T160 Status of the Headwaters in our Changing World: Springs and Base Flow

Tuesday, 24 September 2024
8:00 AM - 12:00 PM
210C

GROUNDWATER DEPENDENT ECOSYSTEMS AND THEIR RESILIENCY AGAINST LANDSCAPE CHANGE IN THE WYOMING ROCKY MOUNTAIN HEADWATERS

Paper number: T160-7
Program: Technical Sessions
Time: 9:20 AM – 9:35 AM

Authors

Abstract

The Snowy Range Mountains, located in Wyoming’s Medicine Bow National Forest (MBNF), are found in the central Rocky Mountain region and are headwater to the North Platte and Laramie Rivers. The Rocky Mountains have experienced many ecohydrological shifts including reduced snowpack, decreased soil moisture, and multiple vegetation disturbances from drought, bark beetle epidemics, and wildfire. Most notably, the MBNF has experienced a multi-decade bark beetle epidemic where dead trees supplied fuel for a 716 km2 fire in 2020 that spurred intense tree kill and soil burn. Lodgepole pines, the dominant MBNF species normally follow a recovery trajectory following canopy fire through the spread of serontinous cones, but in many bark beetle kill areas these cones were not viable to produce new seedlings and promote regeneration. However, seedling regeneration has been observed near wetland springs and perched aquifers. Mature trees that were completely untouched by fire in groundwater supported areas are able to send their viable seedlings and promote forest regeneration to transition areas. The stability that groundwater provides to these ecosystems remains unknown at the landscape scale. In this study, multiple lines of evidence are used to evaluate the ecohydrological setting of wetland springs and their role as hydrologic refugia in the MBNF along a 36 km transect from the headwater region where forests are recovering. This transect is a hillslope gradient that ranges from 2,400 to 3,600m amsl where snow varies from 0.8 m at 2,400m to 1.2 m at 3,500m amsl. Stable isotopes, geochemistry, historical well data, and current hydrological monitoring are used to evaluate the conditions for forming groundwater dependent ecosystems that support forest recovery after one or more disturbances. Results yield new insights into groundwater flow systems in mountain watersheds threatened by climate change and the conditions in which these flow systems function to enhance forest recovery after disturbance.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-404372

© Copyright 2024 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.