Invasive Species Highlight: Tree of Heaven (Ailanthus altissima)

Tree-of-heaven (Ailanthus altissima) also known as Ailanthus, Chinese sumac, and stinking sumac is a rapidly growing, deciduous tree native to a region extending from China south to Australia.

Background:

It was imported into the Philadelphia area around 1784. Immigrants introduced tree-of-heaven into California in the 1850s. It was initially valued as an urban street tree and was widely planted in the United States particularly around the Baltimore and Washington D.C. area. From these areas tree-of-heaven has spread and become a serious weed in urban, agricultural, and forested areas.

Description:

Tree-of-heaven can reach heights of 80 feet and grow to 3 feet in diameter. The tree has smooth grey bark, stout, blunt, chestnut brown twigs, and a long compound leaf ranging in length from 1-4 feet with as many as 30 leaflets. The leaflets are smooth-edged except for 1-3 teeth near the base. Clusters of twisted papery seeds, called samaras, often hang on the trees over winter. The wood is soft, weak, coarse grained, and creamy white to light brown in color. All parts of the tree, especially the flowers, have a strong, offensive odor. Tree-of-heaven is often found growing in clusters around a “parent” tree as new sprouts grow from the roots.

Look-A-Likes:

This species is often confused with some of our native species having compound leaves with many leaflets such as; sumac, black walnut, and butternut. The leaf edges of all of these native trees have small teeth (serrations) while those on tree-of-heaven are smooth. The foul odor produced by the crushed foliage and the scraped bark is also unique to tree-of-heaven.

Site:

Adapted to a wide variety of soil conditions, tree-of-heaven quickly colonizes disturbed areas. Having long been established in some urban areas, it is now found growing in fields, roadsides, fencerows, woodland edges, and forest openings. Tree-of-heaven has become an agricultural pest and may occur as sprouts that pop up from root fragments in recently tilled fields, or persistent thickets in rocky, untillable areas. In forested areas, disturbance created by storms, insect infestation, and timber harvesting can open the way for tree-of-heaven to become established, often displacing more desirable native trees.

Spread:

One female tree-of-heaven can produce over 300,000 seeds in a year. These winged seeds are easily windblown and have a high-germination rate. This allows trees to colonize adjacent areas and invade forest interiors when canopy openings occur. Established trees constantly spread by sending up root suckers that may emerge as far as 50 feet from the parent tree allowing them to rapidly dominate sites. Root suckers as young as two years of age are able to produce seed. Tree-of-heaven also produces a toxin (referred to as allelopathic) in the bark and leaves which acts as a natural herbicide. As the toxin accumulates in the soil it inhibits the growth of other plants. All of these factors combine to make tree-of-heaven a very successful invasive plant.

Tree-of-heaven seedlings

Mechanical Control:

Using only mechanical methods for controlling tree-of-heaven may be counter-productive since the tree responds to cutting and girdling by producing large numbers of stump sprouts and root suckers. Stump sprouts can reach heights of 10 feet in one growing season. Hand pulling of young seedlings, not root suckers, may be effective when soil moisture is high and the entire root system is removed. However, small pieces of root are capable of generating new shoots.

Biological Control:

In 2009 a fungal wilt disease was discovered causing unprecedented wilt and mortality of tree-of-heaven in south-central Pennsylvania. The pathogen is currently being researched by Don Davis at Penn State, scientists from the U.S. Forest Service, and others. To date, the wilt disease has been reported in three states; Pennsylvania, Virginia, and Ohio. The wilt disease is caused by Verticillium nonalfalfae, formerly classified as V. albo-atrum. In field studies performed by Penn State University (Schall and Davis) all tree-of-heaven seedlings and canopy trees inoculated died within 3 months.

