Assessing Rocky Mountain National Park’s Snowpack Dynamics and Impact on Wetland Vegetation

Abstract

Wetland ecosystems are critical habitat for a multitude of species within Rocky Mountain National Park. Hydrological inputs, such as snowpack and groundwater, are critical for wetland formation and persistence. This study investigated how climate change’s effects on snowpack dynamics in Rocky Mountain National Park (RMNP) has affected wetlands. Using linear regression and mixed effects modeling, I examined associations between vegetation cover and snowpack dynamics. Wetland sites that were investigated were: (1) fen and riparian wetlands on the western region of RMNP; (2) riparian wetlands in Wild Basin; and (3) alpine zone wet meadows. Wetland vegetation cover for this study was derived from the National Park Service’s Rocky Mountain Inventory and Monitoring Network’s historical wetland surveys. Mixed effects models were used to examine the correlation between wetland vegetation cover and hydrological processes. Linear regression models were used to determine if site’s normalized difference vegetation index (NDVI) values were correlated to hydrological processes. Western RMNP fen and riparian vegetation cover did not exhibit significant association with the investigated snowpack dynamics. In Wild Basin, long term trends of riparian vegetation NDVI exhibited significant association with long term snowpack dynamics. Willow coverage exhibited a strong negative association with the timing of peak drainage and flooding, or normalized difference water index. Wetland vegetation at fen and wet meadow wetland sites did not exhibit significant associations with snowpack dynamics. These results suggest riparian wetland vegetation within Wild Basin has been moderately resilient to annual fluxes in water availability but is influenced by long-term snowpack dynamics. Furthermore, these results indicate that riparian wetland vegetation within Wild Basin has been moderately influenced by hydraulic inputs, implying ungulate grazing has not impacted vegetation to the extent of the Kawuneeche Valley riparian wetlands. The findings of this study support the continuation of wetland vegetation monitoring and provide a rationale for further conservation efforts within the Wild Basin region. Elk enclosures and further monitoring of regional wetland sites should be considered to maintain willow stands and identify additional highly productive wetlands. Further research investigating wetland vegetation’s association to changes in snowpack should focus on more northern regions where more drastic shifts in snowpack dynamics have occurred.