Transcript Catastrophic_Events_1_

and their effects on Texas
Ecosystems
What are catastrophic events?
• Catastrophic events are
natural occurrences that
generally have a negative
effect on people and/or
the environment.
• These changes are so
great they may cause
damage to the shape of
the land or to the lives of
people and other living
organisms.
Catastrophic events include, but are
not limited to:
• Those caused by weather
floods
hurricanes
tornadoes
drought
• Those caused by geological forces
volcanoes
earthquakes (tsunami)
• fires
Texas Severe Weather
1. Hurricanes
• 1900: Known as "the Galveston Hurricane," the
deadliest hurricane disaster in U.S. history
occurred on September 8.
• More than 8,000 people died when hurricane
storm tides of 8-15 feet inundated the entire
island city of Galveston, Texas.
• More than half of all the homes and buildings
were destroyed.
• Property damage is estimated at $700 million in
1990 dollars.
Hurricanes‘ effects on the coastal
ecosystems in Texas
• Research over the years has
yielded discoveries that could
help the tender coastal
ecosystem recover,
depending on human
interaction.
• Among findings, when
comparing before and after
2008 Hurricane Ike, is that
the marshes lost elevation,
which is contrary to what
most would expect to
happen in a hurricane.
• Sand dunes in the area hit by Hurricanes are already
eroding at a rate of several feet per year.
• The natural mending of washed-out beaches might not
be possible because of the many structures and nonnative landscapes maintained there, blocking dune reestablishment.
2. Floods
Floods are part of the natural cycle of things.
• The benefits of natural floods almost certainly
outweigh the negative aspects.
• The problems start when flooding occurs in
areas of large-scale human development of
the landscape.
• In areas largely inhabited by people, there
are both positive and negative environmental
effects of flooding.
• Floods can distribute large amounts of water
and suspended river sediment over vast areas.
In many areas, this sediment helps replenish
valuable topsoil components to agricultural
lands and can keep the elevation of a land
mass above sea level.
• The larger a flood is, the more of the
ecosystem it wipes out.
• It could simply wipe out the producer in the
food chain (plant) which would mean the rest
of the food chain would collapse which would
kill other food chains.
• It could also be worse though as it could also
wipe out prey or predators which would also
effect food chains and webs.
• Floods affect the bays
and estuaries in many
ways. These rainfall
events bring pulses of
nutrients which will
cycle through the food
chain for years to
come. They can also
flush certain toxicants
out of the system.
• Floods improve the estuary habitats required
by certain recreationally and economically
important species, facilitating an increase in
their populations, while decreasing habitat
availability and populations of others.
However, almost all life in the bays is adapted
to these periodic events.
• Since many inshore life forms are dependent on either the
lower salinity waters during part of their life, or the habitats
sustained by intermediate salinities, the net effect of floods
on estuaries is very positive.
• Floods ensure that the necessary salinity balances will be in
place for many months following the event.
3. tornadoes
• Tornadoes are the most violent storms on Earth;
violently rotating columns of air exceed 100 mph and
can reach up to 300 mph.
• Tornados are an iconic symbol of the North American
Great Plains; however, their influence on communities
of animals rarely has been studied.
• Lack of information on influence of tornados may be
due in part to their unpredictable and localized
occurrence.
• It is estimated that in the United States tornados
impact 450,000 ha each year, .
• Tornados and other
catastrophic wind storms
affect structure and
composition of plant
communities in forested
areas, particularly in the
Midwest.
• Tornados increase coarse
woody debris and the
number of snags, and they
kill larger trees.
• The tornadoes kill larger trees; thus, increasing openness of canopy,
woody debris, and distance between patches of forest.
• In the area impacted by tornadoes, habitat for forest-edge species
such as field sparrows and brown-headed cowbirds was enhanced;
however, impacted forests still support species dependent on dense
forested habitats.
• There is also a biology researcher investigating the possibility that
this long range transport process could be responsible for the
spread of certain types of small animals and plants across portions
of the U.S.
• Tornadoes destroy
animal habitats, take
away their food, or kill
them right away, so
they either don’t have
a place to live, don’t
have food, or die.
• Trees can fall and
destroy their home.
3. drought
•
The Davis Mountains
suffered through a
prolonged and severe
drought for eight years.
Evidence of this drought
could be seen in the
Gray Oaks that have
turned brown, dropped
their leaves and gone
dormant due to the
drought.
• A combination of record-high heat and recordlow rainfall caused south and central Texas to
the region's deepest drought in a half century
in 2009, with $3.6 billion of crop and livestock
losses piling up during the nine months.
• In late April 2009, the USDA designated 70
Texas counties as primary natural-disaster
areas because of drought, above-normal
temperatures and associated wildfires.
• At Lake Travis, a popular boating and fishing
spot, officials closed the last of the lake's 12
public boat ramps in 2009 because of the
lake's receding waters.
• During times of drought, trees and landscape
plants often show the effects of the hot, dry
weather. The drought of 1999 and 2000 has
had an impact on plants in Texas.
• Not only is drought very harmful to trees, it
contributes to extreme conditions for forest
and range fires.
• Water deficits in trees have an adverse effect on many
of the tree's growth processes. Severe water stress will
injure trees and may kill them. In addition, stressed
trees are more vulnerable to insect and disease pests
when compared to a healthy tree.
• Stressed pine trees may be attacked by pine bark
beetles.
• Immediate effects of drought on hardwood trees are
usually obvious, but delayed effects also occur. When
unfavorable growth conditions occur, growth for the
coming year is often affected.
