In Colorado, anyone can call themselves a tree service company. There’s no state licensing requirement for tree work — meaning the person knocking on your door with a chainsaw and a pickup truck can legally claim to be a “professional.” This guide explains exactly what separates a certified arborist from an uncertified tree guy, and why it matters for your property, your trees, and your liability.
What Is a Certified Arborist?
An ISA Certified Arborist is a tree care professional who has earned the credential issued by the International Society of Arboriculture (ISA) — the world’s leading tree care organization. To earn this credential, a person must:
- Have a minimum of three years of full-time, hands-on professional tree work experience
- Pass a rigorous written examination covering tree biology, pruning science, soil management, tree risk assessment, aerial operations, and safe work practices
- Maintain the credential through ongoing continuing education (CEUs required every three years)
- Adhere to the ISA Code of Ethics
As of 2024, there are approximately 30,000 ISA Certified Arborists in the United States. That might sound like a lot until you consider there are hundreds of thousands of tree service workers across the country. ISA certification represents a small fraction of people doing tree work.
What Is a “Tree Guy”?
There’s no formal definition, but “tree guy” typically refers to someone offering tree services without formal credentials, certification, or verifiable training. This includes door-to-door solicitors, Craigslist tree crews, landscapers who also “do trees,” and companies that advertise low prices without specifying credentials.
Some uncertified tree workers are experienced and do good work. But without a credential, there’s no independent verification of their knowledge, and no accountability structure if something goes wrong.
The Real Differences: Side by Side
| Factor | ISA Certified Arborist | Uncertified Tree Worker |
|---|---|---|
| Verified training | Yes — ISA exam required | No verification possible |
| Tree biology knowledge | Tested and confirmed | Unknown |
| Proper pruning techniques | ANSI A300 standards trained | May use damaging cuts |
| Ongoing education | Required every 3 years | None required |
| Insurance (typical) | Usually carries full coverage | Often uninsured |
| Accountability | ISA Code of Ethics | None |
| Credential verification | Searchable at treesaregood.org | Not verifiable |
Why Improper Tree Work Is Dangerous
Bad tree work doesn’t just look bad — it can kill trees worth thousands of dollars and create safety hazards that cost far more to address later. Specific risks from uncertified work include:
- Hat-racking / flush cutting: Removing too much of a tree’s canopy or making flush cuts that destroy the branch collar, leaving large open wounds that invite disease and structural decay
- Lion-tailing: Stripping interior branches and leaving weight at the end of limbs, making trees more susceptible to wind failure
- Improper rigging: Using the wrong rigging points or knots during removal, risking dropped sections that damage property or injure people
- Topping: Cutting the top off trees — a practice universally condemned by arboricultural science that leads to rapid decay, structural weakness, and eventual tree failure
The Insurance and Liability Issue
If an uninsured tree worker is injured on your property, you could be held liable. If their equipment damages your roof, fence, or neighbor’s property without adequate insurance, you may be left holding the bill. Tree work involves chainsaws, climbing equipment, chippers, and heavy logs — it is inherently high-risk work that demands proper insurance.
ISA-certified companies typically carry general liability insurance and workers’ compensation coverage as standard practice. Always ask for certificates of insurance — not just a verbal claim — before allowing any tree work on your property.
How to Verify a Certified Arborist
You can verify any ISA Certified Arborist’s current certification status at treesaregood.org/findanarborist<. Search by name or certification number. If the company can't provide a certification number, ask why.
Tree Service Denver LLC’(720) 807-2785< to speak with a certified arborist directly about your trees.
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