• A method for surfacing large log cross-sections for scanning and crossdating

      Donato, D.C.; Timme, S.H. (Tree-Ring Society, 2012-07)
      We present a method for obtaining a true flat surface on cross-sections of large logs that exceed the width of many belt sanders, to aid in digital scanning and computer-aided ring-width measurement. The method uses a vertical mill that is available in most university machine shops, gradually removing thin layers of wood to achieve a surface that is planar within ca. 0.3-mm precision. We have tested the method on several sizes, shapes, and decay states of log samples and found that it performs well across these variations. Samples can then be directly sanded with medium- to fine-grit sandpaper to achieve a finished surface that lies flat on a scanner plate and shows rings and cell structure with high clarity.
    • Snowpack reconstructions incorporating climate in the Upper Green River Basin (Wyoming)

      Anderson, S.; Moser, C.L.; Tootle, G.A.; Grissino-Mayer, H.D.; Timilsena, J.; Piechota, T. (Tree-Ring Society, 2012-07)
      The Green River is the largest tributary of the Colorado River. Given that snowpack is the primary driver of streamflow, information on the long-term regional snowpack (regionalized April 1 Snow Water Equivalent (SWE)) variability would provide useful information for water managers and planners. Previous research efforts were unable to develop skillful SWE reconstructions using tree-ring chronologies in the Upper Green River Basin (UGRB) of Wyoming because of limited tree-ring chronologies in the area. The current research uses Principal Components Analysis to regionalize April 1 snowpack data in the UGRB. Recent research efforts developed six new tree-ring chronologies in and adjacent to the UGRB. These new chronologies, along with 38 existing chronologies, were correlated with the regionalized SWE data. Chronologies positively correlated at a 95% confidence level or higher were retained. Stepwise linear regressions were performed and a reconstruction of UGRB regional April 1 SWE was achieved (R2  =  0.21). Climate signals (Pacific Decadal Oscillation (PDO) and Southern Oscillation Index (SOI)) were introduced to the predictor variables and an additional regression was performed. Inclusion of the SOI resulted in a statistically skillful reconstruction (R2  =  0.58). Temporal drought periods for SWE and for streamflow were examined for the UGRB and a direct relationship was observed.
    • Analysis of the dendroclimatic potential of Polylepis pepei, P. subsericansand P. rugulosain the Tropical Andes (Peru-Bolivia)

      Jomelli, V.; Pavlova, I.; Guin, O.; Soliz-Gamboa, C.; Contreras, A.; Toivonen, J.M.; Zetterberg, P. (Tree-Ring Society, 2012-07)
      This paper reports on investigation of the dendroclimatic potential of three Polylepis species, P. pepei, P. subsericans and P. rugulosa in Peru and Bolivia in the tropical Andes, where they form the world's highest treeline forests up to 5,000 m a.s.l. In Bolivia, P. pepei trees were sampled close to La Paz City. In Peru, P. pepei and P. subsericans were sampled in the Vilcanota Mountains close to Urubamba City, and P. rugulosa in the Arequipa region on the slope of Coropuna Volcano. Chronologies span the 20th Century and all three species show intermediate values of mean sensitivity, common variance and signal-to-noise ratio. In general, correlation and response-function analyses revealed significant positive relationships with temperature during the rainy season for all three species in Peru and Bolivia. Relationships with precipitation were more difficult to interpret as positive relationships were observed between radial growth and precipitation at the beginning of the rainy season in all three species in Peru, whereas for P. pepei in Bolivia, the relationships with precipitation appeared to be controlled by local conditions including slope and substrate (moraine or scree slope).
    • Reflections on the foundation, persistence, and growth of the Laboratory of Tree-Ring Research, circa 1930–1960

      Creasman, P.P.; Bannister, B.; Towner, R.H.; Dean, J.S.; Leavitt, S.W. (Tree-Ring Society, 2012-07)
      On the occasion of the 75th anniversary of the Laboratory of Tree-Ring Research, it is appropriate to reflect on the origin of the LTRR and the oft overlooked early period of its history. The period from the “Bridging the gap” event in 1929 to the semi-retirement of A.E. Douglass in 1958 was a crucial time in the development of the LTRR. Although this paper focuses on the history of the LTRR between those events, at points the history of the LTRR is, essentially, the history of the field, making a holistic understanding all the more important. The information presented here is rooted in a series of transcribed historical lectures delivered in 1992 and 1993 by Director/Professor Emeritus Bryant Bannister, and several historical reports composed by him between 1963 and 1998.
    • Dendrochronological dating of wood from the Fountain of Youth Park Archaeological site (8SJ31), St. Augustine, Florida, U.S.A.

