Initial disturbance intensity affects recovery rates and successional divergence on abandoned ski slopes

Abstract

Summary The importance of site history (including initial disturbance intensity and propagule arrival) in determining successional trajectories is a key theoretical and applied line of research in ecology. Abandoned ski slopes provide an opportunity to study successional processes following differing initial disturbance intensities. Some ski slopes are graded with heavy equipment when constructed (‘graded’, severe initial disturbance), while others are simply cleared of tall woody vegetation (‘cleared’, lesser initial disturbance). In a blocked chronosequence study of graded and cleared ski slopes abandoned 10–43 years previously, we found that graded ski slopes did not show predictable recovery trajectories over many decades. In contrast, cleared ski runs showed significant convergence with adjacent reference forest communities. Convergence in community composition on cleared ski runs was driven by trees, though understorey species were more numerous and dominant during succession. Understorey communities did not predictably change in species or life‐form composition over time, regardless of ski run type. Graded ski runs exhibited little or no edaphic recovery over time, showing neither reductions in bare ground and visible soil erosion, nor increases in soil depth. Cleared ski runs, in contrast, showed evidence of recovery in all of these variables except soil depth, which remained uniformly high. Synthesis and applications. The creation of new ski slopes by tree clearing is preferable to the grading of new slopes with heavy machinery, because grading reduces ecosystem function and decreases the predictability of soil and vegetation recovery decades after abandonment. Existing graded ski slopes (both operational and abandoned) may benefit from restoration of soils and vegetation.

Shrub‐encroached grassland as an alternative stable state in semiarid steppe regions: Evidence from community stability and assembly

“…For a non-encroached degraded grassland, both arrival of propagules from outside (Burt & Clary, 2016) and germination from the soil seed bank (Jiménez & Armesto, 1992) are very important at the beginning of restoration, thereby, both random processes (arrival) and environmental filtering (conditions for germination) are expected to dominate the community assembly during the early stages of succession (Marteinsd ottir, Svavarsd ottir, & Th orhallsd ottir, 2018;Meiners, Cadotte, Fridley, Pickett, & Walker, 2015). As succession proceeds, competitive exclusion increasingly influences the community assembly due to the improvement of abiotic conditions (Chen & Tang, 2016) and the intensification of interspecific competition (Dong et al, 2019;Purschke et al, 2013).…”

Mid and long-term ecological impacts of ski run construction on alpine ecosystems

“…After construction, ski runs need to be carefully maintained and managed throughout the snow-free period. The chosen management techniques would further influence the time needed for, and the level of recovery of the ecosystem 9 , 19 – 21 that during winter, could additionally be stressed by snow grooming (the process of moving, flattening, compacting or rototilling the snow with specialized equipment) and the use of artificial snow, both of which impede site recovery 22 . Snow grooming increases soil compaction, significantly reduces infiltration rate, and makes the soil and site more susceptible to erosion processes.…”

“…During the snow free period, cutting or grazing of vegetation is the most widely recommended management technique 20,21 , with the exclusion of the highest elevations where grazing could accelerate erosion and reduce the recovery rate. The level of initial disturbance, combined with restoration techniques and the chosen ski run management, can greatly influence the time needed for disturbed mountain slopes to recover and self-sustain 11,19 .…”

Sustainable Soil Management in Ski Areas: Threats and Challenges

“…This influences the establishment and development of plant communities which in return affects both the biotic and abiotic soil environment and the entire alpine ecosystem [15,28,29]. Therefore, restoration techniques have a crucial role to play in the success of damage mitigation and the rehabilitation of damaged ecosystems.…”

“…Therefore, restoration techniques have a crucial role to play in the success of damage mitigation and the rehabilitation of damaged ecosystems. As the disturbance in graded ski slopes is more severe than in cleared runs, it is more likely that graded sites will follow a primary vegetation succession during the restoration process [29], thereby prolonging the time needed for soil melioration and site rehabilitation.…”