Stringybark Ecological Restoration

Overview

Stringybark Ridge is a part of Berowra Valley National Park and is a very special ecological community. Smith & Smith (2010) map the vegetation on this ridgetop as predominantly Bloodwood-Scribbly Gum Woodland with patches of Scribbly Gum Open-woodland /Heath on the eastern and northern tips. The ridgetop is surrounded by Peppermint-Angophora Forest.

A STEP survey team in 2015 questioned the Bloodwood-Scribbly Gum Woodland classification. Smith & Smith (2008, p32). Their survey considered the dominant species to be Stringybarks with the co-dominant Red Bloodwood.

This area is home to many species of animals and since 2010 the following threatened species have been observed there:

  • The Powerful Owl
  • Grey-headed Flying Fox
  • Tetratheca glandulosa

Stage 1

The area we intend to restore is a strip of the smaller grassy area at Stringybark Ridge in Pennant Hills. NSW Parks and Wildlife Service will provide fencing and Hornsby Shire Council’s Warada Ngurang Community Nursery will provide the plantings required.

Proposed Work

NPWS – Fence off entire strip of the small grassy area in Stage 1 so that it is wallaby proof and will no longer be mowed. We recommend the current pathway is retained and a strip of approx 10m is left on the edge wide enough to drive a vehicle for management purposes.

FoBV – Initially we will revegetate a 10m x 10m plot as a test to ensure success and then progressively work along the strip of the small grassy area that has been fenced off.

Once the10m x 10m plot has been revegetated we will water in the plants for 4 weeks, the first two weeks will require 2 watering sessions and the next 2 week will require one watering session.

The entrance to the small oval area which has a track running along side the oval could be cleaned up with the removal of weeds such as Paspalum, Briza subaristata and Scotch thistle.

Along the track there is plenty of regeneration naturally occurring.

Proposed Plantings in Test Plot

Proposed Plantings in Revegetation area of 10 x 10 sqm test plot:

10 trees – Eucalyptus oblonga (Sandstone Stringybark), Corymbia gummifera (Red Bloodwood), Eucalyptus haemastoma (Broad-leaved Scribbly Gum) and Allocasuarina littoralis

50 shrubs – 5 shrubs/sqm  – Hakeas sericea (It has  colonised the compacted soils), Kunzea ambigua (this should be the dominant shrub as it has demonstrated its ability to flourish on the compacted soils), Ozothamnus diosmifolius(also currently thriving in this area), Acacia suaveolens, Banksia serrata, B. spinulosa, Dillwynia retorta, Grevillea buxifolia, Lambertia formosa, Leptospermum trinervium, Petrophile pulchella, Platysace linearifolia and Pultenaea tuberculata.

Background

Geology

The geology is still slightly ambiguous but it is primarily a sandstone ridgetop with possibly some lateritised fine grained sandstone-top transition beds close to the oval. There are both sandstone and shale fragments in the spoil banks around the ovals but the freshness of the shale means it is unlikely to have come from there.

Vegetation

Smith & Smith (2010) map the vegetation on this ridgetop as predominantly Bloodwood-Scribbly Gum Woodland with patches of Scribbly Gum Open-woodland /Heath on the eastern and northern tips. The ridgetop is surrounded by Peppermint-Angophora Forest. A STEP survey team in 2015 questioned the Bloodwood-Scribbly Gum Woodland classification. Smith & Smith (2008, p32). Their survey considered the dominant species to be Stringybarks with the co-dominant Red Bloodwood.

Bloodwood-Scribbly Gum Woodland

Description: Woodland or open-forest, sometimes low woodland or low open-forest, in which Corymbia gummifera (Red Bloodwood) and Eucalyptus haemastoma (Broadleaved Scribbly Gum) are the dominant species or co-dominant with one or more of Allocasuarina littoralis (Black She-oak), Angophora costata, Corymbia eximia (Yellow Bloodwood), Eucalyptus oblonga (Sandstone Stringybark), E. piperita (Sydney Peppermint) and E. sparsifolia (Narrow-leaved Stringybark). Shrub species include Acacia suaveolens, Banksia serrata, B. spinulosa, Dillwynia retorta, Grevillea buxifolia, Lambertia formosa, Leptospermum trinervium, Petrophile pulchella, Platysace linearifolia and Pultenaea tuberculata. Ground layer species include Actinotus minor, Anisopogon avenaceus, Caustis flexuosa, Cyathochaeta diandra, Dampiera stricta, Entolasia stricta and Lomandra glauca.

