What does crown architecture mean in tree care?

What is crown architecture in trees and what is it about?

 

Crown architecture in trees refers to the structural organization and morphological features of a tree crown. Including the arrangement and growth habit of branches, leaves and sometimes flowers and fruits.

It includes aspects such as crown shape, branch patterns, branch types and angles. And the distribution of leaf mass within the crown. These architectural features influence the functions of the tree. Such as light capture, photosynthesisefficiency, water and nutrient transport and reproductive success.

 

 

How did the study of crown architecture in trees originate?

 

The concept of crown architecture arose from the need to understand and describe the complex structures of trees. And how these structures influence the interaction of trees with their environment. The research into crown architecture is interdisciplinary and includes elements of botany, ecology, forestry and plant physiology.

 

 

Who are the most important people in this field?

 

Important individuals who influenced the study of crown architecture and tree form include:

 

Francis Hello

A French botanist who has done extensive research on tropical trees and crown architecture. Francis Halle is best known for his work on the architectural models of trees. Identifying several strategies that trees use to... to grow and adapt to their environment.

In his further research, Hallé started drawing trees to analyze their shape. He discovered that there are three elements that determine the habitus: 

• the distribution of the branches over the trunk, 
• the orientation of the branches and thirdly,
• surprisingly, the position of the flowering. A branch that blooms at the tip cannot extend linearly. So it has to branch out. 

These three elements together form the basis of a seemingly endless series of variations of tree species, which can ultimately be reduced to just 22 architectural models.

 

Roelof Oldeman

A Dutch botanist who, like Hallé, contributed to the understanding of the architectural models of trees, with a focus on tropical forestry. Oldeman has investigated the relationship between tree structure and forest dynamics and how this knowledge can be applied in forest management and conservation.

 

These and many other scientists have contributed to the understanding of crown architecture through research, fieldwork and theoretical modeling, giving us a better understanding of how trees grow and function in diverse ecosystems around the world.

 

 

Important terms from the architecture of trees

 

In the study of tree crown architecture, there are several terms and concepts used to describe the growth, structure, and functions of tree crowns. Here we provide just a few terms and their meanings, based on recent research.

 

 

Maximum height (H_Max)

This is an important determinant of the height expansion of trees and their ability to capture light and maintain mechanical stability. It influences how species can utilize the vertical elevation gradient in the forest canopy and horizontal light gradients on the forest floor. Species differ in their H_Max, which contributes to niche differentiation in tropical forests (Poorter, Bongers, & Bongers, 2006).

The location has a direct impact on the maximum height and shape of the tree. With free-standing trees, all the different branches will fully grow, creating a low, wide canopy. In a closed forest, branches will grow much higher. There are fewer branches, which will also be less likely to grow. The tree then becomes narrower and taller. 

Crown area and crown height

The crown area and crown height are critical for capturing light. Wide crown areas allow small understory species to intercept light over a large area. At the expense of reduced height growth.
Crown height is negatively correlated with H_Max at medium reference heights; or the smaller the H_Max, the higher the crown height in proportion. And where a relatively long crown in small understory species, in turn, enables them to maximize light interception in a light-limited environment (Poorter, Bongers, & Bongers, 2006).

The tree is helped in this by the way it builds its crown. Trees that grow as a false slow (type B) or a slow rate (type C) will develop wider lateral branches. Trees that go straight up in a solo climb (type A) therefore have more difficulty competing in a closed forest.

 

Functional groups

There are several functional groups within the tree species, such as shade-tolerant, partially shade-tolerant, long-lived and short-lived pioneers, which are confirmed by the principal component and discriminant analysis. These groups are characterized by differences in stem and branch orientation, leaf size and the arrangement of leaves, all of which contribute to their unique architecture and functions within the forest (Poorter, Bongers, & Bongers, 2006).

 

Light question

The light demand of a species may influence tree architecture, probably more strongly than H_Max. Light-requiring species are often, but not always, characterized by orthotropic trunks and branches, large leaves and a monolayer leaf arrangement. An exception to this is, for example, Gleditisia triacantos, which has small leaves and does not grow orthotropically.

Many, but not all, light-requiring species achieve efficient height growth through the formation of narrow and shallow crowns (Poorter, Bongers, & Bongers, 2006).

 

These terms and concepts help understand the complex relationships between tree structure, function and the environment in which they grow. By studying these architectural properties, we can better understand how trees compete for resources such as light and how they adapt to different environmental conditions.

Note that three elements determine the habit of a tree, namely the distribution of the branches over the trunk, the orientation of the branches and thirdly, surprisingly enough, the position of the flower. 

Specific technical terms are used to name and describe growth forms and concepts. We have described these in three parts on this website.

• de most important terms in crown architecture,
• de detailed glossary of crown architecture, from which you can click through to
• each unique term, which is then explained on a separate page, to give you the best possible description and context.