Worried about your tree’s failing during wind or other inclement weather?

We have some tips for identifying potential issues, weaknesses, and the general health of your trees.

The following points are intended as a general reference, and are not to take the place of a professional assessment.

As a homeowner in the great Pacific Northwest, you are probably used to enjoying the trees on your property. You grow accustomed to your trees, and notice how they change during the seasons. It is this observance that can be a great advantage in spotting health issues that may not be immediately or openly visible. Keeping an eye ‘warning signs’ is the best way to preemptively correct an unhealthy tree.

Basic signs your tree’s health may be suffering:

  • Physical damage: Heavy equipment can inadvertently cause damages to your tree. Look for physical scrapes, large knicks, or other wounds in the bark.
  • Foliage changes: A great way to determine declining health is in visible changes to the foliage. Reduced foliage or a sudden absence of foliage at all.
  • Color changes for deciduous & evergreen species: If your tree begins to change color that does not coincide with seasonal changes (or prematurely), this may be an indicator of declining health, or other fungal/parasitic infection or stress/shock.
  • Rot/Decay: Take special note at the base of the tree for rot, fungus, growths/bulges, or termites/ants at the base of the tree and within cavity’s.

It is important to remember that a healthy tree has a considerably higher structural integrity. Keeping your trees healthy is the key to ensuring you have a safe and strong addition to your property.

    The above points are some basic things to look for in a tree of declining health. But there are other common natural indicators of an unstable or potentially hazardous tree that you can look for:

  • Multiple Trunks (or dominance, EG; Co-Dominant, Tri-Dominant). These connections may lose strength over time and with age. The additional windsail aspect of a co-dominant tree also typically creates more overall drag during high-winds. Sometimes a co-dominant trunk can be cabled to increase the stability and life of the tree.
  • Cracks: Cracks that are deep, or extend through the trunk are a clear sign of instability.
  • Lean: The angle a tree is leaning can be an important factor in judging a hazardous tree. Small angles of lean are normal and natural (as are the natural changes in direction a tree can take during its growth), but at noticeably greater angles, the weight distribution can be a major issue during wind storms. Significant leans can also indicate root damage, are are a good indicator that the tree is unstable.
  • Roots: Heaving earth near the base, exposed, or visibly cracked/damaged roots is a sign of instability.

 

    There are many pruning methods that can help save and increase the safety of a tree that may display some of the aforementioned health issues. Deadwood-removal, as well as structure pruning for better weight distribution can drastically increase the health and safety of any mature Northwest tree. There are many other ways to prevent damage or infection, as well as ways to help restore an unhealthy tree that we will cover in the next installment. 

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Western Red Cedar (Thuja Plicata)

Western Red CedarThe Western Red-Cedar can stand to a graceful height of sixty to one hundred and thirty feet tall, but has been known to stand two hundred and seventy seven feet tall with a diameter of nearly fourteen feet. It can take over one thousand years to reach this size. The oldest confirmed Western Red-cedar was one thousand four hundred and sixty years old.

Despite the massive size of this tree, it has a delicate feminine appearance. The foliage is made of small scale-like leaves that spray out from thin arching twigs.  The large lower limbs become heavy and bend down toward the earth, then reach back up to gather the energy of the sun. It is not in appearance alone that this tree can be seen as a feminine tree; the indigenous tribes of the Pacific Northwest used the bark and wood to cloth themselves, make tools they used to hunt, and the boats to transport their goods. It was also used to make totem poles that told the family histories and the history of their religions. One of the many common names for this tree is the Giant Arborvitae, which is Latin for tree of life.

To this day, modern cultures use this wood for its unique properties. In older trees, the Western Red Cedar produces a chemical called thujaplicin that is a natural fungicide, making it resistant to wet rot. This creates a wood that is useful in outdoor locations like deck siding and roofing. It also has an aromatic property that makes it very pleasant for furniture or chest storage. If properly treated, it can retain its scent for up to a century.

Its first introduction to western civilization was through the Lewis and Clark expedition, where the explorers used the soft and light wood to make dugout canoes to travel by water as they approached the Pacific Ocean.

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How to Recognize a Hazard Tree #4 The body Language of Trees

When evaluating a tree for its potential to fail, it is important to understand the way a tree can fail, why it will fail, and the way a tree will react to defects that may increase failure probability. In this article we will explore the visual signs of these defects and combine these observations with the information in the preceding articles, to come to a basic understanding of tree risk assessment.

