Background Information
From the time we awake until we go to bed our activities, our choices and situations imposed upon us have an impact on the world around us. What we eat, how we travel, what we buy, how we heat and cool our spaces and many other decisions we make in a day all affect the environment, which in turn has an impact on populations of animals and plants. Environmental challenges such as acid rain, depletion of the ozone layer, greenhouse effect leading to climate change, hazardous waste, destruction of habitats and air and water pollution, adversely affect animal populations (including human beings!)
Ecology is the study of living things in their natural environment or surroundings which includes both living and non-living entities. Ecology investigates how people, plants and animals live with and affect each other and their environment. Everything we do to our environment will have an effect back on us, as well as on every other living thing sharing our environment with us, creating a vast environmental web.
All living things are dependent on our environment for the essentials of life. The basis of all life on earth is the sun. It provides plants and animals with the energy they need to live. Winds are generated by heating the earth's land masses and the air above them. It powers the water cycle by evaporating water into the atmosphere. Without the sun, life on earth could not exist.
The sun's energy is not evenly spread across the surface of the earth. Polar areas receive far less than equatorial areas. Due to this factor an imbalance is created which drives the winds around the world. There are six major climates which are influenced by distance from the equator, height above sea level and distance from the ocean. They are polar, mountain, cold forest, temperate, dry, equatorial and sub-equatorial.
Natural climate changes take place gradually over thousands of years and pose no great threat to us at present. On the other hand, human's energy needs are causing an array of environmental problems that can have a devastating impact on our earth. Our ever growing energy demands create real threats to our environment! Some of these threats are rapid climate change and the greenhouse effect, which contribute to global warming.
Sources of energy are divided into two groups, renewable and nonrenewable. Fossil fuels (coal, oil and natural gas) and elements needed for nuclear energy are nonrenewable sources of energy. Wind, water, solar and geothermal energy are renewable resources. Wood is a renewable resource, but we are using it faster than it can be replenished and it is rapidly becoming a nonrenewable source of energy.
Daily we consume energy and often waste energy without a second thought. When we jump in our car to take a drive we are depleting limited oil resources and emitting air pollutants. When we use electricity produced from the burning of fossil fuels we deplete limited coal resources and emit air pollutants.
As we burn fossil fuels for energy, carbon dioxide is released into the atmosphere contributing to the greenhouse effect of trapping the sun's heat and warming the earth. The gases, which can stay in the atmosphere for at least fifty years and up to centuries, are building up beyond the earth's capacity to remove them and, in effect, creating an extra-thick heat blanket around the earth. In February 2007, the thousands of scientific experts collectively known as the Intergovernmental Panel on Climate Change (IPCC) concluded that there is greater than 90 percent likelihood that people are causing global warming. (1)
Many scientist and people believe that in all of human history, climate change is the greatest threat our planet has faced! In addition, the sulfur dioxide, nitrogen dioxide, and particulates emitted from the burning of fossil fuels create smog and acid rain. These forms of pollution adversely affect human health and damage our environment through water supplies, vegetation and wildlife resources.
Ecosystems are made up of a given habitat and its community of plants and animals. The living things within an ecosystem interact with each other and their non-living environment to form an ecological unit which is largely self-contained. Ecosystems come in a variety of sizes and can range from very small to very large. Many small ecosystems can be contained within a larger one. Natural ecosystems are made of both abiotic factors (air, water, rocks, energy) and biotic factors (plants, animals, and microorganisms).
Within ecosystems there are habitats that can also vary in size. In a habitat is where a population lives. A population is considered any group of organisms of one species in a certain area. The group of plants and animals that live in a habitat is a community. Within the habitat, the needs of the organisms are met. These needs are food, water, temperature, shelter, oxygen, and minerals.
Biomes are the largest ecosystems. Each biome is home to a large variety of plants and animals. They are named after the main types of vegetation found in them. Biomes are where several habitats intersect. Biomes are natural occurring environments, although people can create controlled biomes. Within all biomes, habitats, and ecosystems is an energy cycle.
