Archive #54 from Online Seminars for Municipal Arborists
January/February 2014
Sections
Natives versus Cultivars
Edited by Len Phillips
How do you define which species are native to an urban area where the built environment has erased the native soil, understory plants, and wildlife that characterize a native ecosystem? Just about every arborist I know has an opinion about growing cultivars instead of native trees. Cultivars are cultivated varieties that have been selected because they have different characteristics from a species. Cultivars, according to definition are stem grafted onto species rootstock, while clones would be selections growing on their own roots. This article will not be including clones in the comparisons below. To be perfectly clear, Red Maple, Acer rubrum is a tree native to the eastern half of the United States, while Red Sunset® Maple, Acer rubrum 'Franksred' is a cultivar that can be found growing from coast to coast in the US. I would like to offer the following comments with the hope that your opinion on this subject will be based on some facts.
Genetic features
Native – Uniform genetics in all native trees of a species being similar but having different minor characteristics.
Cultivar – Called genetically defective from the species by some experts. Cultivars are genetically identical and many arborists feel they are more desirable than the native because you can rely on the desirable characteristics of form, flowers, pest resistance, etc. being identical in all the trees of a particular cultivar. In a formal landscape, all the trees would end up with an identical shape, without pruning.
Suitable for diversification
Native – Despite the uniform genetics of a native tree species, it is not enough to be considered diversified when dealing with pests and diseases. One reason to use natives is that the pest would be known and tolerated by the species.
Cultivar – Cultivars that have been found resistant to particular pests and diseases that attack the native trees can be used for replacing the entire urban forest and maintain proper diversification.
Long-term survival
Native – These trees were growing fine without any human interference and will continue long after humans have left the planet. They breed successfully in their home range without assistance.
Cultivar – They might become extinct without human intervention, support, and management. This would be okay because they were developed to survive in a human environment. Without humans, there is no need for these trees and the forests can revert to native species.
Growth patterns
Native – These trees have a natural form that is somewhat predictable, with minor variations in size and shape.
Cultivar – A tree's special form is one reason the tree is cross bred or selected to become a cultivar. For example, Endowment Maple, Acer saccharum 'Morton' was selected from a field of sugar maples Acer saccharum for its uniformly columnar shape.
Invasive species
Native – Invasive trees tend to be trees that have aggressive growth and reproduction functions. They are invasive because of excessive seed deployment or a high number of root suckers. In many locations, black locust, Robinia pseudoacacia is an invasive tree because of its root suckers that can destroy a hardscape or choke out understory plants.
Cultivar – Most cultivars, especially the newer introductions, do not produce viable seed and are not invasive because they must be grafted on to rootstocks, which limit their ability to spread by root suckers. Bessoniana Locust, Robinia pseudoacacia 'Bessoniana' is a non-invasive cultivar.
Planting locations
Native – Native trees grow best in native soil. Native trees can adapt to growing in poor sites because among the seedlings there will often be one seedling whose specific genotype will tolerate and grow in the poor site.
Cultivar – Cultivars cannot adapt to poor sites unless they were selected because they were found growing in a poor site. Cultivars are often selected because they tolerate urban soils better than the native parent. Since the soils in our cities seldom resemble native soil, cultivars selected for their urban soil tolerance are clearly the best choice for planting in the city. Always grow the right tree in the right place. For example many cultivars of red maple such as, Autumn Flame Maple, Acer rubrum 'Autumn Flame' have been selected from trees growing in swampy areas. These trees are very tolerant of compacted, wet soil and soil low in oxygen; hence they make very desirable street trees (along with being one of the hardiest of the red maples and being the first to turn a brilliant red in the fall).
Unique features
Native – Native trees are seldom known for having unique features but they do provide a stable appearance to the landscape and a stable ecosystem for the flora and fauna that they support.
Cultivar – Cultivars are often selected because they have unique features dealing with forms, special flowers, large fruits, unusual leaf color, etc. Crabapple, Malus spp. is a good example of trees selected for their bloom, fruit color, wildlife food, and disease resistance in certain cultivars.
Flower production
Native – Most native trees have normal single flowers that provide pollen and fruit for native insects and wildlife.
Cultivar – Cultivars are often selected because of outstanding flower production. However, sometimes a certain floral characteristic has bred the nectaries out of the plant. English tea roses and double flowers are a good example. This can have deleterious effect on our native pollinators and wildlife.
Uses in the urban landscape
Native – Use natives in an area of suitable, excellent soil, such as a garden or forest, to provide a uniform appearance, texture, or leaf color. Big Tooth Maple, Acer grandidentatum is a good example of a small round tree suitable for most native landscapes.
Cultivar – Used as a street tree as well as a garden or landscape specimen, Rocky Mountain Glow® Maple, Acer grandidentatum 'Schmidt' is a good example of a cultivar that has intense autumn color and thrives in an urban landscape.
Disease resistance
Native – Native trees have good resistance to common diseases through a long association with native diseases and through the genetic diversity in any long standing breeding population of native trees, but they may not be able to withstand an exotic or a recently introduced diseases like Chalara fraxinea in Europe and more recently in England.
Cultivar – Many cultivars have been selected because they resist a particular disease. A good example is the Stellar Dogwood series of trees that are resistant to the Dogwood anthracnose which is killing the native eastern U.S. Dogwoods. Stellar Pink® dogwood, Cornus x 'Rutgan', is free of the disease and a very popular replacement.
Pest Resistance
Native – Native trees with good resistance to certain pests are acceptable, but many exotic or introduced pests can be fatal. Some naturalists consider this a desirable feature because the pest contributes to the natural food chain. For example, the woodpecker has developed a preference for the bronze birch borer found in many native white barked birches.
