Landscape Level Dynamics in an Endangered Mountain Ecosystem, Northern Rocky Mountains, U.S.A.

The purpose of this dissertation research was to investigate the extent of natural and anthropogenic impacts on declining whitebark pine communities. My research used dendroecology to study multicentury changes in these threatened communities to assess current and past forest dynamics and the overlapping effects of white pine blister rust, mountain pine beetle, and climate change in the northern Rocky Mountains. I created whitebark pine (host) and subalpine fir (nonhost) chronologies and collected species composition, stand structure, and forest health data in sites along a latitudinal transect through the Rocky Mountains in western Montana. The standstructure data indicate over 70% of whitebark pines at all sites are declining or dead. The high mortality of whitebark pines was caused by the overlapping effects of past (1880s, 1920s, and 1970s) and current mountain pine beetle outbreaks, and more recently by white pine blister rust infection. Whitebark pine populations, in the majority of our sites, are being successionally replaced by subalpine fir, grand fir, and Engelmann spruce in all levels of the forest strata (trees, saplings, and seedlings). Shade-tolerant trees began establishing between 150 and 300 years ago at all sites, a finding that suggests 20th century fire suppression is not responsible for the successional replacement of whitebark pine forests. Whitebark pine and subalpine fir growth respond strongly to drought and precipitation. This indicates wet conditions from precipitation and snowpack melt in the previous summer enhance tree growth during the following growing season. My climate reconstruction results support other climate reconstructions, east of the Continental Divide, that found precipitation and Palmer Drought Severity Index (PDSI) have more of an influence on subalpine forest growth than temperature. The reconstruction data contribute an important high-elevation component to existing drought reconstructions from lower elevations in the northern Rocky Mountains. Whitebark pine communities should continue to be monitored as continued periods of drought will likely make whitebark pines more susceptible to mountain pine beetle attack and weaken their resistance to white pine blister rust infection

The Longleaf Tree-Ring Network: Reviewing and expanding the utility of Pinus palustris Mill. Dendrochronological data

The longleaf pine (Pinus palustris Mill.) and related ecosystem is an icon of the southeastern United States (US). Once covering an estimated 37 million ha from Texas to Florida to Virginia, the near-extirpation of, and subsequent restoration efforts for, the species has been well-documented over the past ca. 100 years. Although longleaf pine is one of the longest-lived tree species in the southeastern US—with documented ages of over 400 years—its use has not been reviewed in the field of dendrochronology. In this paper, we review the utility of longleaf pine tree-ring data within the applications of four primary, topical research areas: climatology and paleoclimate reconstruction, fire history, ecology, and archeology/cultural studies. Further, we highlight knowledge gaps in these topical areas, for which we introduce the Longleaf Tree-Ring Network (LTRN). The overarching purpose of the LTRN is to coalesce partners and data to expand the scientific use of longleaf pine tree-ring data across the southeastern US. As a first example of LTRN analytics, we show that the development of seasonwood chronologies (earlywood width, latewood width, and total width) enhances the utility of longleaf pine tree-ring data, indicating the value of these seasonwood metrics for future studies. We find that at 21 sites distributed across the species’ range, latewood width chronologies outperform both their earlywood and total width counterparts in mean correlation coefficient (RBAR = 0.55, 0.46, 0.52, respectively). Strategic plans for increasing the utility of longleaf pine dendrochronology in the southeastern US include [1] saving remnant material (e.g., stumps, logs, and building construction timbers) from decay, extraction, and fire consumption to help extend tree-ring records, and [2] developing new chronologies in LTRN spatial gaps to facilitate broad-scale analyses of longleaf pine ecosystems within the context of the topical groups presented

Separating Trends in Whitebark Pine Radial Growth Related to Climate and Mountain Pine Beetle Outbreaks in the Northern Rocky Mountains, USA

