The 22-year-old underwent a fresh fight to save the right leg at Auckland's Middlemore Hospital after developing a serious infection within hours of touching down in New Zealand in October.
Doctors saved the right leg with further operations and Somervell was allowed home to his family in Nelson three weeks ago.
He returned to work part-time last weekend after getting an invitation from local nursery Big Trees to help prune bonsai trees.
"I saw a story about another young arborist who had lost a leg and was back at work and climbing trees and it gave me hope I could do the same," Somervell said.
"A few weeks ago I was looking at facing life with no legs but I am now determined to continue as an arborist.
"It felt good being off the couch and out of the house and back doing what I love."
Somervell said he now faced a long road to recovery to rebuild the shattered limb.
He is undergoing physiotherapy and hopes to be fitted with a prosthetic left leg in the New Year.
"I just want to be out of a wheelchair and back climbing trees again," he added.
Somervell was less than four months into a working holiday in the US, where he was training as an arborist, when he crashed off his Kawasaki ZX6 motorbike on the Angeles Forest Highway, in Los Angeles.
It was only the quick thinking of a motorist who found the badly injured former Aucklander on the roadside and forest rangers who applied first aid that stopped him bleeding to death.
