Effects of snowmobile noise and activity on a boreal ecosystem in Southcentral Alaska

Abstract

Snowmobiling is a popular winter activity in northern regions of North America. Although snowmobiles are important utility vehicles and serve as a means of outdoor recreation, their activity is known to affect plants and animals. These effects have been a growing concern over the past 20 years as a result of increased snowmobile activity into once inaccessible natural areas. Minimizing the impacts of snowmobiles on biota, preserving the quality and character of wilderness areas, and providing adequate access to snowmobilers for traditional activities has been a challenge for public land managers in Alaska. To address the effects that snowmobiles have on ecological systems at site-specific and landscape-level scales, I conducted a study in the Kenai National Wildlife Refuge, a boreal ecosystem located in southcentral Alaska, to determine 1) the response of woody wetland plants to snowmobile traverses at varying snow depths, 2) thetemporal and spatial variation of a winter soundscape with emphasis on anthrophony, in general, and snowmobile noise, specifically, 3) the effects of snowmobile noise on wilderness character and naturalness, and 4) the spatial and physiological response of moose (Alces alces) to snowmobile activity and noise. I used a combination of traditional experimental designs and statistics, machine learning, and spatially-explicit predictive modeling to assess the effects snowmobile activity has on these four issues. I found that snowmobile activity reduced the number of living stems and inhibited the growth of woody wetland plants by direct contact with protruding vegetation above the snow and indirectly from snow compaction. Snowmobile noise was not a large contributor of noise to the soundscape but was pervasive in remote areas. Snowmobile noise affected a significant area of Congressionally-designated wilderness altering the naturalness and character of the wilderness soundscape. Moose exhibited a distinct spatial partitioning and avoidance from snowmobile activity and developed areas (i.e., oil and gas compressors) at the landscape-level but at a site-specific scale snowmobile traffic and noise had no apparent affect on the stress hormone levels of moose that were selecting habitats close to snowmobile trails. I detected these impacts at both site-specific locations and across large spatial scales indicating that snowmobile effects are more than just localized disturbances. Based on these findings, I conclude that snowmobile noise and activity is an additional and unnatural forcing function on a boreal ecosystem already stressed by the harsh environmental conditions of winter.