Crown Thinning

Crown Thinning

Benefits of Crown Thinning

Crown thinning is like a spa day for your trees. It's not about drastically altering their shape or size, but rather selectively removing branches to improve their overall health and appearance. Think of it as carefully pruning away the excess to let the best parts shine through. And the benefits? They're numerous.


One of the most immediate benefits is increased sunlight penetration. A dense canopy can shade out lower branches and the understory, hindering growth and potentially creating a haven for pests and diseases. Thinning the crown allows more light to filter through, invigorating the tree and promoting healthier growth throughout. This increased light also benefits the plants and grass growing beneath, creating a more vibrant and thriving ecosystem.


Improved air circulation is another key advantage. When a tree's crown is too dense, air can become stagnant, creating a humid environment that's perfect for fungal growth. Thinning opens up the canopy, allowing air to move freely, reducing the risk of disease. This is particularly important in areas prone to high humidity or where trees are closely spaced.


Crown thinning can also strengthen the tree's structure. By removing weak, crossing, or rubbing branches, you reduce the risk of breakage during storms or high winds. This proactive approach can prevent significant damage and prolong the life of your tree. It's like removing potential points of failure, making the whole structure more resilient.


Finally, let's not forget the aesthetic benefits. Crown thinning can enhance the natural beauty of a tree, revealing its graceful branching structure and improving its overall form. It can also improve views from your property and increase the amount of light reaching your home or garden. It's a win-win for both the tree's health and your enjoyment of it.


So, while it might seem counterintuitive to remove parts of a tree to improve its health, crown thinning is a valuable practice that offers a range of benefits. From increased sunlight and air circulation to improved structural integrity and aesthetics, it's an investment in the long-term health and beauty of your trees.

Crown thinning is a specific pruning technique aimed at improving a tree's structure and light penetration without drastically altering its overall size or shape. It differs significantly from other pruning methods, each of which serves a distinct purpose. While crown thinning selectively removes branches throughout the crown, focusing on smaller diameter limbs and reducing density, other methods address different needs.


Crown cleaning, for instance, primarily focuses on removing dead, diseased, or damaged branches to improve tree health and safety. It's a vital maintenance practice but doesn't necessarily address density or light penetration. Crown raising, on the other hand, removes lower branches to increase clearance beneath the tree, often for pedestrian or vehicular access. It alters the tree's shape but doesn't thin the crown itself. Similarly, crown reduction decreases a tree's overall height and spread by cutting back larger limbs to lateral branches. This can be crucial for managing overgrown trees but is a more drastic intervention than thinning.


Another distinct method is pollarding, a more specialized technique involving the removal of upper branches to promote a dense head of foliage. This is primarily used for aesthetic purposes or to manage tree size in confined spaces. It creates a very different visual effect than crown thinning, which aims for a more natural appearance.


Therefore, while all these methods involve pruning, crown thinning stands apart. It's a nuanced approach that selectively removes branches to improve light penetration and air circulation within the crown, promoting healthy growth and reducing the risk of wind damage. It's less about resizing the tree and more about optimizing its structure and vitality, distinguishing it from other pruning practices that target specific issues like deadwood removal, clearance, or overall size reduction. Choosing the right method depends on the specific goals for the tree and its surroundings.

Citations and other links

Finding a Qualified Tree Service for Crown Thinning

Finding a qualified tree service for crown thinning can feel like navigating a dense forest itself. You want someone who understands the delicate art of pruning, someone who won't just hack away at your beloved trees but will carefully sculpt them for health and beauty. So, where do you start?


First, word of mouth is gold. Ask your neighbors, friends, and family for recommendations. Local garden centers and arborists are also excellent resources. Online reviews can be helpful, but take them with a grain of salt – look for consistent themes rather than isolated incidents.


Once you have a few potential candidates, it's time to do some digging. A reputable tree service will be fully insured and licensed. Don't be shy about asking for proof! This protects you from liability in case of accidents. Certification from organizations like the International Society of Arboriculture (ISA) indicates a commitment to professional standards and ongoing education. A certified arborist on staff is a definite plus.