Defect classifications:

     The term defect refers to a part of the tree that is out of the ordinary growth pattern of that species. This often indicates past events that have altered the structure of the tree.  Not all tree defects indicate that a tree should be removed, and this series does not give enough information to come to a conclusion on whether the tree is a risk or not. This series is meant to give you a starting point to determine if you need to call a qualified tree risk assessor for an in depth, thorough analysis.

Cracks:

Cracks will often create weakness that can be exploited by future weather events. The tree will try to make adaptions to compensate for the crack, by forming new wood over the wound. If the crack has not opened up wide, it will be able to create a new layer within a few short years. This wood is often raised higher than all the wood around it, and the bark is smoother due to the rapid growth. This will appear as a vertical or horizontal rib.

Shear cracks:

Most cracks will occur along the long axis of the trunk or branch, and are caused by the opposing compression and extension of the outer edges of the trunk or branch.  This type of crack will appear on the outer edges of the tree trunk or branch, and has a split strait through it.

Horizontal cracks:

These cracks will occur along the short axis of the branch, and is caused by the tension strain (usually wind higher in the tree) exceeding the strength of the wood.  These types of cracks will occur on the upper side of the lean, or on the side of the tree where the wind force direction is most prominent.

“Banana” cracks:

These types of cracks will occur when the compression force pushes down on the wood fibers, leaving them no place to go but outwards. This will happen on the underside of a lean or where the wind force direction is most prominent.

Torsion cracks:

A torsion crack is one that will have a spiraling path along the trunk or branch. This is typically caused by the twisting motion of the tree during a wind storm.

Inrolled cracks:

This form of crack is the adaption of callus wood that forms over an old wound. This kind of crack can indicate a decaying cavity just underneath the new wood – typically identified by a sunken and rounded edge where the two parts connect.

Internal Decay:

Decay in trees can be both easy and difficult to find and assess. This is on account of the visual obscurity of the wound -which can be exposed wood within an open wound, or an old wound that has left an unusual bark pattern. Internal decay can also be caused by a fungus that will “eat” the heartwood.  This can often times be identified as a bulging around the area of decay.

Leaning trees:

There is no set degree of lean that can be surely defined as a risk, but it has been proposed that a critical threshold for a sustainable angle would be around forty degrees (40°) from center.  These factors are contingent on several conditions, with weather being the most likely contributor. Generally, a lean that is sudden or a recent development can be an indication of potential failure or risk. Other factors to be considered are; the condition of the tree trunk, and the roots or the soil the tree is anchored in and the species of the tree.

Root and soil issues:

In general, root problems are the hardest to detect – as most of the indicators or symptoms are buried beneath the tree and soil. Some indicators that would be present are; recent “leans” that start at the base of the trunk, cracking or heaving of the soil, and a decline in health/live growth from the top down (though this particular symptom could be caused by many other issues).

Indicators and their potential causes:

Abnormal Bark patterns:

Each tree species has a unique bark pattern that will change over time, but is relatively consistent within a localized area. These patterns will often times have raised and sunken areas. In areas where there is a lot of recent growth, there will be more of the sunken areas than the raised. The sunken areas will often have a lighter coloration, and it is in this area (when accompanied with bulging) that we can observe a risk indication. This abnormality can sometimes be an indication that the tree is compensating for some internal defect or stress.

Old damage that has had time to occlude the wound will often have a smooth, rounded, or a “puckered” look.

Ribs:

Ribs are raised ridges and often indicate a crack that has been occluded within new wood. If the edge of the ridge is cleft, it indicates the crack has not been grafted closed. If the nose of the ridge has a sharp edge, the crack is close to the surface.  The more blunted the ridge, the more enclosed the crack has become.

Bulges:

Bulges are areas of the trunk that typically have “tumescent” growth within a specific localized area, and are usually at or around the base of the trunk. This kind of bulge can indicate one of two situations that involve internal decay; the outer wall of the wood remaining has begun to buckle under its own weight, or the tree has produced new growth to compensate for the shrinking shell wall.

This can also, on some occasions, indicate that the tree has grown around an object.

