Radial Trenching – A method used to mitigate and replace soil inside the tree root protection zone. Soil is removed from trenches that are 8-12 inches wide and 18-36 inches deep. Trenches are excavated in direct lines toward the base of the tree using air spade, hydraulic excavation or hand careful hand excavation. Backfill can be amended soil, structural soil, a mix of sand and compost, or any combination deemed to be appropriate for the situation.
Raising – Selective pruning to provide vertical clearance; also known as lifting.
Reducing – Pruning to decrease height or spread on entire tree or one section; also referred to as reduction or reduced pruning.
Reaction Wood – Specialized secondary xylem that develops in response to lean or similar mechanical stress, to restore the stem to the vertical. Occurs as compression wood in conifers and tension wood in angiosperms.
Reduction Cut (Drop-Crotch Cut, Lateral Cut) – Reduces the length of a branch or stem back to a live lateral branch large enough to assume the apical dominance- typically at least one-third the diameter of the cut stems.
Restoring – The process of improving the structure of a tree that was preciously topped, damaged, vandalized, lion tailed or overthinned.
Resistograph – A tool which uses a small, pressure sensitive bit to penetrate a tree from the outside to determine the thickness of sound wood surrounding a suspected decay deposit.
Root – An organ of a tree that serves to maintain mechanical support, to provide water and essential elements from the soil through absorption, and to store energy reserves.
Root Ball – Refers to the root system of a container or balled-in-burlap nursery sack.
Root Collar – The junction between the root of a plant and its stem, often indicated by the trunk flare.
Root Crown – Same as Root Collar.
Root Hairs – A hairlike tubular outgrowth, from near the tip of a rootlet, performing the work of absorption.