The Smithsonian Environmental Research Center (SERC) recently published a paper in Wetlands attempting to recreate the history of Phragmites australis in the Chesapeake wetlands.
"We tried to look at every aspect of a plant invasion," said Eric Hazelton, one of the paper's authors and former SERC fellow. A doctoral candidate at Utah State University, Hazelton and a team examined the robustness, insect damage, and types of plants in old and young Phragmites patches, before testing the plants' DNA.
The DNA revealed that young patches (post-1990) had more genetic diversity than old patches (pre-1971). There was more variation among individual old patches, however, than among new. In one interpretation of this, older patches became established by rare seeds that ended up in the marsh, and when these established plants grew close enough together they began to make seeds together, causing the explosion of invasive Phragmites that we see today.
The original article is available here or through the link below.