What is a plaque axel in trees?
What is a plaque axel compared to a normal branch attachment in trees?
A plaque axil, also known as axillary axil or enclosed bark, refers to a weak branch attachment in the crown architecture of trees. Where the bark is clamped or enclosed between the trunk and a side branch. And where there is no tangled tissue between the two branches that are against each other, as is the case with a normal branch attachment.
This phenomenon occurs when two or more trunks or branches, whether upright or not, grow so close together that the bark between them cannot grow normally. And instead it gets trapped between the different parts and no real connection is formed. The cause is partly genetically determined by the species, as some species are more sensitive to the formation of plaque axils.
But the formation of plaque axils is mainly due to the fact that a tree does not have the need to invest in strong reinforcement of an axilla, because this axilla is not sufficiently loaded for one reason or another.
This situation creates a structural weak point because the wood of the trunks or branches cannot grow together properly. Which reduces the integrity and strength of the attachment.
Read much more about branch attachments and plaque axils in the book “Understanding trees better” by Wim Peeters, where he explains everything in detail.
How does a plaque axilla form?
Plaque joints occur as a result of excessively rapid thickness growth in the armpit that is not loaded enough to create tangled tissue and where the branches grow too close to the trunk or to each other, causing the bark to become wedged between them.
This is mainly caused by genetic factors, environmental factors and growth characteristics such as the natural presence of crossing branches that grow together. But it can also be indirectly influenced by the incorrect pruning a tree.
Views on branch attachment
Alex Shigo
Alex Shigo, a pioneer in modern tree care, introduced the concept of Compartmentalization of Damage in Trees (CODIT).
He emphasized the importance of good pruning techniques to support the tree's natural defense mechanisms and prevent the formation of plaque axes.
Shigo advocated pruning at the branch collar (the area where the branch base extends and merges with the trunk), without damaging the collar itself. To enable the tree to effectively close the wound area through callus formation.
Duncan Slater
Dr. Duncan Slater, a researcher in the field of tree mechanics and branch attachments, has contributed to understanding the complexity of branch attachments. And the factors that influence the strength of the bond.
His work has shown that some traditional views on branch attachments and pruning practices need to be reconsidered. Especially with regard to recognizing structurally strong versus weak attachments.
Slater's research highlights the role of branch collar and branch angle in determining attachment strength, and suggests that a more nuanced approach is needed to maintain the health and structural integrity of trees.
Both scientists have contributed to a better understanding of the complexity of tree structures. And the need for careful management and maintenance of trees.
Shigo and Slater's insights have led to improved pruning practices. And greater awareness of the need to respect the natural growth patterns of trees to ensure their health and structural stability.
Influence of Alex Shigo and Duncan Slater
Alex Shigo and Duncan Slater's differing views and research on branch attachments and tree structure have significantly influenced the tree care industry and led to new insights and approaches.
Alex Shigo's contributions
Alex Shigo has done extensive research into how trees heal wounds and deal with damage.
His work emphasized the importance of maintaining the branch collar when pruning. Because this is the area where the tree can respond to the wound most effectively.
According to Shigo's principles, pruning should be done close to, but not in, the branch collar to support the tree's natural healing processes. And prevent the formation of plaque axes.
His approach also emphasized the importance of avoiding major wounds. Which are more difficult for the tree to overgrow. And these can lead to the development of wood rot and structural weaknesses.
Duncan Slater's insights
Duncan Slater has further investigated the dynamics of branch attachments. In particular, how different factors, such as the angle of attachment and the presence of a branch collar, influence the strength of the attachment.
His research has shown that not all plaque axils are weak by definition. And that some attachments that are considered weak may actually be quite strong because of the way the wood tissue develops around the attachment.
Slater emphasizes the importance of a more detailed assessment of tree structure when making pruning decisions. Taking into account the specific shape and properties of each branch attachment.
Evolving practices on sticky axes in tree care
Shigo and Slater's insights have led to an evolution in tree care practices. Where more emphasis is placed on understanding the individual tree structure and responses.
Modern pruning guidelines, such as the European Tree Prunning Standard (ETPS), now often recommend a balanced approach. Which takes into account the health of the tree, the desire to promote strong branch attachments, and the need to prevent potentially dangerous situations. By removing weak attachments.
The work of both Shigo and Slater emphasizes the importance of evidence-based practices in tree care. And the ongoing research into the complex interactions within the tree structure.
Identifying and properly managing branch attachments, including plaque axils, is critical to maintaining the structural integrity and health of trees. In both natural and landscaped environments.
The evolution of insights into branch attachments and the contributions of experts such as Alex Shigo and Duncan Slater have led to a refined approach to tree care and management. Particularly in relation to pruning practices and assessing the structural integrity of trees.
These developments have some important implications tree care.
Well-founded pruning decisions
Knowledge of how and where to prune has evolved, with more emphasis now placed on understanding the individual growth patterns and structure of each tree. Which therefore requires more and more knowledge about crown architecture.
The pruning trees is now being performed with a thorough evaluation of branch attachments, taking into account the presence of a branch collar and the angle of the attachment, to promote the health and structural stability of the tree.
Recognition of structural diversity
Slater's work has contributed to the recognition that not all plaque axils are inherently weak. And that the structure of branch attachments is more complex than previously assumed.
For example, Slater demonstrated the presence of tangled tissue (wood vessels that grow very tangledly through the branch joint) at normal branch attachments, causing these attachments to form strong connections. Where previously the view existed that the wood vessels, mainly growing in a straight line (not confused), were present in alternating layers; wood vessels branch, trunk, branch, trunk, ... and thus formed a layered structure.
This has led to a more nuanced approach to assessing potential risks and the need for pruning. Considering the unique properties of each branch attachment.
Prevention and management of plaque axillae
There is a greater awareness of the importance of early intervention and good tree management to prevent the formation of plaque axils. As well as how to deal with crossing fused branches in the permanent crown of a tree.
Prevention and management of plaque ulcers includes:
- selecting the right tree species for a particular location,
- carrying out guidance pruning in the early stages of the tree's life,
- avoiding unnecessary damage or excessive pruning,
- assessing each individual plaque axilla to assess its sensitivity to fracture,
- and the appropriate pruning or correct anchoring of branches or crown parts with adhesive axes.
Importance of Research and Education
The continued contributions of researchers in the fields of tree physiology and crown architecture underscore the importance of scientific research and education in tree care practice.
Sharing knowledge and best practices helps arborists, arborists and the public make informed decisions. Which promote the health and longevity of trees.
Technological Applications
Modern technologies, such as structural analysis and visualization software, allow arborists to gain a better understanding of crown structure and potential risks associated with branch attachments.
This can lead to more personalized and effective management strategies for individual trees.
In essence, Shigo and Slater's insights, and subsequent developments in the tree care, led to a deeper understanding of the complexity of trees. And the need for careful, knowledge-based tree management to ensure their health and structural integrity.
This holistic approach to tree care recognizes the value of each tree as a living organism with unique needs and characteristics.