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Logan City Council has developed this guideline to advise landowners on how to protect Melaleuca irbyana from development impacts.

DESCRIPTION

Melaleuca irbyana (M. irbyana) plants are small trees growing to 8-12m in height with thick, spongy, papery bark. They have tiny, stalkless, pointed leaves, 5mm or less long, arranged spirally and pressed close to the branchlets. M. irbyana flowers in spring to summer with 20mm fluffy creamy-white flower spikes. They produce small woody seed capsules to 3mm.

GUIDELINE FOR MANAGING LAND DEVELOPMENT IMPACTS ON

MELALEUCA IRBYANA

Melaleuca irbyana trees (Photograph Deb Metters)

Melaleuca irbyana seeds (Photograph Anna Markula)

Melaleuca irbyana leaves (Photograph Rachel Booth)

Melaleuca irbyana flowers (Photograph Glenn Leiper)

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GUIDELINE FOR MANAGING LAND DEVELOPMENT IMPACTS ON MELALEUCA IRBYANA

ECOLOGICAL COMMUNITIES

M. irbyana forms communities that occur in two structural forms:

• the more common form consists of a dominant Eucalypt canopy with an understorey containing M. irbyana thickets 8-12 metres in height

• the less common form is an open forest or thicket of M. irbyana with emergent Eucalypt trees

• the understorey is sparse and can comprise of grasses, sedges, and herbs with a few shrubs, vines and possibly orchids present.

WHEN IS MELALEUCA IRBYANA CONSIDERED PART OF A COMMUNITY?

There are fairly clear descriptions of M. irbyana communities, however there are no clear indications of the point at which an individual tree or small number of trees are considered to be part of a community.

An individual tree may still contribute reproductively to a community, or may have the potential to regenerate and in time create a community.

Logan City Council defines an M. irbyana community as:

•where Melaleuca irbyana occur in a patch size of 0.25 hectares or greater, or where a patch of Melaleuca irbyana less than 0.25 hectares adjoins a second patch and the sum of the patches is greater than 0.25 hectares.

This definition has been determined using methodology from the Melaleuca irbyana (swamp tea-tree) Community 1:25,000 Scale Mapping Project (Ryan, 2010).

As Logan City Council currently uses the M. irbyana mapping that was produced as a result of this project, it is important to use the same methodology to define currently unmapped M. irbyana to achieve consistency.

LEGISLATIVE PROTECTION

Less than 10% of the original M. irbyana forest remains, hence its high level of protection and concern for the survival of this species.

Logan City Council: M. irbyana is protected under the Beaudesert Shire Planning Scheme 2007 as an overlay in the Nature Conservation Overlay.

Queensland Legislation: individual plants are listed as endangered under the Nature Conservation Act 1992.

The regional ecosystems 12.9-10.11 and 12.3.3c contain Melaleuca irbyana and are listed as endangered under the Vegetation Management Act 1999.

Federal Legislation: Melaleuca irbyana communities are listed as Critically Endangered under the Environment Protection and Biodiversity Conservation Act 1999.

A Melaleuca irbyana community (photograph Deb Metters)

What does this mean?

If an action has the potential to impact upon M. irbyana it must be referred to the Queensland State Government for assessment, and to the Federal Government if a community is likely to be impacted.

For landowners, this means that activities (such as clearing, earthworks and development) which are likely to have a significant impact on either individual M. irbyana plants or on M. irbyana communities should be referred to the appropriate government department for approval.

•Queensland State Government: Department of Environment and Heritage Protection. Ph 13 74 68

•Federal Government: Department of Sustainability, Environment, Water, Population and Communities. Ph 1800 803 772

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WHAT IS KNOWN ABOUT MELALEUCA IRBYANA?

Very little is known about M. irbyana despite its rarity. It is found in small number of restricted sites in north-eastern New South Wales and south-eastern Queensland. It occurs on sedimentary rocks and alluvial soils.

In Logan, M. irbyana is found mostly around the Jimboomba and Waterford West areas.

It is currently thought that M.irbyana is likely to be dependent on specific groundwater and /or surface water hydrology. However no scientific studies have investigated this in detail.

In addition, M.irbyana communities are likely to be negatively impacted by edge effects such as weed invasion, increase in wind and evaporation, and changes to solar radiation and temperature changes.

WHAT CAN BE DONE TO PROTECT MELALEUCA IRBYANA?

With these issues in mind, two main outcomes need to be achieved for the long-term protection of the remaining patches of M. irbyana.

