Tree terms: r
- rabbit
 - rabbit damage
 - rabbit fence
 - rachis
 - radial trenching
 - radiation frost
 - radicle
 - raft
 - raft (urban trees)
 - rafter
 - rail
 - railing
 - railway yard knotweed
 - rain garden
 - rain shadow
 - rainwater goods
 - raised bog
 - ram’s-horn
 - ramify
 - Ramsar site
 - ranch fencing
 - rank
 - ranker
 - ray
 - raywood ash
 - RC
 - reaction wood
 - reaction zone
 - rebar
 - recalcitrant seed
 - receptor
 - recklessness
 - reclaimed land
 - recovery (ground movement)
 - recovery (planning appeal)
 - recovery growth
 - recumbent
 - recycled aggregate
 - red band needle blight
 - red deer (Cervus elaphus)
 - red list
 - red squirrel
 - REDD
 - redwood
 - reflectance
 - Regency gardens
 - regeneration felling
 - Regional strategy
 - register of judgments, orders and fines
 - register of land-based operatives (ROLO)
 - register of parks and gardens
 - registered consultant
 - registered contractor
 - registered social landlord
 - regulated pruning
 - regulating course
 - reinforced concrete
 - reinforced turf
 - reintroduction
 - relascope
 - relative humidity
 - relict
 - remediation
 - remedy
 - render
 - rendzina
 - renewable energy
 - Renewable Energy Association
 - renewable heat incentive
 - renewable heat premium
 - renewable resource
 - renewal pruning
 - replacement planting
 - replant disease
 - repointing
 - Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995
 - reptile
 - Repton, Humphry
 - reserved matters
 - resilience
 - resin
 - resin canal
 - resin-bonded surface
 - resin-bound surface
 - resistograph
 - resonant frequency
 - respiration
 - respondent
 - restocking
 - restoration ecology
 - restoration pruning
 - restricted byway
 - resupinate
 - retaining wall
 - retention value (BS 5837:2012)
 - retrenchment pruning
 - reversion
 - revetment
 - rewilding
 - RFS
 - RFS Certificate in arboriculture
 - RFS Professional diploma in arboriculture
 - rhizome
 - rhizomorph
 - rhizosphere
 - rhododendron
 - RHS
 - rib
 - RIBA
 - RICS
 - RIDDOR
 - ride
 - ridge line
 - rigg and furr
 - right to light
 - right to roam
 - rights of common
 - ring bark
 - ring beam
 - ring porous
 - ring shake
 - riparian
 - riparian strip
 - ripewood
 - ripewood stem cutting
 - risk
 - risk assessment
 - risk-based cost-benefit analysis
 - riven
 - riven fencing
 - river basin
 - RLR
 - road planings (road scalpings)
 - road safety
 - rock flour
 - rod
 - rod brace
 - rodding
 - rodding eye
 - roe deer (Capreolus capreolus)
 - roll out
 - ROLO
 - roof garden
 - roof light
 - roof truss
 - roofing felt
 - root
 - root anchorage
 - root barrier
 - root buttress
 - root cage
 - root collar
 - root collar diameter
 - root cutting
 - root deflector
 - root delamination
 - root extension
 - root exudates
 - root flare
 - root graft
 - root heave
 - root identification
 - root impedance
 - root path
 - root plate
 - root plate area
 - root plate displacement
 - root plate instability
 - root pressure
 - root protection area
 - root pruning
 - root regeneration potential
 - root rot (infection)
 - root rot, butt rot
 - root spread
 - root strangulation
 - root suffocation
 - root system
 - root volume
 - root-balled
 - rooter (drains)
 - rooter (engineering ripper)
 - rooting depth
 - rooting powder
 - Root-out
 - root-shoot junction
 - root-shoot ratio
 - rootstock
 - rosin
 - rot
 - rotation
 - rough shooting
 - rough-cast
 - roundel
 - Round-up
 - roundwood
 - Royal charter
 - Royal forest
 - Royal Forestry Society
 - Royal Horticultural Society
 - Royal Institute of British Architects (RIBA)
 - Royal Institution of Chartered Surveyors (RICS)
 - Royal parks
 - Royal Town Planning Institute (RTPI)
 - RPA
 - RTPI
 - ruderal
 - run-off
 - rural land register
 - Rural Payments Agency
 - russet
 - rust diseases
 - RWG