Tree-Ring Research, Volume 57 (2001)
ABOUT THE COLLECTION
Tree-Ring Research is the peer-reviewed journal of the Tree-Ring Society. The journal was first published in 1934 under the title Tree-Ring Bulletin. In 2001, the title changed to Tree-Ring Research.
The Tree-Ring Society and the Laboratory of Tree-Ring Research at the University of Arizona partnered with the University Libraries to digitize back issues for improved searching capabilities and long-term preservation. New issues are added on an annual basis, with a rolling wall of five years.
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Contact the Editor of Tree-Ring Research at editor@treeringsociety.org.
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Tree-Ring Bulletin, Volume 57, Issue 2 (2001)Tree-Ring Society, 2001
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Tree-Ring Bulletin, Volume 57, Issue 1 (2001)Tree-Ring Society, 2001
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Editorial PolicyTree-Ring Society, 2001
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FHX2 - Software for Analyzing Temporal and Spatial Patterns in Fire Regimes from Tree RingsMany studies use the temporal record of dendrochronologically-dated fire scars to document properties of fire regimes before human interference (e.g. fire suppression, logging, and agriculture) became pervasive. Such reconstructions provide vital information that can be used by land management agencies when designing and implementing fire management policies, and are especially useful for justifying the reintroduction of fire to areas where fire has long been excluded by humans. Tree-ring based fire history studies produce large quantities of data that require efficient tools for compilation, organization, and analysis. In this paper, I describe the development and use of FHX2, software comprised of individual modules designed specifically for (1) entering and archiving of fire history data, (2) creating graphs that display both temporal and spatial features of the site fire history, (3) conducting statistical analyses on fire intervals and seasonality, and (4) performing superposed epoch analysis to analyze climate /wildfire interactions. Although designed to analyze fire history, the software can be used to analyze any set of events recorded in the tree- ring record, such as growth suppressions and releases, floods, and insect outbreaks.
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Relationships Between Ring-Width Variation and Soil Nutrient Availability at the Tree ScaleWithin the framework of the linear aggregate model of dendrochronology, the potential role of soil nutrient availability in explaining multi-decadal variation in radial growth at the tree level was studied in the central Spanish Pyrenees. Increment cores were collected from 20 mature Pinus uncinata Ram. and analyzed dendrochronologically. One ion-exchange resin capsule was buried within the root zone of each sampled tree for just over eight months. The resins were chemically extracted and measured for NH₄, NO PO₄, Ca, and K. Statistical relationships between indexed tree growth and soil nutrient availability were determined with regression analysis and bivariate plots. The single most important soil nutrient with respect to decadal-scale dendrochronological tree-growth variables in this study was N in the form NO which explained 22% of variation of trend in growth since 1950. The 20 values of NO₃ availability fell into two subgroups, one of trees with relatively higher NO₃ availability and the other with lower NO₃ availability. When the tree-growth data were grouped based on NO₃ availability, the two resultant index chronologies had different low-frequency features since 1950. Trees with low NO₃ availability have been growing as expected based on past growth, but trees with high NO availability have been growing better than expected. Measuring and analyzing soil nutrient availability at the tree level might enhance environmental applications of dendrochronological research. With soils information at this spatial scale, it is possible to distinguish between subgroups of trees within a tree-ring site and thereby construct subchronologies that differ significantly, especially for variation at the decadal scale. Subsite-chronologies may then lead to different and presumably more informative environmental interpretations relative to those based on a full-site chronology.
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Tree-Ring Evidence for Great Plains DroughtA new collection of tree-ring chronologies developed from trees and remnant material located in the western and central Great Plains makes an important contribution to the spatial coverage of the US tree- ring chronology network. Samples from 24 sites were collected from the west-central Great Plains, and to date, ten chronologies have been produced. When correlated with a set of 47 single-station PDSI records, the chronologies display relationships with regional spring and summer drought. The reconstruction of spring PDSI for eastern Colorado generated in this study suggests that the inclusion of Great Plains trees can improve the quality of Great Plains drought reconstructions. The eastern Colorado drought reconstruction explains 62% of the variance in the instrumental record and extends to 1552. This reconstruction provides information about the regional character of major droughts over the past four and a half centuries. Major eastern Colorado droughts include events in the 1580s, 1630s, 1660s, 1730s, and the 1930s. The late 16th century drought, noted as an especially severe drought in the southwestern US, appears in this reconstruction as only slightly more severe than other major droughts in this region.