1. Protection from edge effects such as weeds, wind, fire and increased solar radiation.

2. Protection of the near natural ground water and surface water hydrology.

In the absence of detailed scientific understanding a precautionary principle should be applied in the interim while detailed scientific understanding is gained.

Interim options include:

1. postponing development decisions where M.irbyana exists until detailed scientific understanding is gained, or;

2. buffer the areas of M.irbyana to manage edge effects plus minimise the changes to groundwater and surface water hydrology.

EDGE EFFECTS ON INDIVIDUAL PLANTS

Individual M. irbyana plants are described as quite hardy and tolerant. However it is not known how sensitive reproductive output is when plants are close to development.

EDGE EFFECTS ON MELALEUCA IRBYANA COMMUNITIES

Communities may be impacted by edge effects such as invasion by weeds, an increase in wind, increase in evaporation, increase in fire effects, and changes in solar radiation and thermal variation.

GUIDELINE FOR MANAGING LAND DEVELOPMENT IMPACTS ON MELALEUCA IRBYANA

Recommendation:

A 50m Edge Effect Buffer Zone surrounding M. irbyana should be

• vegetated with native vegetation, to the original Regional Ecosystem, and;

•any site works should be compatible with the outcome to minimise edge effects.

This edge effect buffer is sized and structured to minimise the impacts by protecting the core M. irbyana area from the effects of:

•weed invasion

• increased wind and increased evaporation

•changes in solar radiation and thermal variation

A vegetated buffer zone of 50m is recommended based

on advice from the Federal Government (Matthew White,

Director Ecological Communities, pers. comm. 2012).

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HYDROLOGY

M. irbyana is described as growing in tea-tree clay soils (seasonal cracking clay soils) that drain slowly after heavy rains, become waterlogged and form temporary ponds. It also occurs on perched water tables in locations where runoff flows overland rather than in distinct drainage lines.

The hydrological requirements of M. irbyana are not known. It can be found in a variety of locations, for example areas with pooling water, and areas with water run-off such as hillsides. It has been described as having a deep root system. Therefore it is feasible to suggest that M. irbyana has some reliance on groundwater supplies.

Changes to the groundwater hydrology therefore would have the potential to impact on the longterm viability of M. irbyana ecological communities.

CLOSING THE KNOWLEDGE GAP (FUTURE RESEARCH REQUIREMENTS)

•More information is needed on the hydrological requirements of M. irbyana. Firstly the relationship between groundwater and the occurrence of M. irbyana needs to be established. If it is found that M. irbyana does rely on groundwater, it may be important to identify and protect aquifer recharge areas from development. These are commonly wetlands (small wetlands especially), streams, and areas where water pools. Areas with high perimeter to volume ratio are the most important.

•Additionally, it needs to be determined how development and the associated reduction in catchment permeability may cause changes to water table levels, amount of run-off, sedimentation, water flow, and soil compaction, and how this may in turn impact M. irbyana.

•More information is needed about the reproductive output of M. irbyana. In Logan, particular attention should be paid to individual or scattered M. irbyana that are growing close to buildings, road sides etc. The importance of individual or scattered M. irbyana to maintaining genetic variation in the species needs to be determined.

•Additionally, general knowledge on reproduction in M. irbyana is required, particularly information that will be useful when attempting to re-establish M. irbyana communities.

•An increase in knowledge of hydrological requirements and reproduction in M. irbyana will further refine mapping and identify potential future habitat where revegetation may be suitable.

REFERENCES AND FURTHER INFORMATION

Department of Sustainability, Environment, Water, Population and Communities (2012). Swamp Tea-tree (Melaleuca irbyana) Forest of South-east Queensland in Community and Species Profile and Threats Database, Department of Sustainability, Environment, Water, Population and Communities, Canberra. Available from: http://www.environment.gov.au/sprat

Ryan, T. S. (2010) Melaleuca irbyana (swamp tea-tree) Community 1:25,000 Scale Mapping Project. Department of Environment and Resource Management, Brisbane.

GUIDELINE FOR MANAGING LAND DEVELOPMENT IMPACTS ON MELALEUCA IRBYANA

Recommendation:

In the absence of detailed and extensive scientific investigations this guideline takes a precautionary principle approach and identifies the provision of a hydrology protection buffer of 100m where development should ensure that infiltration is maximised and the change to surface water and groundwater hydrology is minimised.

This is to be achieved by ensuring that the amount of infiltration and overland flow remains constant from pre-development to post-development. For example, avoiding soil compaction can maintain infiltration.