The virtual forest sampling theory exercise provided insight into the advantages and disadvantages of the different sampling techniques you can use in the field.
I have provided a summary of my findings in table 1 below.
Overall, the Systematic: Sampling along a topographic gradient technique had the fastest sampling time.
The two most common species were the Eastern Hemlock and the Sweet Birch. In general, the percentage error was much lower in the common species versus the two most rare species, Striped Maple and White Pine, which had a percentage error of 100% in some cases, meaning it was not sampled at all. This suggests that sampling accuracy increases with species abundance.
Overall, when adding up the percentage error calculations, the Random Sampling (sampling technique # 2) was more accurate than the systematic topographic and the haphazard sampling techniques.
| Table 1. Sampling techniques using the Virtual Forest Exercise | ||||||||
| Species | Measures | Actual | data(systematic topographic) | data (random) | data (area haphazard) | % error calculations (Topographic) | % error calculations (Random) | % error calculations (Haphazard) |
| Eastern Hemlock (common) | Density | 469.9 | 520 | 437.5 | 536 | 10.7 | 6.9 | 14.1 |
| Frequency | 73.00% | 80.00% | 79.00% | 76.00% | 9.6 | 8.2 | 4.1 | |
| Dominance | 33.3 | 40.2 | 40.5 | 38.2 | 20.7 | 21.6 | 14.7 | |
| Relative Density | 50.6 | 53.3 | 47.3 | 56.8 | 5.3 | 6.5 | 12.3 | |
| Relative Frequency | 33.8 | 37.7 | 36.4 | 33.3 | 11.5 | 7.7 | 1.5 | |
| Relative Dominance | 44.4 | 50.4 | 48 | 50.9 | 13.5 | 8.1 | 14.6 | |
| Importance Value | 42.9 | 47.1 | 43.9 | 47 | 9.8 | 2.3 | 9.6 | |
| Morisita Index | 1.89 | 1.76 | 1.96 | 1.86 | 6.9 | 3.7 | 1.6 | |
| Sweet Birch (common) | Density | 117.5 | 124 | 100 | 128 | 5.5 | 14.9 | 8.9 |
| Frequency | 43.00% | 36.00% | 42.00% | 48.00% | 16.3 | 2.3 | 11.6 | |
| Dominance | 20.2 | 22.1 | 18.2 | 22.1 | 9.4 | 9.9 | 9.4 | |
| Relative Density | 12.7 | 12.7 | 10.8 | 13.6 | 0 | 15.0 | 7.1 | |
| Relative Frequency | 19.9 | 17 | 19.4 | 21.1 | 14.6 | 2.5 | 6.0 | |
| Relative Dominance | 26.9 | 27.7 | 21.6 | 29.4 | 3.0 | 19.7 | 9.3 | |
| Importance Value | 19.8 | 19.1 | 17.3 | 21.3 | 3.5 | 12.6 | 7.6 | |
| Morisita Index | 2.27 | 2.96 | 2.43 | 1.71 | 30.4 | 7.0 | 24.7 | |
| Striped Maple (rare) | Density | 17.5 | 0 | 4.2 | 28 | 100 | 76.0 | 60.0 |
| Frequency | 6.00% | 0.00% | 4.00% | 12.00% | 100 | 33.3 | 100.0 | |
| Dominance | 0.7 | 0 | 0.1 | 2.2 | 100 | 85.7 | 214.3 | |
| Relative Density | 1.9 | 0 | 0.5 | 3 | 100 | 73.7 | 57.9 | |
| Relative Frequency | 2.8 | 0 | 1.8 | 5.3 | 100 | 35.7 | 89.3 | |
| Relative Dominance | 0.9 | 0 | 0.1 | 3 | 100 | 88.9 | 233.3 | |
| Importance Value | 1.8 | 0 | 0.8 | 3.7 | 100 | 55.6 | 105.6 | |
| Morisita Index | 17 | ** | ** | 8.33 | NA | NA | 51.0 | |
| White Pine (rare) | Density | 8.4 | 4 | 8.3 | 0 | 52.4 | 1.2 | 100.0 |
| Frequency | 4.00% | 4.00% | 4.00% | 0.00% | 0 | 0 | 100.0 | |
| Dominance | 0.9 | 0.2 | 0.3 | 0 | 77.8 | 66.7 | 100.0 | |
| Relative Density | 0.9 | 0.4 | 0.9 | 0 | 55.6 | 0.0 | 100.0 | |
| Relative Frequency | 1.9 | 1.9 | 1.8 | 0 | 0 | 5.3 | 100.0 | |
| Relative Dominance | 1.2 | 0.3 | 0.3 | 0 | 75 | 75.0 | 100.0 | |
| Importance Value | 1.3 | 0.9 | 1 | 0 | 30.8 | 23.1 | 100.0 | |
| Morisita Index | 16.13 | ** | 24 | ** | NA | 48.79 | NA | |
| Shannon-Weiner Diversity | 1.5 | 1.3 | 1.4 | 1.3 | ||||
| Estimated time to sample | 12 hours, 38 minutes | 12 hours, 43 minutes | 13 hours, 1 minutes | |||||
some good thoughts here re interpretation