• 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.
    • Application of the Minimum Blue-Intensity Technique to A Southern-Hemisphere Conifer

      Brookhouse, M.; Graham, R. (Tree Ring Society, 2016-07)
      Minimum blue-intensity (BI) appears to be a viable source of proxy-temperature data, but is yet to be applied to a Southern-Hemisphere species. Here, we apply the BI technique to Podocarpus lawrencei, a conifer endemic to the Australian Alps. We develop sample-preparation protocols and examine the climate sensitivity of resulting tree-ring width (TRW) and BI chronologies. We found that extractable resins were removed from P. lawrencei samples after 28 hours of Soxhlet extraction and a highly-significant negative correlation (r =-0.79, p<0.0001) exists between the resulting BI chronology and growing season (August-April) temperature maxima. The climate sensitivity of our BI data, combined with an apparent teleconnection with a previously-reported dataset, suggests that an unparalleled opportunity exists to develop a powerful proxy for growing-season temperatures in southeast Australia. © 2016 by 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.
    • 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.
    • 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.
    • Dating Wooden Beams from the Grancia Monastic Abbey in Southern Italy

      Gentilesca, T.; Todaro, L.; Ripullone, F.; Saracino, A.; Moretti, N.; Borghetti, M. (Tree Ring Society, 2016-01)
      We present the results of a dendrochronological study carried out on timbers from the monastic abbey Grancià of Brindisi di Montagna in Southern Italy. Our objective was to date cross-sections of oak (Quercus spp.) taken from structural timbers to determine the felling dates, the time span covered by the series and to evaluate whether the retrieved tree-ring data could be used to extend an existing living trees chronology of oak from Southern Italy. Dendrochronological analyses were performed on samples collected from eight oak timbers in 2006 during the restoration of the abbey. Raw tree-ring series were crossdated and grouped into a floating chronology that was compared with an absolute reference chronology, specifically constructed from living Quercus pubescens (Willd.) trees, from the nearby Pollino National Park. Seven of eight samples could be absolutely dated in the early 19th, late 18th and mid late 17th Centuries, providing a chronology that reaches back to AD 1545. © 2016 by The Tree-Ring Society.
    • Dendrochronology and the Complex History of the William Hawk Cabin, Salt Lake City, Utah

      Bekker, M.F.; Naylor, J. (Tree Ring Society, 2016-07)
      The William Hawk Cabin is considered one of the oldest pioneer structures in Salt Lake City, Utah. Tradition suggests that it was originally constructed in 1848 inside the "Old Fort" established by Mormon settlers in 1847, and then moved to its current location between 1850 and 1852. We examined tree rings from 23 Douglas-fir (Pseudotsuga menziesii var. glauca) and eight white fir (Abies concolor) timbers in the cabin to (1) evaluate and refine the suggested range of construction dates of 1848-1852, (2) verify or refute the suggestion that the cabin was originally constructed within the Old Fort, (3) identify any evidence of use of deadwood, timber re-use, stockpiling, or renovation, and (4) determine the provenance of the timbers. We built a 209-year floating chronology from 36 cores crossdated visually and verified statistically with COFECHA. Statistically significant (p < 0.0001) comparisons with established regional chronologies indicated that the Hawk Cabin chronology extends from 1651-1859. Cutting dates ranged from 1832-1860, with strong clusters in 1846 and 1851-1852, and a weaker cluster in 1855. The 1851-1852 cluster accounted for over half of the cutting dates, suggesting that a version of the cabin was built by 1852, and the later timbers were incorporated as part of a major renovation in or after 1860. The 1846 cluster may reflect wood salvaged from road building efforts by the Donner-Reed Party, and suggests that a version of the cabin may have been originally built in the Old Fort, although probably not by Hawk. These results confirm the historical significance of the William Hawk Cabin, and the complexity of its construction history argues for large sample depths in dendroarchaeological studies in semi-arid regions. © 2016 by The Tree-Ring Society.
    • Dendrochronology of Utah Juniper (Juniperus osteosperma (Torr.) Little)

