Late Holocene Climate And Environmental Change In A High-Elevation, Whitebark Pine Ecosystem, Beartooth Mountains, Wyoming, USA

Authors: Maegen Rochner*, University of Tennessee Knoxville
Topics: Paleoenvironmental Change, Physical Geography, Mountain Environments
Keywords: dendrochronology, environmental change, treeline, whitebark pine
Session Type: Paper
Day: 4/6/2019
Start / End Time: 3:05 PM / 4:45 PM
Room: Marshall East, Marriott, Mezzanine Level
Presentation File: No File Uploaded

Whitebark pine ecosystems of the western United States and Canada are currently threatened with possible extinction. The combination of warming temperatures and subsequent increases in infestation, competition, and disease is leading to wide-spread mortality of the keystone species, and continued study is necessary to improve understanding of which threats are and will be the most detrimental to the survival of whitebark pine ecosystems in an uncertain future. One way to improve projections for the future is to examine how past climate change affected whitebark pine ecosystems. For this study, we used methods in dendrochronology to (1) investigate late Holocene climate change and (2) evaluate possible modern analogues in a high-elevation, whitebark pine ecosystem. Using data from remnant and living whitebark pine and Engelmann spruce, we examined the influence of the Medieval Warm Period (MWP) and Little Ice Age (LIA) on establishment and mortality and investigated modern climate-growth relationships. Findings support the hypothesis that large whitebark pine and Engelmann spruce trees thrived at the study site during the MWP and perished during the LIA. However, while these trees most likely thrived during the purported warmer and drier conditions of the MWP, results from climate-growth analyses suggest that high-elevation species, and especially whitebark pine, may not respond positively to future climate, especially if drier conditions accompany warming. Emerging negative growth responses to previous summer temperatures, along with emerging positive growth responses to previous summer moisture, suggest that the moisture conditions that accompany warming will greatly influence future growth.

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