Tree Species at Snyder-Middleswarth Natural Area.
Out of the three techniques Systematic sampling is the most efficient in terms of time spent sampling compared to the other two, at 12 hours and 5 minutes. Seven species of trees were recorded from all three sampling techniques. These are Eastern Hemlock, Sweet Birch, Yellow Birch, Chestnut Oak, Red Maple, Striped Maple, and White Pine. The estimated density of all these trees differs from their actual density in all sampling techniques.
In the sample data, Eastern Hemlock and Sweet Birch are the two most common species in this natural area, while Stripes Maple and White Pine are the rarest. Sample error is calculated below: Percent Error=(E-T)/T x 100
- Systematic Sampling
Eastern Hemlock: Estimated value=587.5, True Value=469.9
(587.5-469.9)/469.9X100=25%
Sweet Birch: E=100, T=117.5, (100-117.5)/117.5X100=14.9%
Striped Maple: E=16.7, T=17.5, (16.7-17.5)/17.5X100=4.6%
White Pine:E=16.7, T=8.4, (16.7-8.4)/8.4X100=98.9%
- Random:
Eastern Hemlock: Estimated value=620.8, True Value=469.9
(620.8-469.9)/469.9X100=32.1%
Sweet Birch: E=187.5, T=117.5, (187.5-117.5)/117.5X100=59.6%
Striped Maple: E=16.7, T=17.5, (16.7-17.5)/17.5X100=4.6%
White Pine:E=0.0, T=8.4, (0.0-8.4)/8.4X100=100%
- Haphazard:
Eastern Hemlock: Estimated value=612, True Value=469.9
(612-469.9)/469.9X100=30.2%
Sweet Birch: E=144, T=117.5, (114-117.5)/117.5X100=3%
Striped Maple: E=4, T=17.5, (4-17.5)/17.5X100=77%
White Pine:E=12, T=8.4, (12-8.4)/8.4X100=42.9%
I calculated the average percent based on the results above, and the Haphazard technique has the least percent error average at 16.6%, therefore this is the most accurate sampling strategy for the common species. For the rare species on the other hand, the Systematic is the most accurate with a percent error average of 51.75% which is the least among all three. The accuracy of the percent error average on the rare species declined from systematic (51%) to haphazard (59%).
Was 24 a sufficient number of sample points to capture the number of species in this community? Was it enough sample points to accurately estimate the abundance of these species
If tree species are evenly distributed, 24 points might provide a good estimate of abundance. However, if certain species are clustered in specific areas, you may miss key species or under- or overestimate their abundance. On the virtual website, I noticed that the tree species are clustered unevenly throughout the study area, and thus, I believe that 24 points are not enough to capture the full number of tree species. Additionally, there are about 750 quadrants in the area, and we only sampled 24 quadrants, which I think is not an accurate estimate of the abundance of these species. This is especially true for the rare species, as indicated by the high percentage error.