      DeRose, R.J.; Bekker, M.F.; Kjelgren, R.; Buckley, B.M.; Speer, J.H.; Allen, E.B. (Tree Ring Society, 2016-01)
      Utah juniper was a foundational species for the discipline of dendrochronology, having been used in the early 20th Century investigations of Mesa Verde, but has been largely ignored by dendrochronologists since. Here we present dendrochronological investigations of Utah juniper core and cross-sectional samples from four sites in northern Utah. We demonstrate that, contrary to the general opinion among many dendrochronologists, Utah juniper exhibits excellent crossdating that is reflective of its sensitivity to climate-a desirable characteristic for dendroclimate reconstruction. Across all four sites the dominant signal for annual ring-width increment occurred during the growing season and was positive for precipitation and negative for temperature. This corroborates ecophysiological studies that highlight Utah juniper's aggressive water-use behavior and desiccation tolerance that together enable survival at extremely negative soil water potentials. This behavior differs from co-occurring Pinus spp. (i.e. P. edulis and P. monophylla) that avoid cavitation at the cost of carbon starvation. We determine that the annual radial increment of Utah juniper rings is particularly responsive to soil moisture availability, and is in fact a useful proxy for hydroclimatic variables such as precipitation, drought, and streamflow. Its geographic distribution spans a large swath of the Interior West, including areas where other more commonly sought-after species for dendrochronology do not occur, and ought to be considered crucial for complementing the rich network of tree-ring chronologies in the western U.S. © 2016 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.
    • 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.
    • Forgotten Waterways: Analyzing Beams from the Wabash and Erie Canal

      Taormina, R.; Speer, J.H. (Tree Ring Society, 2016-07)
      The Wabash and Erie Canal system was an important transportation network in the early 1800s prior to the dominance of trains and later automotive transportation. In this work, timbers from Culvert 151 were examined, after they were exhumed during construction of Hwy 641 on the south side of Terre Haute, Indiana. Cross-sections were taken from each of 22 beams and allowed to air dry to determine the stability of the timbers. We examined the wood to determine the genera or species of each sample that was used in this construction project and developed a floating chronology from our white oak group samples. The mix of species present included 11 beams of American beech (Fagus grandifolia), five white oak group (Quercus subgenus Lepidobalanus), and one each of American elm (Ulmus americana), winged elm (Ulmus alata), sugar maple (Acer saccharum), shagbark hickory (Carya ovata), white ash (Fraxinus americana), and black walnut (Juglans nigra). This suggests that the timbers were cut from the available trees in a certain size class without much regard for wood properties. The oak trees were an average of 186 years in age and the floating chronology dated to AD 1827. We also compared our chronology to 16 other oak chronologies in the region using an Inverse Distance Weighting (IDW) algorithm in ArcGIS to determine the most likely provenance of the samples. Our oak chronology correlates the strongest to archaeological samples from southeastern Indiana in Jefferson County along the Ohio River. It is possible that the timbers were cut near Madison Indiana, shipped down the Ohio River and up the Wabash River prior to incorporation in Culvert 151 on the Wabash and Erie Canal. © 2016 by 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.
    • Meeting Report: The 2016 Ameridendro Awards

      Sutherland, K.E.; Mundo, I.A. (Tree Ring Society, 2016-07)
    • 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.
    • Notice: Bryant Bannister 1926–2016

      Dean, J.S.; Towner, R.H. (Tree Ring Society, 2016-07)
    • Precipitation Variations in the Eastern Part of the Hexi Corridor during AD 1765-2010 Reveal Changing Precipitation Signal in Gansu

      Chen, F.; Yuan, Y.-J.; Zhang, R.-B.; Wang, H.-Q.; Shang, H.-M.; Zhang, T.-W.; Qin, L.; Fan, Z.-A. (Tree Ring Society, 2016-01)
      We reconstructed August-May precipitation from AD 1765 to 2010 for the eastern part of the Hexi Corridor, northwest China, using tree rings of Picea crassifolia. The precipitation reconstruction explains 44.1% of the actual precipitation variance during the common period of 1951-2010. The precipitation reconstruction is representative of precipitation conditions over a large area of the Hexi Corridor. Multi-taper spectral analysis reveals the existence of significant variability with periods of 9.3, 6.7, 3.1, and 2.6 years. Comparison between the precipitation reconstruction of the eastern part of the Hexi Corridor and other nearby precipitation/drought reconstructions shows high coherency in the timing of dry/wet episodes on annual to decadal scale. The divergences existing between the reconstructions may reflect the influence of different geographic features in Gansu and differences in seasonality of the various precipitation/drought reconstructions. © 2016 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.