Cultivar – Many cultivars have been selected because they are resistant to a devastating pest. A good example might be the Heritage® Birch, Betula nigra 'Cully' which was selected for its resistance to the bronze birch borer. What impact this may have on the woodpecker population is unknown at this time but as an apex predator it may just move to its next favorite food item.
Global Warming Survival
Native – Native trees are not likely to tolerate global warming stress. The warming subjects the trees to increased disease and pest attacks. The genetic diversity of breeding native populations may somewhat buffer that species against the worst effects of warming by favoring those in its population that can adapt to changing environmental conditions. The Amur Maple, Acer ginnala might be a good example of a tree that tolerates the cold in USDA Hardiness Zone 2 and will have to migrate even further north to survive.
Cultivar – Cultivars that have been selected from warmer climates will be better survivors. An example here might be the Red November™ Maple, Acer ginnala 'JFS-UGA' which is a Zone 4 tree that is heat tolerant and evolved from the heat of Georgia. However, cultivars will likely be from a narrow genetic base and as such, will not have the diverse genetic ability to adapt.
Water needs
Naturalists, such as the National Audubon Society, claim that cultivars will require much more water use than native trees. However, a sugar maple tree and a cultivar of the same size sugar maple tree will both require the same amount of water assuming all other aspects and the physiology of the two trees is the same.
Whether you prefer natives or cultivars, keep in mind that natives define the region where you live and provide the ultimate in sustainability because they breed and survive without intervention. Cultivars provide the diversity of amenity and interest to the landscape. Another thought to consider deals with municipal budgets and that the cost to plant and maintain a cultivar is almost always less than the cost to plant and maintain a native tree because the cultivar was bred to survive without intervention. A cultivar can be selected as suitable for a site, instead of needing frequent maintenance and pruning that might be necessary to maintain a group of native trees in the urban environment.
Sources
* Special thanks to Jay Banks and David Lloyd-Jones for their comments on this subject.
* Audubon at Home, “Plant Native Species”, National Audubon Society, Inc., 2013.
* Lloyd -Jones, David, “Tree Morphogenesis Book 1 Reduction Via Thinning” Kindle Edition, Chapter 8, 2013.
* Ramstad, Kristin and Cynthia Orlando, “Tree Choices: Native? Non-native? Invasive? The terms can be relative”, Oregon Department of Forestry Urban and Community Forestry Assistance Program, 2009.
Editor's Note: If you know of other reasons to use natives or cultivars, please click here to send an email with your comments. comments@on-line-seminars.com
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the .5 CEUs toward Certified Arborist or BCMA science credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to gibneyCE.com’. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
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All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website *SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
A Guide to Chain Saw Chain Sharpening
By Rip Tompkins
The chain saw is one of an arborist’s most important tools. A well-maintained saw with a sharp chain will help make the job run smoothly and safely. A dull chain causes both the saw and the saw user to work harder and actually makes the chain saw more dangerous and prone to kickback. Proper chain sharpening has become something of a lost art, as many users actually waste a lot of chain and cause the saw to cut poorly because of improper sharpening.
It is important to understand the different parts of the cutter tooth and how the chain is designed to cut. There are five parts of the cutter tooth that work together to make the chain cut properly.
One – the depth gauge
Often called a raker, guide, or drag, the depth gauge sits in front of the cutter tooth. The clearance from the top of the depth gauge to the cutter tooth sets up the thickness of the chip. Generally this is designed to be between 0.25 and 0.3 inch (6.35 – 7.62 mm).
Two – the working corner
This is the rounded corner on a semi-chisel chain and pointed (hence called the point) on a full-chisel chain. This working corner starts the cut. If it has been damaged, the chain won’t cut properly.
Three – the top of the tooth or the top plate
The top plate angle is the angle at which the chain is sharpened, usually 25 or 30 degrees. On many chains there is a line on the rear of the top plate. This is the witness mark, showing that the chain can be sharpened back to that line and still cut effectively. It is also parallel to the top plate angle and may be used as a filing guide.
Four – the bottom of the top plate or the chisel
The chain cuts by chiseling off a chip of wood. The chisel angle is normally between 45 and 60 degrees.
Five – the side plate
The side plate severs the chip and is angled often the same as the chisel angle depending on the type of chain and the filing technique. It is important to have a razor edge on both the side and top plates, with no nicks or shiny spots.
Round Filing
There are numerous ways and tools to sharpen chain, such as: bench grinding, using Dremel tools, round filing and square bit filing. We will focus here on round filing, but it is important with any sharpening technique that the user gets proper training with those specific tools in order to use them effectively.
While it is important to have a sharply defined point and sharp top and side plates, it is also important to try and maintain the same working angles on the various parts of the cutting tooth as when it was new. Some people suggest its better to increase the top plate angle to between 35 and 45 degrees; the chain will cut faster because there was less chain traveling through the wood. Experience has shown that this may help somewhat in soft wood but definitely not in hard wood. In addition, this technique exposes more of the point and thins out the side plate, making it much easier to dull the chain.
One of the hardest things to do when round filing by hand, is to hold the file in the in the proper position with 20% of the file visible above the tooth. This is necessary so that the chain is sharpened and the tooth angles are maintained. A common mistake is to put too much down pressure on the file, eventually putting the file under the tooth, creating a hooked tooth and changing the side plate and chisel angles. The chain will cut rough and hardly ever cut straight.
The opposite to this is pulling up and into the tooth with the file too much as you sharpen. This can flatten out the chisel angle and side plate angle leading to the chain not feeding into the wood and not cutting well. Learning to place the file on the tooth in the correct position during sharpening is very challenging physically and mentally. Therefore I have found that there are a few different filing guides that can make the job much easier.