If V. nonalfalfae proves to be widespread, it may represent a natural biocontrol for tree-of-heaven. Since USDA APHIS evaluates and regulates new potential biocontrol agents on a state-by-state basis, it is important to document each state where V. nonalfalfae is killing tree-of-heaven, so that in-state inoculum can be used for biocontrol efforts. This will simplify the regulatory process. Pending further studies, including a risk analysis, Verticillium wilt of tree-of-heaven may be available as biocontrol agent. Currently no inoculum is available for public distribution. To assist you in locating trees that may be infected with Verticillium wilt a photo guide has been developed.

Chemical Control:

Typically the most effective approach for controlling tree-of-heaven involves the use of herbicides applied to foliage or frill (downward angled) cuts in stems. Foliar sprays are the method of choice where tree height and distribution allow effective coverage. Treatments can be applied with equipment ranging from truck-mounted high pressure sprayers to backpack sprayers. It is important to cover all portions of the canopy. Difficulties arise when trying to get adequate coverage of tall plants while protecting surrounding vegetation. To be most effective apply sprays in later summer or early fall, prior to the onset of fall color. This timing will limit re-sprouting from the root system. Herbicide mixtures containing glyphosate alone or in combination with metsulfuron methyl, triclopyr (amine), or imazapyr will provide control when applied to the foliage.

Control using a hack and squirt is effective if cuts are spaced

Frill herbicide applications, referred to as hack-and-squirt where a hatchet is used to make downward angled cuts through the bark, are highly selective. The cuts must penetrate the bark into the living tissue or sapwood. The downward angled cuts produce a cupping effect to hold herbicide. Concentrated herbicide solutions are sprayed into cuts using a squirt bottle. This method can be used on trees of any size and is most effective if applied from late summer to early fall when plants move the herbicide to the roots. Space the cuts so that 1 inch of uncut living tissue remains between them. Make approximately 1 frill cut per inch of tree diameter. If the stem is completely girdled the herbicide will not move to the roots and the tree will likely re-sprout from the stump and roots. Herbicides containing glyphosate, imazapyr, 2,4-D & picloram, and dicamba provide effective control using the hack and squirt method.

For well established, high density infestations a combination of foliar and frill herbicide applications are most effective. The initial foliar application will control most of the shorter stems while the hack and squirt application is used as a follow-up treatment to control stems that were missed or were too tall for adequate coverage.

Basal bark herbicide applications provide an additional method for treating tree-of-heaven with little or no non-target injury. Using a low volume spray wand, the herbicide and oil solution is applied completely around the stem from the ground line up to a height of 12-18 inches. To maximize herbicide translocation to roots, applications should be made during the same window as foliar and frill applications, late summer or early fall. Herbicides containing the ester formulation of triclopyr used in combination with imazapyr in oil are recommended for this type of application. Triclopyr ester alone has been shown to not translocate well in root systems and will likely require follow-up applications to root sprouts.

For safety reasons where the tree needs to be cut and removed from the site, the preferred approach is to kill the tree using one of the above mentioned methods prior to cutting. Cutting tree-of-heaven and treating the stump will prevent stump sprouts, but will have little impact on root sprouts. No matter the time of year, if the tree has to be cut it is better to treat the stump than not. When using water soluble herbicide solutions spray or paint the living tissue of the stump immediately after cutting. Glyohosate based herbicides in a 50% solution with water work well for this application.

Well established tree-of-heaven stands can only be eliminated through repeated efforts and monitoring. Treatments often only reduce the root systems making follow-up measures necessary. Small portions of the original root system that survive can quickly re-establish new trees. Persistence is the key to success.

Additional references:

DCNR Invasive Plants In PA: Tree-of-heaven

Penn State Wildland Weed Management: Tree-of-heaven

Plant Conservation Alliance: Tree-of-heaven

Habitat Hero: John Hoover

Landowner, John Hoover

John Hoover, a Centre County Pennsylvania forest landowner, in fact, John was Tree Farmer of the Year for Pennsylvania in 2011, is featured as a “Habitat Hero” by the USDA Natural Resource Conservation Service (NRCS). Habitat Heroes are America’s farmers, ranchers, and forest landowners who demonstrate how wildlife and working lands can prosper together. They are caring for wildlife while producing food and fiber the nation needs to strengthen rural communities.

