Glossary

Tree Survey Terms,
Plainly Defined

DBH, TRAQ, BS5837 categories, RPA — the terms that show up in arborist reports and planning submissions, defined the way practitioners actually use them, not the way a dictionary would.

Fundamentals

What is a tree survey?

Inventory, BS5837, risk assessment, condition survey — and who commissions each.

Measurement

DBH

Diameter at breast height — the standard stem measurement, single- and multi-stem.

Crown spread

Measuring canopy width N-S and E-W, and deriving canopy area.

Multi-stem tree

When a tree is multi-stem, and how to measure and record each stem.

Risk & Assessment

TRAQ

The ISA tree risk assessment qualification and its likelihood/consequence matrix.

Tree condition rating

Good, fair, poor, dead — what each rating looks for.

CTLA trunk formula

Valuing a tree from trunk area, species rating, condition, and location factor.

UK Planning & Preservation

BS5837 categories

Category A/B/C/U grading and what each means for a development site.

Root protection area (RPA)

The 12x stem diameter formula and what it means for construction.

Tree Preservation Order (TPO)

What a TPO protects, what counts as an offence, and how to check for one.

Want the full field workflow, not just the definitions? Start with the tree inventory guide or browse the downloadable templates.

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