twigs that are occupied by ants and have larger, hairier, thicker, more toothed leaves with longer petioles, axillary inflorescences with more flowers, infructescences with more fruit, fruits that are smaller in size and smaller seeds.

scholarly journals The geochronology of the Scoresby Sund area Progress report I: Rb/Sr mineral ages

1971 ◽  
Vol 37 ◽  
pp. 55-57
Author(s):  
B.T Hansen ◽  
R.H Steiger
Keyword(s):  
Age Determination ◽  
Crystalline Rocks ◽  
Progress Report ◽  
Rock Types ◽  
Age Determinations

A general age determination programme has been proposed for the crystalline rocks of the Scoresby Sund region. The various field geologists are contributing to this by delivering material of significant rock types from their individual areas, and subsequently the actual age-determinations are carried out at the "Institut für Kristallographie und Petrographie" of the "Eidg. Technische Hochschule" in Zürich.

scholarly journals Does Cedrela always form annual rings? Testing ring periodicity across South America using radiocarbon dating

Trees ◽  
2017 ◽  
Vol 31 (6) ◽  
pp. 1999-2009 ◽  
Author(s):  
Jessica C. A. Baker ◽  
Guaciara M. Santos ◽  
Manuel Gloor ◽  
Roel J. W. Brienen
Keyword(s):  
South America ◽  
Radiocarbon Dating ◽  
Annual Rings
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