Stomping in silence: Conceptualizing trampling effects on soils in polar tundra

Abstract

Ungulate trampling modifies soils and interlinked ecosystem functions across biomes. Until today, most research has focused on temperate ecosystems and mineral soils while trampling effects on cold and organic matter‐rich tundra soils remain largely unknown. We aimed to develop a general model of trampling effects on soil structure, biota, microclimate and biogeochemical processes, with a particular focus on polar tundra soils. To reach this goal, we reviewed literature about the effects of trampling and physical disturbances on soils across biomes and used this to discuss the knowns and unknowns of trampling effects on tundra soils. We identified the following four pathways through which trampling affects soils: (a) soil compaction; (b) reductions in soil fauna and fungi; (c) rapid losses in vegetation biomass and cover; and (d) longer term shifts in vegetation community composition. We found that, in polar tundra, soil responses to trampling pathways 1 and 3 could be characterized by nonlinear dynamics and tundra‐specific context dependencies that we formulated into testable hypotheses. In conclusion, trampling may affect tundra soil significantly but many direct, interacting and cascading responses remain unknown. We call for research to advance the understanding of trampling effects on soils to support informed efforts to manage and predict the functioning of tundra systems under global changes. A free Plain Language Summary can be found within the Supporting Information of this article.

Location of studies and evidence of effects of herbivory on Arctic vegetation: a systematic map

“…Similarly, outbreaks of invertebrate herbivores can influence the livelihood of northern communities [5] through their dramatic impacts on vegetation and the subsequent cascading effects on local wildlife [6,7]. Herbivores also play an important ecological role in Arctic tundra ecosystems by influencing soils [8] and plant communities [9,10], with consequences for ecosystem processes [11]. Moreover, herbivores have the potential to offset some of the effects of ongoing warming in tundra ecosystems by counteracting increases in deciduous shrub cover [12,13] or advances of the treeline [14].…”

Plant and soil nitrogen in oligotrophic boreal forest habitats with varying moss depths: does exclusion of large grazers matter?

“…after grazer exclusion, in support of our first hypothesis. In tundra, exclusion of ungulate grazing also deepens moss carpets most likely due to ceased trampling (Tuomi et al 2020). In the sunlit habitats, the deepening resulted in moss depths that were nearly the same as in the (grazed) shaded habitats and, thus, sunlit habitats without grazing became more shaded-like with respect to their moss carpet (Fig.…”

Hiking trails shift plant species' realized climatic niches and locally increase species richness

“…Many of these species are associated with snowbeds (Coker, 1966;Taylor & Rumsey, 2003;Totland & Schulte-Herbrüggen, 2003;Väre et al, 1997), which are moist environments; they may, therefore, be favoured by increases in moisture along trails resulting from soil compaction and funnelling of precipitation (Kuss, 1986;Tuomi et al, 2020) Totland, 1999;Totland & Schulte-Herbrüggen, 2003). This underlines that trails can allow disturbance-adapted species to move into colder locations.…”