John’s Habitat Hero story is by the Appalachian Mountains Joint Venture (AMJV), one of NRCS’ conservation partners working to help private landowners adopt conservation measures that benefit forestry and agricultural operations while helping birds and other wildlife species. John is working with the NRCS, AMJV and other partners including the American Bird Conservancy to manage for both golden-winged warbler and cerulean warbler habitat through Working Lands for Wildlife and the Regional Conservation Partnership Program.

John says walking through his Pennsylvania forest is like walking through rooms of a house. "Each room is different and has its own use," he says, referring to the different age classes of tree stands on his property. Some are old. Some are young. Over the years, John has learned a diverse forest can yield better timber while benefiting wildlife.

Click here to view an interactive version of the feature presentation.

Habitat Hero: John Hoover

Story by Matt Cimitile, Appalachian Mountains Joint Venture

View from Hoover's property

Since 1866 – a year after the end of the Civil War – John Hoover’s family has owned property in Centre County, Pennsylvania. Over the decades, the largely forested property became subdivided and boundary lines and titles blurred with most of the land going into disuse. Nearly 40 years ago, when John inherited a portion of the original property, he figured the best way to unclutter boundary lines and make better use of the land was to buy as much of the surrounding forest and original deed as possible.

“I’m a mechanical engineer and mostly dealt in new product design and development,” said Hoover. “And this land issue was a challenge, a unique problem that I wanted to solve. It took me more than a dozen years but I ended up bringing together 600 acres under single ownership.”

Hoover currently lives in Connecticut but plans to retire soon and relocate to a home next to his forest.

The land is situated in a corridor that connects the 5,900-acre Bald Eagle State Park with 4,000 acres of State Game Lands. Its location makes it a potentially valuable commodity as a linkage for wildlife and natural resources, a vital connector between two protected areas.

“Something that occurred to me after I acquired all this land, is that I didn’t really have a goal in mind for the property itself,” said Hoover. “So, I talked with a forester, and he told me about the benefits of harvesting trees for the health of the forest and as a way to enhance game species such as deer, turkey and grouse.”

The first harvest, which cut and thinned out aspen trees, saw a dramatic increase in game species on the land. Six more harvests followed. Each targeted at a specific section of the property.

Each successful harvest helped his bottom line by selling timber while diversifying both his forest and the species of wildlife that visited it.

“As I walk through the land, I look at it as entering different rooms of a house. Each room is different and has its own use," Hoover said.

"The property is subdivided like that, with individual smaller and uneven aged tracts created by forest harvests conducted at different times. Some with really intense management, and others where I have not done anything."

Getting Help

Hoover has reached out for help along the way, including the Appalachian Mountains Joint Venture (AMJV), USDA's Natural Resources Conservation Service (NRCS), American Bird Conservancy, Pennsylvania Department of Conservation and Natural Resources, Pheasants Forever and others.

Through these groups, Hoover was able to get technical and financial assistance to help plan and implement forest management practices. With this help, he has not only improved his bottom line, but he has been able to create top-notch wildlife habitat.

Right now, Hoover is participating in two conservation efforts.

golden-winged warbler

The first is Working Lands for Wildlife, an NRCS-led effort to help private landowners like Hoover restore declining habitats to help at-risk species. In the Appalachians, NRCS is helping landowners manage for young forests to benefit the golden-winged warbler and other species.

Golden-winged warblers in the last 45 years have suffered one of the steepest population declines of any songbird. Since the 1960s, the young forests that the bird uses for nesting has decreased by 43 percent in the Appalachians.