      Garland, N.A.; Grissino-Mayer, H.D.; Deagan, K.; Harley, G.L.; Waters, G. (Tree-Ring Society, 2012-01)
      Settled in 1565 by the Pedro Mene´ndez de Aviles expedition, St. Augustine, Florida, holds great educational, historical, and anthropological interest for current researchers as the oldest continuously occupied European community in the continental United States. Archaeological excavations produced two large (ca. 20 cm diameter) posts from the Fountain of Youth Archaeological Park site. Our objective in this project was to use tree-ring dating to determine the outermost dates of the two posts and to use these dates to assist archaeological interpretations. Sample 8SJ31-2741 was pine and contained tree rings that were successfully crossdated using the Lake Louise reference chronology from southern Georgia to AD 1620–1668. Sample 8SJ31-2766 was a cypress sample that we could not crossdate using a nearby reference chronology from the Altamaha River in southern Georgia. The date for sample 8SJ31-2741 places its cutting and deposition within the Mission Period occupation and verifies that the Nombre de Dios mission village was still active and building after 1668 into the late 17th Century. Furthermore, the dendrochronological date confirmed the stratigraphic interpretation, suggesting that disturbance of the upper layers of the surface in this part of the site was perhaps not as disruptive to the soils as originally assumed. This project demonstrates the feasibility of dating wood extracted from sites from the historic Spanish-era period in the Southeastern US.
    • Tree-ring dating of an Arkansas antebellum plantation house

      Therrell, M.D.; Stahle, D.W. (Tree-Ring Society, 2012-01)
      As part of the Lakeport Plantation Restoration Project conducted by Arkansas State University, we examined tree-ring samples of baldcypress (Taxodium distichum L. Rich.) timbers from the Lakeport Plantation house in Chicot County, Arkansas. Our objectives for the study were to: (1) determine cutting dates of timbers used in the construction of the plantation house and an ancillary log shed in order to support or refute available historical and archaeological evidence for the construction date of the structures, and (2) provide tree-ring data to improve the spatial and temporal tree-ring record for the region. We determined that virtually all the cutting dates for the plantation house were confined to the dormant season of 1858–1859 suggesting that cutting and construction occurred at approximately the same time. We positively dated a total of 25 samples against the exactly-dated master chronology based on living baldcypress trees at Black Swamp, Arkansas, and compiled a 346-year chronology extending from 1537 to 1883. These findings provide absolute quantitative evidence of the age and construction history of one of the most important antebellum buildings in Arkansas and additional background on the material culture of the “cotton aristocracy”.
    • Dendrochronological potential of Quercus garryana, Saltspring Island, British Columbia

      Jordan, D.; Vander Gugten, K. (Tree-Ring Society, 2012-01)
      Garry oak (Quercus garryana Dougl.) is the cornerstone tree species of one of the most biologically diverse yet threatened ecosystems in Canada. The Canadian Garry oak ecosystem is located only in southern coastal British Columbia and is home to numerous endangered species. This study tests the dendrochronological potential of Garry oak trees near their northern range limit by successfully crossdating a sample from the Crow's Nest Ecological Research Area (CNERA) on Saltspring Island, British Columbia. Forty-five samples were collected from 39 trees to determine accurate age estimates and develop a crossdated tree-ring chronology that spans 180 years (A.D. 1825–2005). Wood anatomy and periodic growth suppression made crossdating challenging. However, distinct marker rings were readily identified on nearly all cores showing a synchronous response among trees to a common radial growth signal. The majority of trees sampled were established during 1860–1880 and 1947–1967. Correlation analyses show that radial growth of Garry oak at CNERA is influenced by both temperature and moisture availability. Our study demonstrates that extraction of high-quality dendrochronological data from Garry oak trees near their northern range limit is possible, so this species should be recognized as having good dendrochronological potential.
    • Fire History in black pine (Pinus nigra Arn.) forests of the Valia Kalda, Pindus Mountains, Greece

