Regional vegetation communities for the Namoi Catchment Management Authority

Abstract

This dataset and its metadata statement were supplied to the Bioregional Assessment Programme by a third party and are presented here as originally supplied.

This product is a compilation of existing spatial vegetation data and development of a vegetation classification hierarchy for the Namoi CMA, which can be uniformly assigned to such data. Preparation of a spatial vegetation layer classified according to regional vegetation communities (RVCs).

This project has constructed a pre-European and extant vegetation map of the possible distribution Regional Vegetation Communities (RVCs) for the Namoi CMA area by expert on screen digitising using existing extant vegetation mapping and a combination of field validation traverses, local knowledge and a variety of spatial GIS layers.

Once a complete pre-European layer was completed for the CMA area, the existing extant vegetation map was updated and various area statistics were calculated to enable the conservation significance of the vegetation types that were mapped to be assessed.

Purpose

To map extant vegetation in the Namoi CMA. The product was developed to provide a good instrument for regional conservation planning and management and to assist with identification of priorities for investment in the Namoi CMA.

Dataset History

Construction of a spatial vegetation layer for the CMA involves acquisition and compilation of all baseline datasets developed for various local and regional initiatives using aerial photograph interpretation (API). A total of 12 major datasets were sourced and integrated into an API composite for the catchment and gaps in the mapping were completed using on-screen digitising of vegetative patterns against SPOT5 imagery.

The final product contains about 38,000 polygons, each tagged with its likely RVC based on a combination of available polygon attribution, rapid field reconnaissance and local knowledge and expertise. A total of 69 RVCs are mapped. The major types include derived native grasslands, grassy white box woodlands, shrubby white box woodlands, and Pilliga ironbark forests.

The product provides a very good instrument for regional conservation planning and management, and will assist with identification of priorities for investment. However, the product also exhibits certain limitations.

• RVC allocation was largely informed by the underlying spatial data (which was compiled from a number of existing projects), and thus it is only as reliable as the original mapping. While some field checking was undertaken, much of the layer remains unverified.

• Many of the larger polygons were observed from SPOT5 to contain significant heterogeneity, inferring that two or possibly more RVCs may occur in them. This often resulted from clearing of native vegetation after it was mapped.

• The linework was found to contain spatial inaccuracies as a result of the small scale at which contributing datasets were originally captured, or possibly the approach used to capture data.

• A subset of contributing polygons (often occurring in clusters) were not coded with any vegetation information, so RVC allocation was dependent on application of underlying vegetation modelling where field checking was not possible.

Dataset Citation

NSW Office of Environment and Heritage (2009) Regional vegetation communities for the Namoi Catchment Management Authority. Bioregional Assessment Source Dataset. Viewed 29 September 2017, http://data.bioregionalassessments.gov.au/dataset/69253ff8-78c0-42b7-a5d0-a8a48021e208.