Working with foresters and biologists, Hoover developed a management plan and then went about creating young forest habitat on his property to provide ideal foraging space, shelter, and nesting sites for a host of wildlife that depend on this type of ecosystem.

cerulean warbler

Meanwhile, Hoover is also participating in the Cerulean Warbler Appalachian Forestland Enhancement Project, which is led by AMJV and funded through NRCS' Regional Conservation Partnership Program. The regional project seeks to implement active forest management on private lands to improve 12,500 acres of forest habitat and 1,000 acres of reclaimed mine lands for the cerulean warbler, offsite link image     which like the golden-winged warbler, has suffered from population declines.

Cerulean warblers prefer older forests with canopy openings, which like young forests, are not common in Appalachia. Hoover is currently thinning out dense mature forest areas that contain tall deciduous trees to create open canopies and gaps to allow sunlight to reach the forest floor, promoting the growth of saplings, shrubs, and other vegetation in the forest understory.

Multiple Benefits

In addition to helping the golden-winged warbler and cerulean warbler, managing for healthier forests also leaves the best trees on the tract: tall, straight, and defect free. They will be the seed source for the next trees that make up the future forest, Hoover said.

“I am blessed and lucky to have a good chunk of land that allows me to do different activities on different sections,” said Hoover. “I’m able to focus on hardwood development in one area that doesn’t benefit wildlife as much but benefits trees, and in other areas I can focus management that is best for bird and other wildlife habitat.”

“The mix of all this activity creates various forest stages on the property that works out very well for wildlife and the overall health of the land.”

Want to Learn More?

To learn more about assistance opportunities, landowners should contact their local USDA service center.

You can meet some of the other producers managing for top-notch wildlife habitat on their working lands by visiting the NRCS Habitat Hero web page.

Which Trees to Cut.....And Why

I had the below article sent to me earlier this month.  I thought it would make a great follow-up to some earlier posts on harvesting I made that received a lot of interest.

The first article I posted on April 27, 2016 entitled "Why the Forestry Profession Should Harshly Criticize High Grading" by Dan Pubanz.  Dan is a consulting forester out of Wisconsin.  His article first appeared in the winter issue of the National Woodlands magazine.

The second article, posted June 21, 2016, was a great follow-up written by Dr. Jim Finley, Penn State, Department of Ecosystem Science and Management. Jim's article was called "Describing Sustainable Timber Harvesting: What Do Words Mean?"  In the article Jim describes sustainable timber harvests as focusing on the residual trees you leave and/or the regeneration you establish.

The third article, posted November 2016, was a news story posted by the Pittsburgh Tribune about a logging job that was taking place in the Lower Burrell.  The article includes an interview with Tom McQuaide, a forestry consultant in Pennsylvania, where Tom compares a forest to a garden. He states, "you pick the mature fruit."

Now on to the most recent article, this one is a radio interview produced by West Virginia Public Broadcasting.  The person being interviewed is Kelly Riddle, a procurement forester with Allegheny Wood Products.  Give it a listen (6 minutes) or read the text I provided below.  Let me know what you think?  Was Kelly on track with his answers?

Timber Management: Which Trees To Cut and Why

By Jean Snedegar • Jun 28, 2017

In the next part of our occasional series on the timber and forest products industry, we find out how timber cruisers -- or procurement foresters -- help landowners decide when to harvest trees in a timber stand, which trees to take and which ones to leave behind. 

Photo: Jesse Wright / West Virginia Public Broadcasting

Independent producer Jean Snedegar joined Kelly Riddle, of Allegheny Wood Products, in early June at a privately owned forest near Kingwood, in Preston County.

“One of the interesting things about being a forester is that not every stand or site is the same,” he said. “You know, you walk to the other side of the hollow or the other side of the ridge, the site conditions change, the species change, the understory changes, and so it’s kind of a new canvas any place that you walk.”

