| A | B |
| Ecology | Study of the interactions of living organisms with one another and with their physical enviroment |
| Habitat | Place where a particular population of a species lives |
| Community | The many different species that live together in a habitat |
| Ecosystem | Ecological system encompassing a community and all the physical aspects of its habitat |
| Species Diversity | The number of species in an ecosystem |
| Succession | The regular progression of species replacement that occurs after disturbance or the creation of new habitat |
| Primary Succession | Succession that occurs in a newly formed habitat that has never before sustained life |
| Secondary Succession | An episode of succession that occurs in areas where there has been previous growth, such as abandoned fields or forest clearings |
| Primary Productivity | The amount of organic material that the photosynthetic organisms of an ecosystem produce |
| Producers | Organism that makes its own food from energy and carbon atoms in its enviroment; autotroph |
| Consumers | Organism that must obtain energy to build its molecules by consuming other organisms; heterotroph |
| Trophic Level | A group of organisms that have the same source of energy; a step in the food chain |
| Herbivores | Organism that eats only plants or algae |
| Carnivores | Flesh-eating organism |
| Omnivores | Animal that eats plants both plants and animals |
| Detritivores | Organism that obtains its energy by feeding on dead organisms or wastes |
| Decomposers | Organism that causes decay |
| Food Chain | Linear pathway of energy transfer in an ecosystem |
| Food Web | A network of feeding relationships in an ecosystem |
| Biomass | The dry weight of tissue and other organic matter used to determine the amount of energy present in trophic levels |
| Ground Water | Water found beneath Earth's surface |
| Nitrogen Fixation | Process of combining nitrogen gas with hydrogen to form ammonia |
| Diversity | The number of species in an ecosystem |