How are environments catagorised?

Ecosystems in Victoria are classified using a hierarchical system that combines broad landscape analysis with site-specific vegetation details. The two main units are Bioregions and Ecological Vegetation Classes (EVCs).

Bioregions provide landscape-scale classification based on shared environmental features such as climate, geology and geomorphology, soils, and vegetation. Victoria contains 28 bioregions, including the Central Victorian Uplands, Gippsland Plain, and Victorian Alps.

Ecological Vegetation Classes (EVCs)

The standard unit for classifying vegetation types at a more granular/local, level is the Ecological Vegetation Class (EVC). EVCs are defined and grouped according to several criteria:

• Floristics: The specific plant species present.

• Lifeforms: The structure and types of plants (e.g., trees, shrubs, herbs, graminoids).

• Ecological Characteristics: The processes and interactions within the environment.

• Environmental Fidelity: An inferred connection to particular environmental attributes like soil type or moisture levels.

Our area.

Deep Creek itself is situated between two Bioregions; the Victorian Volcanic Plains on the South-West side and the Central Victorian Uplands on the North-East side. The main EVC's around Deep Creek are:

• Pains Grassy Woodland (EVC 55), across basaltic flats, following along the Melbourne-Lancefield Rd.

• Herb-rich Foothill Forest (EVC 23), occuring on stony, volcanic rises along Deep Creek and the Eastern flank of Mt Macedon.

• Valley Grassy Forest (EVC 47) occurs within valleys and undulating slopes where microclimates occur alowing for greater moisture retention.

• Heathy Dry Forest (EVC 20) typically found on nutrient-poor soils along ridgelines and adjacents slopes where water is a limiting factor of greater tree recruitment.

• Grassy Dry Forest (EVC 22) occuring on flat to oderately undulating slopes with a westerly/northerly aspect as this community tolerates intermediated drought conditions.

• Creekline Herb-rich Woodland (EVC 164) exists on ephemeral mountain tributaries, or forested slope watercourses that only exist seasonally.

• Swampy Riparian Woodland (EVC 83) occurs on floodplains and where the creek widens to become a pool. 

• Stream Bank Shrubland (EVC 851) exists where the creek is more shallow and allows for encroachment of trees and shrubs.

The mentioned habitat distribution can be seen in the two maps below which were sourced from Naturekit. A Government funded application by the Department of Energy, Land, Water and Planning, that is an interactive geospatial portal that displays ecological territories and distributions but also other environmental data.

Each EVC number corresponds to a matching benchmark sheet which contains the floristics structure, plant/species composition and other ecological characteristics that is typical for that habitat/environment. 

The benchmarks sheets for EVC's in the Victorian Volcanic Plains bioregion can be found here and other bioregions on the Naturekit website.

Benchmark sheet issues

Benchmark sheets are foundational to Australian vegetation assessments; However, ecologists and research have identified several critical flaws that undermine their ecological accuracy and reliability. Most flaws primarily relate to using the Benchmark sheets to accurately assess native vegetation and existing pressures/disturbances to the relevant site.

Ecological succession describes the process of change in species composition and structure over time. Traditional assessment methods have historically relied on a "climax" model, assuming that plant communities move consistently toward a single, stable, long-undisturbed state.

In the context of Australian vegetation assessment, habitats often exist as dynamic systems rather than static patches, manifesting either as spatially complex mosaics or as communities at various stages of ecological succession, consisting or two or more EVCs (DSE, 2004).

Natural landscapes are rarely uniform, and vegetation boundaries on the ground are often "fuzzy," occurring in transition zones (McCarthy et al, 2004).

Benchmarks are typically based on long-undisturbed sites, reflecting an outdated "climax" environment theory that assumes plant communities move toward a single, stable ideal. Modern ecology recognizes that floral communities/ecosystems have multiple states and complex pathways of change. By using a single benchmark, the system often penalizes appropriate disturbance regimes; for example, healthy indigenous grasslands that require regular fire to maintain diversity are often marked down for not being "undisturbed" (Lorimer et al, 2024).

Sources

McCarthy, M. A., Parris, K. M., van der Ree, R., McDonnell, M. J., Burgman, M. A., Williams, N. S. G., McLean, N., Harper, M. J., Meyer, R., Hahs, A., & Coates, T. (2004). "The habitat hectares approach to vegetation assessment: An evaluation and suggestions for improvement," published in Ecological Management & Restoration, Volume 5, Issue 1, pages 24–27.

Lorimer, G. S. (2024). "Indices for ecological condition of native vegetation: A review, and introducing the HH2.0 method," published in Ecological Management & Restoration, Volume 25, Issue 2, pages 139–150.

Victoria. Department of Environment, Land, Water and Planning (2018). NatureKit. [Online] Available at: https://nla.gov.au/nla.obj-2994794916 

Department of Sustainability and Environment (DSE). (2004). Vegetation Quality Assessment Manual: Guidelines for applying the habitat hectares scoring method (Version 1.3). Melbourne: Victorian Government Department of Sustainability and Environment.