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The Importance of Sample Context in Dendroarchaeological Interpretation: An Example from Northwestern New Mexico, USAArchaeological tree-ring samples provide environmental, chronological, and behavioral information about past human use of the landscape. Such information, however, can only be fully exploited if sample pro- veniences and beam attributes are completely documented. This paper discusses implications of the sample proveniences, beam attributes, and dates from McKean Pueblito, an eighteenth century Navajo site in northwestern New Mexico, USA. Although the date distribution suggests at least three different interpretations of the site construction history, the contextual data indicate that the site was built in AD 1708 and remodeled in 1713. Areal contextual and tree-ring data from McKean Pueblito and other sites in the area are used to discuss larger scale Navajo behavioral and demographic adaptations to the changing physical and social environments of eighteenth century New Mexico. These examples illustrate how sample context at various spatial scales can significantly enhance interpretations of tree-ring data.
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Aegean Tree-Ring Signature Years ExplainedAs a long master tree -ring chronology for the region around the Aegean approaches completion, timbers from monuments and archaeological sites as far as 2,000 km apart, and as far back as 7000 BC, are being dated. The patterns used in this dating are characterized by signature years, in which trees at the majority of the sites have smaller or broader rings than in the previous year. We show that the signature years are consistently associated with specific, persistent, circulation anomalies that control the access of precipitation- bearing systems to the region in springtime. This explains the feasibility of dating wooden objects from widely dispersed sites, and opens the possibility of reconstructing aspects of the climate in which the wood grew.
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Dendroclimatic Analysis Using Thornwaite-Mather-Type Evapotranspiration Models: A Bridge Between Dendroevology and Forest Simulation ModelsThe objective of this study was to document correlations between radial growth of white oak (Quercus alba L.) at 128 sites in the eastern US and variables related to early growing season site water balance, including the ratio of actual to potential evapotranspiration (AE/PE) computed based on the procedure described by Thornthwaite and Mather (1957). White oak radial growth was strongly correlated with all measures of early growing season water balance, but was most consistently and strongly correlated with Palmer Drought Severity Index (PDI) and AE /PE ratio computed using a modified Thornthwaite-Mather model. We propose that dendroecological analyses of tree growth responses to climate based on AE /PE variables could provide empirical data useful for improving climate response algorithms in forest simulation models. This change of standard practice could also improve biological interpretations derived from such dendroecological analyses.
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Xylem Tracheid Development in Pinus Resinosa Seedlings in Controlled EnvironmentsProgressive tree-ring xylem cell size changes may reveal the influence of changing environment during the growing season. This study examines xylem tracheid cell growth in red pine (Pious resinosa Ait.) seedlings grown in cabinets under controlled environment, where single parameters (temperature, light, soil moisture and CO2) were varied step-wise in each chamber at ca. 30-day increments for ca. 6 months. Control and temperature treatments were replicated. Cross-sections (20 μm thick) sliced with a sliding microtome from each of four seedling stems from each cabinet were mounted on glass slides. Lumen diameters and cell-wall thickness were measured on 4 orthogonal tracheid radial files on 4 radii of each stem. Mean cell sizes were 11-17 μm among treatments and growth periods, whereas numbers of cells formed averaged 0.2-1.3 cells per day. Cell size increased throughout the experiment in most of the treatments, including one of the control treatments and those with the greatest potential to limit growth (decreasing temperature, light and soil moisture). Soil moisture was the only environmental parameter that tended to cause late declining growth, and CO, up to 500 (μmol mol⁻¹ did not appear to influence cell development. Despite a substantial range of environmental shifts in the chambers (100 μmol mol⁻¹ CO₂; 125 μEinsteins m⁻² s⁻¹ light; 8 °C temperature; 35% relative humidity; watering every day to every 5th day), the continued stem elongation and cell-size increases indicate that conditions never became significantly limiting to growth in most treatments. Although the range of environmental variability is undoubtedly much greater in most natural red pine systems, these results indicate that fairly large variations in environment during development of juvenile wood in seedlings may not leave an imprint retrievable from cell-size measurements made on the earliest rings of mature trees.