Another type of bulging happens below the joining of two trunks known as co-dominant stems, and indicates there is a present condition called included bark. This is a very common issue here in the Northwest, and can pose a serious threat as a result of a very poor connection between the co-dominant stems. Additionally, this poses a problem as the growth between them continues to increase. At this stage, the co-dominant stems have a high likelihood of splitting apart. There are preservation techniques available(such as cabling and bracing), but this condition has to be taken into serious consideration – as we are often times dealing with a great deal of weight, and the mechanics behind this potential risk can be tricky to assess or determine.

Fissures:

A fissure is a flat depression on the trunk of a tree. It can indicate an area of the tree that has stopped or slowed its growth in a localized area. Not all fissures indicate decay, as some species have them in their normal growth pattern. Further investigation is needed to determine the cause of such an abnormality.

In closing this series I hope that I have outlined the basic factors that are considered when evaluating the potential risk of your trees.

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How to Recognize a Hazard Tree #3: Tree Mechanics

Tree mechanics is a very important and very difficult subject to summarize into a single blog, but I am always excited to take on a challenge.

The first thing to understand in tree mechanics is a few engineering terms. After covering some of these basic terms, I will then attempt to explain how the reality of these terms affects the trees in our local Northwest environment.

Force = Mass  X  acceleration

Stress = Force per unit area

Strain = Extension per unit area

Strength = The maximum stress that can be tolerated without permanent deformation of the material.

Bending moment = Force X length of the lever arm

Force

Trees encounter two main types of force in their lives – the first being consistent (and therefore predictable) in Gravity. Gravity is always pulling down on branches and leaning trees, while compacting the wood in trunks that have grown strait. Being this is a force that is without fluctuation, the tree is able to adapt easily to this force by adding more wood in the locations where stress (compaction) and strain (extension) is greatest.

There are less predictable forces such as wind, ice and snow that (if it remains consistent year after year) the tree can adapt for. It is the unexpected forces that can cause the greatest threat to any healthy trees. This can be a strong wind storm coming from the wrong direction, or if a tree has grown in the middle of a stand of trees for which all surrounding trees have been removed.  In this case, the tree has never been exposed to wind forces now standing all alone. It has had no reason to add the supportive woody material, or expand its root-plate to increase its strength through the course of its growth. Trees do leave behind signs of these adaption’s to such forces, and that will be covered in my next post; The Body Language of Trees.

Leverage

Trees that have grown in the open will grow shorter than trees that have grown within a stand or forest. This behavior is on account of two reasons:  They don’t need to compete for sunlight, and they are also more exposed to open winds.  The taller the tree, the greater the lever-arm. Just like our ancestors discovered, the longer the lever-arm the less force it takes to move an object.  This principle is tree forcescalled the bending moment, and is not exclusive to the height of a tree that carries that force down to the root plate. Also considered is the length of a branch that carries that force to the trunk.  In both cases there are two movements in the trees structure; compaction or stress on the inside of the leaning trunk (or the bottom of the trunk), and extension or strain which is on the bending side of the branch or trunk. These adaptions I have been talking about are in direct relation to these movements. If you read my last blog you may remember me talking about lignin and cellulose. Lignin is responsible for the compaction strength in trees and is found in abundance on the underside of a leaning trunk or its branches, but is less abundant on the top side where you find a great deal of cellulose. Cellulose is responsible for tensile strength.  The space in-between these two sides is called the shear zone, and is the weakest point under these two opposing forces.  It is this neutral place where cracks will form, permanently weakening the tree – or causing it to outright fail.

Torsion

There is a third force that trees need to deal with in torsion or “twisting”. In wind, trees don’t just move in a strait path back-and-forth… they will move back, then to the left or right – all while twisting to relieving the wind from their crown before returning back to center. Often they will twist more on one side than another, creating adaptive wood that works like a rope which tightens as it twists in that direction.  It is when the unexpected wind comes and twists the structure the opposite direction, that torsion cracks or failure occurs. It has been said by Ed Hayes, that this is the most common type of crack that is found in trees.

When engineers are designing a structure, they always build it to exceed its normal conditions by three to four times. In empirical studies, researchers have found that trees will also build its structure to exceed normal conditions by a factor of four and a half times that of normal conditions.  This of course, is affected by many factors including; the condition of the wood within the tree structure, the strength of the force applied, and the species of tree. Often it is the difference between normal conditions and abnormal conditions that represents the risk factor.

