Ecosystem Investigation Flashcards

Flashcards covering key vocabulary and concepts related to measuring biodiversity and studying ecosystems, including quadrats, transects, capture-recapture, abundance, and distribution.

Quadrat

A square frame, usually 1m square, used to measure biodiversity by randomly sampling an area to avoid biased data and estimate plant populations.

Transects

Lines used to study the distribution of organisms across an area, by counting organisms that touch the line or by placing quadrats along the line.

Quadrat

A square frame, usually 1m square, used to measure biodiversity by randomly sampling an area to avoid biased data and estimate plant populations.

Transects

Lines used to study the distribution of organisms across an area, by counting organisms that touch the line or by placing quadrats along the line.

Capture-Recapture

A method to estimate animal population sizes by capturing, marking, releasing, and then recapturing a sample to calculate population size based on the number of marked animals recaptured.

Abundance

How many individuals you find in an area (i.e., population size).

Distribution

Where an organism is found in a habitat.

Important feature in capture-recapture method

Making sure that the marking does not affect the organism’s chance of survival.

Steps to capture-recapture method

1. Captured a sample of the population and mark the organism in a way that their chance of survival will not be impacted

2. Release them back into the environment

3. Recapture another sample of the population and count how many are marked

4. Use equation to estimate population size

Population size equation

Population size = Number in first sample x Number in second sample

Number of marked organisms

Assumptions made in capture re-capture technique

1. There has been no change in population size between the samples taken, such as no births or deaths or immigration or emigration

2. The marking has not affected the individual’s chance of survival (e.g making them more visible to predators)

Important features in using Quadrats

The quadrat sample must be completely random to avoid bias

Steps of using a quadrat

1. Place a quadrat on the ground at a random point within your chosen sample area.

2. Count organisms within quadrat

3. Repeat steps 1 and 2 plenty of times. The larger the sample size the better, because bigger samples are more likely to be representative of the whole population. Also helps to make sure results are valid.

4. Work out the mean number of organisms per m2

Steps of using a quadrat

1. Mark out the line you want to study using a measuring tape

2. Collect data along the line by using quadrats that are placed next to each other along the line (or at small intervals such as every 2m)

Things to measure when investigating factors affecting population size

Take measurements of environmental factors such as:

• Light intensity

• Soil pH

Do this whilst using a quadrat or transect. This allows you to investigate how environmental factors impact distribution of organisms.