Arbor M.D., Memphis

Instead of exercising at the gym, Jeff Cochran stays fit by competing in races—the vertical kind. The certified arborist and his crew clamber up trees in their leisure time, thereby sharpening their safety skills and prepping their physiques for when they're on the job. Their work sends them to neighborhood lawns for trimming, planting, and tree-removal services, though the botany enthusiasts use the third option only as a last resort.

The staffers both diagnose and treat potentially hazardous branches, pruning away obstructions and detaching diseased boughs. They remain on call 24 hours a day to deal with emergency appointments following storms. Many of their treatments are also preventive: they take measures to conserve trees that stand on active construction sites and erect reliable lightning-protection systems. In the interest of healthy growth, Jeff and company fertilizes and aerates the soil to nourish roots, with regular inspections to ensure that each plant's heart rate is a plucky six beats per year. Every visit is followed by a thorough yard cleanup that clears away debris, sawdust, wood chips, and ruts.