Tundra Disturbance Studies, I: Long-term Effects of Vehicles on Species Richness and Biomass

• Published in: Environmental Conservation
• Main Author: Forbes, Bruce C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1992
• Subjects: Baffin Island; Baffin; Devon Island; Tundra
• Online Access: http://dx.doi.org/10.1017/s0376892900030241; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0376892900030241

This paper describes up to two decades of unassisted plant recovery from uncontrolled tracked-vehicle disturbance within tundra meadows on two physiographically distinct high-arctic coastal lowlands. Data are presented which emphasize the status of species-richness and above-ground vascular biomass. Although they exhibit similar vascular floristics, the undisturbed vegetation communities of the two sites differ greatly in terms of the abundance of dominant species. In particular, Salix spp. characterize the larger, more mesic hummocks of the Baffin Island site, while Cyperaceae characterize the more level and generally wetter meadows on Devon Island. Despite these differences, both vascular and cryptogamic species-richness are consistently reduced under a variety of low-intensity disturbance regimes in different vegetation-types. In many cases these reductions are significant. In addition, total vascular biomass is significantly reduced in 88% of all stands. Reductions are most severe among woody species and, in cases where the biomass of monocotyledons was increased, these increases were more than offset by the losses among dicotyledons. This is contrary to the situation in mesic low-arctic meadows, where significant biomass increases among graminoids have more than offset losses among dicotyledons after less than 8 growing-seasons. The literature of mechanical disturbance in the high-arctic is briefly reviewed, and it is noted that few long-term data are available, there being virtually none which address either cryptogamic species-richness or vascular biomass. The data presented here reaffirm previous short-term findings that lateral reinvasion by rhizomatous graminoids is slower than in the low-arctic. In addition, it has been determined that even after 18–20 years, seedling establishment by dicotyledons is virtually lacking in multi-pass tracks, and is limited to only the driest microsites (hummock tops and sides) in single-pass tracks. The few colonists are mostly slow-growing, woody species and are not ...