Filing Guides
Before looking at these filing guides, let’s make sure we have the right tools. A vise is a nice way to immobilize your chain saw and allows you to sharpen with both hands on the file. A stump vise will allow you to easily file out on the job site. Make sure you know what size chain you have on your saw so you know what size file and filing guide(s) to use.
Most cutting in the tree-care industry is done with three different sizes of chain pitch. The pitch of the chain is the distance between any three consecutive rivets, divided by two. A three-eighth-inch (9.52 mm) pitch chain generally uses a 7/32-inch (5.56 mm) file, a .325-inch (8.25 mm) pitch chain uses a 3/16-inch (4.76 mm) file and a 3/8-inch (9.52 mm) low-profile chain uses a 5/32-inch (3.96 mm) file.
If you are using a file guide, make sure it is for the correct size chain. When filing, be sure the file cuts on the push motion and not on the pull stroke. Dragging the file back and forth will only dull the file. It is also important to file from the inside of the tooth out. This will lessen the chance of filings dropping down into the channel of the bar. Also, filing from the outside will chip the chrome on the side plate. File the tooth back until you get a nicely defined point and a razor-sharp top plate edge. If the leading edge is shiny, the chrome plating has been chipped off. It is important to bring the edge back until you get the dull chrome-plated finish along the edge. Generally, try to keep the file level when sharpening, as there is already an 8 degree angle on the tooth.
Oregon makes a chain-filing plate for the file to sit in. Simply lay the file plate on top of the tooth you are sharpening and it sets the file on the tooth in the correct position. Line angles on the top of the plate help you set up the proper filing angle. Another handy tool is the roller-guide. This sits on top of the bar/chain tooth. Push the file along the tooth with gentle strokes so that both rollers move. Once again this puts the file on the tooth in the correct position. I usually use the witness mark on the tooth to line up my filing angle.
After filing all the teeth, it is important to set the depth gauges. There are a number of different types of depth gauge plates; probably the easiest comes with the roller guide combo. Lay the plate on top of the filed tooth with the depth gauge protruding up through the hole in the plate. Take a flat file and file the depth gauge down to the plate. Now you have set the depth gauge to that tooth. While the best cutting occurs when all the teeth are the same size, because the chain is well balanced, the most important thing is to have each tooth sharp and have each depth gauge set to that tooth so all the teeth are taking the same amount of bite when cutting.
A very handy two-in-one filing guide is the Husqvarna Sharp Force guide. This unit uses both a round file and flat file and takes down the depth gauges at the same time you are sharpening the tooth. This is very useful for touch-ups out in the field. The Sharp Force tool must be used on a full complement chain, as the file guide rides on top of the tooth you are sharpening and the tooth in front of it.
Just when you thought it couldn’t get any easier, along comes the new Power Sharp precision saw chain sharpening system from Oregon. This system will allow you to sharpen your chain in as little as three to five seconds. For a closer look visit Oregon.
Any of these handy filing guides can help make sharpening a little less burdensome. Of course, a good sawyer who keeps the bar/chain out of the dirt will need to spend a lot less time sharpening their chain. A sharp chain will make the job easier and safer and allow the saw to do the work. A dull chain requires the operator to push harder on the saw, which leads to more wear of the bar and sprocket.
So, when using a chain saw, please remember to work safely, wear the proper Personal Protective Equipment and keep both hands on the saw, and make sure the chain is properly sharpened.
Rip Tompkins is a co-founder of ArborMaster
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the .5 CEUs toward Certified Arborist, Tree Worker Specialist, Utility Specialist, Aerial Lift Specialist, or BCMA practice credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to gibneyCE.com’. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website *SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Tree of the Seminar 54
By Len Phillips
Botanical Name: Acer griseum
Common Name: Paperbark Maple
Parentage: Native of China
Height: 20' – 30'
Spread: 10' – 30'
Form: Oval growth
Bloom Period: Spring
Flower: Sparse, greenish
Fruit: Samaras one inch to one and one half inches long
Summer Foliage: Bluish green in summer, trifoliate
Autumn Foliage: Bronze to red in autumn
Winter Color: Unusual bark provides winter interest, especially the contrast between the bark & snow
Bark: Young stems are brown to reddish brown, older wood cinnamon, exfoliation varies with each seedling.
Habitat: Introduced to US in 1901
Culture: Adaptable to wide range of soils and pH, best in moist well drained soil, tolerates clay, urban pollution, and dry conditions
Hardiness Zone: 4 – 8
Growth Rate: Slow, 5' in 10 years
Pest Problems: None
Storm Resistance: Excellent
Salt Resistance: Excellent
Planting: Transplants easily BR, B&B, and container, well-suited for CU Structural Soil planting
Pruning: Prune at planting and 3 years later to mature form
Propagating: Seed
Design Uses: Used as a garden specimen, good street tree for under wires
Companions: Use with Heuchera or Stachys as groundcovers
Other Comments: Easily pruned and transplanted, useful as screen or hedge planting, excellent urban tree, every tree has a different amount of exfoliation
Photo and Fact Sheet: J. Frank Schmidt & Son
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the .5 CEUs toward Certified Arborist, Utility Specialist, Municipal Specialist, or BCMA science credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to gibneyCE.com’. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website *SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Arborist Rope Care
Edited by Len Phillips
Regular inspection of arborist's rope is the only way to know when an arborist's climbing line or tree rigging rope is ready to retire. There is no set life span for a rope, because usage, shock-loading, dirt and grit, and even how the rope is stored will all affect the life span of the rope. The following will help an arborist get the most out of the ropes and know when it is time to replace them.
Rope Lifespan
Arborists' ropes must endure heavy loads, the potential of shock-loading, dirt, grit, weather, and abrasive working conditions. Some simple things to do to make sure the rope remains useful for as long as possible:
· select the right rope,
· be aware of the Working Load Limit (WLL),
· keep the rope clean,
· bag the rope,
· inspect the rope.
