As the years have progressed, white-tailed deer populations all over the U.S. have increased significantly. While a larger number of deer has been beneficial to hunters and the insect population, it’s had negative effects on certain native plant species.
Studies have shown that overabundant deer populations in wooded areas increase the growth of invasive plant species that kill native plant species. In a recent study published in Proceedings of the National Academy of Sciences, Temple assistant professor of biology Rachel Spigler explains the situation:
“When you have these deer coming in, they are almost mowing the forest floor of these native species, like trillium, which the deer find tasty,” she says. “They reduce the abundance and competitiveness of the native species, so it lowers what we call the ‘biotic resistance’ of the native plant community to resist the invasion of these plants species…”
Many invasive plants grow quickly and have no problem spreading, so once a species is introduced, it can easily kill off weaker native plants. One in particular is garlic mustard. Because deer don’t eat garlic mustard, it can quickly cover forest floors. This is a problem because many U.S. forests rely on slow-growing native plants to maintain a healthy ecosystem.
In a study by Carol Horvitz, an ecology professor at the University of Miami, researchers tested whether deer directly affect the spread of garlic mustard. They planted two fields of garlic mustard – one fenced in and one open to the deer in the area. After several years, the researchers found that the number of garlic mustard plants was fewer in the fenced area than in the area where the deer roamed.
The good news is if deer are removed from an area, native plants can usually recover and begin to repopulate the area, however, there may be some controversy as to when the situation reaches the point that this is necessary.
So, if you have a garden, we recommend installing a deer fence to protect your plants from being eaten and from invasive species wiping them out.