Life on the Rocks

Wed, 01 May 2013 10:32:00 CDT  — by: Jane Brown, C'1

Resting on top of a mountain (The Mountain), Sewanee is not known for its good soils. It does, however, rest on top of a quartz rock layer known as the Sewanee Conglomerate, which received its name due to its frequently exposed nature in the area. With an average soil depth of around 4 feet deep, there are a number of outcrops that exist on the Domain. These outcroppings are distinct for their unique biodiversity. Two such rare endemic species are plants- Diamorpha smallii (Elf orphine) and Minuartia glabra (Appalacian sandwort or Appalachian stichwort) (shown below). Students in Bio 130 are exploring how thes threatened species live. By looking at twelve different outcrop sites, the group is studying how these two species compete over the same resources and exist in this relatively unstudied habitat.

imgp18862Sandstone, according to the three group members, “is a hotspot for biodiversity on the Domain”. To quantify their findings, a 500 cm-squared circular lot was made at each of the twelve outcrops to monitor Diamorpha and Minuartia presence. In addition to recording their density, insect presence, moss and lichen, amount of direct sunlight, and types of substrait were recorded as indicators. These indicators were used to define a preferred growing condition for Diamorpha and Minuartia. By identifying responses from the endemic species, this research will be helpful in understanding the favorable conditions needed for supporting the biodiversity of these short-lived annuals.


The Cumberland Plateau is prized for its richness in biodiversity. Endemic plant species such as Miamorpha and Minuartia play even with their relatively short-life cycle a key part in this wide range of biodiversity and in supporting other habitats.

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