|
What are the impacts
of oil exploration and drilling on ANWR producers (vegetation and certain
botanic species)?
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.
See: http://www.absc.usgs.gov/1002/section5.htm
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.
See: http://www.worldwildlife.org/arctic-refuge/anwr_position.pdf
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.
Read: Ecology of Arctic Environment (Edited by Sarah J.
Woodin & Mick Marquiss)
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.
Read: Ecology of Arctic Environment (Edited by Sarah J.
Woodin & Mick Marquiss)
5. Mosses and lichens on 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.
Read: Ecology of Arctic Environment
(Edited by Sarah J. Woodin & Mick Marquiss)
6. Permafrost
Permafrost layer restricts the drainage of water through the soil, making
it moist in the short summer growing season. It is easily broken by road construction
or the seismic explosions used in oil exploration, changing the water drainage
patterns of the soil and thus retention of moisture. Melting permafrost has
also led to widespread damage of buildings, costly road repairs, and increased
maintenance for pipelines and other infrastructure – impacts that will continue
to grow in magnitude. Permafrost also stores large amount of ancient carbon
and methane; thawing is likely to release some of this stored carbon and
methane back into the atmosphere, amplifying the risk of further climate
change. The boreal forest will advance northward into present coastal plain
tundra, and mixed forest into present boreal forest. Forest fires and insect
outbreaks, both of which have increased sharply in recent years, will further
increase. If the permafrost thaws, the vegetation will in the long term dries
out, altering plant communities and use by wildlife.
IMPORTANT: It has been observed that in areas where the
permafrost thaws, there is a sudden rapid growth of plants, which attract
more animals to feed on. However, this is only momentary. Once the permafrost
thaws, temporarily there is much water for plants to grow well for like a
month or two, but then the water is continuously used up and drained away
as there is no layer to prevention drainage now; yet the permafrost, once
destroyed, take years to resume. Therefore, a few months after destruction,
water will finally be deficient and no plants can grow well even during summer
when water has already been used up, drained away but no permafrost exists
to trap them for the growing season. This detrimental effect on vegetation
is permanent, while the vast growth of plants is just transient.
See: http://www.ucsusa.org/global_environment/archive/page.cfm?pageID=780
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.”
(From http://www.csa.com/hottopics/ern/01aug/01aug16.html)
By Amos Tai
|
|