There four types of failure that will happen in trees

Root failure

Under force, the tree root system will experience two opposite and opposing forces. One side of the root plate will work like guy cables while the other side will be working like support beams – both working to keep the tree from failing. When the root system does fail to support the tree, it will happen because the soil itself is unable to hold the tree. This is usually due to wet soil that works to lubricate the roots system or in cases where the roots have been physically damaged by disease or during human activity above.

Trunk failure

Trunk failure can occur when the force acting upon the tree, exceeds the strength of the tree trunk. The tree is most often weakened by physical or biological damage to trunk beforehand, or throughout its life. The amount of damage (loss of wood) that can occur before the tree has the potential to fail is staggering. In the same way that a solid bar has the same strength as a hollow bar that is made of the same material, so long as it has a shell wall thickness of thirty three percent or more of the diameter. This same principle is true in trees, but the percentage is a matter of debate in our community – mostly due to other factors of consideration including the often uneven distribution of the shell wall.

Branch failure

The most common reasons for branch failure is an overly extended branch receiving more than its own weight in snow, ice or wind. This can also occur when a branch has a poor attachment to the trunk.

branchunionThe ideal branch attachment is has an angle around forty-five degrees and are forty to fifty percent the size of the trunk. The negative shape in-between the trunk and the branch, can be very helpful to determine the quality of the attachment.  A branch that is strong and well secured to the trunk will have a “U” shape, whereas a poorly attached branch will look more like a “V”. The tighter the “V” shape, the more critical that branch can become – as this creates what is called Included Bark.

When looking at the tree as a whole, I am often amazed with their ability to support their own massive weight despite the seasonal winds and snow that greatly increase the forces trying to pull them down to the earth. They have earned my respect and admiration, and we should do everything in our limited power to maintain what old trees we have. This being said, I will quote both a book and a movie; “On a long enough timeline, the survival rate for everyone drops to zero.”

In a sense, there are no 100% safe trees in existence. This is why this information is vital to living with our beautiful native trees, as it is important that we are able to judge the probability of any given tree failing. Furthermore, it is always important to have an ISA certified Arborist give a proper assessment before making any decisions, and to have a skilled and experienced crew perform appropriate safety and preventative maintenance before any part of a tree becomes unsafe.

The majority of the information given is taken from the “Tree Risk Assessment In Urban Areas And The Urban/Rural Interface” Manual written byJulian Dunster and published in 2009

 

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How to recognize a possible hazard tree #2 Types of decay in trees

Last week I hope I was able to adequately impart an understanding of how trees deal with decay in their woody structures. This week we will discuss the types of decays that will invade the woody structures of trees.

Decays that are caused by fungus have three basic stages that are useful in risk assessment. The first marks the initial stage of decay and can be hard to detect. This is called incipient decay, as the fungus has just started to break down the cell walls and has only lost a small amount of its strength. In the intermediate decay stage the wood begins to become discolored and the strength of the wood has been significantly compromised, but the cell walls remain intact. After many years (the amount of time depends on tree species) the wood reaches the advanced decay stage, at which point all wood strength and cell structure has been lost.

There are three basic types of decay that breaks down wood; they are divided by what cells are broken down by the invading fungus:

White rot

White rots will break down the lignin which is responsible for the brown pigmenting and compaction strength in wood, hemicellulose and cellulose which is responsible for the tensile strength in trees.  White rots are divided into two types; one that breaks down lignin and cellulose at the same rate, leaving the wood severely compromised. The other will break down the lignin at a much faster rate, leaving the trees tensile strength but removing its ability to withstand its own weight. Trees under the latter influence will show bulging on a vertical trunk as the tree buckles under its own weight.

White rots are more commonly found in broadleaf trees but can also be found in conifers. Wood decayed by white rot will be fibrous, wet, spongy and white or yellow due to the oxidation and loss of lignin.

Brown rot

Brown rot is exclusively caused by the fungi basidiomycotina, and primarily affects conifers. This type of rot will break down the cellulose and hemicellulose but will leave the lignin intact. When the wood is attacked by these fungi, the wood is left brittle and dark brown due the loss of cellulose and the oxidation of the lignin.  As the decayed wood dries, the wood will shrink and breaks into cubes.