Scribbly Gum Open-woodland/Heath

 Description: May take the form of closed-heath or closed-scrub without a tree layer, but more typically open-woodland or low open-woodland with a closed-heath or closed scrub understorey. The tree species usually include either or both of Eucalyptus haemastoma (Broad-leaved Scribbly Gum) and E. racemosa (Narrow-leaved Scribbly Gum). Other tree species that may be present include Allocasuarina littoralis (Black She-oak), Banksia serrata (Old Man Banksia), Corymbia gummifera (Red Bloodwood), Eucalyptus oblonga (Sandstone Stringybark), E. punctata (Grey Gum) and E. sparsifolia (Narrow-leaved Stringybark). Shrub species include Angophora hispida, Banksia oblongifolia, B. ericifolia, Boronia ledifolia, Bossiaea scolopendria, Dillwynia retorta, Epacris pulchella, Grevillea buxifolia, G. speciosa, Hakea laevipes, H.teretifolia, Isopogon anethifolius, Kunzea ambigua, Leptospermum trinervium, Leucopogon microphyllus, Petrophile pulchella, Phyllota phylicoides, Platysace linearifolia and Pultenaea tuberculata. Ground layer species include Actinotus minor, Cyathochaeta diandra, Dampiera stricta, Entolasia stricta, Lepyrodia scariosa, Lomandra glauca, Patersonia sericea and Ptilothrix deusta. Cassytha glabella is a common climber. Wetter sites support a closed-heath or closed-scrub of species such as Allocasuarina distyla, Banksia ericifolia, B. oblongifolia, Dillwynia floribunda, Epacris microphylla, Hakea teretifolia and Leptospermum squarrosum. This ‘Wet Heath’ form of the community, which corresponds to Benson and Howell’s (1994) map unit 21g, subunit (v), is rare in Hornsby Shire, but more common further east, closer to the coast. Heath vegetation in Hornsby Shire is generally characterised by species of drier conditions, such as Angophora hispida and Leptospermum trinervium.

Benefits

Three threatened species have been recorded near Stringybark Ridge based on observations from the Atlas of Living Australia from 2010 onwards.

Ninox strenua (Powerful Owl)

Powerful Owls have been heard frequently in this area and an adult with chicks has been seen on the ridge slopes. This species is listed as vulnerable under the Threatened Species Conservation Act.

The main threats are:

  • Loss and fragmentation of suitable forest and woodland habitat from land clearing for residential and agricultural development. This loss also affects the populations of arboreal prey species, particularly the Greater Glider which reduces food availability for the Powerful Owl.
  • Loss of hollow-bearing trees reduces the availability of suitable nest sites and prey habitat.
  • Can be extremely sensitive to disturbance around the nest site, particularly during prelaying, laying and downy chick stages. Disturbance during the breeding period may affect breeding success.
  • High frequency hazard reduction burning may also reduce the longevity of individuals by affecting prey availability.
  • Road kills.
  • Predation of fledglings by foxes, dogs and cats.

 Pteropus poliocephalus (Grey headed Flying Fox)

This species is listed as vulnerable under the Threatened Species Conservation Act and the Environment Protection and Biodiversity Conservation Act.

The main threats are:

  • Loss of roosting and foraging sites.
  • Conflict with humans.

Tetratheca glandulosa – small shrub

This species is listed as vulnerable under the Threatened Species Conservation Act and the Environment Protection and Biodiversity Conservation Act. For more information see this link: https://www.environment.nsw.gov.au/threatenedspeciesapp/profile.aspx?id=10798

Wildlife Corridor and Habitat

Stringybark Ridge is very valuable as habitat and as a corridor. It is an integral part of the corridor from the Parramatta River to the Hawkesbury River as it the closest point to Lane Cove National Park. Nomadic and migratory fauna, as well as dispersing young, all need safe corridors for survival of the species.

Ridge Topography

The simple fact that it is a ridge makes it of conservation significance. Ridgetops are particularly rare and valuable in the valleys of the Lane Cove River and Berowra Creek. From Parramatta River, the first substantial undeveloped ridgetops in the Lane Cove National Park occur at Pennant Hills (and a large section of this ridge has been cleared for sports fields) and Thornleigh. The nearest undeveloped ridgetop to these is Stringybark Ridge in Berowra Valley. Most of the ridges on the eastern side of Berowra Valley National Park are heavily developed for housing and commercial purposes. On the western side of Berowra Valley National Park, the next ridge north of Stringybark is the tiny Refuge Rock remnant and then Tunks Ridge between Dural and Hornsby

If you are interested in helping us with this project please contact us.