BIOL 1011 Lecture 9: Ecosystems
Ecosystems
February 26, 2014
Living and non-living components – capture and store energy and nutrients
Energy and nutrients flow through ecosystems.
Energy – used to produce and transform organic material
• One-way flow: enters as radiant energy but lost as heat
Primary Production (Photosynthesis):
• Light energy is captured and stored as chemical energy
• Inorganic nutrients are captured and stored as organic molecules
Autotrophs: Plants, Algae (& other protists), Cyanobacteria
Secondary Production (Consumption):
• Get energy and nutrients from other organisms
Heterotrophs: Consumers (eat living organisms) and Decomposers (eat detritus)
Detritivore (decomposers) include invertebrates, fungi and bacteria.
Decomposition – release of energy and nutrients from detritus
Biomass – amount of organic matter present (kg/m2)
Production – amount of biomass produced per unit time
Global Primary Production – 1.05X1014 kg of organic matter per year
Gross Primary Production – total light energy converted to chemical energy
Net Primary Prooduction=GPP – Autotrophic Respiration
• Energy available for the ecosystem
• Units: energy (J) or mass (kg)
• NPP<GPP
Net Ecosystem Production=GPP – Total Respiration
• If NEP is negative, ecosystem is losing biomass
What limits primary production?
• Terrestrial: latitude, elevation, moisture, temperature, soil nutrients
o Limiting nutrient: nitrogen
• Marine: nitrogen, iron, nitrogen and phosphorus
Biogeochemical Cycles: movement of nutrients through organisms and physical
reservoirs
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Document Summary
Living and non-living components capture and store energy and nutrients. Energy used to produce and transform organic material. Energy and nutrients flow through ecosystems: one-way flow: enters as radiant energy but lost as heat. Primary production (photosynthesis): light energy is captured and stored as chemical energy. Inorganic nutrients are captured and stored as organic molecules. Secondary production (consumption): get energy and nutrients from other organisms. Heterotrophs: consumers (eat living organisms) and decomposers (eat detritus) Decomposition release of energy and nutrients from detritus. Biomass amount of organic matter present (kg/m2) Production amount of biomass produced per unit time. Global primary production 1. 05x1014 kg of organic matter per year. Gross primary production total light energy converted to chemical energy. Net ecosystem production=gpp total respiration: energy available for the ecosystem, units: energy (j) or mass (kg, npp
