Classification of Ecosystems (PPT4-5B) [U3/ T1] Flashcards
Define classification
Grouping things that have similarities together
Define habitats
The environments were organisms live and grow
How are habitats classified
By their abiotic and biotic factors
Define microhabitats
Small unique places to live within bigger places to live
Define ecosystems
Are composed of varied habitats
Define ecoregion
Contain geographically distinct groups of plants and animals that have evolved in relative isolation
Why classify ecosystems?
It groups common areas, improves understanding, helps differentiate, helps improve ecosystem management and ecosystem protection.
SPECHT classification
NOT DONE
ANAE classification
NOT DONE
Determine population size
It describes the number of individual organisms present in a given population at a given time.
Give an example of population size
Does not need to be identical, just similar
E.g. There are 100 eucalypt trees in one square kilometre of a forest then it’s reasonable to estimate that there is about 1000 eucalyptus in 10 square kms.
What is the formula for calculating population density?
Population density = Number of individual
——————————-
Unit Area
Determine community composition
Sampling can reveal which species are present in an ecosystem and this helps build a picture of community structure.
Determine population distribution
The way individuals are spaced in the physical environment.
Identify environmental gradients
Changes in abiotic factors can influence biotic distribution and frequency.
When is random sampling used?
When the are under study is fairly uniform, very large and there is limited time available.
How is bias minimised when using random sampling
- A random number generator
- A grid system
What are the advantages of random sampling?
- Unbiased data
- Easy to understand & implement
- Data analysis is straight forward
What are the disadvantages of random sampling?
- Difficult to get truly random samples
- Limited by population pattern
- Hard to see clear trends
- May miss specialised habitats
When are systematic samplings taken?
Taken at regularly spaced individuals over space or time.
What is systematic sampling useful for finding out?
- Estimating spatial patterns
- Ensures uniform coverage of the site
What does systematic sampling involve?
Normally a transect line where a sampling line is set up across areas where there are clear environmental gradients.
What are the advantages of systematic sampling?
- Useful when the population distribution is unknown
- More complete coverage
- Identifying an environmental gradient
What are the disadvantages of systematic sampling?
- Very time consuming
- Not as efficient
- May miss microhabitats
What is stratified sampling
A statistical technique that divides an area into manageable non-overlaping strata for separate sampling.
How do we stratify sample?
- Breaks a population/ ecosystem down into subgroups or layers called strata.
- Data samples are randomly or systematically taken from each stratum in preparation for its representation in the total population.
What are the advantages of stratified sampling?
- Useful for a heterogenous/ non-uniform population
- Greater precision
- Considers all different areas
- Good for comparing subsets
What are the disadvantages of stratified sampling?
- Need prior knowledge of the area
- Difficult to establish a different area of a habitat
- Identified areas can be difficult to reach
What are the three general types of surveying techniques used to select individuals?
- Quadrats
- Transects
- Capture tag and release
How can quadrats be located?
- Randomly using a random number table
- Randomly but proportionally within an identified stratum
- Systematically at regular intervals across a transect line or grid pattern.
What are the adventages of quadrats?
- Easy to use
- Inexpensive
- Suitable for studying a variety of plants and animals
What are the disadvantages of quadrats?
- Work must be completed in the field
- Prone to study errors
Compare transects to quadrats
Quadrats:
- fairly uniform
- remove bias
- good for limited time
Transects:
- show zonation of species along some environmental gradient
- sample linear habitats
Compare line to belt transects
Line:
- faster process
- shows the location of species
- uses transect diagram
Belt:
- more data
- shows location & number of species
- allows bar charts
What is the formula for Mark and recapture?
N= M x n
———
m
What does each letter in the mark and recapture formula stand for?
M= number of individuals caught, marked and initially released.
n= Number of individuals caught on second sampling
m= number of marked individuals recaptured
What can qualitative data be broken down into?
Ordinal - if you can order it, it’s ordinal (often, rarely, never)
Nominal - if you can brand it, it’s nominal (coloured blue, red, etc)
What can quantitative data be broken down into?
Discrete - if you can count it, it’s discrete (1, 3, 54, etc)
Continuous - if you can measure it and reduce it by half but still make sense, it’s continuous)
What are the types of graphs generally used
- Scatter plot
- Line graph
- Bar and column graph
- pie charts
What do error bars communicate?
- spread of data
- reliability of the mean
- likelihood of there being a significant difference between data sets
GRAPH CONSTRUCTION
IDK
Stratified sampling in terms of data analysis
IDK
Measure of spread
IDK
Define null hypothesis
- Assumption you’re beginning with
- Opposite of what you’re testing
Define alternative hypothesis
- The claim your testing
What are the two types of T-tests
- Unpaired t-tests
- Paired t-tests
When do you complete a paired T-test?
- independent groups
- equal sample sizes
When do you complete an unpaired T-test?
- non-independant group
- unequal sample sizes
