1. 2.5 Investigating Ecosystems

2. Review Zonation and Succession on your notes

3. Monitoring Abiotic Factors
Ecosystems can be roughly divided into:-
Marine
Freshwater and
Terrestrial systems

4. Monitoring Abiotic Factors
Complete the diagram in your notes

5. MONITORING BIOTIC (LIVING) FACTORS
Once the abiotic conditions within an environmental gradient have been measured, we can begin to ask questions about the distribution of organisms within the study area
Which species are present
The size of a particular population of organisms
The productivity in a particular area
The diversity of a particular area

6. MONITORING BIOTIC (LIVING) FACTORS
Complete the table in your notes

7. COLLECTING DATA - Where?
When collecting environmental data, it is almost impossible to collect every possible data point
We use sampling methods to make estimations
These methods enable us to get a random sample from an entire ecosystem and then use extrapolation to make estimates and predictions
In order to avoid bias it is important that these methods are truly random.
Two methods used in ecology to determine where to collect a sample are quadrats and transects.

8. Assumptions Made When Sampling
The sample is representative of the whole system
It is necessary to take enough samples so that an accurate representation is obtained
It is important to avoid bias when sampling

9. Estimating Populations of Organisms
We estimate populations because it would take way too long to count every living thing in a given ecosystem.
We can estimate populations of plants or animals
Random Sampling: All organisms must have an equal chance of being captured.

10. Common Sampling Methods
Abundance of Non-motile Organisms
Transects and Quadrants
Abundance of Motile Organism
Actual Count (very difficult if large system)
Lincoln Index
Capture – Mark - Recapture
Species Diversity
Simpson Diversity Index
For comparing 2 habitats or the change in one habitat over time

11. Lincoln Index

12. Measuring abundance of Mobile Organisms
If the organism is mobile we use a method called the capture-mark-recapture method
We then use this data to calculate the Lincoln Index

13. How to Capture Motile Organisms
REMEMBER: IB Animal Experimentation Policy
Pitfall Traps
Small Mammal Traps
Tullgren Funnels (invertebrates)
Kick Net

14. Estimating Populations of Animals
Lincoln index (capture-mark-release-recapture)
n1 x n2
N = n3
N = Total number of population
n1 = Number of animals first (mark all of them)
n2= Number of animals captured in second sample
n3= Number of marked animals in second sample
Ex. 40 mice were caught, marked (tail tattoo) and released. Later, 10 mice were recaptured, 4 of which had tattoo marks.

15. Lincoln Index

16. Example
50 snowshoe hares are captured in box traps, marked with ear tags and released. Two weeks later, 100 hares are captured and checked for ear tags. If 10 hares in the second catch are already marked (10%), provide an estimate of N
**Realize for accuracy that you would recapture multiple times and take an average**

17. Lincoln Index Assumptions
The marked animals are not affected (neither in behavior nor life expectancy).
The marked animals are completely mixed in the population.
The probability of capturing a marked animal is the same as that of capturing any member of the population.
Sampling time intervals must be small in relation to the total time of experiment of organisms life span.
The population is closed (no immigration and emigration)
No births or deaths in the period between sampling.

18. Some Possible Sources of Error
Emigration & Immigration
Natural disaster or disturbance between captures
Trap happy or trap shy individuals
Organisms did not have enough time to disperse back into ecosystem
Animals lost marks between recapture

19. Quadrat Sampling

20. Estimating Populations of Plants
Quadrat Estimation
Population Density- The
number of plants within the
given area of the quadrat (m2)
Percentage Coverage-
How much of the area of a
quadrat is covered by plants?
Frequency- How often does a plant occur in each quadrat?
Acacia senegalensis was present in 47 of 92 quadrats, for a frequency of 51%

21. Square Quadrat Method
N = (Mean # per quadrat) (total area) Area of each quadrat
This estimates the population size in an area
Ex. If you count an average of 10 live oak trees per square hectare in a given area, and there are 100 square hectares in your area, then
N = (10 X 100 hectare2) / 1 hectare2 = 1000 trees in the 100 hectare2