      Touchan, R.; Baisan, C.; Mitsopoulos, I.D.; Dimitrakopoulos, A.P. (Tree-Ring Society, 2012-01)
      The past fire regime of European black pine (Pinus nigra Arn.) forests in Valia Kalda in Greece was investigated by standard dendrochronology methods. The sampled trees contained a record of fires from the early 14th Century through the late 19th Century with the last fire recorded in 1891. Evidence of non-lethal surface fires over the past seven centuries suggests that in addition to its destructive power, fire also plays a role in ecological functioning of the region. This is the first fire history study in Greece and can provide a basis for development of the first fire history network in the region. It also provides insight and perspective that may be useful for planning and justifying future ecosystem management programs.
    • A 435-year-long European black pine (Pinus nigra) chronology for the central-western Balkan region

      Poljanšek, S.; Ballian, D.; Nagel, T.A.; Levanič, T. (Tree-Ring Society, 2012-01)
      We describe the development of the first black pine (Pinus nigra Arnold) regional chronology for the central-western Balkan area, Bosnia and Herzegovina (BiH), based on seven site chronologies from different parts of the country. Pointer-year analysis identified a common signal (possibly climate) in the site chronologies—at least five positive (1876, 1930, 1941, 1969) and nine negative pointer years (1874, 1880, 1891, 1931, 1943, 1963, 1971, 1987, 2000) are common to all seven study sites. Site chronologies were compared using statistical parameters and visual crossdating, from which we constructed a 435-year-long tree-ring width chronology for P. nigra for BiH and compared it with existing P. nigra chronologies from Montenegro, Greece, Albania, Austria (Vienna region), and France (Corsica). The resulting statistical and visual similarity indicated that the chronology has a strong regional signal and therefore can be included in the dendrochronological network for P. nigra for the Western Balkans.
    • Tree-ring growth and wood chemistry response to manipulated precipitation for two temperate Quercus species

      Wagner, R.J.; Kaye, M.W.; Abrams, M.D.; Hanson, P.J.; Martin, M. (Tree-Ring Society, 2012-01)
      We examined the relationship among ambient and manipulated precipitation, wood chemistry, and their relationship with radial growth for two oak species in eastern Tennessee. The study took place on the Walker Branch Throughfall Displacement Experiment (TDE) site, located at the Oak Ridge National Laboratory in Oak Ridge, TN. Two dominant species, white oak (Quercus alba) and chestnut oak (Quercus prinus), were selected for study from a 13-year experiment of whole-stand precipitation manipulation (wet, ambient and dry). The relationships between tree-ring width and climate were compared for both species to determine the impact of precipitation manipulations on ring width index. This study used experimental spectroscopy techniques to measure the sensitivity of tree-ring responses to directional changes in precipitation over 13 years, and the results suggest that oaks at this study site are resilient to imposed changes, but sensitive to inter-annual variations in climate. Laser-induced breakdown spectroscopy (LIBS) allowed us to measure nutrient intensities (similar to element concentrations) at 0.5–1.0 mm spacing along the radial growth axis of trees growing in the wet, ambient, and dry treatment sites. A difference in stemwood nutrient levels was observed between the two oak species and among the three treatments. Significant variation in element intensity was observed across treatments for some elements (Ca, K, Mg, Na, N and P) suggesting the potential for long-term impacts on growth under a changing climate regimes for southeastern oaks.
    • Assessment of dendrochronological year-of-death estimates using permanent sample plot data

      Jones, E.L.; Daniels, L.D (Tree-Ring Society, 2012-01)
      We combined crossdating with permanent sample plot (PSP) data to assess the precision and accuracy of year-of-death (YOD) estimates obtained by crossdating white spruce and lodgepole pine snags and logs. Crossdating indicated trees died between 1833 and 2006. Comparison of crossdated YOD dates for pairs of samples (n  =  121) showed that 90% of YOD estimates were within 10 years of each other. Of 100 trees that died after PSP establishment, 59 YOD dates were within the documented interval of death (IOD). Of the 41 inaccurate dates, 77% of YOD dates preceded the IOD midpoints and error increased with time since death. Regression models increased the accuracy of spruce YOD estimates for trees that had been dead ≥17 years, but the corrections were modest (e.g. +5 at 50 years). For pine, the correction models increased accuracy regardless of time since death and corrections were greater than those for spruce (e.g. +4 and +11 at 5 and 50 years, respectively). Precision and accuracy errors resulted from many factors including loss of bark, wood decay, lack of ring formation prior to tree death, and human error. Our results reinforce the need for multiple lines of evidence when reconstructing tree deaths using tree rings. We urge others with access to PSP data to assess the quality of crossdated YOD estimates. Ideally, PSP re-measurements intervals would be short and consistent, facilitating comparisons through time and among genera and locations.