The ecosystem you grow up in will always trigger nostalgia. I can walk through an oak forest anywhere and feel at home. A walk through the high desert of Oregon, as entrancing as it is, feels foreign. When biologists from the United States first studied forests of central Asia many felt right at home. The ecosystem mirrored much of our eastern US forests biologically. This affinity for home is at the heart of the invasive species problem at Wintergreen and throughout much of the United States. This Nine Minute Naturalist will delve into why some invasive species feel right at home in our ecosystems.

The first plant hunters traveling from North America to Asia felt oddly at home amongst a very similar overstory surrounding them in China and Japan. Many samples brought back show great similarity to much of our native canopy. Recent DNA studies have proved they were right to feel a nostalgia amongst the tree species of Asia. Over half of the native trees and shrubs of the Appalachians can trace their ancestry to relatives across the globe. Fossil evidence suggests similar forests spread over the Northern Hemisphere when Asia, Europe and North America were connected in the supercontinent Laurasia. The problem is that plant hunters are not the only ones who feel right at home traveling from Asia to North America. Our ecosystem is under bombardment from invasive species that have made their home in our forests.

Japanese stilt grass

The list of invaders is long and depressing. Our forests at Wintergreen are overrun with invaders from Asia such as Japanese stilt grass, oriental bittersweet, autumn olive, tree-of-heaven, emerald ash borer and more coming our way such as wavyleaf basket grass and spotted lanternfly. Why do these plants and insects from Asia find our area to be a home away from home? One easy answer is latitude. The study of the geographical distribution of plants is called phytogeography. Large scale patterns of phytogeography are strongly related to latitude. Adaptations existing from previous land connection as well as similar climate allows for quick adjustment to their new home. Wintergreen is about 38 degrees latitude which if we traveled around the globe would put us right around Beijing, which as a 39-degree latitude. Tokyo is in between 35-36 degrees latitude.

Invasive species are not just successful because they are at the right latitude. A lack of natural predators tends to allow unfettered growth of non-native species. For instance, emerald ash borer has a host of predators in their native land. These predators include several species of parasitoid wasps that aid in population control. Another tool that enables invasive species establishment is allelopathy. Garlic mustard inhibits the growth of other surrounding plant species aiding in site competition. Garlic mustard and many other successful invasive species are also prolific seeders. Garlic mustard produce between 600-7000 seeds per plant that are viable in the soil for up to five years. Many successful invasives at Wintergreen are generalists that can thrive in a variety of soils, light conditions and water regimes.

Nostalgia is a fun feeling especially as you age. Nostalgia in the plant world has proved to be negative for Wintergreen and much of the United States. Plants and animals that arrive on our shore and feel right at home cost the state of Virginia $1 billion annually. Keep a look out in our events calendar for efforts this coming spring and summer to aid in controlling invasives in a couple critical sites at Wintergreen.