Post 4: Sampling Strategies

Description of Results

For my sampling strategy, I chose area-based sampling strategies. The most accurate sampling strategy  was systematic transect. Of the 56 measures calculated (8 measures per species, 7 species), systematic transect was the most (or equally as) accurate for 38 measures. Random sampling was the most (or equally as) accurate for 13 measures and haphazard sampling was the most (or equally as) accurate for 12 measures.

For the 5 species with greater abundance (>25% frequency), the systematic transect sampling method was the most (or equally as) accurate for an average of 5.6 measures out of 8 (with a range of 4-7 measures).

For the 2 species with low frequencies (striped maple frequency = 6%; white pine frequency = 4%) the result was split. For the Striped Maple, the systematic transect method was only the most (or equally as) accurate for 2 of the 8 measures, whereas random and haphazard sampling methods were both the most (or equally as) accurate for 4 of the 8 measures. In contrast, the systematic transect method was most accurate for all 8 of the measures of the White Pine. The haphazard method did not capture any White Pine.

Fastest Estimated Sample Time

The technique with the best sampling time was the systematic transect method at 12hr 6min. However, the other 2 methods weren’t far behind estimating 12hr 37 min for random sampling and 12hr 38 min for haphazard sampling.

Percent Error Between Strategies for the Two Most Common and Two Rarest Species Results

When calculating percent error of density for each species, I found that the systematic transect method was the most (or equally as) accurate for the 2 most common species (Eastern Hemlock & Sweet Birch). It had a percent error of 5.5% and 2.8% respectively. For the 2 rarest species (Striped Maple & White Pine), it was only the most accurate method for the White Pine with a 1.2% error.

The random method was only the most accurate for the Striped Maple with a 52.6% error.

The haphazard method was equally as accurate for the Sweet Birch as the systematic transect method with a 2.8% error; however, it completely missed counting any White Pine.

Accuracy vs Species Abundance

When looking at percent error of density, it is noticeable that the percent error increased with species rarity.

For the 5 species with greater abundance (frequency >25%), the max percent error that occurred was 38.1% (found with random and haphazard sampling of Chestnut Oak). In contrast, the 2 species with the lowest abundance (a frequency ≤6%) had wildly different percent errors across species and methods. The Striped Maple ranged from 52.6% to 76% error, and the White Pine ranged from 1.2% to 296.4% error.

Most Accurate Strategy

The most accurate sampling strategy across the board was systematic transect. Of the 56 measures calculated (8 measures per species, 7 species), systematic transect was the most (or equally as) accurate for 38 measures (68%).