• Drought has a tremendous effect on wildlife
populations as the food and water is
nonexistent during the time that many species
are breeding to provide next year’s crop of
youngsters. The losses are not just in big game
but affect turkeys, quail, dove and other
animals. This goes right up the food chain and
we even see losses in the predators as the
prey base decreases.
5. Volcanoes
• There are at least two extinct volcanoes
in the Davis mountains of West Texas.
• There is one extinct volcano in Travis
County, southeast of Austin, named
"Pilot Knob”.
• The University Of Texas at El Paso also
happens to be sitting on a volcano.
• Ash deposits from the powerful
Yellowstone Caldera eruptions in
Yellowstone National Park have been
mapped as far away as Iowa, Missouri,
Texas, and even northern Mexico.
• Between roughly 38 and 32 million years ago Big
Bend itself hosted a series of volcanic eruptions.
Volcanic activity was not continuous during these
eruptive cycles. Periods of hundreds of thousands
or perhaps millions of years passed between
eruptions. During the quiet interludes the forces
of erosion carved new landscapes, many of which
were destined to be buried under layers of ash
and lava from later eruptions. Life returned to the
land only to be displaced by future eruptions
• The Davis Mountains, the most extensive
mountain range in Texas, were formed by
volcanic activity during the Tertiary geologic
period, which began around 65 million years
ago. The mild climate and volcanic soils
support a most biologically diverse selection of
mountain plants and animals.
• As lava, heat, and ash cover the landscape, trees
and other plants are burned, buried, and
destroyed. Thus, it is easy to suppose that
volcanoes and plants don’t mix.
• While it is true that the immediate effect of
volcanoes on plant life is death, the long term
effect is very positive. Magma from the Earth’s
core contains a rich source of nutrients that
plants need to survive. Each time a volcano
erupts, it brings these nutrients with it. When
volcanoes explode, spreading ash around a large
area, this ash acts as a fertilizer, enriching the soil.
It is no surprise that the soil near volcanoes is
among the richest and most fertile on Earth.
6. fire
• Pine forests are fire climax systems, meaning that
fire is necessary in order for pines to maintain
dominance in the presence of hardwood
competition.
• Historically, fire has played an important role in
shaping East Texas as a pine community by
controlling hardwood competition.
• Damage caused by fire in the Gulf Coast Area
has been minimal because prescribed fire is
used as a tool for range management for
cattle operations and wildlife management.
• Controlled fires in open areas have benefited
the area by clearing up surface fuels.
• Tree mortality after a wildfire is minimal
because fires in this region are mostly winddriven with rapid rates of spread.
• Most fires in the Trans-Pecos
region are started by
lightning strikes, which are
common during the summer
storms.
• For the most part, it has
been mostly the large areas
of grassland that burn.
• These fires have kept
juniper and oak trees at bay
on the higher, wet and cool
areas and desert shrubs at
bay on the lower, dry and
hot areas.
• Fire historically had
an impact on the
Rolling Plains region,
by suppressing woody
species and favoring
open grasslands.
• Fire kept honey
mesquite and juniper
populations at low
densities.
• Early Native Americans understood the use of fire
to improve the grass lands of the panhandle.
Because of this periodic burning of the plains,
wildlife (mainly buffalo), did not have to leave the
area to search for more nutrient-rich lands. The
fire ecosystem has always played a vital role in
the panhandle. Fire kept invader species of trees
limited, while enriching the grass lands. Due to
human population growth in the High Plains, fire
is no longer allowed to burn. As a result, the
panhandle has seen a dramatic increase in the
number of juniper and mesquite trees. Fires that
occur today are much harder to control, because
of overgrowth of grass fuel types.
• Fire serves an important function in
maintaining the health of certain ecosystems,
but as a result of changes in climate and in
human use (and misuse) of fire, fires are now
a threat to many forests and their biodiversity.
Forest fires have many implications for
biological diversity.
• At the global scale, they are a significant source of
emitted carbon, contributing to global warming
which could lead to biodiversity changes.
• At the regional and local level, they lead to change
in biomass levels, alter the hydrological cycle with
subsequent effects for marine systems such as
coral reefs, and impact plant and animal species‘
functioning.
• Smoke from fires can significantly reduce
photosynthetic activity and can be detrimental to
health of humans and animals.
(Earthquakes)
• Earthquakes do occur in
Texas. Within the twentieth
century there have been
more than 100 earthquakes
large enough to be felt;
their epicenters occur in 40
of Texas's 257 counties.
• Four of these earthquakes
have had magnitudes
between 5 and 6, making
them large enough to be
felt over a wide area and
produce significant damage
near their epicenters.
In four regions within Texas there have been
historical earthquakes which indicate potential
earthquake hazard.
• Two regions, near El Paso and in the Panhandle, should expect
earthquakes with magnitudes of about 5.5-6.0 to occur every 50100 years, and even larger earthquakes are possible. In
northeastern Texas the greatest hazard is from very large
earthquakes (magnitude 7 or above) which might occur outside of
Texas, particularly in Oklahoma or Missouri-Tennessee.
• In south-central Texas the hazard is generally low, but residents
should be aware that small earthquakes can occur there, including
some which are triggered by oil or gas production. Elsewhere in
Texas, earthquakes are exceedingly rare. However, the hazard level
is not zero anywhere in Texas; small earthquakes are possible
almost anywhere, and all regions face possible ill effects from very
large, distant earthquakes.