Biology Lecture No. 24: Ecosystem Ecology
Monday, December 5 , 2011
Key Points Of Ecosystem Ecology:
-Energy flows and nutrient cycles.
-Pyramids of Energy and pyramids of numbers/biomass.
-Nutrient cycles and reserves of water and carbon.
-Community: All of the organisms living in some defined place.
-Ecosystem: a biotic community and its abiotic environment functioning as a system.
-Ecosystems are open, not closed systems. (Energy inputs and outputs, nutrient inputs and outputs).
Four Major Functional Components of Production & Consumption In Ecosystems:
-Producers (autotrophs): Organisms that can convert obtained energy into suitable food sources.
-Consumers (heterotrophs): Organisms that must obtain energy converted by producers by consuming
them directly or indirectly; includes decomposers.
-Energy: The fundamental unit for sustaining and developing all organisms in a particular ecosystem.
-Nutrients: A particular manifestation of energy required by organisms to thrive in an ecosystem.
Where Does The Energy Come From? :
-Light energy, harvested by photoautotrophs (producers that convert the energy of the sun and other
-Chemical energy, harvested by chemoautotrophs (producers that convert the energy of various
chemicals and chemical reactions).
-Chemical elements or compounds needed for growth and reproduction. Consists of:
-Organic: Nutrients containing mainly carbon and hydrogen. E.g. glucose,
-Inorganic: Nutrients lacking organic elements (Carbon and Hydrogen).
-Micronutrients: Nutrients that are needed in very small quantities by an org