ENVR 200 Lecture Notes - Lecture 12: Keystone Species, Understory, Herbivore

• School: McGill University
• Department: Environment
• Course: ENVR 200
• Professor: Anthony Ricciardi

Document Summary

Population: organisms of same species living in same habitat. Fundamental property: species diversity and food web structure (how they are connected). Ecosystem: set of organisms that interact with each other and with their physical environment. Ecosystem = all organisms + habitat + biotic & abiotic interactions. Fundamental properties: energy flow & productivity (rate of production of biomass), nutrient cycling (movement of nutrients needed by plants or animals) and habitat structure. Disturbances can change ecosystems by altering their fundamental properties: P. e. a fire in a forest can cause loss of principal habitat, loss of understory diversity (mosses, shrubs), release of stored nutrients and this all results in the conversion of a forest to a grassland. Redfield ratio: relative number of atoms in living phytoplanktons. Liebig"s law of the minimum: only 1 nutrient limits growth at any one time the nutrient in least supply relative to what is needed.