ODWS icon

The Open Door Web Site
HOMEPAGE BIOLOGY HOMEPAGE CHEMISTRY PHYSICS ELECTRONICS HISTORY HISTORY OF SCI & TECH MATH STUDIES LEARNING FRENCH STUDY GUIDE  PHOTO GALLERY
IB BIOLOGY HOMEPAGE SCIENTIFIC INVESTIGATIONS DRAWING IN BIOLOGY DRAWING TABLES ERROR ANALYSIS IN BIOLOGY ALL ABOUT GRAPHS ICT IN BIOLOGY STATISTICS SCIENTIFIC POSTERS MOLECULAR IMAGES
WS

 

Ecology Field Trip Index

Transects
The Mann-Whitney U-Test (opens in a new window)
Critical Values for the Mann-Whitney U-test (opens in a new window)

Topic Chapters Index

 

The Edge Effect

With quadrats it is always a problem to know what to do with plants which touch the edge. Are they counted "in" or "out"? The rule is if they touch the right side or the top, count them "in". If they touch the bottom or the left side, count them "out". When you are working as a group you must decide between you, which is the top of the quadrat, before you start counting

 

edge effect

 

ECOLOGY : FIELD TRIP

Custom Search

Estimating the size of a Population of Plant Species

Plants are sessile, they do not move around. They can be sampled using a quadrat.

Our aim is to estimate the size of the population of a plant species.

You will need to:

  • Clearly identify the species of plant you are investigating.

  • Determine the area in which the population is to be sampled using tape measures.

  • Use a suitable sized quadrat to sample the plants

 

Distributing Quadrats Randomly

For samples to be representative of an area all the parts of the area must have an equal chance of being sampled. This can be achieved by using a regular grid, sampling at precise points over the whole area, or by using a random sampling technique. This exercise will use the random sampling technique.

 

Materials

Quadrat, pencil, random number tables, notebook, plus a calculator or LabQuest.

 

Method

  1. Determine the limits of the area to be sampled. Spin a pencil and heading in the direction indicated by the pencil, pace out a random number of steps using the numbers given in the random number tables. If you encounter the boundary of your sampling area continue pacing, as though you have bounced of the boundary inside your sampling area. See diagram below:

     

    sample area

     

  2. After the correct number of paces, place the quadrat on the ground and count the number of plants of the species that you have chosen.

 

The Open Door Web Site is non-profit making. Your donations help towards the cost of maintaining this free service on-line.

Donate to the Open Door Web Site using PayPal

SITE MAP
WHAT'S NEW?
ABOUT

PRIVACY

COPYRIGHT

SPONSORSHIP

DONATIONS

ADVERTISING

© Paul Billiet 2018
Any questions or problems regarding this site should be addressed to the webmaster

Hosted By
Web Hosting by HostCentric


SiteLock