Day 2
AT HOME:
Reading Assignment
Read pages 125-129
Read pages 125-129
- What are the IB guidelines for studying ecosystems and humans?
- What are quadrats? How are they used?
- What are transects? How are they used?
IN CLASS
Comparing Meadows in the Waun Las National nature Reserve (Carmathenshire, Wales)
Objectives:
The Sites:
Both of the pieces of meadowland being sampled in this exercise are shown in aerial view. They are 5m x 5m, and tapes have been laid along two edges divided into 0.25 m intervals which are the length of one side of the quadrat being used. Squares on the site image indicate the location of the quadrats. Close ups of 10 quadrats per site are supplied as separate images. To view the close-up images, click on appropriate quadrat in the site image. Click the 'view full-sized image' link to be able to zoom in and out.
Procedure:
You will each be assigned a quadrat in Site A and Site B.
Objectives:
- To practice using random sampling to measure the abundance of various different species on an area of grassland
- To explore two different measures of abundance: density and frequency
The Sites:
- Site A - Species-rich hay meadow, which is managed organically and traditionally, allowing time for plants to flower and seed. It is low in nutrients, fairly damp, and high in plant diversity. The yellow rattle, a hemiparisitic plant, gains some of its nutrients from the roots of neighboring plants which has significantly helped to reduce the dominance of large leaved grasses.
- Site B - An agriculturally-improved cattle-grazed meadow. Here the nutrient levels are fairly high, bulky grasses dominate and it is low in plant diversity.
Both of the pieces of meadowland being sampled in this exercise are shown in aerial view. They are 5m x 5m, and tapes have been laid along two edges divided into 0.25 m intervals which are the length of one side of the quadrat being used. Squares on the site image indicate the location of the quadrats. Close ups of 10 quadrats per site are supplied as separate images. To view the close-up images, click on appropriate quadrat in the site image. Click the 'view full-sized image' link to be able to zoom in and out.
Procedure:
You will each be assigned a quadrat in Site A and Site B.
- Start at Site B. Find your assigned quadrat and measure density. Use the Plant ID sheet and record your data in the table (make a copy in your Drive).
- Now measure the frequency and record the presence or absence of each species in your quadrat on the data table (make a copy in your Drive).
- Now go to Site A and record the frequency in the data table.
- Go to the frequency spreadsheet and indicate the presence or absence of each species by entering a 1 for presence and a 0 for absence in each of your assigned quadrats.
Analysis:
- Why do we use random sampling to estimate abundance of an ecosystem? Evaluate this method.
- Is it easier to measure density or frequency? Explain.
- Which is more meaningful in comparing the meadows? Why?
- Which of the two sites was richer in species? Why do you think this is?
- Assume you use the quadrat method to estimate the population of moose in a park that covers 7,500 square km. Each quadrat is 25 square km. From the results below, determine a mean estimate of the total Moose population in the park. How reliable is this data? What is a better way to estimate abundance of motile organisms?