Benger Bio-landscape

Posted on Dec 23, 2014


Benger bio-landscapeTerrestialBiodiversity

Priority Bio-landscapes were identified across the region in the 2009 Biodiversity Sub-strategy. A 5 km by 5 km grid was placed across the region and those landscapes that had the highest concentrations of biodiversity value within the region were identified. Those landscapes that were identified as having a combination of high rarity for flora/fauna/communities and vegetation associations were classified as Highest Priority bio-landscapes. Those that were identified as having high rarity for flora/fauna/communities but the vegetation associations within them were not rare were classified as Second Priority Bio-landscapes. The full report can be read here: 2009 Biodiversity Sub-Strategy

The Benger bio-landscape is an area found within the Shire of Harvey and the Leschenault catchment on the Swan Coastal Plain.

The Benger bio-landscape is identified as a high priority bio-landscape within the 2009 Biodiversity Sub-strategy due to the presence of rare vegetation associations as well as high rarity for flora, fauna and ecological communities.

Reserves found in this bio-landscape include the Benger Swamp Nature Reserve, Byrd Swamp Nature Reserve and Myalup State Forest. There are many wetlands including the Benger Swamp and the Kemerton Wetlands which consists of lots of smaller wetlands that are seasonally dry, but are in relatively pristine condition. The natural waterways that did once occur within this landscape have been severely altered and are now drains; including the Harvey Diversion Drain, Mangosteen Drain and the Wellesley River Drain.

Due to the extensive clearing that has occurred in the past along the entire Swan Coastal Plain, 1 vegetation association present within the bio-landscape is well under-represented with there being less than 10% remaining of the Pinjarra 968 vegetation association and 10-30% remaining of the Bassendean 1000, Spearwood 6 and Bassendean 1182 vegetation associations.

The remaining vegetation within the bio-landscape provides north-south regionally important ecological linkages on the Swan Coastal Plain. However, due to the extensive clearing in the past, east-west linkages across this bio-landscape is missing. Benger Swamp Nature Reserve is isolated on the Swan Coastal Plain with very limited opportunities for landscape connections with the coast or the Darling Scarp. Even so it has been an important wetland for migratory birds, with many species protected under International Agreements identified in the past including the Common Sandpiper, Eastern Great Egret, Red-necked Stint, Glossy Ibis, Common Greenshank and the threatened Australasian Bittern.

An aerial shot of Benger Swamp Nature Reserve (LCC, 2011)

An aerial shot of Benger Swamp Nature Reserve (LCC)

Threatened Ecological Communities found within this bio-landscape include:

  • SCP25 – Southern Eucalyptus gomphocephala Agonis flexuosa woodlands, shrublands and woodlands on Muchea Limestone and
  • SCP09 – Dense shrublands on clay flats (part of the Critically Endangered Commonwealth listed Clay pans on the Swan Coastal Plain).

More information on the Commonwealth listed Clay pans community can be found on the Glimpses into disappearing landscapes website here.

1 DRF and 8 priority flora populations are found here including orchids such as the dwarf hammer-orchid, sandplain white spider orchid, carbunup king spider orchid and tall donkey orchid.

There are 2 endangered and 78 priority fauna populations which includes species such as the Little Bittern, water-rat, Southern Brush-tailed Phascogale, Forest Red-tailed Black-Cockatoo and the black stripe minnow.

Benger bio-landscape and Climate Change

Projected level of risk due to:

Decreasing rainfall

Best case   VeryHighCircle

Worst caseVeryHighCircle

 

Increasing temperature

Best case   HighCircle

Worst caseHighCircle  to VeryHighCircle

 

  • where Best Case = MIROC5 and Worst case = CanESM2 at 2090 and RCP8.5; see more here
  • Decreasing rainfall = annual rainfall change as % of initial
  • Where Very High = greater than 25% reduction; High = 20-25% reduction; Moderate = 15-20% (Note: no where in the region is there projected to be less than 15% reduction in rainfall).
  • Increasing temperature = change in maximum summer temperature
  • Where Very High = greater than 4 degree increase (maximum projected being 4.7 degrees within the Region); High = 3-4 degree increase; Moderate = 2.5 – 3 degree increase; Low = 2 – 2.5 degree increase (Note: no where in the region is there projected to be less than a 2 degree increase which although lower than the very high 4 degree increase, will still have significant impacts on the environment).

This analysis is a simplistic way of looking at the potential risk of an asset to projected changes in rainfall and temperature. Assets may respond to climatic changes differently and species may be able to adapt in ways we don’t yet fully understand.

SWCC Strategic Priority

The Benger bio-landscape is identified as a first order priority asset within SWCC’s NRM Strategy under the Terrestrial Biodiversity theme.

Projects

DPaW have been working for a number of years within the Benger Swamp Reserve, managing the introduced typha species and other weed species.

 

Source:

  • 2009 Biodiversity Sub-Strategy for the South West Catchments Council Prepared for the South West Catchments Council by Ecosystem Solutions Pty Ltd 2009.

 

Header and thumbnail images supplied by LCC.

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