Deer proliferation disrupts a forest's natural growth

Mar 08, 2014

By literally looking below the surface and digging up the dirt, Cornell researchers have discovered that a burgeoning deer population forever alters the progression of a forest's natural future by creating environmental havoc in the soil and disrupting the soil's natural seed banks.

The study, "Deer Browsing Delays Succession by Altering Aboveground Vegetation and Belowground Seed Banks," was published online March 7 in PLOS ONE.

"Deer are slowing down forest succession or natural establishment. In fact, the deer are preventing forests from establishing," says Anurag Agrawal, Cornell professor of ecology and evolutionary biology, a co-author on the paper.

Deer typically prefer to eat native, and rebuff invasive species. The study showed that when deer consume native plants, the non-native species are left to flourish, dropping seed in the .

As forests normally mature, their grasses give way to herbs and shrubs, and then new trees eventually take root. Expanding deer populations in the Northeast, however, stall forest development and promote the growth of thorny thickets of buckthorn, viburnum and multiflora rose bushes. If deer leave the forests alone, such trees as cottonwood, locust and sumac can sprout and grow unimpeded.

The researchers found that the impacts of deer grazing on vegetation were severe and resulted in bare soil and reduced plant biomass, less recruitment of woody species and relatively fewer native species. And the deer's negative impact on seed banks resulted in significantly decreased overall species richness and relatively more short-lived species of both annual and biennial plants.

Co-author Antonio DiTommaso, Cornell associate professor of weed ecology and management, and research technician Scott Morris gathered soil cores – from both within and outside of fenced "deer exclosures" – and germinated the seed. They found the soil cores from outside of the exclosures contained many more seeds from non-native species.

Deer select forests for their trees but in doing so disrupt forest system growth trajectories, concludes the study.

"It's obvious that the are affecting the above-ground , but it's like an iceberg. There are major effects below the . We are seeing a divergence of seeds contained within the soil from what should be there," says DiTommaso. "We are not seeing the seeds of woody plants. Instead, we're seeing an escalation of non-native seed and the virtual elimination of woody plant seeds."

Explore further: Study supports policy of culling young deer alongside mother

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User comments : 23

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alfie_null
2 / 5 (1) Mar 08, 2014
What happens then, when the deer finally run out of their preferred native vegetation? Do they crash? The deer in my neighborhood seem to prefer everything.
mosahlah
3 / 5 (2) Mar 08, 2014
Having too many deer, is like having too many coins. You just need to cash them in once in a while.
crabjack
4 / 5 (8) Mar 08, 2014
Further proof that we can't tamper with our environment. This was happening in Yellowstone until the wolves were re-introduced. Now everything, including vegetation and the river, are in beautiful balance.
Wolf358
4.8 / 5 (6) Mar 08, 2014
crabjack, we just saw a video about that; what suprised me was that the wolves weren't actually killing large numbers of deer; they were mostly just preventing the deer from congregating along the banks. There's a balance between predators and prey; upset that balance by removing the predators and an avalanche of effects happens..

Sinister1812
3.2 / 5 (5) Mar 08, 2014
That happens everywhere these days. Farmers, the government and trophy hunters go out and kill all the predators, and wonder why there are too many herbivores. You couldn't tell them that though, as ignorance is bliss.
ab3a
3 / 5 (3) Mar 08, 2014
Sinister1812: time for a reality check. Wolves, Coyote, and Mountain Lion will prey on deer, but they also prey on cattle, cats, dogs, and even small children.

We participate in managed hunts in local watersheds. We eat what we kill. It is no different than fishing. For some reason, recreational fishing is socially acceptable, but hunting isn't. However, philosophically, I see no distinction.

On the other hand, predators are no laughing matter. We have Eastern Coyote in our area. Farmers are reporting predation of cattle. Pets have disappeared. Our dog refuses to walk with us in to certain areas, and we didn't figure out why until we saw the tracks in the snow.

