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.

The biogeochemistry and ecology of the Arctic environment have been heavily impacted by anthropogenic pollution and climate change. We used ICP-MS to measure concentrations of 26 elements in the AD 1300-2000 tree rings of larch from the Taymyr Peninsula in northern Siberia for studying the interaction between environmental change and wood chemistry. We applied a two-stage data reduction technique to identify trends in the noisy measurement data. Statistical assessment of variance of normalized time series reveals pronounced depletion of xylem Ca, Mg, Cl, Bi and Si concentrations and enrichment of P, K, Mn, Rb, Sr and Ba concentrations after ca. AD 1900. The trends are unprecedented in the 700-year records, but multiple mechanisms may be at work and difficult to attribute with certainty. The declining xylem Ca and Mg may be a response to soil acidification from air pollution, whereas increasing P, K, and Mn concentrations may signal changes in root efficiency and excess water-soluble minerals liberated by the permafrost thaw. The changes seem consistent with mounting stress on Arctic vegetation. This study supports the potential of tree rings for monitoring past and ongoing changes in biogeochemistry of Arctic ecosystems related to pollution and permafrost thaw. © 2016 by The Tree-Ring Society.

The benefit of using multiple species in dendroclimatic reconstructions in the eastern U.S. has been demonstrated. However, the benefit of including rarely-used species in multispecies reconstructions has been little explored. This paper shows the utility of using a rarely-used species in dendrochronology, Juglans nigra, in a multispecies Palmer Drought Severity Index (PDSI) reconstruction at a site in southern Indiana. First, the crossdating J. nigra is established, followed by determining the climate response. The standardized J. nigra chronology is then compared with co-occurring standardized species chronologies (Quercus alba, Quercus rubra, and Liriodendron tulipifera) reported in Maxwell et al. (2015). Using a principal component regression model, the bi-weights of each species were calculated to determine how much J. nigra contributed to the explanatory power of the model. J.nigra had a high interseries correlation (0.604) and mean sensitivity (0.304) and a strong correlation with summer PDSI, which was comparable in strength and more consistent through time than the cooccurring species. The inclusion of J. nigra in the composite reconstruction provided more consistency and better captured the observed PDSI variability. This is compelling evidence for why rarely-used species should be tested for inclusion in multispecies climate reconstructions. © 2016 by The Tree-Ring Society.

The processing of subfossil wood poses some difficulties in densitometric research. Problems arise because of the physiochemical changes of wood occurring in the sedimentation environment. Subfossil wood modification can result from the uptake of mineral and organic substances into the wood tissue. It can also occur as the effect of microbiological degradation of wood. The goal of this study was to identify the appropriate method of subfossil wood preparation for the densitometric research. For this purpose the wood of Norway spruce from Lake Schwarzensee was subjected to extraction in deionized water, acetone and diluted acetic acid. The application of acetic acid did not significantly influence the density of the wood and acetone seemed to be too aggressive. The best result was obtained by rinsing the samples in cold de-ionized water. This extraction procedure allowed removal of unwanted water-soluble, organic and inorganic compounds from wood and simultaneously did not lead to the degradation of subfossil samples. © 2016 by The Tree-Ring Society.

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.