Selecting the Right Rope
Selecting a rope involves evaluating a combination of factors. Some of these factors areless quantitative like a preference for a specific color or how a rope feels in your hand. Cutting corners, such as reducing sizes or strengths during the initial purchase creates unnecessary replacements, potentially dangerous conditions, and increases long term costs.
Keep in mind that a large rope will outlast a smaller one of the same construction, because of the greater surface area wear distribution. By the same token, a stronger rope will outlast a weaker one, because it will be used at a lower percentage of its break strength with less chance of over-stressing. It is better to buy a quality line once than buy several cheaper, poorer lines that have to be replaced frequently. More information
The same concerns for a climbing rope must be applied to a rigging rope. When you are rigging down tree limbs or chunking down a tree, you may have loads weighing several hundred pounds exerting thousands of pounds of force on your rigging rope. More information
Before making a purchase, seek the opinions of local professional climbers who have experience with how a rope performs. Consider also the reputation of the rope manufacturer. Are they involved with and supportive of the arborist industry? Do they stand behind their products with consistent quality and reliable service? Buying unproven ropes because they are a little less expensive is false economy and can lead to disaster.
Awareness of the WLL
No matter how well-made a rope is, a rope is likely to fail if it is used to handle loads beyond those outlined in the rope manufacturer's WLL. This is generally 10% of the rope's breaking strength for climbing lines and 20% of the rope's breaking strength for rigging lines. Any use of loads higher than these may weaken the rope in ways which may or may not be apparent to the naked eye.
For example, shock loads are simply the sudden change in tension from a state of relaxation or low load to one of a high load. Any sudden load that exceeds the work load by more than 10% is considered a shock load. This means that a rope that was previously shock-loaded or used to handle loads larger than it was intended to handle could fail suddenly and without warning. A point to remember is that a rope may be severely overloaded or shock loaded in use without breaking. In addition, synthetic fibers have a memory and retain the effects of being overloaded or shock loaded and can fail at a later time, even though loaded within the normal working load range.
When given a choice between ropes, select the strongest of any given size. A load of 200 pounds (90 kg) represents 2% of the strength of a rope with a breaking strength of 10,000 pounds (4600 kg). The same load represents 4% of the strength of a rope that has a breaking strength of 5,000 pounds (2300 kg). The weaker rope is having to work harder and as a result will have to be retired and replaced sooner.
Keep the Rope Clean
Modern arborists' ropes often have 12. 16, or 24 strands of fiber bundles making up their construction. Dirt and grit can work their way in between the strands where they act like tiny knives and significantly shorten rope life. As the rope flexes, the grit and abrasives cut away at the strands of the rope from the inside.
It is important to keep ropes as clean as possible, especially if working in an area with lots of sand or grit. A brush tarp or rope tarp laid out at the base of the tree to pile the rope on is a great way to keep it clean. Better still is deploying the rope directly from the arborist's rope bag. This ensures that the rope stays as clean as possible, and also helps prevent tangles and snags. Keep them clean, bagged and properly stored when not in use.
Ropes can also be washed, either by hand in a rope washer or by placing it in a mesh rope-washing sack and washing it in a front-loading washing machine with a gentle detergent or rope soap. Chemical solvents or abrasive cleaners should never be used on an arborist rope. Always let the ropes dry before storing them to prevent mildew and mold.
Bag the Rope
A rope bag is a cheap and easy way to keep the rope ready to use and does wonders to prolong the life of the rope. Not only does it keep the rope clean at the job site, but it protects it from being snagged, cut, or abraded during storage and transit. A small nick or cut caused by snagging the rope on something sharp as it is pulled out of the truck or shop can ruin a whole length of line, and is easily prevented with a rope bag. More information
Inspect the Rope
Regular inspection can prevent problems and wear on the rope. Inspecting your rope should be a continuous process of observation before, during and after each use. In synthetic fiber ropes the amount of strength loss due to abrasion and/or flexing is directly related to the amount of broken fiber in the rope’s cross section. After each use, look and feel along every inch of the rope length inspecting for damage. When the rope is first put into service, the outer filaments of the rope will quickly fuzz up. This is the result of these filaments breaking and this roughened surface actually forms a protective cushion and shield for the fibers underneath. This condition should stabilize and not progress any deeper into the rope. If the surface roughness increases, excessive abrasion is taking place and strength is being lost.
Look closely at the inner fibers as well. Open the strands and look for powdered fiber, which is one sign of internal wear. When they show signs of wear, the rope is obviously weakened. Estimate the internal wear to determine the total fiber abrasion. If total fiber loss is 20%, then it is safe to assume that the rope has lost 20% of its strength as a result of abrasion.
Also, inspect for flat areas, bumps, or lumps. This can indicate core or internal damage from overloading or shock loads and is usually sufficient reason to replace the rope. Inconsistent texture or stiff areas can indicate excessive dirt or grit embedded in the rope or shock load damage and is usually another reason to replace the rope.
With use, all ropes get dirty. But be on the lookout for areas of discoloration that could be caused by chemical contamination. Determine the cause of the discoloration and replace the rope if it is brittle or stiff.
Temperature Effects on the Rope
When using rope, friction is creating heat. The greater the friction, the more the heat is building up. Heat is an enemy to synthetic fiber and elevated temperatures can drastically reduce the strength and/or cause rope melt-through.
