Cottonwoods, Water, and People—Integrating Analysis of Tree Rings with Observations of Elders from the Eastern Shoshone and Northern Arapaho Tribes of the Wind River Reservation, Wyoming

Open-File Report 2020-1072
Prepared in cooperation with the Eastern Shoshone Tribe of the Wind River Reservation, Wyoming, the Northern Arapaho Tribe of the Wind River Reservation, Wyoming, and Colorado State University
By: , and 

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Abstract

We assessed the history of flow and riparian ecosystem change along the Wind River using cottonwood tree-ring data, streamgage records, historical temperature and precipitation data, drought indices, and local observations and Traditional Ecological Knowledge from elders of the Eastern Shoshone and Northern Arapaho Tribes of the Wind River Reservation, Wyoming. This assessment identified impacts that have occurred to riparian resources of concern to the Tribes, which will assist in prioritizing drought planning efforts. Impacts included reduced abundance, reduced regeneration, and increased mortality in cottonwoods (Populus deltoides and P. angustifolia); an increase in invasive species, especially Russian olive (Elaeagnus angustifolia), that are gradually replacing cottonwoods and other native woody plants; decreased abundance of native and culturally important plants; reduced abundance of culturally important fish; reduced volume and changes to the timing of flows; and changes in river course. This assessment documented the biophysical and social factors that have contributed to riparian ecosystem change and to reduced water availability and flows, including agricultural diversion, drought, and fire. Cottonwoods along the Wind River are as much as 300 years old. By relating tree-ring width to recorded streamflows, we were able to reconstruct streamflows confidently back to the 1850s and speculatively back to the mid-1700s. Extending the historical record of streamflows allows for a more-complete understanding of hydroclimatic variability and provides a foundation for developing preparedness and response strategies for drought management. Ring width of cottonwood trees at the Boysen Site was more strongly correlated to river flow than to local precipitation or temperature, indicating that growth of trees is controlled more by montane snowmelt than by local weather. Therefore, tree rings are a better indicator of water supply than of the local conditions controlling water demand. The extended flow record from tree rings revealed the occurrence of a major period of low flow from 1870 to 1910 that was not evident in the shorter instrumental records of flow and weather. Information from tree rings, streamflow measurements, drought indices, and elder observations all suggest that the early 2000s drought was the most severe, sustained drought in the last century. Our results illustrate how drought is experienced in different ways across locations and sectors, which underscores the importance of using multiple indicators for drought management. These results will contribute to ongoing assessment, monitoring, and planning efforts at the Wind River Reservation.

Suggested Citation

McNeeley, S.M., Friedman, J.M., Beeton, T.A., and Thaxton, R.D., 2020, Cottonwoods, water, and people—Integrating analysis of tree rings with observations of elders from the Eastern Shoshone and Northern Arapaho Tribes of the Wind River Reservation, Wyoming: U.S. Geological Survey Open-File Report 2020–1072, 33 p., https://doi.org/10.3133/ofr20201072.

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Research Methods
  • Human Modification of the River and Flow
  • Cottonwood Species
  • Relation Between Riparian Forest and Tribes
  • Cottonwood Ages
  • Impacts of Social and Environmental Changes on Riparian Environments
  • Mechanism of Observed Impacts on Riparian Forest
  • Cottonwood Growth
  • Flow Reconstruction from Multiple Sources
  • Summary
  • References Cited
  • Appendix 1. Interview Questions
  • Appendix 2. Details of Cottonwood Sampling and Analysis

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Cottonwoods, water, and people-Integrating analysis of tree rings with observations of elders from the Eastern Shoshone and Northern Arapaho Tribes of the Wind River Reservation, Wyoming
Series title Open-File Report
Series number 2020-1072
DOI 10.3133/ofr20201072
Year Published 2020
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Fort Collins Science Center
Description Report: iv, 33 p.; Data Release
Country United States
State Wyoming
Other Geospatial Wind River Reservation
Online Only (Y/N) Y
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