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Distribution and abundance of Phragmites and cattails in the Nature Park

Susan Cordes, Brandon Dawson, Jerilyn Kremer, and Ryan Miller

Class project for Conservation Biology, BIO 345, spring 2006

Susan Cordes measuring the size of
a patch of wetland grasses.

Invasive species can sometimes be a threat for destruction of the ecosystems that they inhabit and the surrounding biodiversity.  Phragmites australis, an invasive wetland grass, is common throughout the Midwest.  Phragmites co-occurs with cattails (Typha angustifolia) in the quarry bottom at the DePauw University Nature Park. We collected baseline data on three types of patches in the quarry bottom: pure patches of Phragmites, pure patches of cattails, and mixed patches of Phragmites and cattails. Our goal was to monitor the growth of Phragmites as an invasive species within this ecosystem. We collected data on distribution, size, and geographic location of a total of 37 patches in the quarry bottom. Along with providing baseline data for future research, our study also sought to determine the correlation between elevation and the different patch types and to determine the spatial distribution of all wetland grass plots. We used aerial photos and GPS data to generate GIS maps that show the spatial distribution, location, size of plot areas, and plot types for all thirty-seven plots. Although the difference was not statistically significant.

A patch of Phragmites at the Nature Park.

Phragmites patches tended to be larger than mixed patches, which were larger than cattail patches. Our map demonstrates that the growth of Phragmites appears to be spreading from a centrally located patch towards the boundary of the quarry bottom. Phragmites is gradually migrating into pure cattail patches, converting these into mixed patches. The farthest patches from the central Phragmites patch presently remain as pure cattail patches. Phragmites patches on average were located at higher locations than cattail and mixed patches, but the difference was not significant. We recommend that future research be conducted to study the growth, spread, and spatial distribution of the wetland grass patches. Our baseline data should also be used to monitor and manage the spread of Phragmites throughout the quarry bottom. Eradication methods should be used if Phragmites begins to displace cattails, as expected, and alters the ecosystem.

Click here to download:
Susan Cordes's report (microsoft word; 3.7 MB)

Another patch of Phragmites in the quarry
bottom. Phragmites is often used as an
ornamental grass in homeowners' lawns, but
the plant easily escapes "captivity" and invades
other ecosystems. Phragmites is an aggressive
plant, readily outgrowing its competitors in
areas with shallow standing water.