Next, ask for a detailed estimate. It should outline the scope of work, including which branches will be removed and why. A vague estimate is a red flag. A good arborist will take the time to explain the process and answer your questions. They'll also be able to assess the overall health of your tree and identify any potential problems.


Beware of companies that push for topping or excessive pruning. Crown thinning is a selective process aimed at improving light penetration and air circulation, not drastically altering the tree's shape. A qualified arborist will prioritize the long-term health and structural integrity of your tree.


Finally, trust your gut. If something feels off, it probably is. Choose a company that communicates clearly, respects your property, and demonstrates a genuine passion for trees. Finding the right tree service for crown thinning is an investment in the health and beauty of your landscape. Take your time, do your research, and you'll be rewarded with thriving trees for years to come.

Finding a Qualified Tree Service for Crown Thinning

Cost of Crown Thinning and Factors That Influence It

Crown thinning is a common tree pruning practice that selectively removes branches to reduce the density of the crown, allowing more light and air to penetrate. While beneficial for tree health and aesthetics, it comes with a cost, and understanding the factors that influence this cost can help homeowners budget effectively.


The cost of crown thinning varies considerably, ranging from a few hundred dollars for a small tree to several thousand for a large, mature, or difficult-to-access tree. Several key factors play a role in determining the final price.


Tree size is a primary driver. Larger trees require more time, effort, and equipment, leading to higher costs. A tall tree might necessitate a bucket truck or specialized climbing gear, adding to the expense. Similarly, a tree with a dense crown will require more extensive thinning than one with a naturally open canopy.


Location and accessibility also influence cost. A tree situated close to power lines or buildings presents greater challenges and risks, requiring more skilled arborists and potentially specialized equipment. Difficult-to-access trees, such as those in a fenced backyard or on a steep slope, also increase labor and equipment costs.


The health of the tree and the complexity of the work are further considerations. A diseased or damaged tree might require more careful pruning to avoid further harm, increasing labor time. Similarly, complex pruning involving intricate shaping or the removal of large, heavy branches will cost more.


Finally, the arborist's experience and reputation play a role. Certified arborists with extensive experience and a strong track record often charge more, but their expertise can ensure the job is done correctly and safely. Getting multiple quotes from reputable arborists is recommended to compare prices and services.


In summary, the cost of crown thinning is influenced by a combination of factors, including tree size, location, accessibility, health, the complexity of the work, and the arborist's experience. By understanding these factors, homeowners can make informed decisions and budget appropriately for this valuable tree care practice.

An arborist using a chainsaw to cut a eucalyptus tree in a public park
Arborists in Ontario
Two arborists climbing and dismantling a Norway Maple in Ontario, Canada

An arborist, or (less commonly) arboriculturist, is a professional in the practice of arboriculture, which is the cultivation, management, and study of individual trees, shrubs, vines, and other perennial woody plants in dendrology and horticulture.[citation needed]

Arborists generally focus on the health and safety of individual plants and trees, rather than managing forests or harvesting wood (silviculture or forestry). An arborist's scope of work is therefore distinct from that of either a forester or a logger.[citation needed]

Scope of work

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An ISA Certified municipal arborist examining a Japanese Hemlock at Hoyt Arboretum in Portland, Oregon

In order for arborists to work near power wires, either additional training is required or they need to be certified as a Qualified Line Clearance Arborist or Utility Arborist (there may be different terminology for various countries). There is a variety of minimum distances that must be kept from power wires depending on voltage, however the common distance for low voltage lines in urban settings is 10 feet (about 3 metres).[1]

Arborists who climb (as not all do) can use a variety of techniques to ascend into the tree. The least invasive, and most popular technique used is to ascend on rope. There are two common methods of climbing, Single Rope System (SRS) and Moving Rope System (MRS). When personal safety is an issue, or the tree is being removed, arborists may use 'spikes', (also known as 'gaffs' or 'spurs') attached to their chainsaw boots with straps to ascend and work. Spikes wound the tree, leaving small holes where each step has been.[citation needed]

