Post 4: Sampling Strategies

The three types of sampling used in this activity were systematic, random, and haphazard all by distance.

The systematic sampling technique of sampling along the gradient had the quickest sampling time at four hours and seventeen minutes. The haphazard method was next with four hours and twenty seven minutes. My method for haphazard was choosing clusters that appeared to have a variety and higher abundance so many points were close together but some clusters were at a further distance. The random sample had the longest estimated time at four hours and fourty-eight minutes. With both the haphazard and the random sample, sometimes the same point was sampled twice and sometimes points very close but not all along the study area were chosen.

 

Percent Error for Density:

Species: Distance Systematic, Distance Random, Distance Haphazard

Eastern Hemlock:  16.1%,  16.9%,  124.9%

Sweet Birch:  34.2%,  47.2%,  86.7%

Yellow Birch:  7.81%,  34.6%,  138.1%

Chesnut Oak:  20.6%,  18.6%,  83.4%

Red Maple:  28.5%,  2.7%,  84.5%

Striped Maple:  165%,  41.7%,  84.5%

White Pine:  100%,  122%,  11.1%

Eastern Hemlock is the most prominent species followed by Sweet Birch. Striped Maple and White Pine are the most rare. The more abundant the species is, the better the accuracy was for the systematic sampling approach and for these species, systematic sampling had the lowest percent error. When a species is rare, the accuracy is lacking in the systematic approach. It is possible for most of the rare species to be located in one particular area within the study area so systematically sampling the area can either way over or way under represent the species. The haphazard approach lacks accuracy in all samples except (likely just by chance) the most rare species the white pine. Repeating that low of a percent error for a species using the haphazard approach would be very unlikely. The random approach had a comperable percent error in most samples to the systematic approach and provided lower percent error in the less abundant species (except the white pine). Although the random sampling did not provide as percise data as the systematic did in the most abundant species, when considering the entire representation of the species composition, it has the lowest overall percent error. By increasing the number of samples and using a random approach, the representation of the study area would be the most accurate especially if duplicate coordinates were not used.

Leave a Reply

Your email address will not be published. Required fields are marked *