Giant Ant Mounts in Stony Swamp

Monday, October 26, 2015

By Professor Richard Amos

 

ENSC students inspect a giant ant mound made by the Lasius minutus species.

ENSC students inspect a giant ant mound made by the Lasius minutus species

 

Giant ant mounds may sound like something from a horror movie, but ENSC 2000 Environmental Science Field Camp students recently discovered that they are just another example of the incredible biodiversity in Ottawa’s NCC Greenbelt. The ant mounds at Stony Swamp, measuring up to 80 cm high and over a meter in diameter, are created by the Lasius minutus species, a small yellowish ant. While the ant mounds are thought to contain upwards of 10,000 ants, they are not seen on the surface of the mounds in large numbers. These subterranean ants do their work underground, herding aphids to live off secretions the aphids produce from the sap of nearby tree roots.

Stony Swamp, designated as a Provincially Significant Wetland and an Area of Natural and Scientific Interest, contains many diverse habitats and is home to a large number of regionally rare plant and animal species, including 17 species at risk. While the swamp is protected from development by the NCC, invasive species can potentially have a significant impact on the swamp. Of particular concern is the Emerald Ash Borer, which threatens the Ash trees that dominate in the areas of the swamp where the Lasius ants are found. It is thought that the ants, and the aphids they depend on, live off the sap of Ash trees. It is not clear if the ants will survive in the swamp as the ash trees succumb to the effects of the Ash Borer. 

The ENSC 2000 class visited Stony Swamp with Robert Lee and Barbara Gaertner, members of the Ottawa Field Naturalists’ Macoun Club. Robert and Barbara introduced students to the diverse species found in the swamp and engaged the class in a project to remove Glossy Buchthorn, another invasive species that threatens the swamp habitat. In addition, the class mapped the location of ant mounds and their proximity to Ash and other tree species in a 100 m by 200 m section of the swamp. This information will be used to determine the relationship of the ants to the Ash trees and quantify changes in ant mound abundance in the future. 

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Professor Richard Amos is cross-appointed between the Institute of Environmental Science and the Department of Earth Sciences. 

 

ENSC Class at Stony Swamp gather around a pile of invasive Glossy Buckthorn that they have just cleared from the swamp.

ENSC 2000 class at Stony Swamp gather around a pile of invasive Glossy Buckthorn that they have just cleared from the swamp