line transect lecture
DESCRIPTION
Line transect lecture. Vegetation transects (Offwell, UK). High seas salmon off BC’s Coast. Duck transects along roads (N. Dakota). Example 1: UK Butterfly monitoring scheme. Example 2: Raptor Census - Kyle Elliott (2002) and the Vancouver Natural History Society. Bald eagles. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/1.jpg)
Line transect lecture
![Page 2: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/2.jpg)
High seas salmon off BC’s Coast
Vegetation transects (Offwell, UK)
Duck transects along roads (N. Dakota)
![Page 3: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/3.jpg)
Example 1: UK Butterfly monitoring scheme
![Page 4: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/4.jpg)
Bald eagles
Red-tailed hawks
Short-eared owls
Example 2: Raptor Census - Kyle Elliott (2002) and the Vancouver Natural History Society
![Page 5: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/5.jpg)
Q1. Why transects, not always quadrats?
Q2. What are potential biases in method?
![Page 6: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/6.jpg)
Animals (in particular): detection bias
![Page 7: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/7.jpg)
Animals (in particular): detection bias
![Page 8: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/8.jpg)
Example: VNHS Raptor census (Elliott, 2002)
![Page 9: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/9.jpg)
Two general methods (see Krebs)
1. Distance from random point to organism.
2. Distance from randomly selected organism to neighbouring organism.
12
![Page 10: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/10.jpg)
Two general methods (see Krebs)
1. Distance from random point to organism.
r
Area of circle (π r 2) contains one individual
Inverse of: Density = individuals per unit area
nearest
![Page 11: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/11.jpg)
Two general methods (see Krebs)
1. Distance from random point to organism.
r
r
r
All methods: calculate area per individual for each circle, calculate mean area per indiv., invert
= n π sum (r2)
byth-ripley
![Page 12: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/12.jpg)
Two general methods (see Krebs)
1. Distance from random point to organism.
r
r
r
If look at third closest organism, we are calculating area per three organisms, or if divide by three, mean area per organism (n = 3).
= 3n - 1 π sum (r2)
ordered distance
![Page 13: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/13.jpg)
Two general methods (see Krebs)
1. Distance from random point to organism.
2. Distance from randomly selected organism to neighbouring organism.
12
![Page 14: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/14.jpg)
Two general methods (see Krebs)
2. Distance from randomly selected organism to neighbouring organism.
r
Area per two individuals, but two circles: cancels out to same π r 2 formula as before
![Page 15: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/15.jpg)
Two general methods (see Krebs)
2. Distance from randomly selected organism to neighbouring organism.
r
Area per two individuals, but two circles: cancels out to same π r 2 formula as before
= n π sum (r2)
byth-ripley
![Page 16: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/16.jpg)
Two general methods (see Krebs)
2. Distance from randomly selected organism to neighbouring organism.
Problem: how to randomly select first individual?Nearest organism to a random point: BIASED
Never selected Frequently
selected
![Page 17: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/17.jpg)
WAYS TO RESOLVE PROBLEM:
1. Mark all organisms with a number, and then randomly select a few.
BUT if we could count all organisms, we wouldn’t need a census!
![Page 18: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/18.jpg)
WAYS TO RESOLVE PROBLEM:
1. Mark all organisms with a number, and then randomly select a few.
2. Use a random subset of the area (mark organisms in random quadrats).
Byth and Ripley
![Page 19: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/19.jpg)
WAYS TO RESOLVE PROBLEM:
1. Mark all organisms with a number, and then randomly select a few.
2. Use a random subset of the area (mark organisms in random quadrats).
3. Use a random point to locate organisms, but then ignore area between it and organism (biased to emptiness).
T-square
![Page 20: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/20.jpg)
The 2 snipers
Excellent aim, crooked sights
Cross-eyed cat, Straight sights
![Page 21: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/21.jpg)
Spatial pattern
More uniform More aggregated Random
![Page 22: Line transect lecture](https://reader035.vdocument.in/reader035/viewer/2022081417/56815c2a550346895dca01cf/html5/thumbnails/22.jpg)