General Science Review: Ecology

Ecology is the study of interrelationships between  organisms and their physical environment. Ecologists  consider animals and plants in terms of an ecosystem—  the interaction of different populations of the same  species in a shared environment. The sun fuels all of the  energy in an ecosystem. 

Ecosystems vary in size. Each contains air, soil, Producers, Consumers, and Decomposers; the latter  three transfer energy in a process called the food chain. 

A food chain can be visualized as follows:  sunlight . green plants (Producers) . herbivores  (Consumers) . carnivores (Consumers) .  bacteria (Decomposers) . soil . green plants, etc. 

Producers, such as green plants, use sunlight in  the photosynthesis process to create their own food. 

The Producers are the food for Consumers, such as animals,  which can’t make their own food. The two main  types of Consumers are herbivores and carnivores. Herbivores  are animals that eat only vegetation. They have  teeth and digestive systems adapted for processing  plants. Examples of herbivores include rabbits, cows,  and squirrels. Carnivores are animals that feed only on  the flesh of other animals. They have powerful jaws and  teeth. Examples of carnivores are tigers, wolves, and  hyenas. Human beings are omnivores. Our bodies are  capable of meeting nutritional needs using both plants  and animal matter. All Consumers eat either Producers  or other Consumers and use the energy to do work or  radiate the energy back into the atmosphere. 

When animals die, the dead organic matter is  broken down by Decomposers, such as fungi. During  this process of decay, Decomposers reintroduce minerals  back into the soil in the ecosystem. Producers  then recycle the minerals as they grow, and the process  begins again. 

Biomes are established ecological systems that  extend over a large geographical area and are characterized  by a dominant type of vegetation or climatic  condition. Organisms in a biome are adapted to the climate  associated with the region. The seven major biomes  on Earth are: 
- Arctic Tundra: treeless plains surrounding the Arctic Ocean, with permanently frozen subsoil 
- Deciduous: leaf-shedding forests in mild climates 
- Desert: environment with irregular or infrequent  rainfall and high temperatures 
- Grassland: areas with rainfall insufficient to support  many trees; grass species dominate 
- Marine: oceans and seas 
- Taiga: evergreen forests that survive long winters 
- Tropical rainforest: constant precipitation and  high temperatures, with many plant species