Never let ropes under tension rub together or move relative to one another. High temperatures can be achieved when surging rope on a capstan, checking ropes on a cable, or running over stuck or non-rolling sheaves or rollers. Each rope’s construction and fiber type will yield a different coefficient of friction (reluctance to slip) in a new and used state. It is important to understand the operational demands and ensure the size, rope construction and fiber type be taken into account to minimize heat buildup. Under no circumstances let any rope come in contact with an exhaust muffler or any other hot object. Excessive heat, can melt and fuse the fibers making the rope extremely stiff. Unlike fiber compression, melting damage cannot be mitigated by flexing the rope. Melted areas must be cut out and rope respliced or retired.
Strength of the Rope
It is wildly accepted that ropes with a lower elongation under load will give you better load control. However, ropes with lower elongation that are shock loaded, like a lowering line, can fail without warning even though it appears to be in good shape. Low elongation ropes should be selected with the highest possible strength.
Both twisted ropes and braided ropes are suitable for rigging. Twisted rope has lower strength and more stretch, while braided rope has higher strength and lower stretch on ropes that are the same size and fiber type.
Elongation of the Rope
Select ropes that are firm and round and hold their shape during use. Soft or mushy ropes will snag easily and abrade quickly causing accelerated strength loss. Because the fibers are in a straighter line, which improves strength but compromises durability, loose or mushy rope will almost always have higher break strengths than a similar rope that is firm and holds its shape.
Retire the Rope
There are no definitive rules or industry guidelines to establish when a rope should be retired because there are so many variables that affect rope strength. Factors like load history, bending radius, abrasion, chemical exposure or some combination of those factors, make retirement decisions difficult.
As a general rule for braided ropes, when there is 25% or more wear from abrasion, the rope should be retired from service. With three-strand ropes, 10% or more wear is accepted as the retirement point. Sometimes rope displays a snagged strand. If the strand can be worked back into the rope, there is no need to retire the rope. If not, this indicates a retirement point.
Proper use of your ropes, maintaining them, and staying within recommended working loads will allow you to get the most from your rope investment.
Sources
- “Samson Technical Bulletin: Rope Inspection & Retirement of Arborist Ropes”, 2013. Website
- WesSpur Tree Equipment, “Arborist Rope Care: Protection, Inspection, and Retirement“, 2013. Website
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the .5 CEUs toward Certified Arborist, Tree Worker Specialist, Utility Specialist, Municipal Specialist, Aerial Lift Specialist, or BCMA practice credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to gibneyCE.com’. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
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All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website *SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
City Brands
By Len Phillips
Does your city need to improve its image?
Does it need a boost in tourism?
Has local economic development come to a halt?
Is your citizen pride level low?
Do you have a lot of large trees that could be helped if they were given more attention?
All of these things can be improved with “branding” which is a specialized type of marketing that promises to tell a community’s story, its essence, character, spirit, and anything else to grab attention.
Every city would like to capture a bit of the branding magic that has helped put some of America's best known cities on the map. Many are associated with catchy slogans like “The Big Apple” or “The Windy City” (which is no windier than any other city). The consultants will say that while slogans or motto's are part of a brand, they like to see a broader image of a community , like the reputation of Portland, OR, that is a haven for environmentalists or Miami's role as a place for sun and surf. You only have to say “Vegas” and everyone knows “What happens in Las Vegas...”.
A city’s brand is developed over years by its policies and its amenities. The best brands have been developed by high priced consultants who are brought in to help, while other communities have done it themselves. Most of the American cities that are small and midsized don't have much of a reputation beyond their own borders.
Branding Defined
“Branding” as defined by the consultants includes a logo, a slogan, and a broad message or narrative about a community as well as a list of steps that should be taken to help spread that story. Branding can also help repair a city's image problem and raise awareness of what makes the city a good place to live. It goes so far as to call branding “the foundation of what makes a place desirable”. Good branding can bring the sum of the parts together and give you an identity. Branding success will be measured by social and economic indicators, job creation numbers, tourist trips, a boost in the economy and community pride, and opinion surveys about the brand itself.
Starting
It all begins with establishing a commitment from the city leaders that indicate an improvement is necessary. They will set up a committee or hire a consultant. The committee must have a lot of members from all parts of the city, all economic levels, and all backgrounds. The idea is to get as many people involved as possible. When everyone works together, a whole city identity will evolve. However, city leaders must realized that there are so many variables at play that there is no guarantee of a good return on investment of this effort. They may also not be able to point to specific results of a branding campaign, but at least there will always be a lift in community pride, regardless of the outcome.
The actual branding process begins with an inventory of all things about the city that provide a positive image. They could be festivals, foods, traditions, ethnic backgrounds of the residents, the history, an industry, etc. For example, Bardstown, Kentucky has an annual Kentucky Bourbon Festival that touches on a food industry, and a long tradition. Another example is Oktoberfest-Zinzinnati USA. This Ohio city takes advantage of its ethnic background. Once some key features are identified, they should be exploited with new signage, highlights on the community calendar, photo contests, races through the city, and anything else that will generate discussions about the city. Some cities develop a new logo and color scheme. Others have developed a new website. Others have sent representatives to regional conventions, trade shows, and put up big outdoor advertising signs to promote the city.
Skeptics will argue that with cities struggling financially, it is not the time to spend money on branding campaigns that don't provide a concrete return on investment. Other naysayers claim that this process works well for corporations, but will not work for a community. There are also some communities that already have a brand but it is not working as well as hoped. In these situations, it is time to start over using the previous efforts as a place to start, not finish.