Brown rots are considered more serious than white rots as there is a dramatic loss of flexibility in the tree, and make them much more vulnerable to wind.

Soft rot

Soft rots can be cause by both fungi and bacteria and will break down lignin, hemicellulose and cellulose – but only in localized areas that spread slowly, making them less serious  than brown rots and white rots.  Soft rots will normally only infect broadleaf trees and only infect pockets of decayed wood that is softer than the wood around it.  There is one fungus Kreutschmaria (Ustulina) deusta that will cause more extensive damage and create major structural issues.

These three types of rot are further classified by the region of the tree they infect.

Root rot

The fungi will enter the tree through root grafting on an infected tree, and by fungal rhizomorphs in the case of Armillaria species. Roots rots can also be contracted by waterborne or airborne spores.  Root rots can affect trees in three ways: They can cause dieback of the fine roots and root hairs, lessening their ability to uptake nutrients and gas exchange. This will stress the tree and often lead to crown dieback.  The fungi will move through the tree by developing on the underside of the roots, where others will move into the heartwood of the roots and spread into the butt of the trunk.

Root rot can be difficult to assess and detect, as the roots are buried and beneath the standing tree. More often than not, it is impractical to expose the required amount of roots to gather a full understanding of the extent of infection. At the right time of year (depending on the age of the fungus, the type of fungus, and the time of year the tree is assessed), there is a chance of finding an identifiable mushroom at the base of the tree. Often times this process is identified by exposing small patches of roots, and sampling for signs of infection.

Butt rot

Butt rot can be caused by decay moving up into the trunk through the roots, or by injuries to the trunk giving entry to formally protected wood.  Tree injuries at the lower-trunk are the easiest to detect and assess, as the tree leaves behind “body language” that will tell a story of how the tree has compensated for the decay.  This will be the subject for next week’s blog.

Heart rot

Heart rots are located in the heartwood at the center of the tree trunk. The fungi generally need a wound to gain entry into the otherwise-sound wood of a tree. These wounds can be caused by branch failure, pruning wounds, fires, vandalism, animals, insects, or mechanical damage. Heart rot can also be caused by root rot spreading up into the trunk of the tree.  In all cases, the bark and cambium has been damaged and the sap wood has become exposed to oxygen and airborne pathogens.

Sap rot

Sap rots are often found on dead wood or are a secondary fungal invasion after an area of the tree has been killed by other factors (IE; bark beetles or mechanical or weather related injuries). Sap rot often will progress rapidly but are not normally associated with structural failures.

Now that we have prefaced how trees deal with rot and what types of rot are to be found in trees, we are now ready to get to the real point of this series: How to recognize hazard trees. Please stay tuned for next week’s blog; The body language of trees.

 

The majority of the information given is taken from the “Tree Risk Assessment In Urban Areas And The Urban/Rural Interface” Manual written byJulian Dunster and published in 2009

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How To Recognize A Possible Hazard Tree #1 C.O.D.I.T.

Tree risk assessment can be a heavy burden to carry as life is always on the line. This includes the lives of your family, and the lives of your trees. I take this responsibility with great care and solemnity, and hope to impart to you the basics of risk recognition in the field of arboriculture.

This brief article is the first in a four part-series, and only gives you a starting point in understanding a trees reaction to environmental stresses and the “body language” those stresses leave behind. This being said, I would always recommend seeking the guidance from a certified tree risk assessor if you have any concerns with your trees.

Modern tree risk assessment methods weigh the risk factors in three categories; the probability of failure, the size of the part that is likely to fail, and the target that would most likely be struck in the case of failure.  These three factors are quantified into a numerical rating that equals the risk rating of your tree. Using this method we are able to prioritize the work that is needed in your yard, and are able to make a long term plan that works for your budget.

Before moving into the “body language” of tree stress, I will explain the way trees deal with decay as explained by Dr. Alex Shigo.

Compartmentalization Of Decay In Trees.  C.O.D.I.T

When Trees are wounded, they are unable to heal themselves by replacing or repairing damaged cells like you and I. Instead, they work to contain the wounded area and grow new tissue around the wound. This damage can be caused by physical injury, physiological stress (such as droughts), flood, excessive heating or cooling, nutrient deficiency (or excess), or decay resulting from invasion by fungal and bacterial pathogens/insects.