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Paleoclimatic Analyses of Tree-Ring Reconstructed Summer Drought in the United States, 1700-1978A 155-point US grid of tree-ring reconstructed summer (JJA; Cook et al. 1996) averaged Palmer Drought Severity Index (PDSI) was used to document the history and investigate the external forcing of growingseason climate anomalies for the period 1700 to 1978. Statistical analysis software was used to composite years temporally by computing averages for the years of known dates of major potential climate-forcing events. A geographic information system (GIS) was used to display the composites as well as individual years. The forcing factors investigated were the 22-year Hale solar magnetic cycle, major El Niño (warm) and La Niña (cold) events based on the Southern Oscillation Index (SOI), and large magnitude low latitude volcanic eruptions. Positive and negative moisture anomalies appear around Iowa in the alternate 11-year sunspot cycles that make up the Hale solar magnetic cycle. Experimentation with the grouping of years in the Hale cycle composites led to unexplained spatial shifts of the moisture anomalies in the same region. The El Niño episodes usually show positive (wet) PDSI anomalies in the Southwest from California to Texas, while La Niña events usually have drought in the same area, with some inconsistent signals in the north central Plains and the Northwest. The eastern and northern US were unaffected by the Southern Oscillation, although the summer season reconstructed PDSI may have missed the SOI variation, which is primarily a winter signal. The three largest tropical volcanic eruptions since 1800 failed to follow a consistent pattern, but the 1815 eruption of Tambora in Indonesia was followed by a very strong positive growth anomaly in the Southwest in 1816 and 1817. Important regional studies with the winter-spring season could be done with this network of tree-ring chronologies and observed monthly PDSI data.
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Response to Winter Precipitation in Ring-Width Chronologies of Pinus Sylvestris L. from the Northwestern Siberian Plain, RussiaSix mean ring-width tree-ring chronologies were constructed for living Scots pine (Pious sylvestris L.), growing near the species' upper and northern limits in the area between the Ob River and the subpolar Ural Mountains in Russia. All ring-width series were standardized by fitting cubic smoothing splines and chronologies were constructed as biweight robust means. The six chronologies ranged from 181 to 276 years in length. Response function analysis showed all chronologies to have negative responses to winter precipitation. Most chronologies also showed positive, but relatively low responses to temperatures of the current and previous summer. Total October-May precipitation was reconstructed back to A.D. 1843 using the lagged and unlagged chronologies as candidate predictors. In addition to reflecting an unstable and time-varying growth-climate link, moderate verification results may partly be due to problems with short verification periods. The reconstruction contains almost equal amounts of high-frequency (<8 years) and low-frequency ( >8 years) variations, among them a significant 30-year variation. The precipitation signal may add an important aspect to reconstructing paleoclimatic fluctuations in the northern hemisphere. Continuing work with the Scots pine from this area depends on improving the quality of a precipitation reconstruction and finding older living and subfossil wood.
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Tree-Ring Dating and the Ethnohistory of the Naval Stores Industry in Southern GeorgiaSince the mid-1700s, slash (Pinus elliottii Engelm.) and longleaf (Pinus palustris Mill.) pines growing in the coastal plain region of the southeastern United States were intentionally wounded ("boxed" and/or "chipped ") to induce the production of resin, which was then collected and distilled into turpentine and its derivatives (termed "gum naval stores "). Relicts from this once-dominant industry are seen throughout southern pine forests as boxed and chipped stumps or (rarely) still living trees. In this study, we dated the years of chipping on slash pines growing in two locations in Lowndes County, Georgia, to (1) better understand past forest land use patterns, and (2) raise public awareness of the ethnohistorical importance of these trees to the cultural heritage of southern Georgia. We collected cores from ten living trees with characteristic chipped surfaces ("catfaces ") from Taylor-Cowart Memorial Park (TCMP) in Valdosta, Georgia, and cross sections from ten chipped stumps in the area surrounding Lake Louise, 12 km south of Valdosta. We conclude that chipping at TCMP occurred in 1947-1948, while two chipping events occurred at Lake Louise around 1925 and between 1954-1956. Our dating was facilitated by observing periods of growth suppression, distorted and /or discolored rings, and the absence of some growth rings that may indicate possible chipping events. We recommend that these chipped stumps and living trees be preserved intact for their ethnohistorical significance, educational importance, and potential for future research.
