User: | Open Learning Faculty Member:
The results of the three area based sampling strategies used in the virtual forest tutorial are summarized below.
Systematic Sampling (12 hours, 7 minutes):
| Most Common Species | Data Densities
Actual Densities |
% Error |
| Eastern Hemlock | 504.2
469.9 |
7.3 |
| Sweet Birch | 112.5
117.5 |
-4.3 |
| Rarest Species | ||
| Chestnut Oak | 66.7
87.5 |
-23.8 |
| Red Maple | 137.5
118.9 |
15.6 |
Random Sampling (12 hours, 42 minutes):
| Most Common Species | Data Densities
Actual Densities |
% Error |
| Eastern Hemlock | 504.2
469.9 |
7.3 |
| Sweet Birch | 137.5
117.5 |
17 |
| Rarest Species | ||
| Striped Maple | 41.7
17.5 |
138.3 |
| White Pine | 20.8
8.4 |
147.6 |
Haphazard (12 hours, 59 minutes):
| Most Common Species | Data Densities
Actual Densities |
% Error |
| Eastern Hemlock | 540
469.9 |
14.9 |
| Sweet Birch | 108
117.5 |
-8.1 |
| Rarest Species | ||
| Red Maple | 41.7
118.9 |
-64.9 |
| Striped Maple | 8
17.5 |
-54.3 |
Systematic sampling was the most accurate for both common and rare species. % error was quite higher for the rarer species for all three methods.
The most efficient technique timewise was systematic, followed by random, followed by haphazard. The time differences weren’t’ too dramatic, with a spread of only 52 minutes between the most and least efficient.
Considering how close to the actual data the sample was in the systematic method, it would seem to be a sufficient sample size to have a solid understanding of the species numbers and abundance of the common species. However, the rarer species would seem to require further sampling to get more representative data.
very clear!