This is no laughing matter. Reintroducing predators is fine unless the region is actually populated. When that is the case, the only safe, and reasonable course of action is hunting.
Sinister1812
3 / 5 (4) Mar 08, 2014
So? That is the risk they take. There are areas with wild animals. They shouldn't be wiped out everywhere because people choose to live and farm there, when it's not their territory. I agree with protecting your life and stock. But that's a bit like going out into the African wilderness and shooting lions, when I am in their territory.
Pediopal
3 / 5 (4) Mar 09, 2014
Ab3a, you eat what you kill? We are talking about wolves here…do you eat them??
Native Americans and wildlife survived and thrived for 16,000 years along side of wolves and other predators. Then Europeans with their less than savvy livestock and biblical fear of all predators arrived and exterminated anything that got in the way of money…the Indians, the predators even the birds of prey.
Your are a typical sport hunter (you hunt for the meat as long as they have the biggest "rack") …trying the old fear tactic of they even prey on small children, how many have you lost? How many do your really and truly know of being eaten by the big bad wolf (or other predator) let me guess, none.
People lose pets because they let them roam, keeping dogs and cats home is the safest thing for them and for the wildlife as roaming packs of dogs and the lone hunting domestic cats kill more wildlife and spread more disease that any of the predators you fear so much.
AlexCoe
2.3 / 5 (3) Mar 09, 2014
I'm sure Pediopal and Sinister1812 are vegans since they take that whole bent. Those of us who are honest omnivores that are honest about it and hunt or fish know better and put or money where our mouths are. We are the ones putting the money into the preservation and upkeep of wildlife and wild places through our excise taxes and license fees. We don't just buy memberships and calendars once a year we actually spend time, money and effort in the causes. Things like remote guzzlers that provide water and shade for desert sheep and birds in areas where it's a rare commodity.
It's far to easy to point your finger at us, who harvest and use nature as a part of our integrated natural lives and make all kinds of claims that are prejudiced, naive and simple minded without listening to the wisdom of our time spent in understanding and nurturing our preferred species of food.
Do you say idiotic things of farmers and ranchers who provide you with your plastic wrapped meat and fruit?
crabjack
2.3 / 5 (3) Mar 10, 2014
You have a point, AlexCoe, about having to eat and having a right to food, but what you said about "natural lives" is way off base. We became wholly separated from that whole nature thing when we started hunting with guns, or even bows. If you want to claim to be an integral part of nature, hunt with your speed and your strength and your cunning, not your guns. That way you will capture the weakest and sickest, and cull the herds rather than randomly killing, or worse, slaughtering the strongest for the prize, and weakening the community and the species.
And your "wildlife guzzlers": unless they are replacing a water source that recently disappeared, they are more likely to have a negative impact on the area you put them in.
Modernmystic
1 / 5 (2) Mar 10, 2014
Deer proliferation disrupts a forests NATURAL growth? Are these Jesus Deer? Vampire Deer? Are they super natural? People should learn to use language and concepts before they become journalists or conduct scientific research.

This kind of "thinking" is the problem with modern ecology. Everything is a problem and NOTHING is natural so EVERYTHING is worthy of a grant....
Modernmystic
1 / 5 (3) Mar 10, 2014
Further proof that we can't tamper with our environment. This was happening in Yellowstone until the wolves were re-introduced. Now everything, including vegetation and the river, are in beautiful balance.


BAWWHAHAhahahahahahahahahhahahah!!!!!!!

Where do you live? New York? There is no such thing as balance in nature, it's a human fiction. The only thing in balance are wildlife managers bank accounts. We have a few hundred more wolves and tens of thousands of fewer deer, elk, and moose. The wolf reintroduction has been an ecological disaster. The Canadians GIVE away permits to kill grey wolves because they are a blight on the ecosystem.

Oh and the thousands of herbivores slaughtered by wolves are LEFT on the field, not eaten, and it's NOT just the sick and young that are killed. Wolves kill off entire herds routinely. You should live 50 to 100 miles outside Yellowstone before you believe all the propaganda and BS spun by the forest service....
crabjack
3 / 5 (2) Mar 10, 2014
Modern: probably.
Mystic? Not a chance!

Where do you get your (mis)information, Dude?
Modernmystic
1 / 5 (2) Mar 10, 2014
Modern: probably.
Mystic? Not a chance!

