Tree topping
Encyclopedia
Tree topping is the practice of removing whole tops of trees or large branches and/or trunks from the tops of tree
s, leaving stubs or lateral branches that are too small to assume the role of a terminal leader. Other common names for the practice include hat-racking, heading, rounding over, and tipping. Topping damages trees, but the practice is frequently deemed necessary by its practitioners, for several reasons. Some species of trees are more likely to recover from the effects of topping than are others. There are alternatives to topping that can help to achieve the same goals without damaging trees.
are topped each year for a variety of reasons. These include safety
, aesthetics
, reduced shading, and also to stimulate new growth. It has been shown through survey, that the average persons knowledge on tree care is limited.
Many people are under the assumption that a topped tree will be safer, or less likely to hurt someone or damage property. A tree that has grown without major root
zone disturbances is actually more sturdy than a newly planted tree. It is more important to look for problems such as inclusive bark or frost cracks
when attempting to determine the relative safety of the tree or branch.
Another popular misconception is that a topped tree will benefit from increased light penetration. The removal of a large portion of a trees canopy can have detrimental effects. When a tree is topped, newly formed bark may be suceptable to sun scald
. Prolonged exposure can severely damage the bark, thus creating an attractive home for decay
causing organisms. Evidence of decay may be the presence of conks
(fungal fruiting structures) on the outer tree bark. The loss of leaves
reduces a trees ability to photosynthesize
and produce food. If a large tree is unable to produce enough sugars to feed the roots, it will slowly die from starvation.
Some people have been known to top trees in order to stimulate new growth. When a tree is topped, many adventitious chutes, known as suckers
begin to grow from the wound. This is the trees response to the sudden loss of leaves. Although the tree is able to produce an abundance of suckers, they are susceptible to numerous problems. Firstly, this adventitious growth is succulent and susceptible to attacks by insects such as aphids and caterpillars, and pathogens like fire blight (Rosaceae). Secondly, the branch-stubs that the suckers emerge from are rarely able to form a complete callus
. This means that any pathogen that attacks a sucker, may enter the tree directly though the open wound. If wood begins to rot it could create a weak branch connection between the developing suckers and the main tree leading to a possible branch failure. If a tree is unable to compartmentalize the fungi, it may reach the trunk and ultimately kill the tree.
Aesthetics is another reason why people hire arborists to top their trees. A tree may be blocking the mountain view, shading the garden, or interfering with solar energy collection.
. Decay undermines, to greater or lesser extent, the long-term health and physical stability of trees; most notably in those species which compartmentalize
decay less effectively. Should a tree survive topping, tissue regrowth at the site of the original topping wound(s) is generally profuse. These new multiple leaders are less well-attached than was the original treetop, partly due to the effect of advancing decay at the wound site. As these weakly attached trunks increase in size, they become more prone to fall from the tree. Wind
can increase this potential. Previously topped trees can present significant hazards and should be inspected by a qualified arborist
, who can recommend possible solutions, such as removal, cabling, bracing, or ongoing inspection.
Aesthetic appeal is also compromised by topping, as the natural shapes of trees are lost.
Spiral thinning and other forms of canopy thinning can decrease wind resistance and allow wind to pass through trees, reducing the potential for branch failure due to wind-throw. Thinning also allows more light penetration and air circulation; both important to tree health. Other cultural practices include choosing plant material that will fit in the desired location at its mature size.
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s, leaving stubs or lateral branches that are too small to assume the role of a terminal leader. Other common names for the practice include hat-racking, heading, rounding over, and tipping. Topping damages trees, but the practice is frequently deemed necessary by its practitioners, for several reasons. Some species of trees are more likely to recover from the effects of topping than are others. There are alternatives to topping that can help to achieve the same goals without damaging trees.
Why are trees topped
Hundreds of large treesTree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
are topped each year for a variety of reasons. These include safety
Safety
Safety is the state of being "safe" , the condition of being protected against physical, social, spiritual, financial, political, emotional, occupational, psychological, educational or other types or consequences of failure, damage, error, accidents, harm or any other event which could be...
, aesthetics
Aesthetics
Aesthetics is a branch of philosophy dealing with the nature of beauty, art, and taste, and with the creation and appreciation of beauty. It is more scientifically defined as the study of sensory or sensori-emotional values, sometimes called judgments of sentiment and taste...
, reduced shading, and also to stimulate new growth. It has been shown through survey, that the average persons knowledge on tree care is limited.
