OPW25/0012 - Arborist Report & Vegetation Management Plan

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[OCR of page images]
Arborist Report
3 &7 Serenity Close, Noosa Heads

and landscape assessment criteria (Institute of Australian Consulting Arboriculturists
2010). Tree vigour represents the ability of a tree to sustain its life processes,
characterised by an assessment of crown cover, crown density (including potential
accelerated growth due to seemingly beneficial changes to its growing environment),
resistance to predation, evidence of dormancy (deciduous trees). Tree vigour was thus
categorised as normal, high, low or dormant. Tree condition represents a tree’s crown
form and growth habitat, as modified by its environment (aspect, suppression by other
trees, soils, previous pruning), the stability and viability of the root plate, trunk and
structural branches, including defects such as wounds, cavities or hollows, crooked trunk
or weak trunk / branch junctions and the effects of predation by pests and diseases. Tree
condition was categorised as good, fair, poor or dead. In general, trees assessed as being
of low vigour and/or poor condition are generally marked as ‘removed’ as any remedial
work or improvement to the growing environment of such trees is unlikely to render them
viable in the long term.

The assessment included visual assessment of tree hazard and risk in accordance with the
International Society of Arboriculture’s (ISA) Tree Risk Assessment Manual (Dunster et a/.
2013). Physical methods and/or exploratory techniques were not used in undertaking the
assessment. Arboricultural data recorded as part of the assessment included:

e Identification of risk targets,

e Tree dimensions,

e Site conditions,

e Overall condition and vigour,

e Canopy structure and form, disease and any other significant features,
e Trunk condition and form,

e Roots and root collar condition and form, and,

e Habitat features.

For each combination of tree hazard and risk target, risk categorisation was carried out in
accordance with the Tree Risk Assessment Manual (Dunster et al. 2013).

The TPZ and SRZ of the trees was calculated in accordance with Australian Standard AS
4970-2009 Protection of trees on development sites (Standards Australia 2009). The TPZ
is the principal means of protecting trees on development sites and is a combination of
the root area and crown area requiring protection (Standards Australia 2009).

Whilst it is possible to encroach into or make variations to the nominal TPZ for excavation,
fill or trenching, disturbances should generally be restricted to less than 10% of the TPZ
area (Standards Australia 2009). Such encroachments are considered minor. Where more
substantial encroachments are proposed or where proposed encroachment includes areas
within the SRZ, root investigations may be required (Standards Australia 2009). Where
encroachments are proposed, the area lost to encroachment should be offset with
additional area elsewhere contiguous with the TPZ. Assessment of the potential impacts
of encroachment could require an assessment of potential mitigating or site-specific
factors including inter alia (Standards Australia 2009):

e Physical location of roots,

LTORIAS

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