Download guideline for managing land development impacts on melaleuca

GUIDELINE FOR
MANAGING LAND
DEVELOPMENT
IMPACTS ON
MELALEUCA IRBYANA
www.logan.qld.gov.au
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.
Melaleuca irbyana flowers (Photograph Glenn Leiper)
Melaleuca irbyana trees (Photograph Deb Metters)
Melaleuca irbyana seeds (Photograph Anna Markula)
Melaleuca irbyana leaves (Photograph Rachel Booth)
GUIDELINE FOR MANAGING LAND
DEVELOPMENT IMPACTS ON
MELALEUCA IRBYANA
www.logan.qld.gov.au
ECOLOGICAL COMMUNITIES
LEGISLATIVE PROTECTION
M. irbyana forms communities that occur in two structural
forms:
Less than 10% of the original M. irbyana forest remains, hence
its high level of protection and concern for the survival of this
species.
• 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.
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.
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.
A Melaleuca irbyana community (photograph Deb Metters)
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.
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
GUIDELINE FOR MANAGING LAND
DEVELOPMENT IMPACTS ON
MELALEUCA IRBYANA
www.logan.qld.gov.au
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.
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
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.
• 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).
GUIDELINE FOR MANAGING LAND
DEVELOPMENT IMPACTS ON
MELALEUCA IRBYANA
www.logan.qld.gov.au
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.
• 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.
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.
REFERENCES AND FURTHER INFORMATION
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.
Ryan, T. S. (2010) Melaleuca irbyana (swamp tea-tree)
Community 1:25,000 Scale Mapping Project. Department of
Environment and Resource Management, Brisbane.
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.
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