Sampling Techniques and Presenting Data The Sequel Sampling
- Slides: 15
Sampling Techniques and Presenting Data The Sequel
Sampling techniques… A 25 cm² Quadrat Point Quadrat Useful for estimating percentage cover Lower each of 10 needles The number that touch a species is proportional to % cover E. g. 9/10 touch grass =90%
Transect? • Belt transect? Interrupted / continuous • Line transect? • Point quadrat? • 50 cm 2 quadrat?
How many quadrats do we need? Calculate the running mean. When the mean remains relatively stable this is the maximum required Quadrat number Number of species 1 10 2 11 3 5 4 4 5 5 6 12 7 5 8 8 9 4 10 13 11 5 12 9 13 12 14 6 15 8 16 6 17 13 18 10 19 9 Running Mean
Another alternative is to do a pilot study which records when no additional species are being found. Quadrat Number of New Species Found in this Quadrat Total Number of different species 1 5 5 2 4 9 3 4 13 4 3 16 5 3 19 6 2 21 7 2 23 8 2 25 9 1 26 10 1 27 11 1 28 12 0 28 13 0 28 14 0 28
What size quadrat should we use to ensure each one provides a representative sample? A pilot study using different sized quadrats will help you decide Quadrat Size cm² Number of species found 40 2 90 4 160 7 250 9 360 9 490 10 1000 9 A 25 cm² quadrat would be appropriate here.
Presenting data using kite diagrams
Presenting data using kite diagrams This will illustrate distribution and abundance along a transect. The scale for each can be numbers, % cover or you can use ACFOR. Distance from the shore (m)
Species % cover 100 80 60 40 20 40 60 80 100 1 2 3 Distance (m) 4 5 6 7 8
Species % cover 100 80 60 40 20 40 60 80 100 1 2 3 Distance (m) 4 5 6 7 8
Species % cover 100 80 60 40 20 40 60 80 100 1 2 3 Distance (m) 4 5 6 7 8
Rocky Shore Survey Describe how you would survey a rocky shore to show distribution of seaweed from the upper to lower shore. What sampling method? How would you measure abundance of each type of seaweed present Using the data on the sheet present this data as kite diagrams
• Produce a kite diagram for these results
Studying ecosystems; keywords • • Quadrat Transect Abundance Distribution Percentage cover Random/systematic Cumulative frequency