Sixty‐year legacy of human impacts on a high Arctic ecosystem

Abstract

1. The high Arctic is the world's fasting warming biome, allowing access to sections of previously inaccessible land for resource extraction. Starting in 2011, exploration of one of the Earth's largest undeveloped coal seams was initiated in a relatively pristine, polar desert environment in the Canadian high Arctic. Due to the relative lack of historic anthropogenic disturbance, significant gaps in knowledge exist on how the landscape will be impacted by development.2. At an abandoned airstrip located near the area of current exploration, we used a disturbance case-control approach to evaluate the long-term ecological consequences of high Arctic infrastructure disturbance to vegetation and sensitive, ice-rich permafrost. We quantified: (i) long-term effects on vegetation diversity, soil nutrients and abiotic ground conditions and (ii) the alteration of the ground surface topography and legacy of subsurface thermal changes. 3. We found that in over 60 years since abandonment, the disturbed landscape has not recovered to initial conditions but instead reflects a disturbance-initiated succession towards a different stable-state community. 4. Microtopography greatly influenced recovery patterns in the landscape. The terrain overlaying buried ice (ice-wedge polygon troughs) was the most sensitive to disturbance and had a different species composition, decreased plot-level species richness, significant increases in vegetation cover and a drastically reduced seasonal fluctuation in subsurface temperatures. In contrast, disturbed polygon tops showed resiliency in vegetation recovery, but still had remarkable increases in depth of seasonal soil thaw (active layer). 5. Synthesis and applications. Our results indicate that disturbance effects differ depending on microtopographic features, leading to an increased patchiness of the landscape as found elsewhere in the Arctic. Managers who wish to lessen their impact on high Arctic environments should avoid areas of sensitive, ice-rich permafrost, constrain the geographic scale of nearsurface ground disturbance, limit vegetation removal where possible and reseed disturbed areas with native species.

Long-term landscape impact of petroleum exploration, Melville Island, Canadian High Arctic

“…The results are consistent with cases elsewhere where thermokarst has been associated with surface disturbance such as following aggregate extraction or other surface alteration (e.g., French 1975;Becker and Pollard 2016). More broadly, these intense land surface alterations are recognized as increasing the risk of permafrost degradation and infrastructure instability (Mackay 1970;Raynolds et al 2014;Lamoureux et al 2015;Becker and Pollard 2016). Results from this study demonstrate localized areas where permafrost degradation can be associated with past land use and indicate the risk of these intensive activities for landscape stability in Arctic regions.…”

“…It is not clear if these impacts caused permafrost degradation directly or if they contributed to enhanced sensitivity of these locations to regional climate warming induced degradation. The results are consistent with cases elsewhere where thermokarst has been associated with surface disturbance such as following aggregate extraction or other surface alteration (e.g., French 1975;Becker and Pollard 2016). More broadly, these intense land surface alterations are recognized as increasing the risk of permafrost degradation and infrastructure instability (Mackay 1970;Raynolds et al 2014;Lamoureux et al 2015;Becker and Pollard 2016).…”

“…The long-term effects of extended periods of land development or vehicle movement on Arctic environments, particularly in potentially sensitive tundra ecosystems and permafrost landscapes, remain a concern to regulators and communities (ADHR 2004;Jorgenson et al 2010;Becker and Pollard 2016). With the prospect of future development of natural resources in the Arctic, it is important to understand the impact of industrial activity on land and terrestrial ecosystems in order to mitigate socioeconomic and ecosystem impacts.…”

“…Site-specific studies on landscape and vegetation associated with former airstrips and seismic exploration have documented substantial changes to vegetation and soil properties and increased active layer depth (Kemper and Macdonald 2009;Jorgenson et al 2010;Becker and Pollard 2016). Changes to the active layer have resulted in localized permafrost degradation and thermokarst and point to the importance of fine-scale changes in topography, soil properties, and drainage as consequences of surface alteration (Becker and Pollard 2016). These detailed field studies are comparatively resource intensive.…”

“…Their results highlight the differences between the effects of industrial activities completed at different latitudes and biomes in the Arctic. The long-term effects of industrial activity in the Canadian High Arctic have been investigated in a limited manner (e.g., Becker and Pollard 2016). However, in ice-rich permafrost terrain, commonly associated with the western High Arctic, the effects on the landscape are potentially more pronounced and have a lasting impact especially when activity is completed late in the thaw season with repeated vehicle passes (Rickard and Brown 1974;Slaughter et al 1990).…”