Certified Arborist Practice Exam

A ring porous tree species is characterized by its distinct growth rings that consist of large vessels in the earlywood (the part of the growth ring formed in the spring) and smaller vessels in the latewood (the part formed in the summer and fall). This structure allows for efficient water transport and gas exchange during the growing season.

Elm is recognized as a ring porous species because it has a pronounced difference between the earlywood and latewood, featuring larger vessels in the earlywood. This adaptation is particularly beneficial for trees in temperate regions where seasonal changes affect water availability.

Maple, poplar, and ash do not exhibit the same pronounced vessel size differentiation and are generally classified as diffuse porous species, which feature a more uniform distribution of vessel sizes throughout the growth rings. This classification does not offer the distinct advantages seen in ring porous species, particularly in terms of water transport efficiency during crucial growth periods.