• Bridging the Gap with Subfossil Douglas-Fir at Mesa Verde, Colorado

      Stahle, D.W.; Edmondson, J.R.; Burns, J.N.; Stahle, D.K.; Burnette, D.J.; Kvamme, E.; Lequesne, C.; Therrell, M.D. (Tree Ring Society, 2015-07)
      Old Rocky Mountain Douglas-fir (Pseudotsuga menziesii) trees and remnant "subfossil" logs have been found on the outcrop of a mafic igneous intrusion above the Mancos River Valley near Mesa Verde National Park. These trees and logs have been used to develop earlywood (EW), latewood (LW), and total ring width (TRW) chronologies dating from AD 722-2011. The new chronologies include good series replication during the former chronological "gap" from AD 1250 to 1400, which was so problematic for the initial development of the "Central Pueblo" chronology by A. E. Douglass. Discrete reconstructions of the cool-season (September-May) and early warm-season (June-July) moisture balance for Mesa Verde have been derived from the EW and adjusted LW width chronologies from the Mancos Valley. Cool-season drought is estimated to have been more severe and sustained than early warm-season conditions during the "Great Drought" of the late-13th Century when southwestern Colorado was depopulated. The combined archaeological, subfossil, and living tree chronologies of EW, LW, and TRW for the Mancos River and Mesa Verde Douglas-fir now date from AD 480-2011. Copyright © 2015 by The Tree-Ring Society.
    • Dendroecological Methods for Reconstructing High-Severity Fire in Pine-Oak Forests

      Guiterman, C.H.; Margolis, E.Q.; Swetnam, T.W. (Tree Ring Society, 2015-07)
      Recent high-severity fires in pine-oak forests of the southwestern United States are creating shrubfields that may persist for decades to centuries. Shrubfields embedded in conifer forests that pre-date documentary records are potential evidence of older high-severity fire patches, and may therefore provide insights into the occurrence and extent of past high-severity fires and vegetation type conversion dynamics. In this paper we test whether dendroecological evidence can be used to reconstruct a high-severity, type-changing fire of known date in a ponderosa pine-dominated (Pinus ponderosa var scopulorum Engelm.) forest. Dendroecological evidence included (1) Gambel oak (Quercus gambelii, Nutt.) regeneration dates, (2) fire scars, (3) death dates, and (4) tree-ring growth changes. We reconstructed the historical fire regime and fire-climate relationship to evaluate whether the recent high-severity fire was driven by climate or fuel build-up related to a fire regime disruption. The dendroecological evidence correctly dated the year (1993) and season (spring) of the documented fire, and synchronous oak re-sprouts provided a means to estimate the minimum high-severity patch size. The historical fire regime at the site (1625-1871) consisted of frequent, low-severity fires occurring in dry years preceded by wet years. Fires stopped in 1871, coincident with increased regional livestock grazing. The 1993 fire occurred under relatively cool and wet conditions, but followed a 122-year fire-free interval (four times the maximum historical interval). Multiple lines of evidence suggest that increased fuel loads from fire exclusion, combined with high winds, were primary drivers of the high-severity fire. The dendroecological approach we outline can be applied to reconstruct high-severity fire across a range of conifer-shrubland ecosystems. Copyright © 2015 by The Tree-Ring Society.
    • A Method for Tree-Ring Analysis Using Diva-Gis Freeware on Scanned Core Images

      Arenas-Castro, S.; Fernández-Haeger, J.; Jordano-Barbudo, D. (Tree Ring Society, 2015-07)
      Tree-ring analysis is a basic technique of paramount importance in forest management, yet it may prove difficult and time-consuming for many slow-growth hardwood tree species. Moreover, it requires the use of specialized tools and proprietary software, which may hinder researchers working with limited budgets. We describe an innovative and inexpensive method using DIVA-GIS freeware software to analyze true color high-resolution scanned images of cores previously enhanced with ImageJ freeware (GIS-SDI), and test its accuracy against the widely-used LINTAB-TSAPWin™ and WinDENDRO™ methods. For this purpose, Abies pinsapo and Pyrus bourgaeana increment cores were processed independently using each of the three methods and the results were statistically compared. Dating results were consistent across all three methods, although identifying rings was easier and quicker to perform on the digital images. Using a modern but affordable flatbed scanner to digitize tree cores and the free DIVA-GIS software to analyze the scanned digital images proved to be an inexpensive but highly accurate and efficient approach to tree-ring analysis. Furthermore, this method greatly facilitates tree-ring analysis in species with inconspicuous rings, and enables a complete digital record of every core analyzed to be stored. Copyright © 2015 by The Tree-Ring Society.
    • Do Rules of Thumb Measure Up? Characteristics of Fire-Scarred Trees and Samples

