Study reveals deer inhibit trees but raise plant diversity

Twenty years ago, Cornell researchers established experimental plots meant to mimic abandoned agricultural land on university-owned parcels in Dryden, NY. Half of the plots were surrounded by fencing that excludes deer, and half were left open.

"All six of our plots where deer have been excluded by fencing have trees in them now, and in our open plots that deer can access, we have almost no visible trees," said Anurag Agrawal, study co-author and the James A. Perkins Professor of Environmental Studies. "Deer prefer woody things and often forage in the wintertime and eat woody stems. So even when you get small saplings starting to grow, they're not persisting."

Agrawal and Antonio DiTommaso, associate dean and director of the Cornell University Agricultural Experiment Station (Cornell AES), began the experiment 20 years ago. (The findings reported in PLOS One cover 18 years of their data.) Agrawal, who studies ecology and evolution of interactions between plants and animals, took the lead in assessing changes to the above-ground vegetation. DiTommaso, who is also a weed ecologist in the School of Integrative Plant Science, and his lab oversaw analysis of the seedbank - the term for all the viable, dormant seeds stored in soils. Though there have been many studies on how deer impact vegetation, this project is among the first to examine the impact of deer on the seedbank, DiTommaso said. The researchers also published a 2014 PLOS One study on their first seven years of data.

Read the full story in the CALS Newsroom.