An arborist is a person who provides care and maintenance to trees, especially shade or ornamental trees, on private or public property and in a variety of landscape settings both urban and rural. The field in which he or she works is called arboriculture. In the US, a certified arborist is one who has passed the credentialing examination of the International Society of Arboriculture. Working in the field of tree care does not require this credential, but informed homeowners, businesses and government bodies recognize it as an indication of a worker’s knowledge and demonstrated ability in the field.
Arborists must be knowledgeable in all areas of tree care. They are often called upon to identify diseases and insects that can infect or infest trees. Arborists perform tree surgery as needed and render appropriate treatment when required to preserve the health of a tree. Some certified arborists specialize in specific tasks such as preventing disease and insect infestation; others work at diagnosing and treating diseases of trees and shrubbery. Climbing, working in aerial lifts and working around power poles and power lines are additional areas of specialization.
Dead branch removal is part of the work of a certified arborist as is cutting back tree limbs to clear walkways, roads or power lines. A certified arborist does not work on trees alone but often prunes, shapes, trims and maintains shrubs and hedges on residential and commercial properties. Cities and counties employ arborists to maintain trees and shrubbery in parks, on streets and on the grounds of public buildings.
Planting, transplanting or moving trees or shrubs that have outgrown their locations may be a part of an arborist’s work. He or she may decide when and how to remove unhealthy trees or shrubs or those that are hindering the growth of healthier, more desirable plants. Writing reports and making presentations may be a part of the arborist’s job, especially if he works for a business such as a golf course or resort, or for a state or city government.
A certified arborist usually has, at minimum, an associate's degree in arboriculture, forestry, horticulture or some other related field and may have a Bachelor of Science degree in one of these areas. Courses in biology, botany, horticulture and tree care are considered fundamental education. Employers often provide supplemental training in safety precautions and the use of special tools and equipment. A certified arborist must participate in continuing education classes in order to maintain his or her certification.