Ecosystems Keywords: • Biosphere • Habitat • Species • Population • Community • Niche Biosphere • The part of the earth and its atmosphere that is inhabited by living organisms. Habitat • A place with a set of conditions that allow an organism to live. Species • A group of organisms that are closely related and can interbreed to produce fertile offspring. Population • A group of interbreeding individuals of the same species found in an area. Community • The different populations sharing a habitat or ecosystem. Ecosystem • All of the abiotic and biotic components that enable an area to be self-sustaining. Niche • The role of an organism in a habitat. Abiotic factors • The non-living components of an ecosystem. • Solar energy input • Climate • Topography • Oxygen concentration • Edaphic factors (soil pH, mineral ions and geology) • Pollution • Catastrophes. Biotic factors • Competition for resources e.g. light, food, space, water and mates. • Interspecific competition: between different species • Intraspecific completion: within the same species. • Grazing These factors are all • Predation density dependent. • Disease • Parasitism • Mutualism Biotic factors continued • Anthropogenic factors are those that that are caused by human activity. E.g. deforestation, agriculture and construction. Limiting Factors • Any factor that restricts the size of a population e.g. biotic: availability of food or abiotic: access to water Carrying Capacity • The maximum population size of a particular species that a given ecosystem can sustain.