Ecosystem

The interaction between the physical environment and biological community or the interaction between the biotic and abiotic factors

Species→Population→Community

Species - Individuals with similar physical characteristics which can interbreed to produce fertile offspring.

Population - All individuals of a particular species.

Community - Populations of all species living together in an environment.

Biotic

Living organisms - 1) Producers (Autotrophs) 2) Consumers (Heterotrophs) 3) Decomposers (Saprotrophs)

Abiotic

Non living components - sunlight, water, soil, temperature, pH

Energy from the sun is incorporated and made available to all organisms by producers through photosynthesis. Radiant energy is converted to chemical energy that can be utilized for growth, movement. biosynthesis, respiration, etc.

The energy produced by plants during photosynthesis called the GPP (Gross Primary Productivity)

However the plant uses some energy for respiration growth

GPP-R=NPP

Gross Primary Production - Respiration = Net Primary Production

Energy moves through the eco-system in a linear flow. Food chains show the feeding relationship between organisms eg. algae crab bird. In an eco-system, many food chains interconnect to form a food web.

Organisms in an eco-system develop symbiotic relationships.

Commensalism - where one organism benefits and the other neither benefits nor is harmed e.g. epiphytes on a tree.

Mutualism - both organisms benefit e.g. nitrogen fixing bacteria in the root of a plant.

Parasitism - one organism lives off another, depriving it of nutrients e.g. ticks and cattle.

Other interactions are competition and predation

Biome - A large eco-system which consists of organisms especially adapted to the conditions of broad climate regions eg tropical rainforest.

Why Eco-systems Vary?

Climate - organisms have optimum conditions in which they. can survive (temperature + rainfall are key in determining where organisms exist).

Soil - the type of soil determines where certain plants can grow. (pH, mineral content of humus affect plant growth + soil fauna.

Biotic Condition - the presence of organisms that can alter how an eco-system functions.

Human Activity - the altering of eco-systems by clearing of vegetation and introduction Orr removal of organisms.