Where do you get your (mis)information, Dude?


From my back yard...dude...
Modernmystic
1 / 5 (2) Mar 10, 2014
For the edification of the community...

http://rmefblog.b...cts.html
Modernmystic
1 / 5 (1) Mar 10, 2014
So? That is the risk they take. There are areas with wild animals. They shouldn't be wiped out everywhere because people choose to live and farm there, when it's not their territory. I agree with protecting your life and stock. But that's a bit like going out into the African wilderness and shooting lions, when I am in their territory.


What makes it "their territory" any more than anything else? Because YOU decide it is? Because that's the way it's been? Nature changes, species move into territory and move out, rise and fall. What you're talking about is YOUR values vs. another human beings values. Nature doesn't know the word "should" or "shouldn't"...that's entirely a human thing.
Sinister1812
5 / 5 (1) Mar 10, 2014
They did a study of the impact of wolves on Yellowstone not too long ago...
http://www.youtub...5OBhXz-Q
Modernmystic
1 / 5 (3) Mar 10, 2014
They did a study of the impact of wolves on Yellowstone not too long ago...
http://www.youtub...5OBhXz-Q


Interesting, but there's nothing wrong with the way it was...or the way it is now for that matter. It's just different. It suits some people to have them there and doesn't others. Some people would rather have more (MUCH more) elk, deer, and moose and some people would rather have a few more wolves at the expense of those other populations. It's simple values. As someone who actually lives in the state we're talking about I'd say mine are more relevant than yours. Make your arguments all you want but make them to ME, don't appeal to the tooth fairy, God, or that other fiction that the environmental religion worships..."mother nature".
crabjack
3 / 5 (2) Mar 10, 2014
So in your back yard you have seen children carried away by wolves, whole herd of deer slaughtered and their carcasses left to rot? Nothing like that has ever been documented. And your link is to a blog by and for elk hunters, who care only about having a lot of animals to hunt and don't care squat about environmental balance (yes there is balance in nature, if you deny that - I don't even know how to finish that statement, it's just inconceivable that anyone could not understand that).

It has nothing to do with values, it's ecology. If you un-balance ecology the whole ecology will collapse. We've seen it time and time again. Human values are meaningless here, unless and until those values come from intelligence, knowledge, and understanding.

Oh, and a large population of herbivores, what you call game, *will* destroy a forest or a grass land or a marsh, or wherever they live.
Modernmystic
1 / 5 (3) Mar 10, 2014
So in your back yard you have seen children carried away by wolves, whole herd of deer slaughtered and their carcasses left to rot? Nothing like that has ever been documented.


Actually both have been.

http://www.kboi2....671.html
http://en.wikiped...d_Gender

And the anecdotal evidence from people who don't work for the game and fish is REPLETE in this State. It's very common for wolves to kill and leave carcasses to rot either for sport and to teach their young.

And your link is to a blog by and for elk hunters


So don't confuse you with the facts? Did you see the State produced stats on the aggregate Elk population?

yes there is balance in nature


Prove it. Define it and demonstrate it. I'll show you your definition is totally subjective and man made. There is nothing "balancing" anything your god doesn't exist...
Modernmystic
1 / 5 (3) Mar 10, 2014
Here's an article from a Montana News agency....unless they're shilling for hunters those numbers are spot on...

http://trib.com/l...0c4.html
crabjack
3.7 / 5 (3) Mar 10, 2014
Here's an article from a Montana News agency....unless they're shilling for hunters those numbers are spot on...

http://trib.com/l...0c4.html


So the number of elk in a certain region is declining. That's not necessarily a bad thing! It's that balance thing....

And it has nothing to do with god. I have NO idea where that came from.
Modernmystic
1 / 5 (2) Mar 10, 2014
So the number of elk in a certain region is declining. That's not necessarily a bad thing! It's that balance thing....


Well it all depends upon who you ask doesn't it...it's that "you don't have a corner on the truth or what's right thing".

The Elk numbers weren't "out of balance" (whatever the hell that means) before the wolves they were simply higher. Most people who actually LIVE here appreciate that more than having wolves around. Where do you live?