Each living thing on earth needs energy and ultimately the sun is the source of energy within an ecosystem. Organisms in a given ecosystem are linked by their feeding relationships. A food chain is how energy is passed from one organism to another. The organisms in the food chain are producers, consumers, or decomposers. Plants act as producers by using the sun's energy to produce food through a process called photosynthesis. In this process plants build carbohydrates from water and carbon dioxide, releasing oxygen (light energy is changed to chemical energy). Decomposers and consumers eat other organisms for their food. A food chain is depicted as a single path, but in the real world there is not a straight path, but rather a web of paths. This is because animals often eat a varied diet and so play different roles in a number of food chains. Patterns of feeding link different ecosystems. A food web is made up of interlocking food chains.
Urban expansion and the spread of industry and agriculture are resulting in destruction of important natural habitats. When habitats are destroyed, disturbed or simply disappear the animals that depend on those habitats either have to adapt quickly, if they can, or they will die out. Human activities can lead to smaller plant and animal populations. Habitat loss, pollution, population growth, introduction of non-native organisms, and overexploitation can cause a population of a species to become so small that it cannot survive. A species that is in danger of dying out due to their critically low numbers is called an endangered species. Animals that are most likely to become endangered due to their small numbers are called threatened species. Animals that are gone forever are called extinct.
Rapid habitat loss is the primary cause of species endangerment. Human beings are the strongest forces in rapid habitat loss. As human population and consumption increase, wildlife habitats are converted to homes, schools and roads. Shopping Malls stand where wetlands once existed. Trees are cut down to build homes and supply us with paper. The population growth means more and more people need more food and more land.
Pollution is another way to degrade habitats. Pollutants disposed of improperly, oil spills, trash and plastics find there way into habitats, destroying the balance of nature. Life depends on water for its survival yet we dump toxic chemicals and garbage right into our oceans, lakes, rivers and streams. Water pollution harms animals in both fresh and saltwater environments. Ships pollute our oceans by dumping waste. Large oil spills have occurred that have killed many animals.
Air pollution also contributes to the loss of habitats. Factories, trucks, cars and buses burn fossil fuels adding chemicals to the air (seen as smog) creating acid rain that pollutes both land and water habitats. As our climate warms from the greenhouse effect many animals will become extinct.
Pesticides sprayed on our crops cause threat to many animals. The toxin is first eaten by a herbivore (plant eater). Predators then eat many herbivores and over time build high levels of concentration of these chemicals in their systems. This is called biomagnifications, the increase in a persistent pollutant by the food chain. Many of the most dangerous chemicals in the environment are those that are biomagnified. These chemicals are similar in that they are long-lived (persistent) in the environment and not easily broken down into non-toxic components. In addition, these chemicals tend to bond with the fatty tissues of the organism. Chemicals of this kind can disrupt physical functions such as reproduction. An example of this is large birds of prey accumulating the pesticide DDT in their systems causing their egg shells to be so thin that they became endangered.
Humans also deplete wildlife populations by killing or capturing animals for their own use. An example of this overexploitation is the killing of thousands of grey wolfs. At one point government agencies even paid hunters cash rewards, or bounties for wolves that were shot. Another example is the sophisticated technology aids fishermen use to take ever increasing amounts of fish, leaving once abundant fisheries with smaller and smaller populations.
Non-native species can be introduced to an area creating additional problems that can disrupt the delicate balance of an ecosystem. The introduced species may prey on the native species or disturb the habitat in unforeseen ways. In the South we do not have to look far to see the effects of the non-native species - Kudzu!
According to the World Wildlife Fund 137 species are estimated to go extinct each day and 50,000 species are estimated to go extinct each year. (2) Extinction is forever. What has been done in the past to help save species? What can we do as individuals to take responsibility for our actions now to help save species?
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