      Yocom Kent, L.L.; Fulé, P.Z. (Tree Ring Society, 2015-07)
      Dendrochronologists studying fire history must be strategic in their search for fire-scarred tree samples. Because it is desirable to extend the period of analysis in a site by looking for old scars, recent scars, and trees with large numbers of scars, researchers have developed rules of thumb regarding which trees are most likely to meet these goals as well as where fire scars are most likely to be found. To test our assumptions and quantify patterns about tree and sample characteristics, we analyzed a dataset of 2800 samples and 16,036 scars. On average, logs had the oldest scars and live trees had the most recent scars, although both very old and very recent scars were found on snags and stumps. Scars tended to be located on the uphill sides of trees, particularly on steeper slopes. The number of years between pith date and first fire scar ranged from 2 to 473 years, with a median of 52 and a mean of 67. The data confirm that searching for a variety of sample types and looking on the uphill sides of trees are useful methods for efficient sampling and extending a fire history record. Copyright © 2015 by The Tree-Ring Society.
    • Competitive Strength Effect in the Climate Response of Scots Pine Radial Growth in South-Central Siberia Forest-Steppe

      Babushkina, E.A.; Vaganov, E.A.; Belokopytova, L.V.; Shishov, V.V.; Grachev, A.M. (Tree Ring Society, 2015-07)
      This paper presents a method for classification of trees in groups depending on parameters of the age trend in tree-ring width. The method is tested on a sample containing 194 trees of Scots pine (Pinus sylvestris L.) growing in the forest-steppe zone of the South of Central Siberia. The climatic response of tree-ring width in such climatic conditions is complex. The influence of temperature in May-September is negative (moisture reducing). Warm-season precipitation serving as a source of moisture is a positive factor. Another positive factor is cold-season precipitation as frost protection. We determined the dependence of this response on the local conditions (soil, landscape and anthropogenic factors). The competitive strength of the trees influences both the sensitivity of individual trees to extreme climatic factors and the timing of growth processes. The latter implies the duration of the period of significant response to climate. It appears promising to take this influence into account in dendroclimatic reconstructions by using separate clusters of trees based on the competitive strength and having the maximum response to the reconstructed factor. Copyright © 2015 by The Tree-Ring Society.
    • Trimming and Planing Rough-Cut Wood for Efficient Dendrochronological Sample Preparation and Storage

      Minor, J.J.; Arizpe, A.H. (Tree Ring Society, 2015-07)
      Wood samples larger than increment cores collected for tree-ring studies are often obtained using chainsaws and, less frequently, 2-person crosscut saws. Saw marks on cross-sectional wood samples can be quite deep and uneven, and sanding rough-cut wood cross-sections is inefficient in terms of processing time and wear on sanding belts. Trimming rough-cut wood samples with a band saw or treating with a surface planer creates a smoother initial surface for sample sanding and polishing. Sample trimming with a band saw or surface planer is also useful for post-analysis archiving and wood storage, when excess wood can be removed and smaller samples entered into storage. Band saw and surface planer safety techniques are also discussed. Copyright © 2015 by The Tree-Ring Society.
    • Tree-Ring Investigation of Holocene Flood-Deposited Wood from the Oneida Lake Watershed, New York State

      Panyushkina, I.P.; Leavitt, S.W.; Domack, E.W.; Wiedenhoeft, A.C. (Tree Ring Society, 2015-07)
      Glacial deposition and fluvial/lacustrine sedimentation interact over terrains in central New York State to preserve a history of geological and hydrological events as well as hydroclimatic transitions. The lower reach of Fish Creek draining the eastern watershed of Oneida Lake, NY, is an area with prominent wood remains. This study explores a collection of 52 logs encased in organic-rich deposits exposed by bank erosion at three locations along Fish Creek near Sylvan Beach, NY, with respect to radiocarbon ages, species, and the crossdating potential of tree rings. Radiocarbon ages and successful tree-ring crossdating document what we interpret as seven major hydrologic episodes ca. 10 ka (i.e. ca. 10,000 cal yr BP), 7.4 ka, 6.8 ka, 6.4 ka, 5.5 ka, 3.1 ka and 2.2 ka cal BP, during which channel aggradation and tree burial may have been associated with abruptly increased flood frequency and/or high water tables. This pilot study establishes four floating tree-ring records: [1] early Holocene hemlock (Tsuga), mid-Holocene [2] walnut (Juglans sp.) and [3] sycamore (Platanus), and [4] late Holocene elm (Ulmus sp.), with sample sizes of 8-14 series of 55-135 years length. Despite the complexity of distribution of radiocarbon ages at each site, the wealth of well-preserved wood demonstrates great promise for understanding the paleoflood history of the Oneida watershed by documenting the magnitude, location, and timing of floods. Further additional systematic sampling can add and strengthen tree-ring dating and tree-ring based flood records, confirm results, and contribute to the Holocene hydrological history of the region. Copyright © 2015 by The Tree-Ring Society.
    • Reconstructing Evaporation from Pine Tree Rings in Northern Mexico

