ES101 Lecture Notes - Lecture 22: Tropical Rainforest, Indicator Species, Citizen Science
Week 7, Lecture 2: Community Ecology
● Refers to interactions among species living in a given environment/location
● How they respond and react to one another
● How the community changes in response to exogenous forces (e.g. human impacts)
● Exogenous changes (human intervention)
Criteria for distinguishing biological communities
● Physical characteristics, species diversity, niche structure
● Physical →
○ macro vs micro scale (large/small, shoreline/tide pool)
○ Habitat vs niches
■ habitat = location or type of environment where a population ordinarily
lives (e.g. tropical rainforest)
■ niche = particular types of physical, chemical, and biological resources a
species uses within its habitat (e.g. rainforest canopy, or particular tree
types within canopy)
○ Intact vs fragmented habitats (forests)
● Niche structure →
○ Number of different ecological niches (tropical water = few, coral reef = many)
● Species diversity →
○ Describes the number of different species and
○ The number of individuals within each species
○ Boreal forest: small # of tree species, large # of each species/unit area
○ Tropical rainforest: large # of tree species, smaller # of each species/unit area
● Species diversity and habitat disturbance →
○ The number of individuals of a given species typically changes when the habitat
is disturbed
○ Can be natural disturbance or anthropogenic
● Indicator species →
○ Refers to species that are especially sensitive to changing environmental
conditions
○ Scientists can monitor changes in their population numbers to assess ecosystem
health
○ Common example = amphibians
○ Amphibians make good indicator species because their life cycles have aquatic
and terrestrial phases - are therefore sensitive to pollution and habitat change in
water and on land, they have permeable skins, so their bodies easily absorb
environmental pollutants, toxins
Global frog populations have declined since 1960’s
● Steep declines were experienced globally from 1960-1990
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Refers to interactions among species living in a given environment/location. How they respond and react to one another. How the community changes in response to exogenous forces (e. g. human impacts) Macro vs micro scale (large/small, shoreline/tide pool) Habitat = location or type of environment where a population ordinarily lives (e. g. tropical rainforest) Niche = particular types of physical, chemical, and biological resources a species uses within its habitat (e. g. rainforest canopy, or particular tree types within canopy) Number of different ecological niches (tropical water = few, coral reef = many) Describes the number of different species and. The number of individuals within each species. Boreal forest: small # of tree species, large # of each species/unit area. Tropical rainforest: large # of tree species, smaller # of each species/unit area. The number of individuals of a given species typically changes when the habitat is disturbed. Refers to species that are especially sensitive to changing environmental conditions.
