Deer prefer native plants leaving lasting damage on forests

October 6, 2017 by Lindsey Hadlock, Cornell University
Credit: CC0 Public Domain

When rampant white-tailed deer graze in forests, they prefer to eat native plants over certain unpalatable invasive plants, such as garlic mustard and Japanese stiltgrass. These eating habits lower native plant diversity and abundance, while increasing the proportion of plant communities made up of non-native species, according to a new study.

The findings were published in the open access, online journal AoB Plants. The study pooled data from previous studies conducted at 23 sites across the northeastern U.S.

"Overall, deer reduce community diversity, lowering native plant richness and abundance and benefiting certain , showing that deer have a pervasive impact on forest understory plant communities across broad swaths of the eastern U.S.," said Kristine Averill, a research associate in Cornell's Section of Soil and Crop Sciences and lead author of the study.

By altering the balance of in favor of a higher fraction of invasive plants, deer change forest plant ecology. In this way, invasive plants could have a bigger influence on the forest ecosystem and leave fewer opportunities for native animals who depend on the native plants. Such changes in plant community structures also have long-term impacts on forest regeneration, Averill said.

In the study, Averill and colleagues analyzed raw data from previous research. The data came from sites that each had multiple pairs of fenced and unfenced plots, where deer were mostly excluded from fenced plots. "We compared the where deer were excluded against the communities where they had access," Averill said.

The researchers were surprised to find that the diversity of - the total number of - and the total abundance (or land cover) of invasive plants stayed the same in areas where deer grazed and where they were excluded. Since deer find some invasive species unappetizing in favor of more palatable plants, deer indirectly promote the success of these invasives, Averill said.

"The study results suggest we should try to maintain lower deer densities through hunting and fencing if the goals are to support more native plants and foster reduced relative abundance of introduced ," Averill said.

Explore further: Taste test? Deer preferences seem to help non-native invasive plants spread

More information: Kristine M Averill et al, A regional assessment of white-tailed deer effects on plant invasion, AoB PLANTS (2017). DOI: 10.1093/aobpla/plx047

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1 / 5 (2) Oct 06, 2017
Hunting deer is a positive thing for the environment.
1 / 5 (1) Oct 07, 2017
This raises many complex issues, and it's not as simple as "hunting deer is good." Of course, the best thing would be to have natural predators such as wolves, mountain lions and bears interact with the deer and cull the weakest individuals to keep the deer population healthy and maintained, as "nature intended." Since this is not possible because the species that introduced the invasive plants also killed off most of these natural predators (of course, reducing our numbers would also have a wonderful effect on the environment, but we'll leave that aside for the moment) we can perhaps promote RESPONSIBLE hunting. Responsible hunters don't hunt for trophies and don't use bows and arrows for their own entertainment, but try to make a clean head kill. They avoid killing the bucks with the beautiful antlers because they know that these are vital to the health of the species and the ecosystem as a whole. Maybe the government could employ hunters and ensure the distribution of the meat?
not rated yet Oct 07, 2017
You can't expect anything else from deer. They eat what they estimate is good and avoid possibly dangerous plants. Invasive plants will probably never disappear anyway.

It is said wolves do something similar. They would attack only animals they recognize as prey, by the fact those animals run away from them. It is said that a human can avoid a wolf attack by not running away, that way fooling the wolves he is not prey. Now I don't know if the trick really works and I don't expect it to help much with rabid wolves, but it seems somewhat reasonable.
1.7 / 5 (3) Oct 07, 2017
ktd, you have never met an ethical hunter, have you? If that's what you think they are, you probably never will. Go back to your apartment and enjoy your tofu burger...
1 / 5 (1) Oct 08, 2017
When rampant white-tailed deer graze in forests, they prefer to eat native plants over certain unpalatable invasive plants

Then harvest the deer and where possible, work towards increasing the number of native predators.
2.3 / 5 (3) Oct 08, 2017
No better example of anthropocentric bias than this one. How in the world can deer "damage" a forest? It's too ridiculous for words.
5 / 5 (2) Oct 08, 2017
The real source of the problem is the invasive plants. I see people planting bamboo here in the US. It escapes into the wild and forms large impenetrable stands among the trees. This makes an ideal predator free habitat for rats and mice which spread disease.
not rated yet Oct 09, 2017
"The real source of the problem is the invasive plants."

Correct. It's not only the deer who don't eat invasive plants (such as Japanese stiltgrass) but also rabbits, sheep,horses, and cattle. Japanese stiltgrass has been declared the #1 invasive plant species in Pennsylvania. Culling the dear population may slow down the spread of stiltgrass, but the only way to stop it is to introduce a new grazer or plant disease that will directly attack Japanese stiltgrass.
not rated yet Oct 10, 2017
I've read on Wikipedia that cattle like that plant.
4 / 5 (1) Oct 10, 2017
@Gigel: I checked Wikipedia, and indeed there was a statement that cattle will "avidly" graze it in the summer when it is green. However, there was no footnote to reference the source for this assertion. In contrast, the internet is full of statements that cattle and horses will not eat it. Even goats will not eat it unless there is nothing else, and it is necessary to have a goat that has been "trained" to eat stiltgrass so the other goats can watch.

The internet had several statements that stiltgrass can be poisonous when it turns brown during the winter. I don't know if this is true.

I do know that my brother has a herd of Highland cattle in Pennsylvania. They are allowed to roam in the woods and the pastures, and stilgrass is one of the few things they won't eat.

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