      Pompa-García, M.; Camarero, J.J. (Tree Ring Society, 2015-07)
      Here we reconstructed evaporation using tree-ring width variability. Drought variability and its effects on forest growth have been mainly characterized by changes in precipitation and temperatures, whereas atmospheric drought and evaporation rates have been little investigated. The area of study corresponds to northern Mexico, a region where water resources are increasingly limited. We used correlation analyses to identify the months in which evaporation is most strongly related to tree-ring width series. Then, we built a linear regression model to predict seasonal winter-to-spring evaporation as a function of ring-width indices. Correlation analyses showed that the radial growth of P. cooperi decreased in response to reduced water availability and increased evaporation during the winter prior to the growing season, and also during spring and the early summer of the year of tree-ring formation. Pine growth mainly benefitted from wet and cool conditions from winter to early spring. Linear regression models used in reconstruction were statistically robust and allowed reconstructing January-to-April evaporation for the period 1900-2010. Our study contributes to a better understanding of historical changes in evaporation in northern Mexico and, most importantly, it also emphasizes how atmospheric moisture demand is linked to tree growth. Copyright © 2015 by The Tree-Ring Society.
    • The Dendroclimatological Potential of Willamette Valley Quercus garryana

      Gildehaus, S.; Arabas, K.; Larson, E.; Copes-Gerbitz, K. (Tree Ring Society, 2015-01)
      We develop a 341-year Oregon white oak (Quercus garryana Dougl.) tree-ring chronology in Oregon's Willamette Valley to evaluate climate-growth relationships and determine the species' dendroclimatological potential at our site and in the surrounding region. The standardized and residual chronologies exhibit significant positive correlations with previous-year April and May temperatures, inverse correlations with previous-year spring precipitation and summer PDSI, a positive correlation with current-year July precipitation and summer PDSI, and inverse correlations with current-year June temperatures. The strength of these relationships varies over time. Significant shifts in the chronologies' mean and variance align with phase changes in the Pacific Decadal Oscillation (PDO), with lower and more variable growth during the warmer, drier positive phase of the PDO over the instrumental record. The absence of similar shifts prior to the 1900s, suggests a lack of temporal consistency in the expression of PDO variability at our site. The strong crossdating at our site reflects a cohesive climate signal, and the climate analysis illustrates the potential to develop proxy data over multiple centuries. Together, these results indicate a potential to expand the network of currently available climate proxy data by utilizing Q. garryana in dendroclimatological research. © 2015 The Tree-Ring Society.
    • August to July Precipitation from Tree Rings in the Forest-Steppe Zone of Central Siberia (Russia)

      Shah, S.K.; Touchan, R.; Babushkina, E.; Shishov, V.V.; Meko, D.M.; Abramenko, O.V.; Belokopytova, L.V.; Hordo, M.; Jevšenak, J.; Kędziora, W.; et al. (Tree Ring Society, 2015-01)
      The goal of this research report is to describe annual precipitation reconstruction from Pinus sylvestris trees on three sites in the Abakan region, located in the Minusinsk Depression, at the confluence of the Yenisei and Abakan Rivers, Russia. The study was performed during the 4th annual international summer course "Tree Rings, Climate, Natural Resources and Human Interaction" held in Abakan, 5-19 August 2013. The reconstruction, for the 12-month total precipitation ending in July of the growth year, is based on a reliable and replicable statistical relationship between precipitation and tree-ring growth, and shows climate variability on both interannual and interdecadal time scales. The regional tree-ring chronology accounts for 56% of the variance of observed annual precipitation in a linear regression model, with the strongest monthly precipitation signal concentrated in May and June of the current growing season. Composite 500 mb height-anomaly maps suggest that the tree-ring data from this site, supplemented by other regional tree-ring data, could yield information on long-term atmospheric circulation variability over the study area and surrounding region. © 2015 The Tree-Ring Society.
    • Morphological and Physiological Phenology of Pinus longaeva in the White Mountains of California

