International Society of Arboriculture (ISA)


Why hire an arborisT

Arborists specialize in the care of individual trees. They are knowledgeable about the needs of trees, and are trained and equipped to provide proper care. Hiring an arborist is a decision that should not be taken lightly. Proper tree care is an investment that can lead to substantial returns. Well cared-for trees are attractive and can add considerable value to your property. Poorly maintained trees can be a significant liability. Pruning or removing trees, especially large trees, can be dangerous work. Tree work should be done only by those trained and equipped to work safely in trees.


Tree owners manual

This US Forest Service publication highlights proper tree care from installation to maintenance, with many easily understood images and text.

Tree Owner’s Manual

A printed version of this product is available for purchase in ISA’s webstore.

Tree owner information

Basic knowledge of proper tree care helps individual tree owners understand the quality of care necessary for the health of their trees. An overview of tree care essentials is provided in this section.

For additional information on the topics below, ISA also provides detailed educational brochures to help tree owners understand best management practices and to promote a greater awareness of the benefits that trees provide in our communities. The brochures offer guidance for management throughout the life of a tree, from tree selection and planting to mature tree care and risk assessment.

Trees are Good

Trees are good. Trees provide many benefits to people and the communities they live in.

Trees need care. Proper long-term care is essential to maximize the benefits a tree has to offer.

Arborists care for trees. Professional tree care providers (arborists) are individuals knowledgeable in the care needed to sustain a tree's life and long-term benefits. provides the public with educational information about the benefits of trees and how to properly care for trees in the urban environment. The site contains resources from the International Society of Arboriculture, and also provides a collection of reliable tree care information provided by other industry organizations.

Trees are Good site:


Friends of the Urban Forest

(Non profit tree planting and urban greening)

Statewide IPM program

University of California Integrated Pest Management (Disease and pests diagnosis and management)