Measuring Biotic and Abiotic Components of a System

2.1.1, 2.3.1-2.3.5, 2.7.1-2.7.3

Biotic = Examples:

Abiotic =Examples

Terrestrial • Marine • Freshwater

Precipitation: rain gauge Temperature: thermometer pH: pH strip; pH probe wind speed: aerovanes Dissolved Oxygen: DO Probe or chemical

test Salinity: Hydrometer

Quadrat - A quadrat is a frame of any shape that can be placed over vegetation so that species can be listed or counted, and population density, percent frequency and percent cover can be estimated. = For non-mobile organisms

Capture-Mark-Release-Recapture (Lincoln Index) = For mobile organisms

N= the estimated population (what you are looking for)

T1: total organisms you caught and marked in 1st sample

T2: total organisms you captured in 2nd sample

M: the number that were marked in the 2nd sample. (meaning they have been recaptured)

N = T1 x T2 MExample…

So, do you have a larger population if you have a large or small “M”? Why?

Cap/Mark/Recap:Only works with a static

population…..does this occur in nature?Marked individuals are more noticeable to

predatorsLosing their marks by molting, rain, etc

Quadrats:Limit accuracy by amount of money you

have to spend on counters.Less counters or smaller quadrats mean

less accuracy.Placement of quadrats can cause results

to be skewed.

Biomass - estimate of dryweight in g/m2 of an organism.

Method?

Three types: Habitat, species, genetic 2 components:

1. Richness = # of different species in an area

2. Evenness = a measure of relative abundance of each species in an area. (number of organisms of each type of specie)

A community that is dominated by one or two species is less diverse than one that has several different species with a similar abundance, even if they have the same richness amount.

Ex?

A measure of species richness of an area.

A high value suggests a stable, climax community.

A low value could suggest pollution, early stages of succession or agricultural management………Why?

D= Simpson’s Diversity Index N = TOTAL # of organisms of all

species found. n = number of individuals of a particular

species. D = N(N-1) Σ[n(n-1)]

Species N A 3 B 4 C 2 D 2 E 4 Total = N = 15 N(N-1) = 15(15-

1) = 210 (210 is your top

number!)

n(n-1) 6 12 2 2 12 Σ[n(n-1)] = 34

(34 is your bottom number!)

Simpson’s Index:D = N(N-1) Σ[n(n-1)]

D = 15(14) = 210 34 34

D = 6.17

Is this area diverse? Here is the problem:

You CAN’T tell from this equation.

All you can do is tell relative diversity when compared to another area/Diversity number

ie: This area would be less diverse than an area whose Simpson’s Index number is 10.

Only used for comparative purposes

Rainfall = rain gauge Temp = thermometer Species diversity = quadrats or mark and

recapture and then Simpson’s Diversity Index Species abundance = quadrats or mark and

recapture All of these stats would be taken over a set

amount of time………..mutiple data sets (at least 2....when?)

What is a gradient?

Therefore an environmental gradient is a change in abiotic or biotic factors over an area.

Examples of where you can see this? How should you measure this?

YOUR LABS DO THIS!! Examples of human effects and how to

measure them? Could also include satellite images and

maps.

An EIA is a government report prepared before a development project that will change the use of land (in the planning process). Ex: major new road networks, airports, building power

stations, dams, quarrying, planting a forest, converting fields to a golf course, large-scale housing projects, etc.

The EIA weighs up the relative advantages and disadvantages of the development.

It will try to quantify how the abiotic and biotic factors would change if the development occurs.

Therefore, a baseline study is necessary first....what the environment is like now.

The EIA will forecast both negative and positive impacts on the natural environment and human populations (if the development might have an effect on human health or a community’s economy).

EIA’s measure the social and environmental costs of the development and tries to translate these into monetary values.Ex: number of jobs provided, net profit of the

development, land degradation, habitat loss, pollution, human health, etc.

What issues can there be with many of these assessments?

Homework: Find pictures of or draw 8 organisms

and print them out.Make a dichotomous tree and then a

keyOn a third sheet of paper, print the

pictures out again and make an answer key.