Riddle said deciding on which trees to take depends on several factors. “One that we look at is, first of all if we’re dealing with a private landowner, what their goals and objectives are. Second, we look at merchantability of the trees. What I mean by that – is it useable for a commercial process – whether it be for saw timber, or pulp wood or some other product? And then we look at the overall health of the stand and the trees,” he said, looking around a stand of trees he’d marked.

“This stand is composed primarily of yellow popular and soft maple, with some scattered oaks in here. I look at the size of the trees as an indication of whether they’ve reached their biological maturity or financial maturity,” Riddle said.

“Generally, once a tree reaches about 18 inches in diameter – and this depends on the site it’s growing on and other factors – it’s probably reached its financial maturity – meaning, if you harvested that tree, gained the revenue from that tree, reinvested in something else, you could do better from a financial standpoint than if you left that tree to grow. Biologically, the tree may have 50 more years that it could live and produce wood and other values. “The other thing we’re trying to do is create optimum growing space for the residual trees that you have.”

Age and Condition

Riddle walked up to tree in the stand. “This tree happens to be a yellow poplar – 24 inches in diameter. And given the age and condition of the stand I marked this tree because it’s mature, it’s ready to be harvested. And there are other trees adjacent to it – this hard maple for instance – that is one of the trees that I want to be the next stand,” he said. “So, by taking this yellow poplar out, it creates product for our sawmill and it also creates space for that maple to grow and be part of the next stand.”

When to Revisit a Timber Stand

Riddle said he typically goes back to any given stand about every five years to re-evaluate the growth and response since the last thinning.

“We typically look at a 12-15 year cycle of re-entry to harvest. In these stands that are even-aged – they were all re-generated about the same time – you can do that three or four times depending on the stands, the site and the characteristics of how good a site it is,” he said. “And then, towards the end of that 80 – 100 year period, you have to look at regeneration, maybe in the form of a ‘shelter wood’ type harvest, and get a more uneven aged management distribution.”

Riddle said a shelter wood-type harvest is a little more intensive harvest where you have fewer trees per acre that are remaining.

“It allows full sunlight to reach the forest floor, which most of our species here in Appalachia need in order to regenerate. All of our poplar, cherry, all of our oaks are shade-intolerant and they will not regenerate without that full sunlight, so it’s a requirement to initiate the next stand,” he said.

Signature Marking

Walking through the forest, Riddle pointed out the various types of marks he has put on the trees. These marks tell the loggers which trees to cut – and whether they should go to the sawmill nearby or the pulp mill in Luke, Maryland.

“Foresters have their own signature way of marking. If I have a tree that’s primarily a saw timber tree, I’ll just put a dot, whereas a lateral slash may mean that there’s some imperfection in that tree, or that it’s a pulpwood, or a cull type tree. A full cull tree would be an ‘X’,” he said.

‘Bad Management’

Riddle said there are some misconceptions about what “bad” management is. “Sometimes you have something that doesn’t look aesthetically pleasing and people might consider that to be bad management,” he said. “As foresters, we know that that’s not necessarily the case. There are some fairly intensive harvests where most of the material is removed that can be very good management, though it’s not aesthetically pleasing.”

Riddle said as a forester now for more than 30 years, the worst thing we can do is high-grade timber stands. 

“That was a harvest philosophy where all you took was the best and left only the low-grade, non-commercial species – something like these soft maples that are damaged or have issues already. And all you were taking was the ‘cream’, so to speak,” he said. “If you do that more than one thinning cycle, then you’ve left a stand that has trees – it might look fine – but from a commercial standpoint, it has no value to the landowner.”

Riddle said we have a great resource in West Virginia as a whole. “We say that we’re trying to provide a resource for today and manage it for future generations,” he said.

This series is made possible with support from the Myles Family Foundation.

Credit Jesse Wright / West Virginia Public Broadcasting

Editor's Note: This story is part of an occasional series from independent producer Jean Snedegar about the timber and forest products industry here in the Mountain State -- from seedlings to final products.