Vegetation Succession and Environmental Conditions following Catastrophic Lake Drainage in Old Crow Flats, Yukon

Trevor C Lantz

doi:10.14430/arctic4646

Abstract

Increases in the frequency and magnitude of disturbances associated with the thawing of ice-rich permafrost highlight the need to understand long-term vegetation succession in permafrost environments. This study uses field sampling and remote sensing to explore vegetation development and soil conditions following catastrophic lake drainage in Old Crow Flats (OCF). The data presented show that vegetation on drained lake basins in OCF is characterized by two distinct assemblages: tall willow stands and sedge swards. Field sampling indicates that these alternative successional trajectories result from variation in soil moisture following drainage. Increased willow mortality on older drained basins suggests that intraspecific competition drives self-thinning in shrub thickets. This finding, combined with data from paleoecological studies and contemporary vegetation in OCF, suggests that willow stands on drained lake basins are seral communities. These results also indicate that the increase in number of catastrophic drainages that occurred between 1972 and 2010 will alter regional vegetation in ways that affect wildlife habitat, permafrost conditions, and local hydrology.

Highlights

Growing evidence indicates that the frequency and magnitude of natural disturbances at high latitudes are increasing
Drained lake basins more than 30 years old had higher densities of dead stems than reference sites and younger drained basins (Fig. 2C)
The data presented here show that catastrophic lake drainage in the Old Crow Flats leads to the development of two vegetation types

Summary

Introduction

Growing evidence indicates that the frequency and magnitude of natural disturbances at high latitudes are increasing. It is anticipated that continued development in the North will increase the area of tundra affected by disturbance (Holroyd and Retzer, 2005; Burn and Kokelj, 2009). Field studies show that northern ecosystems exhibit a range of recovery trajectories following disturbance (Walker et al, 1987). Disturbances such as tundra fire and seismic exploration create relatively small and transient changes in vegetation structure and species composition (Kemper and Macdonald, 2009b; Bret-Harte et al, 2013). Disturbances like severe Subarctic fire and retrogressive thaw slumping, which remove vegetation cover and soil organics, can facilitate the development and persistence of alternative successional trajectories

Methods

Results

Conclusion