An arborist's work may involve very large and complex trees, or ecological communities and their abiotic components in the context of the landscape ecosystem. These may require monitoring and treatment to ensure they are healthy, safe, and suitable to property owners or community standards. This work may include some or all of the following: planting; transplanting; pruning; structural support; preventing, or diagnosing and treating phytopathology or parasitism; preventing or interrupting grazing or predation; installing lightning protection; and removing vegetation deemed as hazardous, an invasive species, a disease vector, or a weed.[citation needed]

Arborists may also plan, consult, write reports and give legal testimony. While some aspects of this work are done on the ground or in an office, much of it is done by arborists who perform tree services and who climb the trees with ropes, harnesses and other equipment. Lifts and cranes may be used too. The work of all arborists is not the same. Some may just provide a consulting service; others may perform climbing, pruning and planting: whilst others may provide a combination of all of these services.[2]

Qualifications

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An arborist disassembling a tree using a crane and bucket

Arborists gain qualifications to practice arboriculture in a variety of ways and some arborists are more qualified than others. Experience working safely and effectively in and around trees is essential. Arborists tend to specialize in one or more disciplines of arboriculture, such as diagnosis and treatment of pests, diseases and nutritional deficiencies in trees, climbing and pruning, cabling and lightning protection, or consultation and report writing. All these disciplines are related to one another and some arborists are very well experienced in all areas of tree work, however not all arborists have the training or experience to properly practice every discipline.[citation needed]

Arborists choose to pursue formal certification, which is available in some countries and varies somewhat by location. An arborist who holds certification in one or more disciplines may be expected to participate in rigorous continuing education requirements to ensure constant improvement of skills and techniques.[citation needed]

In Australia, arboricultural education and training are streamlined countrywide through a multi-disciplinary vocational education, training, and qualification authority called the Australian Qualifications Framework, which offers varying levels of professional qualification. Government institutions including Technical and Further Education TAFE offer Certificate III or a diploma in arboriculture as well as some universities.[3][4] There are also many private institutions covering similar educational framework in each state. Recognition of prior learning is also an option for practicing arborists with 10 or more years of experience with no prior formal training. It allows them to be assessed and fast track their certification.[citation needed]

In France, a qualified arborist must hold a Management of Ornamental Trees certificate, and a qualified arborist climber must hold a Pruning and Care of Trees certificate; both delivered by the French Ministry of Agriculture.[5][6]

In the UK, an arborist can gain qualifications up to and including a master's degree. College-based courses include further education qualifications, such as national certificate, national diploma, while higher education courses in arboriculture include foundation degree, bachelor's degree and master's degree.[citation needed]

In the US, a Certified Arborist (CA) is a professional who has over three years of documented and verified experience and has passed a rigorous written test from the International Society of Arboriculture. Other designations include Municipal Specialist, Utility Specialist and Board Certified Master Arborist (BCMA). The USA and Canada additionally have college-based training which, if passed, will give the certificate of Qualified Arborist. The Qualified Arborist can then be used to offset partial experience towards the Certified Arborist.

Tree Risk Assessment Qualified credential (TRAQ), designed by the International Society of Arboriculture, was launched in 2013. At that time people holding the TRACE credential were transferred over to the TRAQ credential.[citation needed]

In Canada, there are provincially governed apprenticeship programs that allow arborists' to work near power lines upon completion. These apprenticeship programs must meet the provincial reregulations (For example, in B.C. they must meet WorkSafeBC G19.30), and individuals must ensure they meet the requirements of the owner of the power system.[citation needed]

Cultural practices

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Arborists may use specialised vehicles to gain access to trees, such as this Unimog equipped with a power take-off driven woodchipper

Trees in urban landscape settings are often subject to disturbances, whether human or natural, both above and below ground. They may require care to improve their chances of survival following damage from either biotic or abiotic causes. Arborists can provide appropriate solutions, such as pruning trees for health and good structure, for aesthetic reasons, and to permit people to walk under them (a technique often referred to as "crown raising"), or to keep them away from wires, fences and buildings (a technique referred to as "crown reduction").[7] Timing and methods of treatment depend on the species of tree and the purpose of the work. To determine the best practices, a thorough knowledge of local species and environments is essential.[citation needed]

