Soil contamination. Spilling wet concrete, paint, and solvents within the root zone can poison the tree.
Compaction. Heavy equipment or materials such as pallets of pavers can squash a tree's shallow surface roots.
The value of trees
It's hard to put a price on beauty, but property values of homes whose landscapes include mature trees are 5 to 20 percent higher than those without them.
Located where they'll shade windows from hot afternoon sun, mature trees can lower cooling costs by 10 to 40 percent.
One such tree can cool a house as well as five average room air conditioners running 12 hours a day. Trees planted to block winter wind can reduce heating bills by 10 to 50 percent.
For more information
Colorado State University Cooperative Extension. See "Protecting Trees During Construction."
HortScience, a horticultural consulting firm in Pleasanton, California. (925) 484-0211
The International Society of Arboriculture. (217) 355-9411
PlantAmnesty, a Seattle-based group, promotes respect for trees and encourages proper pruning practices. (206) 783-9813