Overview
PCTs are spatial polygons that define the type and extent of known vegetation communities within the ACT pctCode . PCTs have been further stratified into 'zones' pctZone, which reflect the ecological condition of PCTs relative to benchmark thresholds. The ecological condition of a vegetation community, or a 'zone' pctZone, is assessed using the attributes that define Threatened Ecological Communities (TECs) under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and the ACT Nature Conservation Act 2014 (NC Act). Condition zones can be used to identify sites of high quality for conservation protection (e.g. nature reserve) and candidate sites for offsetting. PCTs can also be used to interrogate the spatial distribution and condition of all mapped vegetation areas across the ACT, and are employed as stocktake, planning and on-ground management units to inform the delivery of conservation, restoration and land development programs.
ACT plant community types
Naturally occurring native plant community types in the ACT are drawn from Sharp (2007), as implemented in the ACT Vegetation Database (2015), and Armstrong (2013). Each community type is identified by a number, e.g., ACT01, ACT25, known as native vegetation codes (pctCode). Non-naturally occurring plant communities such as exotic plantations and native plantings have been assigned numbers not present in Sharp (2007), e.g., ACT65, ACT66, ACT 99. Vegetation communities from Armstrong have been assigned an ACT prefix, while retaining the Armstrong numbering, e.g., ACT152 = u152, ACT118 = u118. Refer to Appendix A for the current list of plant communities in the ACT.
Determining pre-1750 plant community type
PCTs reflect the most likely plant community found prior to European colonisation, except for where they are plantings or plantations. Disturbances caused by agricultural practices and abandonment of land practices can obscure the pre-colonised state. The determination of the most likely pre-European plant community found at a present-day site is informed by signs such as the presence and type of native species; the growth form and density of remnant canopy trees; the presence of stags or stumps; the presence and species of midstorey shrubs and trees; the floristic composition of the groundstorey; landscape position and other geographical features such as elevation, aspect, soils, apparent hydrology etc.
Mapping PCTs and ecological condition zones
The boundaries of each PCT at a site are accurately mapped on-ground by walking the boundaries and recording them using hand-held GPS and marking directly on to high resolution orthorectified aerial photograph field maps. Once PCTs are mapped, a further assessment of condition is undertaken by dividing a PCT into homogenous 'zones' pctZone based on the structure (presence or absence of mature canopy and regeneration), floristic composition (ground story dominance and forb diversity) and overall quality ('intactness') of the vegetation. A simple matrix based on the criteria for conservation protection under the EPBC or NC Acts is used to categorise the condition of PCTs of grasslands (Table 1) and woodlands (Table 2 and 3). Although initially used to identify TECs for protection and/or offsetting, PCT zoning has been extended to other plant communities in the ACT and is considered a general measure of condition. There are currently 32 recognised ACT PCTs. To date, not all have been spatially mapped, with efforts focused on TECs facing higher threats at lower elevations, which are more likely to meet EPBC and NC Act status.
Grasslands and woodland/forest PCTs are assessed using different zone criteria. Note: The zone classifications are based on threatened grassland and lowland woodland community structural and floristic condition and may therefore not reflect non-threatened communities as accurately. Two components are used to assess the condition of grasslands: ground layer nativeness and forbs; whereas woodlands have four components, due to the additional components of mature trees and regeneration of tree species. The highest condition scores end in the numeral one (e.g. PCT 1.1 or PCT 16.1.1). Table 4 contains a worked example to interpret condition zones for Box-Gum Grassy Woodlands. Note that the highest condition zone does not represent a pristine environment, but one that meets baseline listing criteria.
