Disruptions To Ecosystems

Unit: Ecology

Chapter: Disruptions in ecosystem

Reference: Natural Disruptions to Ecosystems

Wildfires, Flooding, Volcanic Eruptions, Human Effects on Ecosystems, Habitat Destruction, Introduced Species, Overhunting

Pollution and Environmental Change, Human Population Growth

Global Climate Change, Geological and meteorological events that cause disruptions in ecosystems, El Nino, Continental drift, Meteor strikes

Learning objectives

  • To understand natural disruptions to ecosystems
  • To identify the effects of human on ecosystem

Natural Disruptions to Ecosystems

  • Ecosystems change over time. Sudden disruptions such as volcanoes, floods, or fires can affect which species will thrive in an environment. Other disruptions are caused by human activities.
  • Some disruptions can be devastating for an individual species and may even cause an entire species to permanently disappear in a process called extinction.
  • As species become extinct, the variety of species in the biosphere decreases, which decreases biodiversity, or the variety of life.
  • Whenever one species is removed, other species in the food chain are affected. These changes influence a community’s biodiversity and can disrupt an entire ecosystem.

Wildfires

  • Fire is a common disruption to ecosystems that can be caused by nature or by human behaviour.
  • Natural wildfires can both help and harm an ecosystem. For example, wildfires kill many small animals and displace others that flee to safety.
  • Animals looking to return after the fire will find their homes and much of their food supply destroyed.
  • Also, bare soil that remains after a wildfire is particularly susceptible to soil erosion because the soil is no longer held in place by roots.

Flooding

  • Flooding can occur after a storm and may be disruptive to an ecosystem, depending on the extent of the flooding and how long the water stays.
  • Flooding can result in saturated soils, or soils that are filled with water. Plant roots require oxygen, so saturated soils can kill plants by drowning the plant roots.
  • Flooding may also cause water and nutrients to run off across land surfaces. Rushing water can cause soil to wash away, particularly bare soil. Burrows, dens, and nests can be destroyed, forcing surviving animals to relocate.

Volcanic Eruptions

  • On May 18, 1980, an earthquake under Mount St. Helens contributed to a tremendous volcanic eruption.
  • The north face of the mountain slid away in a huge avalanche, releasing a blast of superheated, rock-filled gas that ripped up the trees in its path.
  •  Subsequently, slower flows of gas and rock destroyed trees and living organisms in the soil. Mature forests were turned into ash covered wasteland. Since then, hardy plants have reappeared in the ash field.
  • The plants attract herbivores that drop seeds from other plants in their dung. About three decades after the eruption, the forest began to regrow.
  • The steady progression of species changes and replacement in an ecosystem over time, as occurred after the eruption of Mount St. Helens, is called ecological succession.

Human Effects on Ecosystems

Humans impact the natural world more than any other species. Without limits on human activity, humans can damage the environment in many ways. As the human population grows, it requires more resources to keep its members healthy and comfortable. Each new family needs a place to live, food, water, clothing, medicine, and tools.

Habitat Destruction

  • Habitat destruction occurs when a habitat is removed and replaced with some other type of habitat. As a result, the organisms living at the site must move or be destroyed.
  • Habitat destruction can have harmful effects on humans, too. Scientists believe that some of the destruction caused by Hurricane Katrina in 2005 resulted from the removal of wetlands that would normally take up much of the regional floodwaters.
  • Natural coastal ecosystems, including thick vegetation, may be able to buffer the coastline from hurricanes and other storms.

Introduced Species

Wherever humans go, they take animals, plants, and microorganisms with them. Tulips-as well as most crop plants and many other highly-valued garden plants-are not native to the United States but rather are introduced species. Introduced species are an important part of the economy and of society. Some introduced species, however, can be disruptive to an ecosystem. An introduced species that has negative effects in its new ecosystem is called an invasive species.

Invasive species can have serious effects on an ecosystem and on the human population. For example, a vine called kudzu was introduced to the southern United States to control soil erosion. However, the kudzu spread rapidly, choking the roots of some plants, and blocking light for other plants, effectively killing them, and changing the ecosystem.

Overhunting

  • Many species were driven to extinction by hunting thousands of years ago. As the human population grew, more and more species of animals were threatened with extinction from overhunting.
  •  Laws were passed to limit hunting and to ban the killing of endangered species. Nevertheless, poaching, or illegal hunting, continues to threaten many populations.

Pollution and Environmental Change

  • Human activities cause pollution-the release of harmful substances into the environment-including air pollution, water pollution, and the production of hazardous waste. Air pollution in the form of carbon dioxide has contributed to global warming.
  • One effect of today’s heavy use of fossil fuels-including coal, oil, and gas-is air pollution. Air pollution includes noxious compounds and particulate matter. Air pollution can result in respiratory trouble and other human sickness.

Human Population Growth

  • Sources of water pollution include the runoff of fertilizer from lawns and agricultural fields, as well as runoff from oil and other urban pollutants.
  • Water pollution is also caused by oil spills, in addition to smoke from power plants. Fertilizers introduce excess nutrients and result in major changes in water ecosystems, including changing the pH of the water, causing algae blooms, and reducing the oxygen in the water.
  •  Rainwater can wash all pollutants on Earth’s surface into rivers, lakes, and the ocean. Oil spills kill animals and can affect several different food webs.
  • Air pollution can lead to water pollution by causing acid rain that can damage-and even kill-living things. Water pollution can also occur when people do not properly dispose of toxic household or industrial materials.

Global Climate Change

  • Climate change can involve global warming, a slow rise in Earth’s average temperature.
  • An increasing rise in temperatures could affect ecosystems around the globe. For example, rising temperatures can speed up the melting of glaciers and ice caps disrupting or destroying habitats along shorelines as waters rise.
  • Climate change can affect precipitation patterns resulting in droughts or floods.
  • Climate change can also alter ecosystems as populations unable to survive warmer temperatures migrate to cooler regions.

Geological and meteorological events that cause disruptions in ecosystems:

El Nino:

El Nino has produced natural disasters such as fires and floods, and these natural disasters have resulted in a rapid and abnormal migration of birds and animals. Precipitation and wind flow are two of the most important abiotic variables that impact living creatures. As a result, El Nino directly influences population distribution in several ways.

Continental drift:

Even though continental drift is a geological event, scientists have seen its impact on species distribution. Several species have adapted and expanded their range due to these drifting episodes.

Meteor strikes:

Meteor strikes are meteorological phenomena. However, the extinction of dinosaurs due to a meteor strike has biological relevance; it resulted in the loss of nearly three-quarters of the world's population.

Solved examples

Example 1. Which of the following would count as a disruption to an ecosystem?

a) Change in temperature   b) Natural disaster

c)Invasive species d) All the Above

Solution 1: d. All the options cause disruption to an ecosystem.

Example 2. If humans cleared a forest to build homes, we would expect _____________.

a) fewer tree-dwelling animals b) increased insect populations

c) more development of soil d) more frequent thunderstorms

Solution 2: a. If humans cleared a forest to build homes, we would expect fewer tree-dwelling animals.

Summary

  • Sudden disruptions such as volcanoes, floods, or fires can affect which species will thrive in an environment.
  • Fire is a common disruption to ecosystems that can be caused by nature or by human behaviour.
  • Flooding can occur after a storm and may be disruptive to an ecosystem, depending on the extent of the flooding and how long the water stays.
  • Humans impact the natural world more than any other species.
  • El Nino has produced natural disasters such as fires and floods, and these natural disasters have resulted in a rapid and abnormal migration of birds and animals.

 

 

 

 

 

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