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Editorial PolicyTree-Ring Society, 2001
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Evaluating Crossdating Accuracy: A Manual and Tutorial for the Computer Program COFECHACOFECHA is a computer program that assesses the quality of crossdating and measurement accuracy of tree-ring series. Written by Richard L. Holmes in 1982, the program has evolved into one of the most important and widely used in dendrochronology. It is important to note that COFECHA does not perform all the necessary steps in crossdating. Rather, the program is a tool that helps the dendrochronologist assess the quality of crossdating and measurement accuracy. The ultimate decision whether or not a tree-ring series is successfully crossdated must lie with the dendrochronologist and not with the software. Therefore, the program is most useful after initial crossdating is accomplished using visual or graphical techniques (such as skeleton plots), and the rings have been measured. The proper use of COFECHA adds a high degree of confidence that tree-ring samples have been crossdated correctly and measured accurately, ensuring that the environmental signal is maximized. In this paper, I describe the use of COFECHA through all necessary steps, and discuss the meaning of the initial questions posed at program start-up, the various options available in the main menu, the various sections of the output from COFECHA, and interpretation of the diagnostics of crossdating and measurement accuracy. I demonstrate methods used to help crossdate undated series, and offer tips on taking full advantage of the various options available in the program.
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Development of a White Oak Chronology Using Live Trees and a Post-Civil War Cabin in South-Central VirginiaA 280-year old white oak chronology was developed for south-central Virginia to verify the timber harvesting and construction dates of a cabin located on the Reynolds Homestead Research Center. A plaque on the cabin stated that the logs were harvested in 1814. However, the outer rings of the logs dated to 1875 and 1876. From the land-use history of the area, the cabin was most likely constructed to house tenant farmers after the Civil War. Most of the periods of below average growth identified in the 280-year chronology were related to drought events. Correlations between the radial growth of the white oak with temperature and precipitation data from a local weather station were examined. Precipitation had more influence on radial growth than temperature, and significant correlations (p = 0.05) existed between radial growth and precipitation from the previous September, the current April, and the current June.
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¹⁴C Bomb Effect in Tree Rings of Tropical and Subtropical Species of BrazilAtmospheric nuclear tests in the early 1960s introduced large amounts of radiocarbon into the atmosphere, which resulted in an increase of tropospheric ¹⁴CO₂ concentration by nearly 100% during the years 1964-1965. The bomb-produced ¹⁴C was then gradually incorporated within the global carbon cycle. The history of ¹⁴C concentration in the troposphere is preserved within annual growth layers of trees and can be reconstructed for those areas where direct measurements of 14C in the atmosphere were not performed. The paper presents results of ¹⁴C activity measurements in tree rings of tropical and subtropical species from Brazil, for the period 1945-1997. We investigated two species ( Araucaria angustifolia and Parkia sp.) growing at three sites covering the latitudinal band between 7 °S and 24 °S. The results indicate that the maximum ¹⁴C activity in the Southern Hemisphere occurred in 1965, with the Δ¹⁴C values reaching around 700%. Significant differences in Δ¹⁴C were recorded among the studied sites for the period of maximal ¹⁴C levels in the atmosphere, with the highest level observed at the tropical site and lowest in the subtropical zone. This reflects the dynamics of interhemispheric transport of ¹⁴C during the years of high spatial and temporal gradients of this isotope in the atmosphere.