THE FOREST CLASSROOM
Left: Some plants have come to rely so heavily on ants to spread their seeds about that they offer the insects a tasty treat in exchange for the dispersal service. Seeds of these species bear a lipid-filled structure called an elaiosome, whose sole function appears to be the attraction of ants. Here, Aphaenogaster fulva ants disperse bloodroot (Sanguinaria canadensis) seeds. Right: The Allegheny mound ant (Formica exsectoides) makes large, conspicuous mounds in open woods, fields, and forest edges. These ants will kill vegetation within 40–50 feet of their mounds to keep the area clear and open to sunlight.
Where do the Ants Go Marching? How New England’s ants act as ecological barometers By Carrie Deegan
E
veryone knows what an ant looks like. At this time of year, you might catch one wandering along your deck or marching across your kitchen counter toward the fruit bowl. “Look! Ants!” you say, with a bit of dread rising in your throat. For a homeowner, it’s usually not a good sign to see one inside, but there are thousands of species of ants across the globe and only a few of them regularly tangle with humans. In New England, there are roughly 140 species of ants known to science, and they inhabit almost every terrestrial habitat you can think of, from forests and mountaintops to swamps and old pastures. Because they are so ubiquitous and so numerous— some species of ant colonies can easily consist of several thousand individuals—ants play a significant role in many ecosystems. Kyle Bradford, a graduate student at Antioch University of New England in Keene, N.H., is researching the roles ants play as indicators of ecosystem health and resiliency. “Ants are keystone species in 14 | FOREST NOTES Spring 2021
many habitats,” Bradford explains. “They can affect plant distribution and abundance by consuming or moving seeds, [they can] turn and aerate the soil during nest building, and they are masters at finding and devouring dead insects. They also provide food for many woodland animals, from woodpeckers to black bears.” Ants are even responsible for the spread of several of our treasured spring wildflowers such as painted trilliums, bloodroot, and violets. These flowers all produce seeds with a lipid-rich attachment called an elaiosome, which ants can’t resist. The ants carry the seeds back to their nests and feed the fatty elaiosomes to their larvae, leaving the seed to sprout in its new location. Bradford and his faculty advisor Dr. Michael Akresh are currently studying the ant communities that inhabit dry oakpine barrens and heathlands, a globally imperiled habitat type. Oak-pine barrens and heathlands are fire-dependent natural communities that require disturbance in order to keep other plant and tree species
from invading and overwhelming them. In New Hampshire, barrens and heathlands are split into several natural communities found in very specific locations, including the barrens in Ossipee and Concord and on dry, rocky ridges in the southern part of the state. Government agencies and conservation landowners are increasingly interested in restoring these habitats where they have gone “past prime,” by manufacturing controlled disturbances such as prescribed burns, selective timber harvests, or targeted herbicide applications. Bradford is hoping the presence or absence of certain ant species may ultimately help land managers understand whether their restoration efforts in these habitats have been successful. The first step in determining whether ants could be useful in gauging the health and quality of heathland habitats is creating a baseline inventory of which ant species are associated with regional oak-pine barrens and heathlands. Bradford and field
