Sealed Judgement

A PPENDIX 1: D EFINITION OF T ERMS
The terms below are frequently used to simplify the definition of trees during assessments.

 Age Class (AC):
 Young                Early stage of growth, immature size
 Early mature:        Fast-growing well-established tree which has not yet reached mature size
 Mature               The tree reached its mature size and exhibits slowing growth rates with early stages of naturally forming
                      dead or dysfunctional wood.
 Over Mature          The tree has reached mature size and is unlikely to increase significantly in height or mass. Retrenchment
                      of the upper crown with increased vegetative vitality in the lower crown, increased fungal activity and wood
                      decay and increased colonisation by flora and fauna.
 Veteran              Tree with advanced retrenchment, reduced crown size and annual increment growth, extensive hollowing,
                      crown collapse, low vigour, advanced heartwood decay, and advanced colonisation by fauna and flora.
 Health (H):
 Good                 Good: Tree with no defects or disorders which are notable. Full canopy with good colour foliage. Minimal
                      pathogen damage.
 Fair                 Fair: Tree with minor defects or disorders which are notable. Some dead wood within what can be an
                      unbalanced canopy, foliage generally with good colour although some discolouration may be present typical
                      of species in location. Minor pathogen damage.
 Poor                 Poor: Tree with major defects or disorders which are notable. The tree has considerable deadwood present
                      and discoloured or distorted leaves indicating a further decline of the tree. Detrimental pathogen damage.
 Dead                 Dead or dysfunctional moribund tree.
 Structure (St):
 Good                 Tree with good unions and no branch defects. Sound trunk with no / minor defects. Good buttress and root
                      structure.
 Fair                 Tree with minor defects or disorders which are notable. Small areas of bark missing. Small cavities or minor
                      unfavourable branch unions may be present. Minor damage to roots.
 Poor                 Tree with major defects, large hollows, weak unions and/or problematic damaged roots.
 Hazardous            This implies a tree with a major defect that may fail at any time
 Abbreviations:
 DBH                  Diameter at Breast Height - The approximate diameter of the trunk measured visually in millimetres or meters
                      at a height of 1.4m.
 TPZ                  The Tree Protection Zone, as per AS 4970-2009 Protection of trees on development sites, is the principal
                      means of protecting trees on a development site. The TPZ is a combination of the root and crown area
                      requiring protection to be isolated from construction disturbance so that the tree can remain in a viable
                      condition. The TPZ incorporates the Structural Root Zone (SRZ).
                      The radius of the TPZ = DBH x 12
                      A TPZ should not be less than 2m or greater than 15m (unless crown protection is required).
 SRZ                  The Structural Root Zone, as per AS 4970-2009 Protection of trees on development sites, is a mathematical
                      calculation of the surface area of protection required to maintain a tree’s stability – a larger area is required
                      to maintain a tree in viable health. It is only necessary to calculate the SRZ when a major encroachment into
                      a TPZ is proposed.
 Tree Retention Value:
 The retention value status is based on industry-recognised methods of ascertaining the retention value of a tree. The suitability
 of the tree for preservation or retention is based on the individual qualities of each tree. By taking into consideration the health,
 structural condition, aesthetics, age, size, longevity (Safe Useful Life Expectancy) and ability to adapt to new environments the
 viability of the tree can be reasonably determined.
 For trees in non-use areas (e.g., Open spaces) where a range in tree quality is appropriate, all trees may be considered
 suitable, except for invasive species.

 Suitability for Retention/Preservation Categories are:
 High:               Tree retention is the priority.
                     The tree has high amenity, heritage and/or environmental value. It is in reasonably good condition (any minor
                     structural or health problems can be mitigated), has a long life expectancy and can recover from injury or
                     respond to environmental changes.
 Medium:             Tree retention is desirable.
                     The tree is in fair-good condition, is a locally common species, the tree contributes to the aesthetics of its
                     locality and should survive for many years. The tree may have health or structural problems that can be
                     mitigated with treatment.
 Low:                The tree is not considered worthy of special measures to ensure its retention.
                     The tree is in poor condition with significant defects that cannot be mitigated, has a short Useful Life
                     Expectancy, or the tree is expected to decline regardless of treatment. The tree has low value in the
                     landscape or is an undesirable species.
 Dead/               Tree removal is recommended, unless in a suitable area for ecological retention.
 Remove:             Trees are considered potentially hazardous, have very poor specimens, and/or may be environmental or
                     noxious weeds.




25_05_28_AR_RACV_RACV v NSC_Tree Retention Review_V10                                                                  Page 25 of 32




                                                                                                                                          72