Transcript What effects do catastrophic events have on TEXAS ecosystems?

What effects do catastrophic events
have on TEXAS ecosystems?
What is a catastrophic event?
 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…
 Those caused by weather:
~ floods
~ hurricanes
~ tornadoes
~ drought
 Fires
 Those caused by geological forces:
~ volcanoes
~ earthquakes
~ tsunami
HURRICANES…
Effect on Texas coastal ecosystems:
 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.
HURRICANES…
Effect on Texas coastal ecosystems:
 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 non-native
landscapes maintained there,
blocking dune re-establishment.
Floods…
 Part of the natural order 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.
 In areas largely inhabited by people,
there are both positive and negative
environmental effects of flooding.
Floods…
 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.
Floods…
 The larger a flood is, the more
of the ecosystem it wipes out.
 A flood could destroy the producer
in the food chain (plants) which
could cause the rest of the food
chain to collapse…which would
kill other food chains.
 A flood could also wipe out prey or
predators, which would impact
food chains and webs.
Floods…
 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…
 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.
Tornadoes…
 Tornadoes are the most
violent storms on Earth;
intense 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.
Tornadoes…
 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.
 Tornadoes kill larger trees, which opens the canopy,
increases woody debris, and adds 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.
 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.
Drought…
 A combination of record-high heat and record-low
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.
Drought…
 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.
Drought…
 During times of drought, trees and landscape plants
often show the effects of the hot, dry weather.
 The 1999 and 2000 drought had an impact on plants
in Texas.
 Drought is very harmful to trees,
and it contributes to extreme
conditions for forest and range fires.
Drought…
 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 -- such as pine bark beetles –
than a healthy tree.
 Immediate effects of drought
on hardwood trees are usually
obvious, but delayed effects also
occur; growth for the coming
year is often affected.
Drought…
 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 continues up the food chain, with
losses in the predators as the prey base decreases.
Volcanoes…
 There are at least two extinct volcanoes in the
Davis mountains of West Texas.
 There is an extinct volcano
southeast of Austin; "Pilot Knob”.
 The University Of Texas at El Paso
sits on a volcano.
 Ash deposits from eruptions of the
Yellowstone Caldera have been
mapped in Iowa, Missouri, Texas,
and northern Mexico.
Volcanoes…
 As lava, heat, and ash cover the landscape, trees
and other plants are burned, buried, and destroyed;
so volcanoes and plants don’t mix.
 Short-term impact on plant life is
death; the long term effect is positive.
 Eruptions bring magma from the
Earth’s core containing rich nutrients
that plants need to survive.
 When volcanoes explode, the ash
acts as a fertilizer, enriching the soil.
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.
Fire…
 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 wind-driven
with rapid rates of spread.
Fire…
 Many fires are started by lightning strikes,
which are common during the summer
storms, and may burn large areas of
grassland.
 These fires have helped
control juniper and oak
trees in the higher, wet
and cool areas, and keep
desert shrubs controlled
in the lower, dry and hot
areas.
Fire…
 Early Native Americans used fire
to improve the grass lands of the
panhandle.
 This periodic burning of the plains
meant that wildlife (mainly buffalo),
did not have to leave the area to
search for more nutrient-rich lands.
 Fire kept invader species of trees
limited and enriched the grass lands.
Fire…
 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…
 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.
Fire…
 Forest fires have many implications
for biological diversity:
•
•
•
On the global scale, they are a
significant source of emitted carbon,
contributing to “global warming”.
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 the functioning of plant
and animal species.
Smoke from fires can significantly reduce
photosynthetic activity and can be detrimental
to health of humans and animals.
Earthquakes…
 Earthquakes do occur in Texas.
 During the twentieth century, there
were more than 100 earthquakes
large enough to be felt; their
epicenters occur in 40 of the
State’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.
Earthquakes…
 There are four regions within Texas where
earthquakes have occurred:
•
•
Two regions, near El Paso and in the
Panhandle, should expect earthquakes
with magnitudes of about 5.5-6.0 to occur
every 50-100 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.
Earthquakes…
 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.
Catastrophic Events