What is Vascular Sectorality in Trees?
By Mitch Hoy, ISA Board Certified Master Arborist #MN-4814BT
Vascular sectorality refers to the specialized sections in a tree’s vascular system that independently control and supply different parts of the tree.
A tree’s vascular system consists of xylem and phloem tissue that transport water and nutrients throughout the tree. These tissues are further divided into sectors in many tree species, with each sector supplying a particular branch or set of branches. This sectorality allows individual branches to function more independently and for the tree to more precisely control and isolate fluid transport to different areas as needed. Having sectors in the vascular system likely helps tree species survive and adapt by allowing for flexibility in resource allocation and isolation of damage and infection.
Sectorality is a spectrum among tree species (and likely populations), with some species’ vasculation being highly sectored to some being highly integrated. Highly sectored species, such as oak, tend to dominate xeric (dry) sites where resources are temporally variable. Integrated species, such as maples, excel in sites where resources may be consistent but spatially limited. Sectored species have finer control over their water and resource management, where integrated species can (and must!) share water and resources from one sector of their root system across the entire organism.
Vascular sectorality plays a key role in understanding, diagnosing, and predicting tree response to environmental (man-made or otherwise) and biotic conditions. When pruning or treating trees, it is important to recognize and respect their sectorality to minimize stress and risk of damage to these specialized tissue systems.
Sources:
Hirons, Andrew D and Thomas, Peter A. Applied Tree Biology. Oxford, UK: John Wiley and Sons Ltd, 2018.
Image: Author (Mitch Hoy)
