Amur Corktree

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JHarkness
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Amur Corktree

Post by JHarkness » Wed Sep 05, 2018 8:29 pm

The Amur Corktree is yet another invasive species threatening our forests, it displaces native trees and has been known to stunt the growth of, or even kill, native trees by means of a toxin in it's roots, as far as I'm aware the toxin has not yet been identified. It's sugar-rich berries are a favorite of many bird species but have extremely low nutritional value, many migrating birds feed on it's berries and it's feared that an increase of the species could impact native birds drastically. Perhaps even worse is that they've been shown to have a relationship with several species of invasive Asian earthworms, one in which both species benefit from eachothers presence. Most people love the tree as an ornamental and continue to plant it readily. Somehow a couple showed up on my property in the 1980s, fast-forward to 2017 and there were two dozen mature trees, I'm now fighting aggressive new sprouts from the cut stumps and hundreds upon hundreds of seedlings....


I did a search here on the BBS and found that all but one post on the species were from me, so I figured I'd ask if anyone here is familiar with the species? I fear that it's introduced range is much more significant and that it's more of a problem that is currently thought, presently the closest known infestation of them near me is over 80 miles away, so if they've managed to get here from there, why can't they be everywhere in between? That's a scary question. Perhaps the most disturbing thing about them is that they are extremely adaptable and can handle everything from extreme cold to prolonged drought, supposedly they have the potential to range from the northern forest-boreal forest transition south to the southern US and west all the way to the Sierra Nevadas and even into southern and southwestern Alaska, on top of their potential range, they are incredibly shade tolerant and can (and do) get established in mature forests. To say that they should be a species of concern is an understatement.


A more detailed post on the species including photographs of the trees will follow within the next few days.
"Be not simply good; be good for something." Henry David Thoreau

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Lucas
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Re: Amur Corktree

Post by Lucas » Thu Sep 06, 2018 3:14 pm

Wow bummer.

I knew Amur corktree was bad but now it seems really bad. It is planted in town here.

Another of the endless threats to the woods here. I am so glad I don't have your invasive issues.
We travel the Milky way together, trees and men. - John Muir

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JHarkness
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Re: Amur Corktree

Post by JHarkness » Thu Sep 06, 2018 4:47 pm

Lucas,

It is awful how much it's used as an ornamental, isn't it? When I first identified it and searched for it all I could get were nursery sites where I could buy them and sites talking about how adaptable they are and praising their "benefits", one site even claimed that it needs to be used more as an ornamental because of it's adaptability, it took me days to find a single article on it's invasive tendencies, which, by the way, I would consider similar to tree-of-heaven if it were shade tolerant, the only good side to it is that it can't resprout from burried roots. I'm not sure whether it's good news or bad news, but I believe that I found the seed source for my trees, it just so happens that a lot of excotic trees were planted in an old farmfield as part of a reforestation effort, I couldn't find any evidence to what the trees were that were planted, but looking at the site on google earth, their foliage, bark color and limb characteristics certainly look like corktree, they're also just old enough to be the seed source of my trees. The good news? They're on DEC land so if that's what they are, I'm sure they will be removed. The bad news? They're along a river and it's been documented that corktree berries are frequently dispersed in streams and rivers, that means the whole watershed could potentially be invaded by them below that point. I'll be paying a visit to the site soon and will certainly post about it here.
"Be not simply good; be good for something." Henry David Thoreau

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JHarkness
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Re: Amur Corktree

Post by JHarkness » Mon Sep 24, 2018 11:00 pm

Here's the followup to my earlier post, apologies for the delay. I've been doing a survey of all the invasive plants on my property and found an additional mature corktree as part of that to photograph for this purpose.

Basal area of pole-sized somewhat mature tree.  Bark will become slightly rougher with age but retains the same "corky" appearance.  Note the bright yellow inner bark, probably the best way to identify the species.
Basal area of pole-sized somewhat mature tree. Bark will become slightly rougher with age but retains the same "corky" appearance. Note the bright yellow inner bark, probably the best way to identify the species.
Leaves of same tree, amur corktree has large opposite compound leaves with simple leaflets.  It is a documented ELP and deer will readily browse seedlings and saplings before leaf out and after leaf fall of native trees.  Often do not lose leaves until first hard frost.
Leaves of same tree, amur corktree has large opposite compound leaves with simple leaflets. It is a documented ELP and deer will readily browse seedlings and saplings before leaf out and after leaf fall of native trees. Often do not lose leaves until first hard frost.
Large mature corktree cut in September of 2017, tree is approximately 1.5' DBH and 75' tall.  40 years old at time of cut.
Large mature corktree cut in September of 2017, tree is approximately 1.5' DBH and 75' tall. 40 years old at time of cut.

Corktrees stump sprout incredibly aggressively following cutting, I've let one grow back this season to document it's growth and it has achieved about 14' of height since it started growing in June, I only observed mortality of one cut corktree. I noticed that they don't seem to root sucker, so I decided to girdle some of the stumps and standing trees down to where the root flare meets the ground, this has worked extremely well, I've seen no survivors of this method so far, this has allowed me to completely eradicate one infestation of them here. So, the good news is that they can be killed easily, the bad news is that they produce huge seedbanks, seed can remain viable for up to eight years as well and seem to germinate when a parent tree is harmed, I observed very little regeneration of the species prior to cutting the mature trees last fall, seedings are springing up everywhere now though, it seems to be that they're somehow connected to mycorrhizal networks even as seeds and were aware of the harm caused to their parents, I've documented seedlings up to a half mile away from their seed sources. Disturbingly, these are incredibly shade tolerant trees. I've even seen them successfully grow in unthinned Norway spruce plantations that shade out everything but the most shade tolerant of forest floor plants.


Another concerning factor of the species is that cut logs can root even in fairly dry conditions, several of the logs from last fall started growing new trunks this spring and I noticed upon closer inspection that they were rooting as well, rolling them over so that the roots dried out seems to stop this, but it is nonetheless concerning.
"Be not simply good; be good for something." Henry David Thoreau

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Lucas
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Re: Amur Corktree

Post by Lucas » Thu Sep 27, 2018 11:37 am

Amur Corktree is Nasty stuff.


Click on image to see its original size



Click on image to see its original size

I said before I was glad I didn't have to deal with your invasives. Well, shortly after I found Glossy Buckthorn next to one of my oaks. I was very bummed out.

I pulled it out Tuesday without thinking. I had roundup and should have sprayed the stump. I sprayed the root hole as a backup then thought later that may kill the oak. Dumb moves.
We travel the Milky way together, trees and men. - John Muir

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JHarkness
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Re: Amur Corktree

Post by JHarkness » Thu Sep 27, 2018 12:44 pm

Lucas,

Glossy buckthorn is awful, I know of a nice forest out in eastern Massachusetts with some respectable white pines and red oaks, I noticed that there was little regeneration and the herbaceous layer was lacking, but there was a well developed understory, after a while I realized it was all one kind of shrub, which turned out to be glossy buckthorn. I would say that it had completely over run the entire 30 acre site. I'm glad I don't have it, but I do have European buckthorn, which is proving a problem in open and disturbed sites. I hope your oak is okay, and good luck dealing with the stuff, keep an eye out, there probably is more.
"Be not simply good; be good for something." Henry David Thoreau

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