species must be. However, students should understand that rare species can make significant contributions to ecosystem functioning
(Lyons et al., 2005). For perspective, rare species are defined by ecologists as comprising less than 5% of the maximum observed percentage of counts (animals), 1% of the maximum percentage cover
(plants) (Mouillot et al., 2013), or 1–5% ecosystem biomass (Lyons
et al., 2005). It is important to note here that for all practical purposes, Shannon’s H′ is only an estimate of species diversity, because
for communities that are high in species richness, surveys are likely
not to “capture” all species, especially those that are rare.
Applying the QR-C of Diversity Indices
with Real Data: The Student Edge Effect
The QR-C approach involves moving back and forth between the
realms of science and mathematics (L. S. Mead et al., unpublished
data). In our case described here, students move between the science
of ecology and edge effect and the mathematics of diversity indices.
The entire data-collection activity spans several weeks, with sampling
occurring once per week. We use the other classroom days to discuss
various additional ecological concepts in the curriculum. As a culminating activity, student groups write condensed scientific papers (more
to follow). Throughout each component of the activity, the primary
goal is for students to utilize their QR-C skills in the context of a realistic, hypothesis-driven investigation. We encourage teachers to borrow from the information we provide below and create their own
data-based engagement activity that is specific to their local ecology.
Study Area and Sampling Design
The field activity described here takes place annually in a “natural”
unmowed hillside that slopes down to a small lake (Figure 2). The
hillside is ~30 m wide and runs the length of the east side of the lake
and the west side of the school. Between the unmowed slope and
the school is a mowed lawn 10–15 m in width. Where the two areas
meet is a hard tall-grass to mowed-grass edge. The student goal for the
last several years has been to investigate edge effect theory by testing
one of its central hypotheses: edges have characteristics of both con-
verging habitats and thus attract species from both habitats. Students
then make the prediction that when arthropods are collected at the
edge of the unmowed area and within its interior, they will observe
greater arthropod species richness and species diversity in the edges
than in the interior. Sampling within the mowed-grass habitat is not
possible as a third treatment because mowing and other activities
Student groups set up two 40 m transects within the grassy area
west of the school. One transect is placed along the habitat edge where
the mowed and unmowed area meet and the other runs parallel to the
edge transect 10 m within the unmowed area (Figure 2).
Students collect arthropod samples along each transect by using
pitfall traps. Pitfall traps are animal sampling devices, long used by
ecologists to passively collect population and community data on target species when individuals fall into them. Students use a pitfall trap
method similar to that described in Magura et al. (2001). Each year,
student teams dig holes every 5 m along each transect. The holes
are big enough to fit two 470 mL (16 oz.) plastic cups (Figure 3).
The first cup is used as a soil stabilizer so that the inner cup can be
removed and brought inside for analysis and refilling. The inner cup
is filled with a 5% ethylene glycol (antifreeze) solution to mitigate
evaporation and overnight freezing. The solution is also 0.1% detergent to remove surface tension. One class section installs the edge pitfall traps and the other class section installs traps along the interior
Each student team (eight teams per class section) collects data
three times from a single pitfall trap over a three-week period in
October. Trapped arthropod samples are removed with tweezers
from the solution and placed on white paper towel for identification. Students use two online methods to identify their samples:
Google Images and the American Museum of Natural History
dichotomous keys for arthropods ( https://www.amnh.org/learn/
teacher guidance is sometimes helpful. Having students accurately
identify all of the individuals they collect to the species level would
be an overreach in this context, given students’ lack of experience
with systematics. Thus, while students try to identify many individuals to species, they ultimately use the family taxon as a proxy for
“species” in their richness and diversity calculations. Data sharing
with other groups across both class sections is accomplished with a
shared Google speadsheet where students record data from their
weekly collections (Figure 4).
Each lab group then analyzes all the shared data after the three-week collection period as if they performed the entire study themselves. Once students have tabulated and pooled all of their data,
they calculate species richness and use both Simpson’s and Shannon’s indices to calculate diversity.
Figure 2. Rough placement of the edge (E) and unmowed
interior (I) pitfall traps (white circles) within the study area. Figure 3. An edge pitfall trap installed by a student team.