Warren Hoselton, a Humber College Landscape Technology and Arboriculture graduate (1979–1982) from Cobourg, ON, served 40 years with the City of Toronto Parks Department, including 25 years as Park Supervisor on Toronto Island. An Internationally Certified Arborist (ON299) and former Urban Forestry Foreperson for Metro Toronto, he has been a Board member of the Canadian Tree Fund since 2007 and a 23-time Tour des Trees rider, raising over $125,000 for tree research and education.

Warren leads educational outreach for Tour des Trees through his animated “Professor Pricklethorn” presentations across North America and Europe and delivers his “Trees Please” program to Ontario school boards and community groups. A recipient of multiple industry and community awards, he holds an Honorary Lifetime Membership with the Ontario ISA and the Ontario Association of Commercial Arborists’ Deep Roots in the Community Volunteer Award. He has authored three children’s workbooks on urban trees and has been a Chainsaw Safety Awareness Trainer with the Ontario Parks Association since 2025.