Cycling of Materials in Ecosystems Cycles within an Ecosystem Water Cycle Carbon Cycle Phosphorous and Nitrogen Cycle

Cycles within Ecosystems Almost everything within an ecosystem is recycled. Water, carbon, nitrogen & phosphorus pass from the nonliving environment to living organisms & then back to the environment.

Water Cycle Water is the most important, non-living component of the ecosystem. Nonliving cycle: involves condensation, precipitation, & evaporation. Living cycle: involves plants in a process called transpiration.

Water Cycle Nonliving portion: Living portion: Water vapor, as it cools, condenses in the form of clouds and falls to the Earth’s surface as precipitation (as rain, snow, etc) Then water evaporates (turning from a liquid to a gas) and re-enters the atmosphere Living portion: Water is absorbed by roots of plants After passing through the plant, the water evaporates from the leaves in a process called transpiration

Carbon Cycle Carbon dioxide in the air (or dissolved water) is used by photosynthesizing plants, algae and bacteria as raw material to build organic molecules. What does that mean? Autotrophs take in carbon dioxide to help make food in order to grow and survive Involves: Respiration (breathing where CO2 is a by product) Combustion (burning) Erosion (limestone)

Phosphorous and Nitrogen Cycle You need phosphorous and nitrogen to build proteins and nucleic acids (part of DNA) Since more organisms are unable to use nitrogen gas (N2), nitrogen fixing bacteria bind nitrogen with hydrogen to form ammonia (NH3) What does that mean? We need nitrogen, but we can’t use pure nitrogen gas (N2) so certain bacteria convert N2 into a usable forms (ammonia)

Phosphorous and Nitrogen Cycle Stages: Assimilation (absorption of nitrogen gas,N2, by plants) Ammonification (production of ammonia, NH3, by bacteria during organism decay) Nitrification (production of nitrate from ammonia) Denitrification (conversion of nitrate to N2)