Arborist Site Discussion Group
A loose affiliation of volunteer tree working professionals that discuss the needs of tree care within the industry and answer questions for the general public.

Mid-Atlantic Chapter, International Society of Arboriculture
information and links on trees and their care (arboriculture); resources for arborists

National Arborist Association
The trade association of commercial tree care businesses. Site has information (for consumers and for professionals) and links on tree care practices and standards.

Shigo on Tree Systems
A set of articles by Dr. Shigo on arboriculture, and on the growth of garden trees.

Arboricultural Association
Promotes care and knowledge of trees in the UK. Details of activities, members, and journal.

European Arboricultural Council
A forum for arboricultural organizations in Europe to liase on research and education in tree establishment and improvement of working practices.

Arboricultural Information Exchange.
The AIE site (UK) has news, links and collections of resources for arboriculture.

Bag Snaggers
A tool for arborists and urban tree pruners for removing plastic bags and other debris from trees.

International Society of Arboriculture
Arboriculture On-line was developed to assist tree care professionals in developing and maintaining effective plant health care programs. Includes an extensive collection of urban forestry links.

The California Arborists Association
Membership information, details and timetables of activities and workshops.

Wildtrees
Includes views on conservation of native trees for the environment.

ACRT Institute of Arboriculture and Urban Forestry
Training for the line clearing, tree care and urban forestry industry.