Category: Post 4: Sampling Strategies

The virtual forest sampling tutorial really helped me learn the techniques of sampling.  The fastest estimate time was the area haphazard method at 2 hrs and 43 minutes. The percent errors are as follows:

Haphazard- Common

Red maple-  4%

White Oak – 7%

Haphazard- Rare

Black Tupelo- 70%

Downy Juneberry- 76%

 

Random Systematic- Common

Red Maple- 8%

White Oak- 8%

Random Systematic- Rare

Hawthorn- 76%

Black Cherry- 96%

Random Sys- Common

Red Maple- 4%

White Oak- 20%

Random Sys- Rare

White Ash- 68%

Basswood- 66%

 

The accuracy changed greatly with species abundance and most with the rare species. Accuracy seemed to decrease.   Random/Systematic produced data closest to the actual values, although not as fast in time, but the percent error values were lower in haphazard sampling.

 

I chose to sample by area. Please refer to Table 1 for estimated values and percentage error.

Systematic sampling was the fasted technique, taking 12 hours and 41 minutes (compared to 13 hours and 13 hours and 9 minutes for haphazard and random, respectively).

 

In the case of common species (Eastern Hemlock and Sweet Birch), the simple random technique had the highest percentage error, while the haphazard technique had the lowest. When sampling rare species (Striped Maple and White Pine), percentage error was highest when using the systematic technique and lowest using the simple random technique.

 

There was a significant decrease in accuracy based on species abundance. When sampling common species, the average sampling error was 13% compared to that of rare species, which was 104.1%.

 

Overall, the most accurate sampling strategy was haphazard.

 

 

Hello everyone,

The sampling techniques I used in the field were a bit different from the ones listed in the tutorial. The areas I chose to study were located in lentic and lotic ecosystems. The benthic invertebrates and periphyton were mainly collected during the fall. The water samples were collected on a bi-weekly basis (if accessible) for water quality analysis.

Study components:

Water and tissue chemistry: to analyze selenium concentrations in samples of surface water, invertebrates and periphyton.

Field Sampling:

Sampling approach – systematic sampling

Surface water – all the surface water samples that were collected from the stream were based on BC Field Manual. The samples collected were submitted to a CALA certified lab in the lower mainland.

Physical habitat assessment – CABIN field protocols.

Benthic invertebrate samples – kicknet (stream) and sediment grab sampler (wetland). After collecting the benthos, they were sieved from debris, then rinsed, patted dry and put into a freezer. The samples were submitted to a lab for analysis.

Periphyton – collected from hard substrates using a clean scraper (stream), glove hand or 400-µm dip net. After collecting the periphyton, the sample was patted dry, placed in sample packages and put into a freezer.

Cheers,

CQ