There can be a vast difference between the techniques and practices of professional arborists and those of inadequately trained tree workers. Some commonly offered "services" are considered unacceptable by modern arboricultural standards and may seriously damage, disfigure, weaken, or even kill trees. One such example is tree topping, lopping, or "hat-racking", where entire tops of trees or main stems are removed, generally by cross-cutting the main stem(s) or leaders, leaving large unsightly stubs. Trees that manage to survive such treatment are left prone to a spectrum of detrimental effects, including vigorous but weakly attached regrowth, pest susceptibility, pathogen intrusion, and internal decay.[8]

Pruning should only be done with a specific purpose in mind. Every cut is a wound, and every leaf lost is removal of photosynthetic potential. Proper pruning can be helpful in many ways, but should always be done with the minimum amount of live tissue removed.[9]

In recent years, research has proven that wound dressings such as paint, tar or other coverings are unnecessary and may harm trees. The coverings may encourage growth of decay-causing fungi. Proper pruning, by cutting through branches at the right location, can do more to limit decay than wound dressing [10]

Chemicals can be applied to trees for insect or disease control through soil application, stem injections or spraying. Compacted or disturbed soils can be improved in various ways.[citation needed]

Arborists can also assess trees to determine the health, structure, safety or feasibility within a landscape and in proximity to humans. Modern arboriculture has progressed in technology and sophistication from practices of the past. Many current practices are based on knowledge gained through recent research, including that of Alex Shigo, considered one "father" of modern arboriculture.[11]

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Depending on the jurisdiction, there may be a number of legal issues surrounding the practices of arborists, including boundary issues, public safety issues, "heritage" trees of community value, and "neighbour" issues such as ownership, obstruction of views, impacts of roots crossing boundaries, nuisance problems, disease or insect quarantines, and safety of nearby trees or plants that may be affected.[citation needed]

Arborists are frequently consulted to establish the factual basis of disputes involving trees, or by private property owners seeking to avoid legal liability through the duty of care.[12] Arborists may be asked to assess the value of a tree[13] in the process of an insurance claim for trees damaged or destroyed,[14] or to recover damages resulting from tree theft or vandalism.[15] In cities with tree preservation orders an arborist's evaluation of tree hazard may be required before a property owner may remove a tree, or to assure the protection of trees in development plans and during construction operations. Carrying out work on protected trees and hedges is illegal without express permission from local authorities,[16] and can result in legal action including fines.[17] Homeowners who have entered into contracts with a Homeowner's association (see also Restrictive covenants) may need an arborists' professional opinion of a hazardous condition prior to removing a tree, or may be obligated to assure the protection of the views of neighboring properties prior to planting a tree or in the course of pruning.[18] Arborists may be consulted in forensic investigations where the evidence of a crime can be determined within the growth rings of a tree, for example. Arborists may be engaged by one member of a dispute in order to identify factual information about trees useful to that member of the dispute, or they can be engaged as an expert witness providing unbiased scientific knowledge in a court case. Homeowners associations seeking to write restrictive covenants, or legislative bodies seeking to write laws involving trees, may seek the counsel of arborists in order to avoid future difficulties.[19]

Before undertaking works in the UK, arborists have a legal responsibility to survey trees for wildlife, especially bats, which are given particular legal protection. In addition, any tree in the UK can be covered by a tree preservation order and it is illegal to conduct any work on a tree, including deadwooding or pruning, before permission has been sought from the local council.[citation needed]