Trees will react to injury in an ordered and predictable way. They will block or slow the spread of decay through setting up a series of four walls that are made by modifying wood cells, chemically or physiologically.

 

CODITWall 1 works to contain the spread of decay throughout the tree trunk, branch or root. This is the weakest of the four walls.

Wall 2 works to stop the spread of decay moving inward toward the center of the tree, by closing off the latewood cells (dark portion of the growth ring). This is considered the second-weakest wall.

Wall 3 works to stop the spread of decay from spreading from the point of injury around the trunk, by using the ray cells on either side of the injury. This is a discontinuous wall that is very strong.

The first three walls are comprised of normal tissues – These walls change their normal processes to that of a defensive function after the tree has been injured. This change involves the creation of decay-resistant compounds that work to slow or stop the effects caused by the injury.

Wall 4 is the wall that forms between the injured tissue, and new growth that develops after the injury. This wall is also called the Barrier Zone, because it serves to prevent decay from moving outwards into the new growth.  Wall 4 physically separates the old wood from the new wood, making a very strong defense against decay. This portion is structurally weak however, on account of the new ray cells being disconnected from the old ray cells. This is often were cracks will form around, or up-and-down the tree.

The trees ability to use the C.O.D.I.T. walls effectively is affected by genetics, health, vigor, and the growing environment. Please keep in mind that there are still pathogens that are very aggressive, and may continue to breach all the protective walls. It is very important to understanding the nature of the injury, the organisms that has moved in to infect the wound, and the tree that has been injured.

Next week we will be discussing the types of decay that is found in trees.

The majority of the information given is taken from the “Tree Risk Assessment In Urban Areas And The Urban/Rural Interface” Manual written byJulian Dunster and published in 2009

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The Anatomy of Pruning

If you are like me, it’s not enough to just know how to prune correctly – I need to know why this pruning is correct. This article will address the “why’s” of proper tree pruning in three main points; Where to make the cut, when to make the cut, and why it’s important not to cut too much.

Why do I cut at the branch collar?

In each successive year, a tree will divide and expand its cells gaining length at the shoot and root tips.  With this cellular gain, the entire tree will expand along its circumference.  In the simplified picture below (1) you see there is a layering of conical-structures stacked one inside another.   This layering of cones becomes interesting at the branch-to-trunk union, as they grow successively one over the other (as if they were woven together). It is this weaving that creates the branch collar. Inside the branch collar is a decay-resistant inverted cone that is called the branch core.  This is why it is well advised to cut to, but not into the branch collar.  Cutting into the branch collar opens up the wood of the trunk (or parent stem) to decay, and negates the protective barriers that the tree has established.

growthrings.jpegbranchcrosscut.jpeg

This is also why a crown reduction should be done very sparingly, as the cuts that are made are called drop-crotch cuts.  This cut removes the parent stem just above a branch, and leaves no branch collar and no branch core… therefore no protective barrier.

When to make the cut

One of the most common questions I am asked is what time of year should I prune my trees. I usually tell a client that pruning anytime during the year is possible – as we adjust our pruning techniques for each season.  Though with most careful pruning procedures, there are always exceptions.  The best time to prune a tree is late in the dormant season (late winter), as they are expending very little energy and have very little time for infectious diseases to move into the pruning wounds before the tree can begin growing over the cut.

The second best time to prune is mid-to-late summer, before the leaves start to turn.  This is a good time to prune because the tree is no longer growing and has not started to withdraw the energy from the leaves to store it for spring.

The third option for pruning would be in autumn. Pruning in the autumn months interrupts or removes the available energy that would otherwise be put away for the spring flush.  During this time, pruning must be done to a lighter degree.

In spring and during flowering periods of any season, the tree is expending a great deal of energy toward cell expansion – while receiving very little energy from photosynthesis. During this time, the tree is giving growth it’s all and has very little energy to divert towards defense.  It is still okay to be pruning during this time of year, when the tree is too busy to be bothered – but the amount of living branches removed needs to be adjusted to account for the trees physical requirements.

Removing deadwood is a good thing to do at anytime of the year, as it does not interrupt any of the trees natural processes and ensures energy is being used in the most efficient manner.  Deadwood removal on a tree also minimizes potential damage, and allows the branches being removed to be cut clean to the branch collar (as opposed to breaking-out during wind or other environmental effects).

