Tundra disturbance and ecosystem production: Implications for impact assessment

Abstract

Environmental regulations governing industrial activities in tundra environments stem largely from the expected ecological effects of the activities. One of the major ecological effects of industrial activities is the surface subsidence associated with thermokarst, which can result in changes in primary and secondary production. The primary production changes associated with thermokarst are strongly governed by three ecosystem properties--soil temperature, water regime, and nutrient availability. Most disturbances set in motion a more-or-less predictable sequence of landscape change related to these properties: soil warming, thermokarst, surface flooding, accelerated organic matter decomposition, and increased nutrient availability. The warmed soil and the enhanced nutrient availability typically lead to increased annual primary production, increased dominance by graminoids, and reduced plant species diversity. These vegetational changes may in turn potentially enhance secondary production, but in general these second-level responses have yet to be quantified. More information is needed about the food-chain effects of tundra landscape disturbances before regulators can make well-informed predictions of impacts or plan useful habitat rehabilitation.

Response of Pacific Loons (<i>Gavia Pacifica</i>) to Impoundments at Prudhoe Bay, Alaska

“…A recent analysis of pre-development aerial photographs (Noel et al, 1995) indicates that some water bodies depicted as "impoundments" by Lederer originally were natural ponds that were enlarged by the presence of impounded spring runoff following the construction of nearby roads and drilling pads. I found that the accumulation of surface water not only enlarged temporarily the size of these water bodies, but, more importantly, resulted in earlier thaw dates, apparently by enhancing heat absorption (Truett and Kertell, 1992). They were therefore used earlier by loons than nearby natural ponds.…”

“…Selection of island nest sites may be less adaptable on impoundments than on ponds because of hydrological differences between the two water body types. Water levels in natural arctic wetlands tend to be relatively stable and predictable (Hohman et al, 1992), but impoundment water regimes often are not (Truett and Kertell, 1992). Therefore, there is increased risk that island nest sites on impoundments may become attached to the mainland and shoreline nests may become stranded on dry land as water levels fall during the course of the breeding season.…”

Correlation of alpine vegetation degradation and soil nutrient status of permafrost in the source regions of the Yangtze River, China

“…Numerical simulation in typical thermokarst lakes in Alaska has shown that the evolution of thermokarst lakes and climate change are closely related, which induces the variation of permafrost in the adjacent thermokarst lakes (Ling and Zhang 2003). The thermokarst process has a significant impact on the ecological environment in permafrost, and it also accelerates the organic decomposition process which can release soluble substances in permafrost, thus affecting the chemical properties of soil mass and surface runoff (Truett and Kertell 1992;Kokelj and Lewkowicz 1999;Kokelj et al 2002). A previous study showed that CH 4 bubbling from newly forming thermokarst lakes comprised 33-87% of the high-latitude increase in atmospheric methane concentration (Walter et al 2007).…”

The response of two arctic tundra plant communities to human trampling disturbance

“…Since that time studies have been conducted on the impacts of oil field development (Walker et al, 1986;Oechel, 1989), disturbance-induced thawing of permafrost soils (Truett and Kertell, 1992) and the consequences of vehicle trails in summer (e.g. Bliss and Wein, 1972) and in winter (Felix et al, 1992;Emers et al, 1995;Emers and Jorgensen, 1997).…”