Green Branding
Since this article is being read by arborists, I think more cities should look at what is green in their city and use that as a starting point. There are several “Garden Cities”, “Emerald Cities” and “Elm Cities” already. A different kind of example is on the island community of Nantucket, Massachusetts where they have a daffodil festival every spring. The island community plants thousands of daffodil bulbs in the fall and in the spring they have a festival in the downtown area where anything and everything daffodil is sold. When the daffodils have finished, they shift gears and have a fashion show that brings out every resident. The funds raised by this fashion event are used to purchase and plant trees on the island. For some reason, the residents prefer to plant 4 inch (10 cm) caliper trees. Not only are they expensive, but they have to be shipped over from the mainland. However, if you have ever visited Nantucket, you will have to agree that the expense has been worth it. The island is always beautiful and daffodils are a big part of the Nantucket pride and brand.
There is another Massachusetts community that has a love for rhododendrons. Over 100 years ago, a local plant breeder developed a new rhododendron and named it after the community. In the years since then, the community has planted different rhododendrons in all of its parks and traffic islands. This shrub and small tree continues to be a source of pride for the community and it inspired the promotion of the rhododendron. The city is working on plans to convert a linear park running through the heart of the city into a rhododendron arboretum. Garden clubs and residents will be encouraged to purchase blocks of specific rhododendron cultivars, then plant and maintain them for a couple of years. The plan is expected to be implemented over the next 10 years. The intent is to make rhododendron the brand of this city. During the early summer bloom periods, the six garden clubs are planning to celebrate with various events in different locations of the arboretum. The local cultural groups will be sponsoring activities all summer long in various portions of the park that they have “adopted”. Time will tell how well this effort turns out but you may hear more about this effort in the future.
I have been reading about several communities that have developed “urban arboretums” which are collections of trees scattered throughout the community instead of at a park, like a normal arboretum. Self guiding tours provide a way for residents and visitors to go from tree to tree and learn more about them. This effort has not yet been branded, but I am sure it will be someday soon.
In the meantime, do you have a favorite tree or species that is prominent in your city? Many cities have selected a “City Tree” for all celebrations. Usually one is planted on Arbor Day, others are planted at special events. This is not a recommended activity if the city is trying to maintain proper diversification. But if it will improve the diversification plan, then go for it.
Another trend with favorite trees occurs in western New York State, where a city forester, since the 1980's, prefers that all new tree plantings be flowering, conical-shaped, and less than 35 feet (10 m) tall. This city has not yet developed a brand, but when they do, the city forester is hoping his vision of the flowering trees will be a part of it.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the .5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA management credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to gibneyCE.com’. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website *SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
How Trees Grow
(Tree Morphogenesis)
By David Lloyd–Jones
Trees grow in annual increments but there are other growth cycles occurring in multiples of years (or even decades), that profoundly influence the development of branch architecture and the characteristic form of mature trees.
Those annual cycles appear to be environmentally influenced but unlike annual cycles, there is a degree of variability that means that they only influence the tree every few years or decades and as a result the way that they subtly and fundamentally influence the shape and form of almost all trees, have been unreported until now.
It is these cycles that differentiate the structure of trees and provide variable geometry and variable strength branch attachments that literally facilitate wind pruning. Those cycles begin and end with a Growth Phase Change and these chronologically organize points of morphological differentiation, also differentiate the growth of trees from a simple fractal shape.
While some of the triggers for morphogenesis in temperate climates have been described in my book, there are undoubtedly more to discover and then there will be others that affect trees in the tropics. In other words, there are plenty of opportunities for arborists to deliver real and valuable insights into the tree species that they are working with by becoming students of tree architecture and environmental ecology.
Primeval origins
In the primeval woodland that prevailed across the globe until just a few thousand years ago, a tree had to develop in the shade of the forest floor, waiting for a large tree to fall so as to create a clearing and a gap in the high canopy into which the young tree could establish itself. To achieve the high canopy a young tree has to make sure that everything that it does, helps it to grow upwards at the maximum rate of growth which that species can achieve, in that location, and with the resources available. Once there, the tree grows on to full maturity, great age, and reproduction. Such trees are consequentially well represented by their offspring and therefore their contribution to the gene pool and the future of that species is significant.
However, once the tree has reached its mature height, it no longer needs to grow so strongly upward and in fact that upward growth trend places ever more structural leverage on the tree which at this stage is still growing as a simple fractal shape. At this point the primeval tree species has to adapt to the different adversities and the opportunities that come from achieving the high canopy.
Apical Dominance
Apical dominance is the phenomenon whereby the main central stem of the tree is dominant over side branches. The apical bud subjugates all other side branches by producing growth hormones that reach and affect all parts of the tree. Those hormone regulated side branches just grow ever outward and as a result they typically have wide angles of attachment to the stem. Because of this, the apical bud is the only one that grows consistently upward or towards the light while the remaining branches are cast in a supportive role by not being allowed to compete for upward growth.
Tree Emergence above the Forest Canopy
As the tree emerges into the area above the general height of the surrounding forest trees it becomes exposed to environmental influences in various ways. First of all, as the tip reaches up above the canopy of the trees it becomes exposed to wind or frosts and a full range of adverse occurrences. The tree has little choice because the growth hormones produced by the apical bud to continue the upward mode of growth. It is hormonally compelled to grow ever upward and as it does, if the growth tip and the apical bud become damaged or knocked off, it triggers the some profound changes in the structure of the tree.
For the first time and in just one brief moment in its life, there is no apical bud and therefore no hormones to impose apical dominance on all of the lateral branches. In that same moment, the side branches are no longer rigorously controlled and prevented from competing with the missing apical bud, and the side branches have a very brief opportunity to grow in forms that are less rigorously controlled than was the case in the young forest tree. So in addition to the tip forking, many of the lateral branches also form in this moment and a more rounded form develops at the top of the tree. To the tree, this would be the point that it comes of age so to speak as it changes from an excurrent morphology to a decurrent morphology.