Organizations

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  • Australia Limited, a non-profit organisation, is a national organisation promoting and representing tree workers, arborists, professional tree management and urban forestry throughout Australia and the Asia-Pacific region.[20]
  • The Tree Care Industry Association (formerly the National Arborist Association) is a public and professional non-profit organization for the arboriculture field. It has more than 2,000 member companies representing over a dozen countries. TCIA's Accreditation program certifies that tree care companies that have been inspected and accredited based on adherence to industry standards for performance and safety; maintenance of trained, professional staff; and dedication to ethics and quality in business practices. In addition, they provide safety and educational programs, guidelines for tree service operations, ANSI A300 tree pruning standards, and consumer resources.[citation needed]
  • The International Society of Arboriculture, a non-profit organization, maintains a list of ISA Certified Arborists who have passed a written exam and demonstrated a basic level of knowledge in arboriculture.[21] There are also additional classifications of certified arborists with Certified Arborist/Utility Specialist for those who work near power lines, and Certified Arborist/Municipal Specialist for those who deal mostly with community trees. Other certifications exist for Certified Tree Workers, and the highest level of certification, the Board Certified Master Arborist.[citation needed]
  • The American Society of Consulting Arborists is an organization whose membership is exclusive to those with a certain level of industry experience, plus higher educational experience or continuing education; some members may achieve a higher status by fulfilling the requirements to become a Registered Consulting Arborist.[22] Consulting arborists generally specialize in the areas of ethics, law, land planning and development, and tree valuation, among others. Consulting arborists are often called on for legal testimony and report writing in various instances where a particular authority on trees is necessary for consequent actions.
  • In the UK, the professional body representing the sector is the Institute of Chartered Foresters. The trade body representing arborists is the Arboricultural Association. The association maintains a register of consultants who have demonstrated a high level of technical arboricultural knowledge, and operate an Approved Contractor scheme. This scheme assesses both the technical competence and business practices of arboricultural contractors.
  • The European Arboricultural Council is a European group of multiple arboriculture organizations from various countries.
  • Plant Amnesty is a public education and advocacy group, based in Seattle, dedicated to promoting proper pruning methods. Founded in 1987, Plant Amnesty became an international resource for arborists and their clients in the mid-1990s.[23][24]

In literature

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The protagonist in Italo Calvino's novel The Baron in the Trees lives life on the ground as a boy and spends the rest of his life swinging from tree to tree in the Italian countryside. As a young man he helps the local fruit farmers by pruning their trees.[citation needed]

Notable arborists

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Some noteworthy arborists include:

  • Francis A. Bartlett – founded The Bartlett Tree Experts Co., the world's leading scientific tree and shrub care company in 1907.
  • John Chapman – pioneering U.S. frontier nurseryman and orchardist, commonly known as Johnny Appleseed.
  • Canopy Cat Rescue[25] – rescues domestic cats from tall trees; appears on Treetop Cat Rescue.
  • Sebastian Junger – author of Perfect Storm and War. Previous to becoming a journalist, Sebastian was an arborist in Massachusetts.
  • Chuck Leavell – two-time recipient of the Georgia Tree Farmer of the Year award, and author of the children's book, The Tree Farmer. In 2006 Leavell was appointed by Governor Sonny Perdue to the Georgia Land Conservation Council. He is also an accomplished jazz pianist and keyboardist for the Rolling Stones.[26]
  • Alex Shigo – considered the father of modern arboriculture.
  • David Mitchell - Devon born tree inspector and veteran tree expert
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See also

