Team
5
Sueann Lee
Team 5 - Sueann Lee
Name: Sheung Yan Sueann Lee
Team name: Characterization of
the
ANWR
Ecosystem
Email: sueannsy@mit.edu
As Team 5, we aim at developing a
baseline
understanding of the ANWR ecosystem(for details of our aim please refer
to the
Aims section). Currently, I am responsible for finding out some general
background information energy cycles and nutrient cycles of the
ecosystem, and
also something about ecosystem health. I’m working on the topic by
generally
finding information on the internet on the general information as well
as a
book on arctic terrestrial ecosystem. Other topics I'll hopefully look
more
specifically into is the significance of the 'bottleneck' of the
coastal plain,
and trends in migration patterns.
**Carbon Balance in the Arctic(under construction)
**Microbial Processes and Plant Nutrient Availability in Arctic soils(under construction)
**Information about investigating
an
ecosystem:
Vegetation Characteristics and
primary
productivity along an arctic transect:implications for scaling-up
Introduction
-
substantial
changes in both
temperature and precipitation expected in arctic regions -- warming of
~ 1C per
decade observed over the past 30 years
-
vegetation
changes have been
recorded in Alaskan tussock tundra over the past 10 years
-
-> important
feedbacks on
the region’s biogeochemical cycles, through altered rates of carbon
exchange
between biosphere and atmosphere, and changes in the region’s energy
balance
-
arctic: 11% of
world’s organic
matter pool
-
arctic tundra
ecosystems: some
C sinks, some sources
-
modeling
analysis suggests
that the source/sink strength of tundra depends on changes in
photosynthesis that result from the partitioning of nitrogen between
vegetation and soils, and on changes in soil moisture, which affect
soil respiration rates
-
challenge to
global change:
use process-level info, derived from detailed studies at specifific
sties, to
develop regional predictions of C balance in the arctic
Source: Williams, M., Rastetter, E.B. (1999)Vegetation characteristics and prmary productivity along an arctic transect: implications for scaling-up. Journal of Ecology, 87, 885-898
**On using physiological ecology
to predict
ecosystem response to environmental change:
1.
Ecosystem
response to environmental change is often predicted
from simple physiological responses of organisms(e.g.,
estimation of
plant production from temperature and light responses of
photosynthesis).? In the long term, however,
feedbacks
among processes often govern performance under natural circumstances
more
strongly than do short-term, kinetic responses of individual processes.
For
Example, even though photosynthesis always responds to CO2
concentration in the
short term, compensatory changes in photosynthetic potential when
plants are
grown under different CO2 concentrations may counteract these
short-term
effects.?Consequently, environmental
factors that exert strong short-term effects may6 not be influential
over
longer time scales.?To predict
ecosystem responses, we must study feedbacks as well as direct
environmental effects
on plants.
2.
Simulation
modeling based on
physiological studies can incorporate many of the feedbacks
that operate in natural ecosystems.?Experience
suggests, however, that modeling predictions cannot be usefully
extrapolated
beyond two levels of organization.?
For this reason, the types of controls studied at one level of
organization may not be fully relevant at other levels.?Most
past ecophysiological work has
emphasized the direct effect of environment on physiology.?Yet
we need to know the nature, strength,
and timing of the feedbacks and time lags that control resource supply
and,
indirectly, the growth of organisms.?
This will require an integrated, whole-plant approach to
physiological
ecology. ?/span>Ecosystem and community
ecology may provide the criteria for deciding which feedbacks are
important at
these higher levels of organization.
3.
Ecosystem
response to environment has been predicted
from comparisons of current performance in two different
environments(e.g.,
latitudinal comparisons).?A
comparison of two ecosystems under equilibrium condition says nothing
about the
trajectory an ecosystem might follow in going from one equilibrium
state to
another.?Moreover, a new environment
will be occupied by different combinations of species than
those co-occurring
at present.?If the dynamics of the present
community are strongly influenced by specific competitive interactions,
we may
have difficulty predicting how new combinations of species will
interact. ?/span>Forecasting such interactions
is particularly
difficult because there are no present analogs of future climate,
such
as increased atmospheric CO2.?Latitudinal
gradients in temperature, which might provide some insight into
vegetation
response to a changing thermal regime, are complicated by differences
in day length
and soils that will not be mimicked by climate change.? Simulation
modeling and whole-ecosystem
experiments may enable us to test novel combinations of factors.
