Patterns and frequency of site disturbances
What is it? "Disturbance" refers to environmental
changes brought on by fires, floods, volcanic eruptions, storms, winds,
insect invasions, and invasions from non-native or exotic
species.
Why study it? Disturbances periodically reorganize
or destroying ecosystems, allowing for significant changes in plant
and animal populations and communities. Understanding how ecosystems
respond to disturbances can lead to better land management plans.
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How is it studied? An ecosystem
is examined for baseline data before a
disturbance occurs, either naturally (wildfire), or human induced (controlled
burn). After the disturbance, scientists measure changes in the environment,
for example the movement of nutrients,
use by wildlife, and changes in productivity.
Forest succession is
a good example of disturbance recovery.
Many disturbances are natural such as many fires, storms, and drought.
Others are human caused, such as timber harvesting and land development,
recreational use, applications of chemical such as pesticides, herbicides,
and fertilizers.
Disturbance Research in LTER |
The Coweeta LTER Site in the eastern deciduous
forest of the Appalachian Mountains of western North Carolina. |
At Coweeta LTER scientists study the role of fire in the southern Appalachian
Mountains. Forests in this region (and indeed in many parts of the world)
depend on this natural disturbance for their health. Fire helps the ecosystem
by returning nutrients to the soil, clearing vegetation to allow more
light into the forest, and aiding the germination
of many plant species.
Scientists at CWT LTER study the impacts of fire as a tool to restore
ecosystems, to reduce fuel loads, and to study the recovery of vegetation
(tree, shrub, and herb layer). Fire has been suppressed in most of these
areas approximately since the 1920s.
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A scientists measures moisture of the downed branches or "fuel"
before starting the fire. Studying how the fuel relates to the intensity
of the fire and the effect on the biology is an important part of
understanding how fire affects the ecosystem. |
| A prescribed (or human-initiated) burn is started after fuel moisture
and fuel loads are measured. Fires are a natural disturbance and are
necessary for maintaining the health of the mixed pine-hardwood forest
of the southern Appalachian mountains. |
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| After the prescribed burn, the site looks desolate and lifeless.
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A tool called a ‘duff pin’ is inserted into the ground
to study how deeply the soil was affected by the fire. |
| Two years after the prescribed burn, the plant regrowth is green
and vigorous. The nutrients released
and increased light availability will benefit the ecosystem as plants
and animals reclaim the land. Scientists study succession
- or the changes in the plant and animal community following a disturbance
such as a burn. |
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4 years after the burn.
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In another controlled burn project at Coweeta LTER, scientists are trying
to reconstruct he fire regime as it was while Cherokee Indians lived here.
The Cherokee burned frequently (every 1 to 5 years) to maintain meadows
and an open under storey for game hunting and chestnut gathering.
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