22. In addition to population size we can measure…
Density = # of individuals per unit area
Good measure of overall numbers
Frequency = the proportion of quadrats sampled that contain your species
Assessment of patchiness of distribution
% Cover = space within the quadrat occupied by each species
Distinguishes the larger and smaller species

23. Grid Quadrate
Measures percent frequency – the % of quadrats in which the species is found OR
Measures percent coverage –the % of area within a quadrat covered by a single species
NOTE: When you are looking at one species at a time
If not using a 10 x 10, you must turn into a percentage (squares covered/total # of squares)

24. Percent Frequency

25. http://www. slideshare

26. Percent Coverage Find the percent coverage Count full squares
1 m
Find the percent coverage
Count full squares
Now combine pieces to make full squares
Calculate percentage coverage
Percent Coverage 18 14 22 24 24 1 2 14 15 3 4 15
1 m 17 21 23 12 19 20 13 13 17 18 5 6 12 16 7 8 9 10 11 22 19 23 20 16 12 21

27. Calculate Population Density
What is the population density of species x ?
What is the population density of species Y?
What is the population density of
species Z?
Quadrat 1= 0.5m2 X W z Y

28. Calculate Percentage Coverage
What is the percentage of plant coverage in this quadrat?
Quadrat 1= 0.5m2 X W Y

29. Percentage Frequency What is the frequency of species X?
Quadrat 1
What is the frequency of species X?
What about species V? X W V Z Y
Quadrat 2
Quadrat 3 X W Z Y Z W X Y

30. How choose quadrat size?
Think about the size of the organism.
Think about the area of the system.
The smaller the quadrat the more accurate, however the smaller the sample size
Larger quadrats increase inaccuracy but allow for broader sample of an area

31. Measuring Biomass
Get a sample of the organisms, dry them out completely in a dehydrating oven (to remove all water!), find the mass and extrapolate :
If you collect 10 plants, dry them out and find their average dry biomass to be 20g, what would the biomass of a population of 2500 plants be?
50,000g
Remember – biomass can be used to create pyramids of biomass when looking at energy transfers and is needed for many productivity calculations!

32. Transets

33. Transects
A TRANSECT - A line, strip or profile of vegetation which has been selected for study. measure any of these abiotic and/or biotic components of an ecosystem along an environmental gradient

34. Transect
In order to complete a transect, a piece of string or measuring tape is laid out along the selected gradient.

35. Line Transects
A measured line is randomly placed across the area in the direction of an environmental gradient
All species touching the line are recorded along the whole length of the line or at specific points along the line
Measures presence or absence of species

36. Belt Transects
Transect line is laid out and a quadrant is placed at each survey interval
Samples are identified and abundance is estimated
Slow moving animals (limpets, barnacles, snails) are collected, identified then released
For plants an percent coverage is estimated

37. Belt Transects
Data collection should be completed by one individual as estimates can vary person to person

38. Transect
These can either be sampled continuously or as an interrupted transect where samples are taken at regular, fixed distances along the line.

39. Transect
To measure changes in space i.e. zonation, this technique should be completed within a short space of time to avoid any daily cycles
For studies of long term change i.e. succession, the transect should be repeated at the same time of day and at regular intervals over a suitable time period depending on what is being studied or assessed.

40. Kite Diagrams
Used to illustrate changes in species over space or time along an environmental gradient.
The width of each ‘kite’ represents the percentage cover or abundance of that species.

41. Simpson Index

42. Species Diversity
The two main factors taken into account when measuring species diversity
1. Richness
A measure of the number of different species present in a particular area.
The more species present in a sample, the 'richer' the sample.
Takes no account of the number of individuals of each species present. It gives as much weight to those species which have very few individuals as to those which have many individuals.