Growth Phase Change
The first Growth Phase Change is easily understood because just one apical bud controls the development of shape in the tree, but there are subsequent Growth Phase Changes and they require a bit more explanation if only because unlike the first, the second and subsequent Growth Phase Changes need a trigger that affects many or all of the numerous apical buds that replace the single apical bud at the first Growth Phase Change.
If late spring frosts come just as the succulent leaves are emerging, it will have an effect primarily on the most exposed, peripheral buds by causing the cells of the newly exposed leaves and flowers to freeze and rupture. This effectively destroys the bud just at the point in the growing season that the tree is at its most fragile and delicate state.
Mid-summer droughts can also stress the tree and cause it to die back from the tips of the branches so as to make the leaf area smaller which enables the tree to survive the drought and grow on to maturity. Other natural causes include pests, root damage or loss and certain diseases. Any of these can cause the concentrations of major branch junctions all at a point in that structure that represents the same point in time.
This can be seen in the structure of mature trees. Because of these variances to simple fractal growth, the tree oscillates between growth phases and at each it differentiates its structure with a Growth Phase Change creating ever more branches and forked unions supporting them. The variable geometry and structural performance of the branch unions produced at each Growth Phase Change, enable the tree to facilitate wind pruning and by so doing, give the structural elements the ability to reduce loadings in high winds.
In other words, trees are designed by their long evolution to be pruned by wind so that they can come through an energetic storm to reproduce in the future (when less adaptively designed trees might fail). Simply understanding this process enables an arborist to be able to simulate wind pruning. In addition this new way of looking at trees enables an arborist to literally read the life history of the tree and understand that history as a series of events, all of which have changed the tree and left their mark in its mature structures and form.
David Lloyd-Jones is an arborist from Knutsford, Cheshire, UK. You may contact him at this address.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the .5 CEUs toward Certified Arborist, Utility Specialist, Municipal Specialist, or BCMA science credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to gibneyCE.com’. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website *SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Cultivars of Zelkova
Edited by Len Phillips
This Japanese tree is proving to be a worthy replacement for the American elm. The description that follows provides a summary of similarities that all the cultivars possess. This information has been gathered from personal observations of the author, living in Massachusetts, Zone 6, and information provided by J. Frank Schmidt & Son.
Botanical Name: Zelkova serrata
Common Name: Zelkova
Hardiness Zone: 4 – 8 except as noted
Flower: Inconspicuous
Fruit: Small drupe that ripens in the fall, on female trees only
Foliage: Large, 2" – 5" long, dark green leaves, rusty red autumn color
Bark: Straight trunk, smooth and gray, flaky with orange patches on older trunks Growth Rate: Vigorous, 40' in 30 years
Planting: Transplants easily by bare root and B&B, well-suited for
CU-Structural Soil planting
Site Requirements: Medium loam, moist, well drained, sun, adapts to all pH, tolerates pollution, drought, wind, and shade
Pest and Disease Resistance: Highly resistant to Dutch elm disease and Elm beetles as well as the Japanese beetle
Salt Resistance: Good to excellent
Storm Resistance: Narrow crotch angles on some cultivars can split in storms
Of the dozen cultivars and closely related subspecies, the seven listed below are considered by this author to be the best of them.
City Sprite® Zelkova – Zelkova serrata ‘JFS-KW1’ PP #20996 – Height - 24’; spread - 18’; shape - compact, oval to vase shape; foliage - bright green, fine textured; fall color - yellow. Compact, dense, and semi-dwarf, this is the perfect little tree for tight urban spaces. Summer foliage appears brighter green than typical Zelkova. Short internodes, fine textured foliage, and a self pruning growth habit that promises a low maintenance city tree. Photo and Fact Sheet
Green Vase® Zelkova – Zelkova serrata ‘Green Vase’ – Height - 45'; spread - 30'; shape - vase shape, with upright arching branches; foliage: green; fall color: orange bronze. A vigorous Zelkova selection from Princeton Nurseries in 1983, produces a taller, more graceful tree than ‘Village Green’. Its fine textured foliage produces dappled shade. Photo and Fact Sheet
Halka Zelkova – Zelkova serrata ‘Halka’ PP #5687 – Height - 45'; spread - 35'; shape - upright vase shape; foliage - medium green; fall color - yellow to orange. Halka Zelkova has long, gracefully arching branches which make a magnificent canopy. More than any Zelkova, its form comes closest to resembling an American elm. Halka is the fastest growing Zelkova cultivar. Photo and Fact Sheet
Musashino Columnar Zelkova – Zelkova serrata ‘Musashino’ – Height - 45'; spread - 15'; shape – very narrow upright vase shape; foliage - medium green; fall color - yellow. Ideal for narrow street use, tightly upright branches allow good vehicle and pedestrian clearance beneath the delicate green canopy at a mature height. Photo and Fact Sheet
'Spring Grove' Zelkova – Zelkova serrata ‘Spring Grove’ – A potential rival for 'Village Green', this selection is yet to see mass production so a considerable search may be necessary to find an available tree. It exhibits a distinct vase shape with tight branching. It is ornamentally superior for its dark green leaves, red fall color and attractive peeling bark. The plant has the potential to grow 80' tall with a spread of 60'. This tree is rated for Zone 7 – 9.
