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University of California Tree Failure Report Program All About Trees - American Forests
Western Chapter International Society of Arboriculture National Arbor Day Foundation
International Society of Arboriculture On-Line Tree Care Industry Association
American Society of Consulting Arborists California Urban Forests Councel
California ReLeaf  
The California Tree Failure Report Program (CTFRP) was established in 1987 to collect quantitative information on the mechanical failure of urban trees (trunk breaks, branch breaks, and uprootings). This information is used to develop "failure profiles" for genera and species to more accurately assess failure probability in standing trees and thereby reduce failure potential in urban forests.

The Western Chapter of the International Society of Arboriculture was formed in 1934. It is a nonprofit corporation comprised of 2500 persons in Arizona, California, Hawaii and Nevada engaged or interested in the practice of arboriculture.

The International Society of Arboriculture On-Line mission states: Through research, technology, and education promote the professional practice of arboriculture and foster a greater public awareness of the benefits of trees.

American Forest has been protecting and restoring forests for more than 140 years. And, while we may be the nation’s oldest conservation organization, our work today is more important than ever. Since 1990 alone, we have planted more than 50 million trees, helping to restore forests in all 50 states and nearly 50 countries.

National Arborday Foundation Founded in 1972, the centennial of the first Arbor Day observance in the 19th century, the Foundation has grown to become the largest nonprofit membership organization dedicated to planting trees, with over one million members, supporters, and valued partners.

The TCIA develops safety and education programs, standards of tree care practice and management information for tree and landscape firms around the world. We provide continuing education, training, conferences and publications to promote the safe and appropriate practice of tree care.

ASCA represents Consulting Arborists—the authoritative experts on trees, and whose objective, comprehensive viewpoint ensures the safety, health, and preservation of trees. Our members’ extensive level of knowledge and experience makes them highly sought after by consumers, professionals, and other arborists.

California Urban Forests Council As the nation’s oldest urban forest council and a nonprofit coalition, we’re on a mission to expand sustainable urban and community forests to improve the quality of life for all Californians. With your support we can create thriving and prosperous California communities transformed by healthy trees and green spaces. Our seven regional councils provide essential expertise and assistance to their respective regions. They also organize events and activities to help grown great communities. Street Tree Seminar, Inc. serves at the Los Angeles/Orange County Regional Council.

California ReLeaf works statewide to promote alliances among community-based groups, individuals, industry, and government agencies, encouraging each to contribute to the livability of our cities and the protection of our environment by planting and caring for trees.