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References

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  1. ^ American National Standards Institute Z.133- and International Brotherhood of Electrical Workers.
  2. ^ Harris, Richard W., James R. Clark, and Nelda P. Matheny: Arboriculture Integrated Management of Landscape Trees, Shrubs, and Vines, third edition; Prentice-Hall, Inc. 1999.
  3. ^ "Becoming an Arborist". Victorian Skills Gateway. Archived from the original on 2018-03-16. Retrieved 2018-03-15.
  4. ^ "Graduate Certificate in Arboriculture". University of Melbourne. Retrieved 2018-03-15.
  5. ^ "Les formations qualifiantes des arboristes : certificat de spécialisation CS " taille et soin des arbres "". Copalme (in French). Retrieved 2018-03-15.
  6. ^ "Le CFPPA à l'action sur le domaine Paul-Riquet - Enseignement et formation - Un vrai chantier pour les lycéens". La Dépêche (in French). February 23, 2017. Retrieved 2018-03-15.
  7. ^ "Pruning Standards to Maintain Landscape Trees (3)". E. Thomas Smiley, Ph. D., Plant Pathologist and Bruce R. Fraedrich, Ph. D., Plant Pathologist; Bartlett Tree Research Laboratory.
  8. ^ "Follow Proper Pruning Techniques | Earth-Kind® Landscaping". aggie-horticulture.tamu.edu.
  9. ^ "Access Trees Home". treesaccess.com. Archived from the original on 2022-03-22. Retrieved 2022-03-30.
  10. ^ https://joa.isa-arbor.com/request.asp?JournalID=1&ArticleID=1923&Type=2, Wound dressings results of studies over 13 years
  11. ^ Alex Shigo pioneered tree-friendly pruning by Ron Sullivan; San Francisco Chronicle November 15, 2006.
  12. ^ Common Law Branches Off Into New Directions; by Victor D. Merullo; Journal of Arboriculture 20(6): November 1994.
  13. ^ Landscape Tree Appraisal by David P. Mooter, et al.; University of Nebraska–Lincoln Extension; March 2004.
  14. ^ Guide for Plant Appraisal, 9th ed; by the Council of Tree and Landscape Appraisers; International Society of Arboriculture; 2000.
  15. ^ See also specific legal provisions for "tree theft" such as, for example, the Revised Code of Washington title 64.12.030 for Washington (State, USA) or similar state, provincial, or local statutes.
  16. ^ "A Guide To The Laws Of Arboriculture & Tree Legislations". Surrey Tree Surgery. Archived from the original on 4 April 2014. Retrieved 4 April 2014.
  17. ^ "Businessman fined £28,000 for felling protected yew tree". The Daily Telegraph. London. 3 June 2013. Archived from the original on 6 June 2013. Retrieved 4 April 2014.
  18. ^ Arboriculture and the Law in Canada by Julian Dunster and Susan Murray; International Society of Arboriculture; 1997.
  19. ^ Arboriculture and the Law by Victor D. Merrullo; International Society of Arboriculture; 1992.
  20. ^ "About Us". arboriculture.org.au. Archived from the original on 2016-08-08. Retrieved 2016-07-22.
  21. ^ "Verify an ISA Certification / Find a Tree Care Service". International Society of Arboriculture. Archived from the original on 27 March 2014. Retrieved 4 April 2014.
  22. ^ "American Society of Consulting Arborists – Registered Consulting Arborist". Archived from the original on 2003-02-28. Retrieved 2008-04-29.
  23. ^ "The Seattle Times: Pacific Northwest Magazine". The Seattle Times.
  24. ^ Young, Paul. "Bakersfield CA Local Online Stock Brokerage Firms | Berkeley Daily". Archived from the original on 2020-08-09. Retrieved 2019-11-08.
  25. ^ "Cat stuck in a tree in Washington". Canopy Cat Rescue. Archived from the original on 2019-11-08. Retrieved 2019-11-08.
  26. ^ "Chuck Leavell - Trees". chuckleavell.com. Archived from the original on 2007-07-03. Retrieved 2007-07-21.
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An arborist practicing tree care: using a chainsaw to fell a eucalyptus tree in a park at Kallista, Victoria.

Arboriculture (/ˈɑːrbərɪˌkʌltʃər, ɑːrˈbɔːr-/)[1] is the cultivation, management, and study of individual trees, shrubs, vines, and other perennial woody plants. The science of arboriculture studies how these plants grow and respond to cultural practices and to their environment. The practice of arboriculture includes cultural techniques such as selection, planting, training, fertilization, pest and pathogen control, pruning, shaping, and removal.

Overview

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A person who practices or studies arboriculture can be termed an arborist or an arboriculturist. A tree surgeon is more typically someone who is trained in the physical maintenance and manipulation of trees and therefore more a part of the arboriculture process rather than an arborist. Risk management, legal issues, and aesthetic considerations have come to play prominent roles in the practice of arboriculture. Businesses often need to hire arboriculturists to complete "tree hazard surveys" and generally manage the trees on-site to fulfill occupational safety and health obligations.[citation needed]

Arboriculture is primarily focused on individual woody plants and trees maintained for permanent landscape and amenity purposes, usually in gardens, parks or other populated settings, by arborists, for the enjoyment, protection, and benefit of people.[citation needed]

Arboricultural matters are also considered to be within the practice of urban forestry yet the clear and separate divisions are not distinct or discreet.[citation needed]

Tree Benefits

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Tree benefits are the economic, ecological, social and aesthetic use, function purpose, or services of a tree (or group of trees), in its situational context in the landscape.