Village Green Zelkova – Zelkova serrata `Village Green' PP #2337 – Height - 50' – 60'; spread - 40' – 50'; shape - wine glass shape like American elm, short trunk; foliage - dark green leaves; fall color - rusty red. Village Green is a male selection from Z. serrata by Princeton Nurseries in 1964. This vigorous grower and winter hardy selection has a straight trunk with smooth bark that is gray and flaky with orange patches on older trunks. Photo and Fact Sheet
Wireless® Zelkova – Zelkova serrata ‘Schmidtlow’ – Height - 24'; spread - 36'; shape - broadly spreading vase; foliage - medium green; fall color - red. Selected for its low height and broad spreading shape, this cultivar has an ideal shape for street plantings under utility lines. Its red fall color is a surprising extra feature. Photo and Fact Sheet
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the .5 CEUs toward Certified Arborist, Utility Specialist, Municipal Specialist, or BCMA science credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to gibneyCE.com’. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website *SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Research Briefs 54
Edited by Len Phillips
Effects of Fertilizers on Tree Growth in a Compacted Soil
Bryant C. Scharenbroch and Gary W. Watson
The soil quality on a test site was degraded by topsoil scraping and subsoil compacted to what is typically found on urban sites. Nutrient restitution was interrupted when tree growth was hindered, and leaves and wood debris were removed. The physical, chemical, and biological properties of the urban soils were degraded.
The site was then planted with Acer rubrum and Betula nigra. The trees were treated with synthetic fertilizer, hardwood mulch, compost, aerated compost tea, and a commercial biological enhancement product.
The results confirm the hypothesis that compost and hardwood mulch would have significantly greater impacts on soil's physical, chemical, and biological properties compared to fertilizer, aerated compost tea, and commercial biological products. Compost, being relatively labile and nutrient rich, is known for its positive impacts on organic matter and organisms. The findings confirmed the hypothesis that improvement in a soil's biochemical properties would be greatest with compost. Mulch was found to be a strong surface buffer and have greater impacts on soil water, and also impact many soil properties, but at a slower rate than the compost treatment.
The effects of fertilizer, aerated compost tea, and a commercial biological enhancement product was minimal due to the relatively small amount of organisms and nutrients being added in the treatments compared to the other treatments and the background soil levels. The only increases in tree growth were found with compost, mulch, and fertilizer treatments.
Tree Care Industry, October 2013
Urban Trees Remove Fine Particulate Air Pollution
David Nowak, Robert Hoehn, Satoshi Hirabayashi, Allison Bodine
In the first effort to estimate the overall impact of a city's urban forest on concentrations of fine particulate pollution, researchers found that urban trees and forests are saving an average of one life every year per city. In New York City, trees save an average of eight lives every year.
Fine particulate air pollution has serious health effects on humans, including premature mortality, pulmonary inflammation, accelerated atherosclerosis, and altered cardiac functions. The study estimated how much fine particulate matter is removed by trees in 10 cities and associated values and impacts on human health.
More than 80% of Americans live in urban areas containing over 100 million acres of trees and forests. This research clearly illustrates that America's urban forests are critical capital investments helping produce clean air and water; reduce energy costs; and, making cities more livable. Simply put, our urban forests improve people's lives. Cities included in the studies were Atlanta, Baltimore, Boston, Chicago, Los Angeles, Minneapolis, New York City, Philadelphia, San Francisco, and Syracuse, NY.
Overall, the greatest effect of trees on reducing health impacts of fine particulate air pollution occurred in New York due to its relatively large human population and the trees' moderately high removal rate and reduction in pollution concentration. The greatest overall removal by trees was in Atlanta due to its relatively high percent tree cover and lower population.
Trees can make cities healthier. While we need more research to generate better estimates, this study suggests that trees are an effective tool in reducing air pollution and creating healthier urban environments.
The removal of fine particulate air pollution by urban trees are substantially lower than for larger particulate matter, but the health implications and values are much higher. The total amount of fine particulate air pollution removed annually by trees varied from 4.7 metric tons in Syracuse to 64.5 metric tons in Atlanta, with annual values varying from $1.1 million in Syracuse to $60.1 million in New York City. Most of these values were dominated by the effects of reducing human mortality; the average value per reduced death was $7.8 million. Reduction in human mortality ranged from one person per 365,000 people in Atlanta to one person per 1.35 million people in San Francisco.
Researchers used the U.S. Environmental Protection Agency's BenMAP program to estimate the incidence of adverse health effects, such as mortality and morbidity, and associated monetary value that results from changes in fine particulate air pollution concentrations. Local population statistics from the 2010 U.S. Census were also used in the model. i-Tree, a suite of tools developed by the USDA Forest Service and Davey Institute, was used to calculate fine particulate air pollution removal and associated change in concentrations in the study cities.
Environmental Pollution, June 2013
Trees Signal Birds when Insects Attack
Marcel Visser
Trees under attack by insects can waft special odors into the air, which attracts birds eager to perform pest control. The scientists behind the new research show that contrary to conventional wisdom, birds rely on smell, not just sight.
Scientists have long known that when insects nibble on leaves, the damaged leaf tissue releases telltale odors. Some give a freshly mowed lawn its grassy smell, while others draw carnivorous insects such as wasps to the besieged plants' rescue.
Plants being eaten alive would do better to draw birds, which can snap up many more pests than can pest-eating insects. So the researchers decided to find out whether birds, too, can sniff out a pest-ridden plant.
The scientists positioned apple trees in an aviary, then released chickadee-like birds called great tits inside the enclosure. The birds flew more often to trees infested with caterpillars than to uninfested trees. The researchers also found that the preyed-upon apple trees released different levels of airborne chemicals than uninfested trees. But how were the birds getting the message?
To find out, the scientists picked the caterpillars and damaged leaves off a caterpillar-infested tree and put it in the aviary. They made sure the birds could smell it but not see it, by placing the tree behind a fabric door. Next to it they placed an uninfested tree the birds could see but not smell, thanks to a clear plastic door. The birds visited the infested tree more often, apparently drawn by the odors it wafted into the air.
Scientists who weren't connected to the study say the new findings help make the case that birds can sniff out pest-ridden trees. But these scientists say this single study is not totally definitive, because it's hard to know for sure whether the birds are truly following their noses to the caterpillar-infested trees.
Ecology Letters, September 2013
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