Sampling time
In terms of time spent sampling they were all similar. Haphazard was the most efficient at 12 hours 30 minutes (this time could change based on the sample locations chosen), next was systematic at 12 hours 37 minutes and finally least efficient was random at 12 hours 41 minutes (also could change based on the random outputs chosen). The difference between the fastest and slowest method was 11 minutes. Comparing 11 minutes to the 12 hours these methods would take I don’t think this would be a factor when making a decision about either method.
Comparing Percent Error
The most accurate strategy for common species (Eastern Hemlock and Sweet Birch) was systematic with a percent error of 7.2% and 5.5% compared to 11.7/36% and 14.4/31.1% for random and haphazard respectfully. The percent error was higher for more rare species with 174/100%, 100/147.6% and 66.9/147.6% for systematic, random, and haphazard respectfully. This is because the nature of the formula for percent error. If the actual value is small, any small difference between the estimated and actual will yield a larger change in percent error compared to a higher actual value.
Comparisons between methods
I would say in general the systematic approach was more accurate than the other two methods having the lowest on average percent error. However, all methods were less accurate for detecting more rare species with the haphazard method having on average the lowest percent error.
24 sample points were likely on the lower end for an appropriate number to sample the presence/abundance of species in this community. Both systematic and random didn’t sample any Striped Maple or White Pine respectfully with haphazard being the only method to detect the presence of all expected species.
Calculations (from Figure 1)
Common species 1 (the densest species: Eastern Hemlock)
%error = |(E-T)/(T)|*100
Systematic: E=436; T=469.9
| (436-469.9) / (469.9) | * 100
=7.2%
Random: 11.7%
Haphazard: 14.4%
Common species 2 (the second most dense species: Sweet Birch)
Systematic: 5.5%
Random: 36.2%
Haphazard: 31.1%
Rare species 1 (the second least dense species: Striped Maple)
Systematic: 174%
Random: 100%
Haphazard: 66.9%
Rare species 2 (the least dense species: White Pine)
Systematic: 100%
Random: 147.6%
Haphazard: 147.6%
Figure 1. Summarized data from the virtual forest tutorial.