43. Species Diversity
The two main factors taken into account when measuring species diversity
2. Relative Abundance
The relative number of individuals of each species present

44. How Can We Know Diversity?
Use the Simpsons diversity index below
D = ____________N (N-1)_______________
n1(n1−1) + n2(n2 −1) + n3(n3 −1) +…nk(nk −1)
D = Diversity
N = Total number of organisms of all species
n = number of individuals of a particular species
***The higher the D value the more diverse the sample is!!!!!

45. Example Data Calculations
Abundance of Organism
Ecosystem A
Ecosystem B
species 1 3 5
species 2 7 4
species 3 26 12
species 4 9
species 5
Diversity
3.27

46. How can changes in these populations be measured?
Necessary because populations may change over time through processes like succession
But also because human activities may impact a population and we want to know how
Impacts include  toxins from mining, landfills, eutrophication, effluent, oil spills, overexploitation

47. Analyzing Simpson’s Index
Used to compare 2 different ecosystems or to monitor an ecosystem over time
D values have no units and are used as comparison to each other
High D Value Indicates:
Stable and ancient site
More diversity
Healthy habitat
Low D Value Indicates:
Dominance by one species
Environmental stress
Pollution, colonization, agriculture

48. How to Capture Motile Organisms
REMEMBER: IB Animal Experimentation Policy
Pitfall Traps
Small Mammal Traps
Tullgren Funnels (invertebrates)
Kick Net

49. Classification

50. What is classification?
Science of grouping organisms based on their physical characteristics.

51. What characteristics do we use?
Structures (morphology)
Functions (physiology)
Biochemistry
Genetics

52. Why do we classify? Identify organisms Compare organisms
Identify relationships among organisms
Communicate with others (universal language)
Identify evolutionary relationships

53. Why do we classify? What am I? Firefly Lightning bug Glow Fly Blinkie
Golden Sparkler
Moon bug
Glühwürmchen
Luciérnaga
Luciole
We all have different names for the same organism…this is a problem for communication.

54. From Aristotle to Linneaus
Aristotle (Greek philosopher)
( B.C)
First System of Classification
1. Plants
Based on stem type
2. Animals
Land, air or water

55. From Aristotle to Linneaus
Carolus Linneaus (Sweedish botanist)
( )
Came up with modern classification system
Used binomial nomenclature (2 word naming system)
This two word name is called a scientific name
Composed of the genus name followed by the species name

56. Scientific Names Either written in italics or underlined
Genus is always capitalized and species is always lowercase
Based on Latin
Examples:
Cat: Felix domesticus
Mosquito: Colex pipens
Human: Homo sapien

57. Funny Scientific Names
Agra vation (a beetle)
Colon rectum (another beetle)
Ba humbugi (a snail)
Aha ha ( a wasp)
Lalapa lusa (a wasp)
Leonardo davinci (a moth)
Abra cadabra (a clam)
Gelae baen, Gelae belae, Gelae donut, Gelae fish, and Gelae rol (all types of fungus beetles)
Villa manillae, Pieza kake and Reissa roni  (bee flies)

58. Dichotomous Keys
A series of yes/no questions about an organisms structure
Used to identify new and unknown organisms

59. Step 1: Identify the organism
Use dichotomous keys, field guides, observe a museum collection, or consult an expert
Sample key for insect ID
Macroinvertebrate key

60. Example of Dichotomous Key
1a. Hair Present…………..Class Mammalia
1b. Hair Absent……………Go to statement 2

61. Example of Dichotomous Key
2a. Feathers present…………..Class Aves
2b. Feathers absent…………….Go to statement 3
3a. Jaw Present…………………..Go to statement 4
3b. Jaw Absent……………………Class Agnatha

62. Example of Dichotomous Key
4a. Paired fins present……………Go to 5
4b. Paired fins absent…………….Go to 6

63. Example of Dichotomous Key
6a. Skin scales present………………Class Reptilia
6b. Skin scales absent……………….Class Ampibia

64. Review points Dispersion patterns
Carrying capacity and limiting factors
r and K selection
Natural population cycles
Human effects