Title

Gosford LGA Vegetation 2009. VIS_ID 3908

Data Quality Statement

Name: Data Quality Statement

Protocol: WWW:DOWNLOAD-1.0-http--download

Description:

Data quality statement for Gosford LGA Vegetation 2009. VIS_ID 3908

Function: download

Vegetation GosfordLGA 2009 3908

Name: Vegetation GosfordLGA 2009 3908

Protocol: WWW:DOWNLOAD-1.0-http--download

Description:

Data & documents

Function: download

Code

e1cd1849-c26e-4b1a-92f4-2f602c5e3718

Name

ISO 19115

Edition

2016

Type

vector

Code identifying the spatial reference system

4283

Topic category

Title

ANZLIC Search Words

Reference date

2008-05-16

Coordinate reference system

Authority code

urn:ogc:def:cs:EPSG::

Code identifying the coordinate reference system

5711

End position

N/A

Contact info

Contact position

Data Broker

Organisation name

NSW Department of Climate Change, Energy, the Environment and Water

Telephone number

131555

Email address

data.broker@environment.nsw.gov.au

Web address

https://www.nsw.gov.au/departments-and-agencies/dcceew

Responsible party role

pointOfContact

Lineage

Aerial photographic interpretation:

One of the requirements of the mapping phase of the project was to utilise the existing API linework of Eco Logical Pty Ltd (2002) as the basis upon which new API interpretation was made. This linework was undertaken using high resolution, orthorectified digital aerial photo mosaics, to a relatively high degree of accuracy, and was in effect updating the linework of NPWS (2000a). However, it soon became apparent that this linework was not adequate for local planning purposes. Many instances of overlapping and multiple polygons, coarse and poor resolution of linework, poor definition of disturbance classes, and inaccurate allocation of vegetation communities (a carry-over from the modeling process) meant that its use at a local scale was questionable. Consequently, the same digital photo mosaics were obtained by Gosford Council and extant vegetation and condition classes were re-digitised on-screen prior to API, using Mapinfo 6.0 GIS. This proved to be a time-consuming process, and not all of the LGA could be mapped to this level. Digital photographic mosaics used for API were flown in 1998, while hard copy photo pairs flown in 1999 were examined using traditional stereo-viewing techniques to complement digital interpretation. Working at a base scale of 1:3000 in urban areas, and 1:5000 elsewhere, the existing linework of Eco Logical Pty Ltd (2002) was reviewed and amended to better reflect the distribution of extant

woody and non-woody vegetation. Roads, farm dams, unmapped clearings and other such features were cut out of existing polygons, while polygon boundaries were also adjusted where necessary. In addition, mapped polygons of extant vegetation which included disturbed vegetation were segregated, and other areas added. Interpretation, using both on-screen images and hardcopy photos viewed under stereoscopic vision, also enabled merging of many existing vegetation modeling units and the differentiation of obvious structural types such as hanging swamps, heaths and other non-woody types. Tagging and re-tagging of polygons followed the nomenclature of the NPWS (2000a) classification, except where variants could be recognised.

Data analysis and derivation of vegetation communities:

All available high quality plot data was subjected to PATN analysis to assist in understanding the trends present in the native vegetation. Analysis of vegetation data using this software package is widespread in major land management agencies (eg: York, Binns and Shields 1991; Wilson, Gott and Schofield 1997) and has also been employed for numerous vegetation studies elsewhere (eg: Benson 1999; Keith and Bedward 1999; Griffith, Wilson and Maryott-Brown 2000; NPWS 2000a). Relationships within the full dataset were explored using both the Kulzcynski and Bray-Curtis association measures and the default PATN settings. Both the raw cover abundance data and a simpler presence-absence dataset were analysed separately in order to test the rigidity of the data. Weeds species were separately included or excluded in the various analyses. In all cases, an unweighted pair-group arithmetic averaging clustering strategy (UPGMA) was applied to the data matrix to derive a hierarchical classification, and the default beta value of –0.1 was used. Dissimilarity between individual sites and groups of sites were illustrated through the generation of dendrograms (DEND) and group definition (GDEF) files. Interpretation of the resulting dendrograms involved accepting progressively similar groups of sites until no further logical splitting could be justified (based on the analysis as well as an intimate knowledge of the data and the field situation). In most cases, splitting of the dendrogram commonly occurs at around the 0.6-0.9 level of dissimilarity, depending on dataset size and other factors. Scrutinisation of all sites within all groups was undertaken to confirm apparent trends. The large number of sites surveyed by external parties required that this latter process be particularly thorough. Where necessary, provision was made in the classification for additional communities or subcommunitiesto be identified and included, despite there being little or no floristic plot data to describe them. This process relies heavily on expert intuition and familiarity with both the study area and existing classifications, and effectively highlights areas for future survey and analysis. In the main, such communities are those occupying distinct niches in the environment (such as saltmarsh, Typha swamp), and which tend to be overlooked during plot sampling because they are so distinct, and therefore may not require statistical analysis to distinguish them from other vegetation types.

Floristic vegetation map for Gosford LGA

The final floristic vegetation map of the entire LGA was of necessity a hybrid between the existing LHCCREMS GIS model, and the revised map completed using aerial photographic interpretation and ground truthing. Consequently, the map should be interpreted using two levels of confidence: high confidence (resolution) for Council, privately owned, and Crown lands under the management of Council, but lower confidence (resolution) within National Park and State Forest estate. In the western half of the LGA, it should be noted that while vegetation condition classes are accurate within the high resolution area, floristic vegetation types may not be as accurate in all areas. This is primarily due to the limited access to much of this area for ground truthing exercises, in particular the Mangrove Dam catchment area, and south to the settlement of Mangrove Creek. In low resolution areas in the west, a small number of changes have been made to the existing REMS mapping, but much refinement is still required. Figure 6 shows the final floristic map of the extant vegetation of Gosford City. This map should be regarded as indicative only, and no legend has been provided: due to the complexity of vegetation patterns evident, it is best viewed within a compatible GIS.

Limitations on public access

Effective date

2001-01-01

Effective date

2001-01-01

Contact position

Data Broker

Organisation name

NSW Department of Climate Change, Energy, the Environment and Water

Telephone number

131555

Email address

data.broker@environment.nsw.gov.au

Web address

https://www.nsw.gov.au/departments-and-agencies/dcceew

Responsible party role

pointOfContact

Contact position

Data Broker

Organisation name

NSW Department of Climate Change, Energy, the Environment and Water

Telephone number

131555

Email address

data.broker@environment.nsw.gov.au

Web address

https://www.nsw.gov.au/departments-and-agencies/dcceew

Responsible party role

pointOfContact