Blog 4

Results of the three sampling strategies you used in the virtual forest tutorial.

• 7 species sampled
• In order from most abundant to least abundant; Eastern Hemlock, Sweet Birch, Yellow Birch, Chestnut Oak, Red Maple, Striped Maple, White Pine
• Each sampling method measures density, frequency, dominance, relative density, relative frequency, relative dominance, importance value and morisita index for the species.
• Systematic:
  • Only 6 species were found, white pine was absent
  • 12 hours 6 minutes sample time
• Random sampling:
  • 12 hours 46 minutes sample time
• Haphazard/subjective:
  • 12 hours 46 minutes sample time

Which technique had the fastest estimated sampling time

• Systematic/subjective
  • because it’s estimated time to sample was 12hrs 6 minutes while random sampling and haphazard sampling took 12hrs 46 minutes each.

Compare the percentage error of the different strategies for the two most common and two rarest species.
% error = (E – T)/T*100
E – estimated density value
T – true density value

• Systematic:
  • Most common specie (Eastern Hemlock)
    E – 404.2
    T – 469.9
    % error = 14%
  • Least common specie (White Pine)
    E – 0.0
    T – 8.4
    % error = 100%
• Random sampling:
  • Most common specie (Eastern Hemlock)
    E – 491.7
    T – 469.9
    % error = 4.64%
  • Least common specie (White Pine)
    E – 8.3
    T – 8.4
    % error = 1.19%
• Haphazard/subjective:
  • Most common specie (Eastern Hemlock)
    E – 441.7
    T – 469.9
    % error = 6%
  • Least common specie (White Pine)
    E – 8.3
    T – 8.4
    % error = 1.19%

Did the accuracy change with species abundance?

• Yes
• For random and haphazard sampling, the most abundant specie (Eastern Hemlock) has a higher percentage error than the least abundant specie (White Pine) thus, these 2 sampling methods accurately work for the least abundant specie (White Pine)
• For systematic sampling the least abundant specie (White Pine) has a percentage error of 100% while the most abundant specie (Eastern Hemlock) has a significantly lower percentage error of 14% thus systematic sampling accurately works for Eastern Hemlock.

Was one sampling strategy more accurate than another?

• Random sampling is more accurate than haphazard sampling which is more accurate than systematic sampling,