Source: CHAPIN, F.S., JEFFERIES, R.L., REYNOLDS, J.F., SHAVER, G.R. Arctic Ecosystem in a Changing Climate: An Ecophysiological Perspective, 1991
>>>>>>>
Ecosystem and Change
-
how change in
ecological
complexity will affect ecosystem function
-
relationship
between
ecological complexity and ecosystem -- > needs to be investigated
-
“ecological
complexity?rather
than “biodiversity?because more than just the number of species
-
=> spatial
patterns of
species and communities
o
influence
population
dynamics and landscape and regional scale processes(less known about
the relationship
and how affected by rapid environmental change
-
arctic
terrestrial ecosystem
appear to be relatively stable over time and may have little resilience
to
disturbance effects
-
one approach:
reciprocal
experiment ?biological composition(structure) and abiotic environment
(factors
affecting physiolgocial function) are separately altered
-
=> effects on
each other
measured (details of experiment yet to be determined)
Ecosystem Physiology
1.
manipulative
experiments at scale of whole plant
communities/ecosystem
-
determine
effects on system
processes eg. Soil(accumulation and decomposition)
-
competitive
relationships
between plants, changes to nutrient fluxes and pools; plant tissue
quality,
energy and water balance, plant phenology and architecture
-
suggested
experimental
techniques: glasshouses, open top chambers, eco-cosms
2.
gradient
approach
-
long term
commitment(10+
years) since relatively slow dynamics
Freshwater Ecosystem
-
peat lands and
northern
wetlands: potential carbon sources or sinks
-
movement of
nutrients and
organic matter via groundwater, streams and rivers plays a major role
in
regional biogeochemistry
-
(BAHC Biospheric
Aspects of
the Hydrologic Cycle) ?subsurface and surface flow of water and
transport of
nutrients
Source: OECHEL, W.C., CALLAGHAN, T., GILMANOV, T., HOLTEN, J.I., MAXWELL, B.,MOLAU, U., SVEINBJORNSSON, B., Global Change and Arctic Terrestrail Ecosystems
>>>>>>>>>>>>>
Some basic information that I
believe I must
know right now:
Arctic National Wildlife Refuge
Where: Northern Alaska, United
States
What's at stake: Critical
sanctuary for
Arctic wildlife
The controversy: Oil drilling
Area:
Established in 1960, the Arctic
National
Wildlife Refuge is the largest and most northerly of the United States'
500
wildlife refuges. Spanning 19 million acres -- an area roughly the size
of
South Carolina -- it includes 18 major rivers flowing through
landscapes that
range from spruce-covered valleys to arctic tundra.
Nestled between the high glaciers
of the
Brooks Range and the lagoons and ice floes of the Beaufort Sea, the
refuge's
wind-swept coastal plain is often likened to Africa's Serengeti because
of its
abundant wildlife. This 1.5-million-acre expanse -- considered by
scientists
the biological heart of the Refuge ˇV is the also the land most sought
after
for drilling by oil companies
Geography:
Brooks Range(east-west), rises
abruptly from
the flat, tundra-covered plain to heights of 9,000 feet above sea
level.
Animals include:
Fauna:
Birds:
During
the brief
Arctic summer, millions of birds flock to the coastal plain to nest and
raise
their young or to feed and build up fat reserves for their next
migration.
Tundra swans, pintail ducks, Arctic loons and snowy owls are among the
180
species that have been spotted on the refuge.
Bears:
The
refuge is one
of the few ecosystems that's home to all three North American bear
species.
Polar bears and grizzlies roam the coastal plain; black bears inhabit
the broad
valleys south of the Brooks Range.
Mammals:
At least
five
species of marine mammals live in or near the Beaufort Sea along the
coastal
plain's northern edge. These include spotted seals, ringed seals,
bearded
seals, beluga whales and endangered bowhead whales.
Flora:
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.
Aleutian
shield
fern
Some
statistical
data on the animals found on the coastal plain:
http://biology.usgs.gov/s+t/frame/s113.htm#25074
I think
it'll be
important to analyze the statistical data in order to:
Last
updated:
10/21/2003