Environmental Benefits

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  • Erosion control and soil retention
  • Improved water infiltration and percolation
  • Protection from exposure: windbreak, shade, impact from hail/rainfall
  • Air humidification
  • Modulates environmental conditions in a given microclimate: shields wind, humidifies, provides shade
  • Carbon sequestration and oxygen production

Ecological Benefits

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  • Attracting pollinators
  • Increased biodiversity
  • Food for decomposers, consumers, and pollinators
  • Soil health: organic matter accumulation from leaf litter and root exudates (symbiotic microbes)
  • Ecological habitat

Socioeconomic Benefits

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  • Increases employment: forestry, education, tourism
  • Run-off and flood control (e.g. bioswales, plantings on slopes)
  • Aesthetic beauty: parks, gatherings, social events, tourism, senses (fragrance, visual), focal point
  • Adds character and prestige to the landscape, creating a "natural" feel
  • Climate control (e.g shade): can reduce energy consumption of buildings
  • Privacy and protection: from noise, wind
  • Cultural benefits: eg. memorials for a loved one
  • Medical benefits: eg. Taxus chemotherapy
  • Materials: wood for building, paper pulp
  • Fodder for livestock
  • Property value: trees can increase by 10–20%[citation needed]
  • Increases the amount of time customers will spend in a mall, strip mall, shopping district[citation needed]

Tree Defects

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A tree defect is any feature, condition, or deformity of a tree that indicates weak structure or instability that could contribute to tree failure.

Common types of tree defects:

Codominant stems: two or more stems that grow upward from a single point of origin and compete with one another.

  • common with decurrent growth habits
  • occurs in excurrent trees only after the leader is killed and multiple leaders compete for dominance

Included bark: bark is incorporated in the joint between two limbs, creating a weak attachment

  • occurs in branch unions with a high attachment angle (i.e. v-shaped unions)
  • common in many columnar/fastigiate growing deciduous trees

Dead, diseased, or broken branches:

  • woundwood cannot grow over stubs or dead branches to seal off decay
  • symptoms/signs of disease: e.g. oozing through the bark, sunken areas in the bark, and bark with abnormal patterns or colours, stunted new growth, discolouration of the foliage

Cracks

  • longitudinal cracks result from interior decay, bark rips/tears, or torsion from wind load
  • transverse cracks result from buckled wood, often caused by unnatural loading on branches, such as lion's tailing.
  • Seams: bark edges meet at a crack or wound
  • Ribs: bulges, indicating interior cracks

Cavity and hollows: sunken or open areas wherein a tree has suffered injury followed by decay. Further indications include: fungal fruiting structures, insect or animal nests.

Lean: a lean of more than 40% from vertical presents a risk of tree failure

Taper: change in diameter over the length of trunks branches and roots

Epicormic branches (water sprouts in canopy or suckers from root system): often grow in response to major damage or excessive pruning

Roots:

  • girdling roots compress the trunk, leading to poor trunk taper, and restrict vascular flow
  • kinked roots provide poor structural support; the kink is a site of potential root failure
  • circling roots occurs when roots encounter obstructions/limitations such as a small tree well or being grown too long in a nursery pot; these cannot provide adequate structural support and are limited in accessing nutrients and water
  • healthy soil texture and depth, drainage, water availability, makes for healthy roots

Tree Installation

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Proper tree installation ensures the long-term viability of the tree and reduces the risk of tree failure.

Quality nursery stock must be used. There must be no visible damage or sign of disease. Ideally the tree should have good crown structure. A healthy root ball should not have circling roots and new fibrous roots should be present at the soil perimeter. Girdling or circling roots should be pruned out. Excess soil above the root flare should be removed immediately, since it presents a risk of disease ingress into the trunk.