Don’t prune too much

It is important not to over-prune at any time during the year.  Over pruning disrupts the balance of two phytohormones; Auxin (produced in the shoots) and Cytokinin (produced in the roots). When the supply of Auxin is reduced to a level that is too low by over pruning, there is an abundance of Cytokinin. Cytokinin is the hormone that is in part responsible for shoot development.  This is the cause of unhealthy and ugly sucker growth (or “water sprouts”) due to over pruning.  In a sense, it is similar to humans with chemical imbalances… the trees go a little crazy.

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Douglas Fir Pseudotsuga menziesii

The Douglas fir; so tall and majestic in appearance with its tall straight trunk and dense, dark blue-green canopy.  It appears with an almost sorrowful grace as the gentle winds of summer blow through its boughs and down-turned foliage. But in winter when the winds blow stronger and more often, only then do you see its strength and will to live through the ages – into a length of life that is unfathomable to us short-lived bipeds.  There is no other tree that so clearly and nobly defines the Northwest as the Douglas fir.  It is for this reason that this particular species inhabits a groove of its own in my heart.
douglasfircomplete

Here are some Interesting facts on Douglas Firs:

  • The thick bark of an old-growth Douglas fir protects it from fire.  These more mature trees can often survive forest fires, even though their bark may be blackened and charred.
  • Douglas fir is considered the second tallest tree in North America, after the Redwood (Old growth Douglas Firs reach over 300’)
  • Douglas fir comprises most of the old-growth forests of the western United States, and provides the largest percentage of wood harvested in the U.S.
  • The Douglas fir is sometimes known as the “tree of 1000 uses”, and provides a resource for more products than any other tree in the world.
  • The Douglas fir aids in preventing soil erosion by holding soil to the ground surface with it’s shallow roots.  This can provide watershed protection for local environments, but the shallow root system also creates a higher likelihood for single-standing forest firs to uproot under high winds.

 

The Douglas fir is easy to define from other trees, as it has a very distinctive soft cone with broad scales and ribbon-shaped bracts that looks like a 3 forked tongue. It is this trident shaped bract that sets it apart – as no other trees has a cone like it.

The Douglas fir gets its name from David Douglas, a Scottish botanist and explorer who made what was considered “one of the great botanical explorations of a heroic generation” when traveling to the Pacific Northwest in 1824. Although you and I give Mr. Douglas credit, the scientific name Pseudotsuga menziesii name gives credit to another great botanist of the Pacific Northwest, Archibald Menzies. Though Mr. Douglas was not without due credit in the scientific community, as there are over eighty species that bear the name douglasii.

The Douglas fir requires very little tree care to maintain as a safe and beautiful part of your backyard environment.  The first thing to do is to have an ISA Certified Arborist and Certified Tree Risk Assessor evaluate the tree for any defects. If no defects are found and the tree is in good health, then it is best to remove the deadwood and any defective branches.  This is what we at Eastside Tree Works call a Structure Prune.  For the larger more mature Douglas firs, this needs to be done every five to ten years.  As for the younger Douglas firs, a structure prune is recommended for health every three to five years. I highly recommend avoiding “windsailing” your Douglas fir outside of very specific scenarios, as it greatly reduces the amount of “food” the tree can produce and makes it more susceptible to diseases that it could otherwise fend off.

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Tree Pruning Done Like a Tree Surgeon

Pruning forethought

Before setting out into your yard with pruners and handsaws, it is important to give thought as to what your goals are and how best to accomplish them.  There are five basic reasons why we prune; health, beauty, thinning, raising the canopy and reducing the height.  Below I have listed these reasons with a brief description on how to prune with proper care.

Improve health and beauty

This is the most important of all the pruning techniques as it can be applied to most trees.

This is best accomplished with a structure prune or what is more often called “crown cleaning” or “tree cleanup”.  This is the process of pruning the tree by removing the dead, dying and diseased branches. Removing these branches gives the tree a cleaner appearance and improves the health of the tree. It is important to remove branches that are crossing the trunk (or crossing other branches) as they will rub against each other during even mildly breezy conditions.  This friction causes the wood underneath to open up, which will most often be followed by decay and disease from this wound. Pruning for health and beauty also includes removing branches with weak unions (branches with less than a forty-five degree angle or two leads that are in close-contact).  This is a very important step, and is critical while a tree is young and the cuts are small. Removing these branches can make a huge difference in the trees longevity – both for the safety and aesthetics of the tree.