Drought and mountain pine beetle (Dendroctonus ponderosae Hopkins) outbreaks have affected millions of hectares of high-elevation conifer forests in the Northern Rocky Mountains during the past century. Little research has examined the distinction between mountain pine beetle outbreaks and climatic influence on radial growth in endangered whitebark pine (Pinus albicaulis Engelm.) ecosystems. We used a new method to explore divergent periods in whitebark pine radial growth after mountain pine beetle outbreaks across six sites in western Montana. We examined a 100-year history of mountain pine beetle outbreaks and climate relationships in whitebark pine radial growth to distinguish whether monthly climate variables or mountain pine outbreaks were the dominant influence on whitebark pine growth during the 20th century. High mortality of whitebark pines was caused by the overlapping effects of previous and current mountain pine beetle outbreaks and white pine blister rust infection. Wet conditions from precipitation and snowpack melt in the previous summer, current spring, and current summer benefit whitebark pine radial growth during the following growing season. Whitebark pine radial growth and climate relationships were strongest in sites less affected by the mountain pine beetle outbreaks or anthropogenic disturbances. Whitebark pine population resiliency should continue to be monitored as more common periods of drought will make whitebark pines more susceptible to mountain pine beetle attack and to white pine blister rust infection

Forest dynamics and climate sensitivity of an endangered Carolina hemlock community in the southern Appalachian Mountains, USA

During the last century, the eastern United States has functionally lost two major tree species (American chestnut and American elm), two more, eastern and Carolina hemlock, will likely be functionally extinct during much of their ranges by 2050. Carolina hemlock forests are geographically limited to high elevations in the southern Appalachian Mountains and are considered to be endangered. We collected forest stand, composition, and tree age data at the beginning of a hemlock woolly adelgid (HWA) infestation. Prior to the arrival of HWA, Carolina hemlocks were healthy and densely populated in the overstory and understory. While Carolina hemlock regenerated successfully and continuously from 1850 to 2010, the development of this Carolina hemlock forest will be altered by the HWA and may result in an increase in the density of northern red oak, white oak, mountain laurel, and Catawba rhododendron. Carolina hemlocks preferred cool, wet summers with older trees experiencing greater reductions in radial growth than younger trees during droughts. This study demonstrates that dendrochronological techniques can provide critical annual information on Carolina hemlock forest development and tree age-climate response. Our results provide a multi-century perspective for conservation efforts and management of Carolina hemlock forests in the southern Appalachian Mountains.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

“Landscape Level Dynamics in an Endangered Mountain Ecosystem, Northern Rocky

I am submitting herewith a dissertation written by Saskia L. van de Gevel entitle

Variability in Fire Regimes of High-Elevation Whitebark Pine Communities, Western Montana, USA

We investigated the stand history of whitebark pine forests on 3 mountains in the Lolo National Forest, Montana, USA to characterize the fire regimes and other disturbance agents that historically operated at these sites and to explore the potential influences of modern fire suppression on these forests. We used hLarsonistorical fire atlas data and dendroecological data to reconstruct the distinct stand. The fire regimes of each site fit within the general definition of mixed-severity fire regimes, but distinct differences in fire frequency anween them. All 3 stands contained at least 1 post-disturbance cohort and had experienced at least 1 widespread fire over their histories. We found no consistent fire—climate relationship at these sites. Mountain pine beetles were the primary mortality agent in the current stands at all 3 sites. Subalpine fir began establishing at each site within 2 decades of the most recent widespread fire and well before fire suppression was effective in this region. Fire suppression may have reduced the occurrence of fire during the late 20th century at all 3 sites, but only the forest on Point Six has exceeded the mean interval between widespread fires. The differences in fire activity and effects of fire suppression that we observed at these sites are likely the result of different biophysical site characteristics and disturbance legacies and hold important implications for the development of site-specific management strategies for whitebark pine restoration

Tree-Ring Dating Of Old-Growth Longleaf Pine (Pinus Palustris Mill.) Logs From An Exposed Timber Crib Dam, Hope Mills, North Carolina, U.S.A.

On 26 May 2003, intense rainfall from a series of thunderstorms in eastern North Carolina caused flooding that eventually destroyed the concrete dam in Hope Mills, draining Hope Mills Lake, and revealing a formerly submerged and buried structure that was identified as a timber crib dam. Inspection revealed these logs to be old-growth longleaf pines, which are now rare on the coastal plain landscape. Our primary objective was to develop a new multi-century longleaf pine tree-ring chronology by crossdating the tree rings from sections extracted from logs in the crib dam with an anchored tree-ring chronology created from nearby living longleaf pine trees. We also examined the climatic response in the longleaf pine trees to evaluate their potential for reconstructing climate. Using tree-ring measurements obtained from old-growth longleaf pines found at a nearby church, we were able to date the rings on 21 series representing 14 logs from the crib dam, spanning the years 1597 to 1825. Distorted sapwood in many of the logs prevented us from finding absolute cutting dates and lessened the strength of correlation during the period of overlap between the church series and crib dam series. Human disturbances, specifically related to the naval stores industry, likely influenced the growth-ring patterns of the crib dam pine samples, as well. Correlation analyses between the longleaf pine chronology and temperature, precipitation, Palmer Drought Severity Indices, and North Atlantic sea surface temperatures showed a significant response to cool and wet spring months.This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]

The Historical Dendroarchaeology Of The Hoskins House, Tannenbaum Historic Park, Greensboro, North Carolina, U.S.A.

