It's all downhill from here: Ecosystem function declines with ski slope grading

Downhill ski areas occupy large tracts of land, and in mountainous areas around the world they represent a significant source of anthropogenic disturbance. Although constructing ski areas always disturbs the surrounding ecosystem, the intensity of disturbance varies greatly with construction method. Ski runs in forested areas may be constructed either by clearing (cutting and removing tall vegetation) or by grading (grading the soil surface with heavy equipment following vegetation removal). To quantify how these disturbances affect ecosystem function, I measured plant communities and soil attributes on cleared ski runs, graded ski runs, and adjacent reference forests across seven active ski areas in the Northern Sierra Nevada, USA. Grading has strong negative effects on several measures of ecosystem function. Relative to cleared ski slopes, graded slopes had significantly more bare ground, more visible erosion, greater soil compaction, and less litter cover and soil depth. Graded runs also differed from cleared runs in plant community composition and patterns of diversity: graded runs had greater richness and cover of annual herbs and graminoids, while cleared runs had greater richness and cover of perennial herbs and shrubs. Graded ski slopes significantly differed from adjacent reference forests in most attributes measured. Cleared ski slopes, in contrast, were in many ways more similar in function and community composition to reference forests, retaining comparable soil depth and soil compaction, and supporting greater species richness. Because grading is more damaging to ecosystem function, clearing rather than grading should be used to create ski slopes.