ECOLOGY & HUMAN IMPACT

ON THE ENVIRONMENT

Ecology: Unit OutlinePart 1. Organisms and Their Environment

* The environment includes every living and nonliving thing that surrounds an organism.

* The term ecological system, or ecosystem, is used by scientists to describe any portion of the environment.

* An ecosystem includes all the living (biotic) and nonliving (abiotic) factors in it. Biotic factors include the plants, animals, protists, fungi, and bacteria in an ecosystem. Abiotic factors include things such as the air, soil, temperature, water, and physical things in the ecosystem.

* The specific place in the environment where an organisms lives is referred to as its habitat.

* A community consists of all the various types of living things in the environment, while a population consists of only one species in the community.

* All of the Earth’s ecosystems make up the biosphere. The biosphere includes any place on the Earth where live exists.

* All the organisms in an ecosystem are interdependent upon each other. Ecology is the study of the interactions of living things with each other and their physical environment.

* Since factors such as food, water, and shelter are limited, so are the numbers and types of organism living in any ecosystem. Organisms must struggle to get the resources they need to live. This is called competition.

* The relationship between predator (the hunter) and prey (the hunted) helps to limit the size of various populations within an ecosystem.

* Carrying capacity refers to the number of organisms of a single species that an ecosystem can support.

Part 2. Population Interactions

* Biodiversity refers to the wide variety of organisms that interact with one another in an ecosystem. Every population is linked either directly, or indirectly, to all other populations.

* The role, or job, that an organism has in its ecosystem is called its niche. If two organisms attempt to fill the same role, competition occurs.

* Competition can be increased in an ecosystem when a foreign species enters an area. Foreign, or invasive species,

often can be more successful at competing than the native species. This can upset the ecological balance of the food chains and food webs in that ecosystem.

* A food chain shows the relationships between the producers and consumers in an ecosystem. Food chains always begins with a producer (plant/autotroph).

* There are four basic (4) types of consumers (heterotrophs) found in any ecosystem: herbivores (plant eaters), carnivores (meat eaters), omnivores (plant & meat eater), and decomposers (decay dead organisms).

* Scavengers are a type of consumer that eat dead organisms, but they are NOT considered to be predators or decomposers. A true predator kills its own prey, and a true decomposer breaks a dead organism into simpler materials, such as minerals, that can be recycled in the soil or air to be used again by producers.

* Parasites are a special type of organism that do not fit it to the predator/prey relationship. A parasite “feeds” on a host organism, but rarely kill the host. An example of a parasite/host relationship is a flea on a dog.

* Most organisms do not eat only one type of food, Therefore, food chains overlap and intertwine forming more complex food webs.

* Another way to show the flow of energy in an ecosystem is an energy pyramid. The amount of energy decreases at each level because organisms use some of the energy to power their own life processes.

* An ecosystem must have a constant input of energy in order to be sustained. In most ecosystems on Earth, this energy

comes from the sun. Other materials in the ecosystem must be recycled and/or reused. Some materials that are recycled and reused are water, CO2, O2, and minerals such as nitrogen.

* The processes of photosynthesis, respiration, and decomposition help to recycle materials within an ecosystem.

VOCABULARY

Abiotic Ecological niche Limiting factorAutotroph Ecology ParasiteBiodiversity Ecosystem PopulationBiosphere Energy Pyramid PredatorBiotic Environment Prey Carnivore Food Chain ProducerCarrying capacity Food Web ScavengerCommunity Habitat DecomposerCompetition Herbivore HostConsumer Heterotroph Foreign Species

Part 3. Biodiversity & Environmental Changes

* Biodiversity is a measurement of the degree to which the species within an ecosystem are varied, or different, from each other.

* The greater the biodiversity an ecosystem has, the more stable it is. As biodiversity decreases, so does the stability of that ecosystem.

* The interactions between the various organisms in any ecosystem may allow it to be stable for hundreds or even thousands of years.

* Natural disasters and human activities can reduce the biodiversity in the environment. The removal of a species from the environment, for any reason, can upset the delicate balance in the food chains in the area.

* Some human activities that can negatively impact the biodiversity in an ecosystem include: habitat destruction, pollution, overhunting, activities that lead to erosion (soil loss), and the introduction of invasive species.

* Biodiversity represents one of the greatest natural resources known to humans. It ensures the availability of rich variety of genetic material that may provide sources of medicines, insecticides, and other uses.

* Many environments can be changed through natural

processes. As a result, the plants and animals living in that area can also change.

* The series of changes by which one habitat changes into another is called ecological succession. During succession, each community modifies the environment which make it more suitable for another community.

* Ecological succession can occur in both land and aquatic environments.

VOCABULARY

Biodiversity Habitat DestructionStability PollutionInteractions OverhuntingHuman Activities Invasive SpeciesErosion Natural ResourcesEcological Succession

Part 4. Human Impact on Ecosystems

* Human activities directly impact the environment, causing problems to the world around us. These problems must be avoided and/or corrected. Failure to correct ecological problems can result in serious, permanent damage to the biosphere.

* Earth has a limited, or finite, supply of resources. Some of these resources can be replaced over time, like food and solar energy, and are called renewable resources. Some of our resources are nonrenewable, such as aluminum and other metals, as well as fossil fuels (coal, oil, natural gas), and cannot be replaced.

* Humans must conserve as many resources as possible so they are available for future generations. Three ways to preserve our nonrenewable resources are to Reduce, Reuse, and Recycle.

* Human population growth has increased to the point where natural resources are being used at an exceptionally fast rate. This is having a significant and negative impact on the environment.

* One of the most harmful changes due to increased population is pollution, which refers to anything that makes the environment less suitable or desirable for life. Pollution includes harmful changes to the air, water, soil. Increased noise in crowded cities is also considered to be a form of pollution.

* Humans have the greatest negative impact on the biosphere than any other species on earth. Industrialization and human technology have contributed to most of the ecological problems on Earth. These problems include:

- Global Warming - Thermal Pollution - Ozone Depletion - Air Pollution - Acid Rain - Water Pollution - Loss of Biodiversity - Nuclear Wastes - Toxic Wastes

* For each environmental problem, people must learn to assess the risk to the environment, and analyze the costs and risks of the possible solutions. As a result, people must determine which trade-off (compromise) is acceptable, and which is too dangerous to the welfare of future generations.

VOCABULARY

Finite Fossil Fuels Population GrowthRenewable Conservation IndustrializationNonrenewable Recycle Trade-off