Impacts of oil exploration and drilling on ANWR plants


Arctic coastal plain, Alaska, USA
Photo: Bill Eichbaum

“Due to the extreme cold, short growing season and nutrient-poor soils, Arctic vegetation is extremely fragile. Plant communities scarred by bulldozer tracks, oil spills and other human activities can take decades to recover.”
Source: http://oz.plymouth.edu/~lts/conservation/Ecosystems/northslope.html

1.    Sedges and willows for nutrition

There are two major types of plants that are very important in providing the herbivores (caribou, muskoxen, etc) with high quality and nutritious food: tussock cottongrass (Eriophorum vaginatum) and diamond-leaf willow (Salix planifolia ssp. pulchra). Surveys by US Geological Survey have shown that disturbed areas by petroleum development in other parts of Alaska exhibit significant decreasing quantity and quality of these two plants. In disturbed areas, they have lower biomass, lower nutritional values and higher fiber and lignin concentrations which decrease digestibility. This in turn significantly adversely affects reproduction and calving success of caribou that highly depend on them.
(Janet C. Jorgenson, Mark S. Udevitz, and Nancy A. Felix, 2002)

2.    Sedges and willows for inhabitation

Willows in riparian areas are important nesting habitat for migratory birds. Willows will be reduced in amount by heavy tracked vehicles for seismic studies. They will also be affected in the long term by thawing of permafrost, which would be discussed in greater details in the latter part of this essay. Loss of nesting places means unsuccessful calving for birds and higher chances of predation. Successful rehabilitation techniques are yet to be developed for these areas.
(World Wide Fund for Nature, 2000)


Flame orange dwarf birch and golden willow
Photo: Subhankar Banerjee

3.    Mosses and lichens for nutrition

While sedges and willows are important food source for herbivores during summer, the growing and calving seasons, mosses and lichens are more important for local herbivores during the bitter winter as they can still grow well during the winter, though they have lower nutritional values. Construction of drilling site, roads and tracked vehicles all directly destroys the delicate mosses and lichens, lowering the energy source for the herbivores such as muskoxen.
(Sarah J. Woodin & Mick Marquiss, 1997)


4.    Mosses and lichens for carbon and nutrient cycling

Mosses and lichens have a major influence on nutrient cycling in tundra and other northern ecosystems through their role in nitrogen fixation, and the ability of mosses to accumulate and retain elements from precipitation. They restrict the draining away of nutrients and help trap them during the summer and avail the nutrient for the herbivores during the winter. Slow decomposition of mosses allows the mosses to contribute significantly to the Arctic carbon sink. By photosynthesis, they "fix" carbon from the atmosphere to organic compounds and by slow decomposition they help trap the carbon instead quickly releasing them back to the atmosphere. This helps soothing global warming. Destruction means that all these functions cannot carry on.
(Sarah J. Woodin & Mick Marquiss, 1997)


5.    Mosses and lichens for maintaining the permafrost

Mosses and their under-composed remains are particularly efficient in thermal insulation when dry, thus restricting heat penetration into arctic soils in summer. Thermocarst resulting from destruction of the vegetation by the summer use of tracked vehicles during early stages of arctic oil exploration demonstrated the importance of the moss layer in maintaining permafrost. This caused extensive thawing of permafrost. The importance of permafrost on arctic ecology will be discussed in the next paragraphs.
(Sarah J. Woodin & Mick Marquiss, 1997)

6.    Summary

“The effects of winter seismic trails on tundra vegetation were studied on the Coastal Plain of the Arctic National Wildlife Refuge. Plant cover was lower on most disturbed plots than on their adjacent controls, with decreases as high as 87% the first summer following disturbance. The species most sensitive to disturbance were evergreen shrubs, followed by willows, tussock sedges, and lichens. Willow height in riparian shrubland plots was significantly reduced by 5 to 11 cm (from an average of 16 cm, p < 0.05). Little recovery of plants occurred in the second or third summers after disturbance; only four plots in river floodplain habitats (Dryas terrace and riparian shrubland) showed improvements in cover of a few species.”
(Felix NA, Raynolds MK, 1989)


Reference:
1.    Janet C. Jorgenson, Mark S. Udevitz, and Nancy A. Felix, (2002). Arctic Refuge Coastal Plain Terrestrial Wildlife Research Summaries, http://www.absc.usgs.gov/1002/section5.htm
2.    World Wide Fund for Nature. (2000). Protection of the Artic National Wildlife Refuge: Key to Managing one of the World's Most Biologically Valuable Ecoregions, the Arctic Coastal Tundra, http://www.worldwildlife.org/arctic-refuge/anwr_position.pdf
3.    Sarah J. Woodin & Mick Marquiss. (1997). Ecology of Arctic Environment
4.    Felix NA, Raynolds MK. (1989). Arctic and Alpine Research, vol. 21, no. 2, pp., http://www.csa.com/hottopics/ern/01aug/01aug16.html