The Hoskins House is a two-story, single pen log structure located in Tannenbaum Historic Park, Greensboro, North Carolina. The house is thought to have been built by Joseph Hoskins, who lived in Guilford County from 1778 until his death in 1799. Previous archaeological testing of soil around the house yielded over 1000 artifacts, and the ceramics of these gave a Mean Ceramic Date (MCD) of 1810 as a possible initial year of construction. Our objective was to date the outermost rings on as many logs as were accessible in the Hoskins House to determine the year or range of years when the house was likely built. We compared 37 ring-width measurement series from 28 white oak group logs with a composite reference chronology created from three oak reference chronologies from Virginia. We found that the logs were cut over a 3-year period from 1811 to 1813, lending credence to the initial MCD of 1810. Joseph Hoskins had already passed away in 1799 and the property was deeded to his two sons, Joseph and Ellis. Ellis Hoskins eventually was later deeded sole possession of the property. The two-story log house located at Tannenbaum Historic Park may be more correctly called the ‘‘Ellis Hoskins House’’ rather than the ‘‘Joseph Hoskins House.’’This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]

The Dendroarchaeology Of Cagle Saltpetre Cave: A 19th Century Saltpeter Mining Site In Van Buren County, Tennessee, U.S.A

During the historic mining episodes at Cagle Saltpetre Cave, wooden leaching vats needed for the lixiviation of calcium nitrate from mined sediments (from which saltpeter was then produced) were constructed and used in the cave. When mining operations ceased, these features were abandoned and preserved in situ, some remaining virtually intact. Their remarkable preservation enabled tree-ring dating of timbers associated with these vats to be accomplished. Tree rings from oak planks used in the construction of the leaching vats were measured to 0.001 mm precision on a Velmex measuring system. Using COFECHA software, we crossdated the measurement series to both the Norris Dam State Park and Piney Creek Pocket Wilderness white oak reference chronologies, spanning the years from 1633 to 1982, obtained from the International Tree-Ring Data Bank. Graphical comparisons via scatter plots were inspected to ensure correct temporal placements. The final chronology developed from 39 dated series correlated very highly with the Norris Dam State Park reference chronology (r = 0.49, n = 170 yrs, t = 7.29, p < 0.0001) and verified that our site chronology extends from 1692 to 1861. The results of our analyses indicate that saltpeter was mined and processed at the site during separate episodes throughout the 19th Century. Additionally, saltpeter-processing technology changed throughout the course of the mining operations.This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]

Comparing the impact of live-tree versus historic-timber data on palaeoenvironmental inferences in tree-ring science, eastern North America

Dendroarchaeological data from historic structures and artefacts have the potential to extend tree-ring chronologies spatially and temporally, especially where old-growth forests have been extensively modified or harvested. While these data may contribute to an improved understanding of past climate and ecology, critical differences in the properties of live-tree and historic-timber data might affect results and interpretations of large-scale studies, such as those relying on large datasets from public databases like the International Tree-Ring Data Bank (ITRDB). The objective of this work was to compare summary measures of live-tree versus historic-timber datasets likely to affect outcomes and inferences of typical paleoenvironmental applications. We used 99 live-tree (LT) and 41 historic-timber (HT) datasets collected in the Appalachian region of the eastern United States and compared common analytical measures for understanding past climate and ecology, including temporal coverage, species composition, recruitment patterns, segment length, series coherence/mean interseries correlation (as Rbar), expressed population signal (EPS), subsample signal strength (SSS) and response to drought and extreme climate events. We found that tree-ring data from historic timbers record some ecological events similarly to live trees and are sensitive to some climate conditions, with important caveats related to the influence of site and tree selection on analytical measures. In some cases, these caveats can be overcome through improved collection of metadata and additional analyses. In all cases, potential differences in LT and HT data should be considered by those who perform large-scale analyses using public tree ring databases, especially as more scientists contribute historic-timber datasets