Species-Specific Responses to Human Trampling Indicate Alpine Plant Size Is More Sensitive than Reproduction to Disturbance

Abstract

Human disturbance, such as trampling, is an integral component of global change, yet we lack a comprehensive understanding of its effects on alpine ecosystems. Many alpine systems are seeing a rapid increase in recreation and in understudied regions, such as the Coast Mountains of British Columbia, yet disturbance impacts on alpine plants remain unclear. We surveyed disturbed (trail-side) and undisturbed (off-trail) transects along elevational gradients of popular hiking trails in the T’ak’t’ak’múy’in tl’a In’inyáxa7n region (Garibaldi Provincial Park), Canada, focusing on dominant shrubs (Phyllodoce empetriformis, Cassiope mertensiana, Vaccinium ovalifolium) and graminoids (Carex spp). We used a hierarchical Bayesian framework to test for disturbance by elevation effects on total plant percent cover, maximum plant height and diameter (growth proxies), and buds, flowers, and fruits (reproduction proxies). We found that trampling reduces plant cover and impacts all species, but that effects vary by species and trait, and disturbance effects only vary with elevation for one species’ trait. Growth traits are more sensitive to trampling than reproductive traits, which may lead to differential impacts on population persistence and species-level fitness outcomes. Our study highlights that disturbance responses are species-specific, and this knowledge can help land managers minimize disturbance impacts on sensitive vegetation types.

Tourist Trampling on a Peripheral Plant Population Restricted to an Urban Natural Area in the Capo Sant’Elia Promontory (Sardinia, W-Mediterranean Basin)

“…Similarly to what was demonstrated by [ 61 ], our study showed that the morphological traits of G. alypum are vulnerable to human trampling, while the reproductive ability appears not to be significantly affected. In fact, contrary to what was expected, our results provided no support for the hypothesis that human trampling causes differences in the reproductive capacity of G. alypum regardless of individual size.…”

“…The marked, statistically significant, differences in growth traits between the Central and peripheral (Intermediate and Extreme) zones of the path confirm, as demonstrated by [ 61 ], that these traits are sensitive to human trampling, which may lead to differential impacts on population persistence. In fact, we found that human trampling disturbance reduced the overall plant size, particularly the height and the maximum diameter, and, consequently, the plant biovolume, as a probable consequence of direct physical damage, including the breakage of stems, branches, and leaves.…”

Understanding Arctic–Alpine Plants from Ecological and Evolutionary Perspectives

“…In addition to the frequently covered effects of climate warming, many other human-made changes have important impacts on the survival of arctic and alpine plants. Chardon et al [ 13 ] explored the response of arctic shrubs and graminoids to human trampling, an integral component of global change; however, a comprehensive understanding of the effects of trampling on alpine and arctic ecosystems is lacking. The authors surveyed trail-side (disturbed) and off-trail (undisturbed) transects along altitudinal gradients in the Garibaldi Provincial Park in Canada.…”