Blog post # 4 Sampling Methods
After doing the community sampling exercise on the Snyder-Middleswarth Natural Area the Systematic sampling along a topographical gradient was indicated as taking the least time to perform.
I calculated the percentage error for the following species sampled:
Most common species
Eastern Hemlock
- Systematic: -26.8%
- Random: 1.3%
- Haphazard: 12.4%
Sweet Birch
- Systematic: 49.9%
- Random: 56.6%
- Haphazard: 32.8%
Rarest Species
Striped Maple
- Systematic: -31%
- Random: 37%
- Haphazard: 288.5%
White Pine
- Systematic: -4.8%
- Random: 185.7%
- Haphazard: -52.4%
Looking at the above percentage errors it becomes apparent that it is harder to get an accurate sampling of the rarer species with the much higher percentage errors. Additionally, the systematic sampling seems to have less percentage error for rarer species sampling but it becomes less obvious for the common species which sampling method has less percentage error. This may indicate that for adequate sample sizes all of the sampling methods are equally useful but systematic sampling may be superior for smaller sample sizes/rarer species. This all suggests that accuracy does in fact change with species abundance. Overall, if a species is abundant the sampling method does not affect accuracy to a notable degree.
I am surprised to see such high percent errors for your Sweet Birch, a common species. Another indication of more samples needed.