A comparison of sampling protocols for monitoring an invasive exotic shrub, European buckthorn (Rhamnus frangula), with middle school students

Morrison, Heather A. H.
Tom Wessels, MA
Department of Environmental Studies
1998
This study compared the density of Rhamnus frangula (European buckthorn) in three sampling protocols conducted by middle school students to a known test plot of the shrub in the Ashuelot River Park in Keene, NH. The results of the study provide a basis for a long-term monitoring program of R. frangula to be used by schools and community groups. A total stem count and height class data was conducted within a 4900 m² test plot to test three sampling protocols against this known for accuracy. All stems were classified into four height classes: s= seedlings <15.24 cm (6in); 1= >15.24 cm and <1 m; 2= 1-3 m; and 3= >3 m. In protocol 1, students set up two north-south belt transects (1 m by 70 m). In protocol 2, students set up to 10 experimental 15 m² square plots along spokes of a wheel 20 m from the center of the test plot. In protocol 3, students set up to 10 random 15 m² circular plots. Students were given 45 minutes on each of three days to collect data using the three sampling protocols. Protocol densities were analyzed using the Wilcoxon/Kruskal-Wallis (Rank sums) nonparametric test. The stem density of the known inventory was compared to each of the three protocols in each of the four height classes. The transect protocol came closest to the mean density, but the wheel protocol had the least variance around the mean. Students answered a survey to give their opinion about the three protocols, their understanding of the directions and equipment, their preferences and dislikes, and what they would change about the protocols. Although six students chose the random protocol as the easiest to set up, five chose it as the hardest. Students also overwhelmingly chose the random protocol as the protocol that was the most fun to set up. Researcher observations suggest that the transect protocol is best suited for middle school students because it was the easiest to replicate, was completed within the shortest amount of time, and came closest to the known density mean of R. frangula.

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