Please also see ACT PCT Code and Zone Lookup Tables
Woodland zone matrix
Woodland
Mature Trees +
Mature Tree –
Regen +
Regen –
Regen +
Regen –
Native Cover+
Forb Div. +
16.1.1
16.1.3
16.2.1
16.2.3
Forb Div. –
16.1.2
16.1.4
16.2.2*
16.2.4
Native Cover–
Forb Div. +
16.3.1'
16.3.3'
16.4.1
16.4.3
Forb Div. –
16.3.2'
16.3.4'
16.4.2
16.4.4
Grassland zone matrix
Grassland
Groundstory Dominance
Native Forb Diversity
PCT Zone
EPBC of NC Act definition
Native Cover+
Forb Div. ++ (High - Very High)
1.1
EPBC, NC
Forb Div. + (Mod - High)
1.2
EPBC
Native Cover >50% Themeda, Poa OR Carex
1.2
EPBC
Forb Div. – (Low)
1.3
Native Cover–
Forb Div. + (Mod)
1.4
Forb Div. – (Low)
1.4
Table 1 Vegetation zone designations for grassland communities
Groundstorey dominance
Native Forb Diversity
PCT Condition Zone
Type of exotic dominance
EPBC or NC Act
(if relating to PCT01)
Native
Cover of all native understorey plants is greater than the cover of perennial exotics plants
At least 12 non-grass native species OR At least 3 indicator species OR Floristic Value Score more than equal to 6.5
PCT .1
_
EPBC, NC
Floristic Value Score more than equal to 5 but < 6.5 OR Floristic Value Score < 5 AND 8 non-grass native species OR 2 indicator species present
PCT .2A
_
EPBC
> 50% foliage cover of Themeda triandra, Poa labillardieri OR Carex bichenoviana
PCT .2B
_
EPBC
Floristic Value Score < 5
PCT .3
_
_
Exotic
Cover of all native understorey plants is less than the cover of perennial exotics plants
Floristic Value Score more than equal to 5 but < 6.5 OR Floristic Value Score < 5 and 8 non-grass native species OR 2 indicator species present
PCT .4A
_
_
Floristic Value Score < 5
PCT .4B
Pastoral and Agricultural
_
Floristic Value Score < 5
PCT .4C
Stock camp
_
Floristic Value Score < 5
PCT .4D
Noxious weed species
_
Floristic Value Score < 5
PCT .4E
Unknown
_
Table 2 Vegetation zone designations for woodland and forest communities with the groundstorey dominated by native species
Groundstorey dominance
Mature characteristic trees across the patch
Regeneration of characteristic canopy (<5 cm DBH)
Native Forb Diversity
PCT Condition Zone
EPBC or NC Act
(if relating to PCT16)
Native Cover of all native understorey plants is greater than the cover of perennial exotic plants
More than 4 trees > 40cm DBH
Regen present
more than equal to 12 species AND one important species.; +/- disturbance sensitive species
PCT .1.1
EPBC, NC
< 12 disturbance tolerant species only
PCT .1.2
EPBC, NC
Regen absent
more than equal to 12 species AND one important species.; +/- disturbance sensitive species
PCT .1.3
EPBC, NC
< 12 disturbance tolerant species only
PCT .1.4
EPBC, NC
Less than 4 trees > 40cm DBH
Regen present
more than equal to 12 species AND one important species.; +/- disturbance sensitive species
PCT .2.1
EPBC, NC
< 12 disturbance tolerant species only
PCT .2.2
EPBC, NC
Regen absent
more than equal to 12 species AND one important species.; +/- disturbance sensitive species
PCT .2.3
EPBC, NC
< 12 disturbance tolerant species only
PCT .2.4
_
Table 3 Vegetation zone designations for woodland and forest communities with the groundstorey dominated by exotic species
Exotic Cover of all native understorey plants is less than the cover of perennial exotics plants
More than 4 trees > 40cm DBH
Regen present
more than equal to 12 species AND one important species.; +/- disturbance sensitive species
PCT .3.1
NC1
< 12 disturbance tolerant species only
PCT .3.2
NC1
Regen absent
more than equal to 12 species AND one important species.; +/- disturbance sensitive species
PCT .3.3
NC1
< 12 disturbance tolerant species only
PCT .3.4
NC1
Less than 4 trees > 40cm DBH
Regen present
more than equal to 12 species AND one important species.; +/- disturbance sensitive species
PCT .4.1
< 12 disturbance tolerant species only
PCT .4.2
Regen absent
more than equal to 12 species AND one important species.; +/- disturbance sensitive species
PCT .4.3
< 12 disturbance tolerant species only
PCT .4.4
NC1 Zone 3.1 to 3.4 can meet NC Act definition of listed community if there is a characteristic canopy of Yellow Box and/or Blakely Red Gum (i.e. not single isolated tree or clump) (Capital Ecology 2023).
Table 4 Example of PCT zone mapping codes and their interpretation for a Box-Gum Grassy Woodland (PCT16).
Plant Community Type
Condition zone
PCT Zone Interpretation
16
1.1
16.1.1
Eucalyptus melliodora – E. blakelyi Tableland Grassy Woodland
-
More than 50% native understorey
-
Mature trees present
-
Tree regeneration present
-
12 or more forb species AND one important species.; with or without disturbance sensitive species
Remnant Box-Gum Grassy Woodland in good condition that meets the TEC criteria under EPBC and NC Acts.
4.4
16.4.4
-
More than 50% exotic ground cover
-
Mature trees absent
-
Tree regeneration absent
-
Less than 12 disturbance tolerant species only
Cleared Box-Gum Grassy Woodland in poor condition; ‘derived native grassland’.
Offsets Crosswalk Codes
Mature Trees +
Mature Tree –
Regen +
Regen –
Regen +
Regen –
Native Cover+
Forb Div. +
16.1
16.3
16.4
Forb Div. –
16.2
16.5
Native Cover–
Forb Div. +
Forb Div. –
16.6
16.7
16.8
Disclaimer: While all care is taken to ensure accuracy, the ACT Government does not warrant that this map is free from error.Please check the verification status of each polygon to determine whether the information contained is fit for purpose.