Appropriate time of year to plant: generally fall or early spring in temperate regions of the northern hemisphere.

Planting hole: the planting hole should be 3 times the width of the root ball. The hole should be dug deep enough that when the root ball is placed on the substrate, the root flare is 3–5cm above the surrounding soil grade. If soil is left against the trunk, it may lead to bark, cambium and wood decay. Angular sides to the planting hole will encourage roots to grow radially from the trunk, rather than circling the planting hole. In urban settings, soil preparation may include the use of:

  • Silva cells: suspended pavement over modular cells containing soil for root development
  • Structural soils: growing medium composed of 80% crushed rock and 20% loam, which supports surface load without it leading to soil compaction

Tree wells: a zone of mulch can be installed around the tree trunk to: limit root zone competition (from turf or weeds), reduce soil compaction, improve soil structure, conserve moisture, and keep lawn equipment at a distance. No more than 5–10cm of mulch should be used to avoid suffocating the roots. Mulch must be kept approximately 20cm from the trunk to avoid burying the root flare. With city trees additional tree well preparation includes:

Tree grates/grill and frames: limit compaction on root zone and mechanical damage to roots and trunk

Root barriers: forces roots to grow down under surface asphalt/concrete/pavers to limit infrastructure damage from roots

Staking: newly planted, immature trees should be staked for one growing season to allow for the root system to establish. Staking for longer than one season should only be considered in situations where the root system has failed to establish sufficient structural support. Guy wires can be used for larger, newly planted trees. Care must be used to avoid stem girdling from the support system ties.

Irrigation: irrigation infrastructure may be installed to ensure a regular water supply throughout the lifetime of the tree. Wicking beds are an underground reservoir from which water is wicked into soil. Watering bags may be temporarily installed around tree stakes to provide water until the root system becomes established. Permeable paving allows for water infiltration in paved urban settings, such as parks and walkways.

UK

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Within the United Kingdom trees are considered as a material consideration within the town planning system and may be conserved as amenity landscape[2] features.

The role of the Arborist or Local Government Arboricultural Officer is likely to have a great effect on such matters. Identification of trees of high quality which may have extensive longevity is a key element in the preservation of trees.

Urban and rural trees may benefit from statutory protection under the Town and Country Planning[3] system. Such protection can result in the conservation and improvement of the urban forest as well as rural settlements.

Historically the profession divides into the operational and professional areas. These might be further subdivided into the private and public sectors. The profession is broadly considered as having one trade body known as the Arboricultural Association, although the Institute of Chartered Foresters offers a route for professional recognition and chartered arboriculturist status.

The qualifications associated with the industry range from vocational to Doctorate. Arboriculture is a comparatively young industry.

See also

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References

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  1. ^ "arboriculture". Dictionary.com Unabridged (Online). n.d.
  2. ^ "Amenity landscapes • Environment Guide". www.environmentguide.org.nz. Retrieved 2020-04-28.
  3. ^ "Town and Country Planning Association". Town and Country Planning Association. Retrieved 2020-04-28.
  • Harris, Richard W. (1983). Arboriculture: Care of Trees, Shrubs, and Vines in the Landscape. Englewood Cliffs, New Jersey: Prentice-Hall, Inc. pp. 2–3. ISBN 0-13-043935-5.
  • "arboriculture". Merriam-Webster's Collegiate Dictionary, Eleventh Edition. Merriam-Webster.
  • "arboriculture". Encyclopædia Britannica Online. 2007.
  • "arboriculture". The American Heritage Dictionary of the English Language, Fourth Edition Online. Houghton Mifflin Company. 2000.
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Frequently Asked Questions

Crown thinning is the selective removal of branches to reduce the density of a trees crown, allowing more light and air penetration while maintaining its natural shape.
Crown thinning can reduce wind resistance (lessening storm damage risk), improve light penetration for understory growth, decrease weight on heavy limbs, and improve the overall appearance and health of the tree.
The cost depends on the size and location of the tree, accessibility, and the amount of thinning required. Contacting a certified arborist for an on-site assessment is recommended for an accurate estimate.