Introduced Plants, Worms, and Deer

On February 25, 2013, Bernd Blossey, Associate Professor in the Department of Natural Resources at Cornell University, gave a talk at the Cornell Laboratory of Ornithology entitled, “How Introduced Plants, Worms, and Deer are Reshaping our Neighborhoods.”

Cornell ecologist Bernd Blossey sets a trail cam to record deer behavior in the recent PBS Nature episode "The Private Life of Deer." (Click on photo to see the program.)

Blossey is considered a world authority on the biological control of invasive species. His presentation radically changed many people’s ideas about things happening in our woods.

Some examples:

  • Though earthworms, which are not native, may benefit gardens and plowed agricultural soil, they are devastating to the leaf litter and humus of the forest floor, compacting the soil and causing serious soil erosion, leading to the loss of many native plants, amphibians, and invertebrates.
  • Garlic mustard, one of the best-known invasive plants in our eastern forests, and which many people spend hours weeding from parks, preserves, and the woods around their homes, will not infest an area not already invaded by earthworms. (Blossey offers a $5000 reward for anyone who can find an exception to this!) Furthermore, Blossey says the research indicates that pulling up garlic mustard is a waste of time, as it eventually poisons the soil against itself; that pulling the plant actually delays this process and prolongs the presence of the plant; and that the presence of garlic mustard appears not to limit the success of native wildflowers such as trillium.
  • Deer overpopulation, however, does have an enormous impact on the health, biodiversity, and the very future of our forests. Blossey said that research on Cornell lands indicates that sterilization of females to reduce deer numbers is a huge waste of money (at $700 to $1000 per animal), as it is completely ineffective in reducing the overabundance of deer in “open populations.”

Prof. Blossey spoke of much more, including comparing the effects on amphibian populations from invasive plants and native plants in aquatic ecosystems.

When I went to the lecture, I had not planned to record it, but I changed my mind while there. I recorded it with the video function of my shirt pocket camera, finishing off with my iPhone when I ran out of card storage. The video quality is poor, especially the iPhone section, but the audio is acceptable. You can see Dr. Blossey’s slides in more than half of the presentation.  Perhaps think of it as a podcast with some visuals.

I decided to post Prof. Blossey’s talk because I feel much information in it is so new to most of us and challenges a number of the assumptions that many of us have about managing invasive species, one of the biggest environmental issues of our time.

Watch/listen right here:

Forest Floor Invader

It is said that invasive species are second only to habitat destruction in their damaging impacts on wildlife, not to mention agriculture, economics, and human health. Countless billions are spent annually coping with invasives, whether they be insects like the emerald ash borer that is destroying all species of ash trees in our central and eastern U.S. forests, the aggressive tropical aquatic plant hydrilla found last year in Cayuga Inlet, or malaria that has spread around the world’s tropics.

Garlic mustard forms seed pods.

Garlic mustard forms long pods that will dry out and disperse hundreds of seeds in the weeks that come.

In the short video that follows, I introduce and discuss one of the scourges of our forest community, garlic mustard, one of best known introduced plant species that have emerged as major pests. At this moment in the Finger Lakes region, garlic mustard is forming its seed pods, so if you should remove it, be careful to dispose of in a way that prevents the seeds from escaping and spreading (e.g., one suggestion is to put plants in a black plastic garbage bag and leave it in the sun for a few days to thoroughly kill it, and then put it in the trash.). For more information, see the New York Invasive Species Clearinghouse.

And now the video (5 minutes):