Ecosystems and the Biosphere Ecology Unit Newark Academy Summer Session 2014 Advanced Credit Biology Monkemeier

The sun is the ultimate source of energy for all life on Earth. All organisms need energy to carry out essential functions such as growth, movement, maintenance, repair and reproduction. In an ecosystem, energy flows from the sun to autotrophs, then to organisms that eat the autotrophs, then to organisms that feed on other organisms.

Producers Organisms that capture the sun’s energy and transform it into chemical energy contained within organic compounds are known as autotrophs. Some bacteria undergo chemosynthesis to manufacture their own organic compounds. Chemosynthesis is a process that manufactures organic molecules using energy from inorganic molecules. Organisms that manufacture organic compounds using either photosynthesis or chemosynthesis are known as PRODUCERS.

Producers Terrestrial Ecosystems Aquatic Ecosystems Plants are major producers Photosynthetic protists and bacteria are major producers

Gross Primary Productivity

Gross primary productivity is the rate at which energy is produced (by producers mainly through photosynthesis) in an ecosystem. In other words: Gross primary productivity is the rate at which producers in an ecosystem capture the sun’s energy and transform it into chemical energy contained within sugars.

Sugars made by Photosynthesis Plants metabolize some of their manufactured sugars during cellular respiration. Plants also utilize some of their manufactured sugars to grow, repair and reproduce. The sugars made by PRODUCERS increases the BIOMASS in the ecosystem.

Biomass Biomass is all of the ORGANIC MATERIAL in an ecosystem. It includes the bodies of plants, animals, etc. ONLY energy stored as biomass is available to other organisms in the ecosystem. Ecologists measure the productivity of an ecosystem by measuring the rate at which BIOMASS accumulates in a specific ecosystem.

NET PRIMARY PRODUCTIVITY The rate at which biomass accumulates within an ecosystem is known as NET PRIMARY PRODUCTIVITY. NPP is typically expressed in units of energy per unit area per year. (kcal/m 2 /y) NPP = GPP – Rate of respiration of producers

Comparative Productivity of Ecosystems

Consumers Heterotrophs: all heterotrophs rely upon ingestion or absorption of organic compounds made by other organisms (ultimately made by producers) Heterotrophs = Consumers Herbivores, carnivores, omnivores are all forms of Consumers.

Consumers that RECYCLE DETRITIVORES are consumers that feed on the “wastes” of an ecosystem such as dead bodies of organisms, fallen vegetation and wastes of animals. DECOMPOSERS cause decay by breaking down the complex molecules in dead tissues and wastes into simpler molecules.

Energy Flow

Energy Pyramids

Energy Transfers within an ecosystem