ecosystems. introduction species (be…specific!) –bear: not good –american black bear: great...
TRANSCRIPT
Introduction Species (be…specific!)
– Bear: not good– American Black bear: great– Ursus americanus: amazing
Population Community Ecosystem
Habitat Niche
All ecosystems have two sets of components. Biotic
– Living things– How they interact– Relationships
Abiotic– Light– Temperature– Soil– Turbidity– Wind speed– Dissolved oxygen– Slope– Salinity– Flow rate– Elevation– pH– Wave action
How do you measure biotic components? Identify the species
– Use a dichotomous key Estimate the abundance of organisms
– Percent cover– Percent frequency
Estimating biomass– The mass of living material– It’s easiest for plants, but it’s destructive
How do you measure biotic components? We focused mostly on plants. Animals are harder to measure, why? There are some simple ways for smaller
organisms. For larger organisms, the Lincoln Index
is the easiest way.
Lincoln Index
Scientists capture a sample of individuals, mark them, and release them.
Scientists then return, capture another sample, and estimate the total population
Calculating Lincoln Index
25 birds caught, tagged, released. 30 birds caught second time, 18 were marked.
Calculating Lincoln Index
8 elephants caught, tagged, released. 9 elephants caught second time, 6 were tagged.
Calculating Lincoln Index
200 ants caught, marked, released. 185 ants caught second time, 57 were marked.
Calculating Lincoln Index
20 blugill caught, tagged, released. 30 bluegill caught second time, 3 were marked.
Lincoln Index Assumptions
Population must be closed, no immigration or emigration
Time between samples must be small compared to the lifespan
Marked organisms must mix with the population after marking
Lincoln Index Setbacks
Capture can injure animal Mark/tag may harm
animal Mark/tag may be removed Mark/tag may
increase/decrease predators
Different individuals are more/less “capturable”
Individuals may become trap-happy or trap-shy
But it’s not just about HOW MANY living things are in an area. Diversity is very important as well and is
a measure of the health of an ecosystem.
The lower the diversity, the lower the health.
Why do you think this is?
Net Primary Productivity
The amount of energy or mass that is stored by producers
The amount of energy available to consumers
Pyramid of Numbers
Shows the number of organisms at each level.
Good for comparing changes
Bad because numbers can be too great to represent and difficult for organisms at multiple trophic levels
Pyramid of Biomass
Shows the amount of biomass at each level Difficult to measure biomass, biomass varies
over seasons
Pyramid of Productivity Shows the amount of energy flow through an ecosystem
(rule of 10 - each level is about 10% of the previous level) Good because ecosystems can be compared Bad because the data is hard to get and species can be
at multiple trophic levels.
Measuring abiotic components
Marine Ecosystems:– Salinity– pH– Temperature– Dissolved Oxygen– Wave Action
Measuring abiotic components
Freshwater ecosystems– Turbidity– Flow Velocity– pH– Temperature– Dissolved Oxygen
Measuring abiotic components
Terrestrial ecosystems– Temperature– Light intensity– Wind speed– Slope– Soil moisture– Mineral content
Measuring abiotic components
Best method:– Count the organisms
Next best method:– Capture-Mark-
Release-Recapture– (Lincoln Index)
Population Curves S Curve
– Reaches carrying capacity and stabilizes J Curve
– Unchecked population growth
Survivorship
r- strategists– Short generation time– Mature quickly– Small size– Many offspring– Little parental care
Adapted to unstable/ unpredictable environments
Survivorship
K- stragetists– Long life/generation time– Mature slowly– Large size– Few offspring– Parental care
Predictable/stable environments where population stays near carrying capacity
Population Regulation
Density dependent inhibition– Population is
regulated by negative feedback
– Crowding– Competition
Succession
A natural increase in the complexity of the structure and species composition over time
A lifeless area becomes an ecosystem
Bare surface
A lifeless abiotic environment becomes available for pioneer species
Usually r-selected species
Seral Stage 3
Larger plants colonize
K-selected species become established
r-selected species unable to compete get fazed out
Climax Community
Stable and self-perpetuating ecosystem
Maximum development under temperature, light, precipitation conditions.