Many people are under the assumption that a topped tree will be safer, or less likely to hurt someone or damage property. A tree that has grown without major root
Root
In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...
zone disturbances is actually more sturdy than a newly planted tree. It is more important to look for problems such as inclusive bark or frost cracks
Frost crack
Frost crack is a form of tree bark damage sometimes found on thin barked trees, visible as vertical fractures on the southerly facing surfaces of tree trunks...
when attempting to determine the relative safety of the tree or branch.
Another popular misconception is that a topped tree will benefit from increased light penetration. The removal of a large portion of a trees canopy can have detrimental effects. When a tree is topped, newly formed bark may be suceptable to sun scald
Sun scald (flora)
Sun scald is the freezing of bark following high temperatures in the winter season, resulting in permanent visible damage to bark. Fruits may also be damaged.-Causes of Sun scald:...
. Prolonged exposure can severely damage the bark, thus creating an attractive home for decay
Decomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...
causing organisms. Evidence of decay may be the presence of conks
Bracket fungus
Bracket fungi, or shelf fungi, among many groups of the fungi in the phylum Basidiomycota. Characteristically, they produce shelf- or bracket-shaped fruiting bodies called conks that lie in a close planar grouping of separate or interconnected horizontal rows...
(fungal fruiting structures) on the outer tree bark. The loss of leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
reduces a trees ability to photosynthesize
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
and produce food. If a large tree is unable to produce enough sugars to feed the roots, it will slowly die from starvation.
Some people have been known to top trees in order to stimulate new growth. When a tree is topped, many adventitious chutes, known as suckers
Basal shoot
A basal shoot, root sprout, adventitious shoot, water sprout or sucker is a shoot or cane which grows from a bud at the base of a tree or shrub or from its roots. This shoot then becomes, or takes the form of, a singular plant. A plant that produces suckers is referred to as surculose...
begin to grow from the wound. This is the trees response to the sudden loss of leaves. Although the tree is able to produce an abundance of suckers, they are susceptible to numerous problems. Firstly, this adventitious growth is succulent and susceptible to attacks by insects such as aphids and caterpillars, and pathogens like fire blight (Rosaceae). Secondly, the branch-stubs that the suckers emerge from are rarely able to form a complete callus
Callus (cell biology)
Plant callus is a mass of undifferentiated cells derived from plant tissue for use in biological research and biotechnology. In plant biology, callus cells are those cells that cover a plant wound. To induce callus formation, plant tissues are surface sterilized and then plated onto in vitro...
. This means that any pathogen that attacks a sucker, may enter the tree directly though the open wound. If wood begins to rot it could create a weak branch connection between the developing suckers and the main tree leading to a possible branch failure. If a tree is unable to compartmentalize the fungi, it may reach the trunk and ultimately kill the tree.
Aesthetics is another reason why people hire arborists to top their trees. A tree may be blocking the mountain view, shading the garden, or interfering with solar energy collection.
Topping precautions
Large pruning wounds, such as those left behind in trees after topping, may become entry points for pathogens and may result in extensive decayDecomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...
. Decay undermines, to greater or lesser extent, the long-term health and physical stability of trees; most notably in those species which compartmentalize
CODIT
Compartmentalization Of Decay In Trees is a concept created by Dr. Alex Shigo after years of studying tree decay patterns. Though disputed upon its introduction in the late 1970s, the concept is now widely accepted and can be found in many arboriculture textbooks...
decay less effectively. Should a tree survive topping, tissue regrowth at the site of the original topping wound(s) is generally profuse. These new multiple leaders are less well-attached than was the original treetop, partly due to the effect of advancing decay at the wound site. As these weakly attached trunks increase in size, they become more prone to fall from the tree. Wind
Wind
Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space...
can increase this potential. Previously topped trees can present significant hazards and should be inspected by a qualified arborist
Arborist
An arborist, or 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...
, who can recommend possible solutions, such as removal, cabling, bracing, or ongoing inspection.
Aesthetic appeal is also compromised by topping, as the natural shapes of trees are lost.
Alternatives to topping
Better alternatives to tree topping, based on scientific research, are replacing the practice of tree topping. For example, size reduction can maintain the aesthetics and structural integrity of a tree without damage.Spiral thinning and other forms of canopy thinning can decrease wind resistance and allow wind to pass through trees, reducing the potential for branch failure due to wind-throw. Thinning also allows more light penetration and air circulation; both important to tree health. Other cultural practices include choosing plant material that will fit in the desired location at its mature size.