(Please keep in mind all tree diagrams are two dimensional representations and are only imply an idea)

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Thinning

This is done to allow greater light penetration into your yard, or to reduce the presence the tree has in your yard.  The methods used are very similar to the crown cleaning – but includes removing some of the outer lateral branches (a branch that stems from a larger branch).

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Crown raising

This is done by removing the lower branches to a specified height.

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Shortening the trees height

This is the most taboo type of pruning, as it can be highly damaging (especially to larger trees). Luckily there is a better way to do this rather than tree “topping”… and when I say a better way, I mean less damaging (not free from damage).  We are removing portions of the tree to a point where there are no natural protections, which leaves the tree open to infection and decay. That is why it is important to make small cuts so that the tree has time to cover the wounds with new growth.

To minimize the damage, we will follow the branches that need to be shortened down to where there is a “lateral” branch that is at least one-third the size of the parent stem, and make our cut just above the lateral. This will become the new “top” of the tree.  It is important to consider the direction that the new top is growing to prevent any new crossing branches.

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Making the cut

The foremost thing to remember when removing a limb is placement. A proper pruning cut is made with three cuts: The first is an undercut further up the branch(1), to prevent the bark from tearing when the branch is freed from the rest of the tree. The second cut is to be made a small distance from the undercut(2). This is the cut that will release the majority of the branches weight, allowing you to make the final cut free from the worry of the bark tearing into tree trunk.  The last cut is the most important cut(3) as this will be the one that determines the trees ability to “heal” from the damage from removing the branch. This last cut should be made at the branch collar. The branch collar is a small mounding at the union of the branch and the trunk (image 1). The cut should be made half-way between the angle of the trunk and the angle of the branch.

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Remember, it is always a good idea to consult with a professional before making any decisions or cuts.  Handling sharp saws or shears can be dangerous, even at low heights – and pruning too much or incorrectly can sometimes result in tree failure on account of shock.  Stay tuned here for more helpful tips regarding these questions, as well as the best time of year to prune, how much pruning is too much, and more.  When in doubt, give us a call for a free consultation

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Greetings

Welcome to the new Eastside Tree Works blog!

We at Eastside Tree Works will be renewing our resolution to improving our service to the community through expert tree care. This care goes much further than just improving the health of your trees or safely removing the hazardous tree from your yard.  This year we will be educating the public through a weekly blog that will discuss Arboriculture in the Pacific Northwest; which is the best place in the world to be in love with trees.

The trees that live around us are all part of a second growth forest, after a massive harvest over 80 years ago. What we live in now, is just the start of what these trees can become. This forest has the potential to fully revitalize itself, and needs our help to remain healthy, and for the safety of our community and our homes. The Douglas fir is a great example of this potential; it can live longer than fifty generations of humankind and grow to over 350 feet. When I imagine a tree that I have taken care of being passed down that far into our future, I know my work is more than just a career or a job – but is the highest fulfillment of our future potential. We definitely live in a tree paradise, where our environment only becomes greener in the winter.

My name is Benjamin Gray, and I am an ISA Certified Arborist, Certified Tree Risk Assessor, Master Gardener and Watershed steward. I have been working with trees and plants for the last decade and have found that it is much like the rabbit hole that Alice fell into; there is no end to the knowledge that we can find in this vast and interesting world of Arboriculture. This is why I have put most of my focus into trees – as they have always struck me as noble forms of life that are worthy of study and admiration. I hope to impart to some of you the feeling I have when I see the tops of local Douglas Firs twist in the wind, relieving the pressure from the bulk of the tree. I hope to educate you in susceptibilities that can cause such trees to fail in wind, as well as which trees are capable enough to withstand such a storm.

Please check back regularly, as I will be going over proper pruning techniques, highlighting common NW tree species (and which diseases they are susceptible to), current events in the world of growing things, and showcasing some of the more exciting and interesting tree projects here at Eastside Tree Works. Feel free to send me questions or call us for a consultation.

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