      Hallman, C.; Arnott, H. (Tree Ring Society, 2015-01)
      Natural variations and responses to climate change can be identified within climatically sensitive ecosystems by monitoring growing season events. In 1962-1964, Fritts conducted a phenologic study on Pinus longaeva in the White Mountains of California. He monitored growing season events, environmental data, and dendrometer readings. In this study morphological and physiological phenophases, dendrometer traces, and environmental data were collected throughout the summers of 2007 and 2008 in the White Mountains of California to better understand variability in Pinus longaeva phenology and identify any shifts in the growing season since the 1962-1964 study (Fritts 1969). As a result of a late-season snow storm, observable phenophases in 2008 were 12 days later than in 2007. Pollination onset was slightly earlier than in the 1962-1964, which may indicate that accumulated heat or a combination of environmental factors influence these phenophases. Duration and timing of cambial activity in the present study was similar to that recorded in the Fritts (1969) investigation despite a median summer temperature increase of at least 2°C. © 2015 The Tree-Ring Society.
    • How to improve dendrogeomorphic sampling: Variogram analyses of wood density using X-Ray computed tomography

      Guardiola-Albert, C.; Ballesteros-Cánovas, J.A.; Stoffel, M.; Díez-Herrero, A. (Tree Ring Society, 2015-01)
      Knowledge of the spatial heterogeneity of wood is useful for industrial applications and improving dendrogeomorphic sampling, because it allows a better understanding of 3-D wood density structure in tree stems damaged by geomorphic processes. X-ray computed tomography (XRCT) scanning as a means of non-destructive measurement has become an important technique in tree research as it allows the detection of internal variations in wood density. In this paper a new methodology for modelling spatial variations of relative wood density using variograms on XRCT images is developed. For each tree, XRCT images perpendicular to the stem axis were obtained with 1-mm spacing. In a first step, ImageJ software was used to process each image. Then, more than 30 one-dimensional variograms were studied for a selected number of cross-sections. The results show that there is a pattern in the diffusion of relative wood density linked to the attenuation of the geomorphic damage along the stem from the wounded area. Although the number of samples could be increased, these preliminary results demonstrate that variograms of XRCT are a useful tool to optimize dendrogeomorphic sampling, saving time and costs. © 2015 The Tree-Ring Society.
    • Dendrochronological potential and productivity of tropical tree species in Western Kenya

      David, E.T.; Chhin, S.; Skole, D. (Tree-Ring Society, 2014-07)
      This study focuses on tropical tree growth rates in Western Kenya. The dendrochronological potential of each study species was determined by visual examination of rings, and then cumulative growth trajectories for diameter were synthesized for species of sufficient sample size (n ≥ 3), based on ring-width chronologies. The 14 tree species considered were: Acacia mearnsii, Bridelia micrantha, Combretum molle, Croton macrostachyus, Cupressus lustianica, Eucalyptus camaldulensis, Eucalyptus grandis, Eucalyptus saligna, Grevillea robusta, Mangifera indica, Markhamia lutea, Persia Americana, Syzygium cumini, and Trilepisium madagascariensis. The species with the highest dendrochronological potential included Acacia mearnsii, Cupressus lusitanica, the Eucalyptus spp. and Mangifera indica, which are all non-native species that successfully crossdated. The results also indicated that the species with highest dendrochronological potential had strong radial growth synchrony, which was reflected in high inter-tree correlation and (or) high growth variance explained by the first principal component axis. Furthermore, A. mearnsii and E. camaldulensis were sensitive to annual precipitation and moisture index. The species with the lowest dendrochronological potential were Grevillea robusta and Markhamia lutea. In terms of productivity, the three fastest growing species in the study, based on annual diameter increment, were Eucalyptus camaldulensis, Eucalyptus grandis, and Acacia mearnsii. This study also has great potential to extrapolate historical patterns of diameter growth to understanding annual aboveground biomass and carbon dynamics in Western Kenya.
    • An extractor device for stuck or broken increment borers

