Presentation on theme: "And their effects on Texas Ecosystems. What are catastrophic events? Catastrophic events are natural occurrences that generally have a negative effect."— Presentation transcript:
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 non- native landscapes maintained there, blocking dune re- establishment.
2. Floods F loods 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 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.
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 wind- driven 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 to occur every 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.