Information from Treesaregood.org
Why Hire an Arborist?
An arborist is a specialist in the care of individual trees. Arborists 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.
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Recognizing Tree Hazards
Trees provide significant benefits to our homes and cities, but when trees fall and injure people or damage property, they are liabilities. Taking care of tree hazards makes your property safer and prolongs the life of the tree.
For more information http://treesaregood.org/treecare/hazards.aspx