      Loader, N.J.; Waterhouse, J.S. (Tree-Ring Society, 2014-07)
      A lightweight, portable device for extracting stuck or broken increment borers is presented and its operation described. The “Decorum” extractor is compact and weighs less than 400 g. It is easily carried in a belt pouch or pocket and is both reliable and easy to operate. The extractor does not require fixed tie points nor does it damage the tree. It offers an effective solution to a widely occurring problem in dendrochronology and forest research.
    • Shifting climate sensitivity and contrasting growth trends in Juniperus species growing together at opposite range margins

      Riddle, J.; Pederson, N.; Stella, J.C.; Leopold, D.J. (Tree-Ring Society, 2014-07)
      The long generation time of woody plants inhibits detection of shifts in their distributions induced by climatic change. Consequently, assessing growth changes within existing populations, especially those near species range margins, can increase understanding of climate change impacts. We apply dendrochronological methods to examine recent radial growth of the ecologically similar species Juniperus communis L. and J. virginiana L. growing under the same conditions but at opposite latitudinal range margins. We use moving correlations to analyze changes in relationships between growth and monthly climatic variables, and regional curve standardization to identify trends in growth rate independent of plant age. For J. communis, growth sensitivity to temperature and precipitation shifted earlier in the spring whereas for J. virginiana only temperature sensitivity shifted earlier over the last 50 years. Since 1920, J. virginiana growth displays an upward trend, but J. communis growth shows both increases and decreases. Recent precipitation increase, rather than warming alone, appears to drive the growth trends, but interactions with temperature and vegetation dynamics, instead of range position, likely account for the differences in trends between species. Although these results generally agree with climate change predictions, they also point out potential difficulties in modeling future species ranges based on growth-climate relationships and growth at range margins.
    • Dendrochronological dating of the World Trade Center ship, Lower Manhattan, New York City

      Martin-Benito, D.; Pederson, N.; McDonald, M.; Krusic, P.; Fernandez, J.M.; Buckley, B.; Anchukaitis, K.J.; D'Arrigo, R.; Andreu-Hayles, L.; Cook, E. (Tree-Ring Society, 2014-07)
      On July 2010, archaeologists monitoring excavation at the World Trade Center site (WTC) in Lower Manhattan found the remains of a portion of a ship's hull. Because the date of construction and origin of the timbers were unknown, samples from different parts of the ship were taken for dendrochronological dating and provenancing. After developing a 280-year long floating chronology from 19 samples of the white oak group (Quercus section Leucobalanus), we used 21 oak chronologies from the eastern United States to evaluate absolute dating and provenance. Our results showed the highest agreement between the WTC ship chronology and two chronologies from Philadelphia (r  =  0.36; t  =  6.4; p < 0.001; n  =  280) and eastern Pennsylvania (r  =  0.35; t  =  6.3; p < 0.001; n  =  280). The last ring dates of the seven best-preserved samples suggest trees for the ship were felled in 1773 CE or soon after. Our analyses suggest that all the oak timbers used to build the ship most likely originated from the same location within the Philadelphia region, which supports the hypothesis independently drawn from idiosyncratic aspects of the vessel's construction, that the ship was the product of a small shipyard. Few late-18th Century ships have been found and there is little historical documentation of how vessels of this period were constructed. Therefore, the ship's construction date of 1773 is important in confirming that the hull encountered at the World Trade Center represents a rare and valuable piece of American shipbuilding history.
    • Tree-ring dating of historic buildings in Willsboro, northeastern New York, and development of regional chronologies for dendroarchaeology

      Barclay, D.J.; Rayburn, J.A. (Tree-Ring Society, 2014-07)
      Historical timbers have been sampled from buildings at 13 sites in Willsboro, New York, on the west shore of Lake Champlain. Ring-width series from 139 timbers have been successfully crossdated and used to develop tree-ring chronologies for ash (Fraxinus spp.), oak (Quercus spp.), pine (Pinus spp.), eastern hemlock (Tsuga canadensis (L.) Carr.), and spruce (Picea spp.), which collectively span A.D. 1555 to 1878. Tree cutting dates suggest that Windyview Manor was likely built in or soon after 1799, and a barn and farmhouse at the 1812 Homestead were built in or soon after 1812 and 1813, respectively. These dates are all consistent with documentary records for these sites. Aggregate data for the town suggest a shift in wood use for building during the 19th Century, with ash and oak commonly used for large frame timbers from the 1790s to 1820s, and hemlock and spruce dominating from the 1830s to 1860s. Chronologies developed in this project are among the first from historical timbers for northern New York and will facilitate further dendroarchaeological work in the region.