Workshop Notes. Perth Region Plant Biodiversity Project Jarrah Forest Reference Sites of the Perth Metropolitan Area: The Northern Transect

Transcription

1 Workshop Notes Perth Region Plant Biodiversity Project Jarrah Forest Reference Sites of the Perth Metropolitan Area: The Northern Transect Shaun Molloy November

2 Introduction Bush Forever is a 10 year strategic plan instigated by the Western Australian Government in conjunction with the general community and appropriate Local Government organisations to protect some 51,200 hectares of regionally significant bushland in 287 Bush Forever Sites, representing, where achievable, a target of at least 10 percent of each of the original 26 vegetation complexes of the Swan Coastal Plain portion of the Perth Metropolitan Region. Subsequent to Bush Forever, the Perth Biodiversity Project identified the need to catalogue and describe a series reference sites to facilitate consistency in the assessment of local natural areas and to further enhance the capacity of relevant people to undertake site recording tasks. To this end 40 reference sites were established based on Bush Forever on the Swan Coastal Plain part of the Perth Metropolitan Region (PMR) as part of the Perth Region Plant Biodiversity Project (PRPBP), a collaborative project between the WA Local Government Association s Perth Biodiversity Project and the Department of Environment and Conservation. The PRPBP recognises a need to provide a fuller appreciation of the diversity of native vegetation found within the PMR. To that end, it was decided to establish reference sites within, or in close proximity to, Darling Plateau part of the PMR. It is proposed that these reference sites are established so as to represent major variations found in the plant communities found within this area. The purpose of this document is to provide information applicable to the management of Bushland within the PMR part of the Jarrah Forest, and to describe the reasoning for selecting the sites used in the PRPBP Jarrah Forest Reference Sites. Jarrah Forest The Jarrah Forest Interim Biogeographical Regionalisation of Australia (IBRA) region covers an area of approximately 5.4 million hectares stretching from the Shire of Chittering in the north to near Albany in the south (Commonwealth of Australia 2001), although smaller outlying populations of Jarrah (Eucalyptus marginata) occur outside of the Jarrah Forest Region extending into the Wheatbelt and Swan IBRA regions. Jarrah forest itself, generally occurs on the duricrusted plateau of the Yilgarn Craton and is characterised by Jarrah- Marri (Corymbia calophylla) woodlands on laterite gravels, bordered by Wandoo (Eucalyptus wandoo)- Marri woodlands on clayey soils to the east, Darling Scarp shrublands to the west and Karri (Eucalyptus diversicolor) forests to the south. Within this region are areas of eluvial (wind deposited minerals) and alluvial (water deposited) landforms support diverse shrublands. In areas of Mesozoic ( mya) sediments, Jarrah forests occur in a mosaic with a variety of species- rich shrublands. The climate of the Jarrah Forest region is described as warm and Mediterranean. Rainfall varies from 1,200 mm in Serpentine and the lower south west to 500 mm in the east most of which falls between June and September (May and McKenzie 2003)

3 Unlike most of the world s hardwood forest trees, Jarrah occurs as an almost pure stand within the Jarrah Forest region (although outlying populations are usually far less homogenous in structure). Few other trees grow in association with Jarrah, and those that do have specialized requirements and/or prefer soils other than pure laterite. Marri, Wandoo and Powderbark Wandoo (Eucalyptus accedens) prefer clayey soils, Bullich (Eucalyptus megacarpa) preferring wetter sandy duplex soils on valley floors, Flooded gum (Eucalyptus rudis), Blackbutt (Eucalyptus patens), and Melaleuca rhaphiophylla are generally associated with water courses, Melaleuca preissii and Swamp Banksia (Banksia littoralis) being associated with swamps, and Rock Sheoak (Allocasuarina huegeliana) being mainly associated with granite outcrops (Erickson et al 1973). Most other trees that grow in association with Jarrah usually form a second story or are found in small isolated stands. Foremost amongst these are Allocasuarina fraseriana and proteaceous species such as; Banksia grandis, Persoonia longifolia, Persoonia elliptica, Dryandra sessilis and in some areas Banksia menziesii, Banksia attenuata and Banksia prionotes. Beneath the relatively homogenous canopy of the Jarrah Forest there is often found deceptively diverse shrub and herbaceous understorey layers (Erickson et al 1973). These layers can vary from near monocultures in composition to highly diverse understorey mosaics. This diversity of structural units is, in many cases, as much due to disturbance history as it is to variations in climate and geology. There are 3850 current, native flora taxa listed on Florabase (WA Herbarium 1998-) within the Jarrah Forest IBRA region. The western edge of the Darling Range is called the Darling Scarp. This is the surface expression of an extensive geological structure known as the Darling fault. The scarp rises steeply to more than 200 meters above sea level, where it flattens out to form the Darling Plateau (Copp 2001). Patterns in the vegetation structure and floristic associations have long been attributed to the influences of the environment, which is evident at the environmental extremes presented by the Darling Scarp. The vegetation of the Scarp forms a variety of structural units varying from open woodlands of Jarrah, Marri, Wandoo, Darling Range Ghost Gum (Eucalyptus laeliae) and Rock Sheoak (Allocasuarina huegeliana), through to herbaceous lithic complexes and extensive shrublands, which, in the northern part of the Scarp, (including the section of the Darling Scarp included in the Perth Metropolitan Region) have been described by Markey (1997)as a series of 13 Floristic Community Types within 3 Super Groups. Six hundred and eighty nine taxa have been documented within the Northern Darling Scarp (Markey 1997)

4 Northern Jarrah Forest Reference Sites John Forrest National Park - PRPBP Jarrah Forest Reference Site 1 (JF1) John Forest National Park is approximately 20km due east of Perth within two local government areas; the City of Swan, and the Shire of Mundaring. It is managed by the Department of Environment and Conservation and includes a large section of the Darling Scarp and adjoining Jarrah Forest covering an area of 2,676 hectares within which the following vegetation complexes can be found; Forrestfield (FO), Darling scarp (DS), Helena (He2), Yarragil 2 (Yg2) and Dwellingup 2 (D2) (Havel and Mattiske 2000) (see JF1 Map 1 att.). The reference point selected (JFor1 see Map JF2 att.) was towards the top of the Darling Scarp on the Toodyay Rd within the locality of Swan View in the City of Swan (JFor1 reference site description att.). During the summer bushfires severely burnt much of the Northern PMR Darling Scarp. Because of the physical nature of the Scarp this area is very prone to bushfires ignited through natural causes such as lightening strike and (too often) through arson. For this reason much of the Scarp in this area is noticeably impacted through high intensity and high frequency (usually 3 year approx interval) fires. To the south of Toodyay Rd. at JFor1 there is a highly diverse shrubland which is in (generally) Very Good condition. This area has not been burnt for 5-7 years (estimated), has little weed intrusion, includes a diverse selection of species indicative of its floristic community type (Supergroup 1, FCT2, Southern granite shrublands and woodlands) (Markey 1997), and adjoins many structural units unique to this vegetation complex, including lithic complex, drainage line and Marri, Jarrah and Wandoo Open Woodland. To the north of Toodyay Rd. at the reference site there is a clear vista over a large area of the Scarp within in which a large selection of vegetation structural units are visible. These units form an easily viewed representational landscape ranging from Dwellingup through Darling Scarp to Forrestfield vegetation complexes on the Swan Coastal Plain. Unfortunately much of this area was burnt during the bushfires (Molloy 2007). However, if allowed to regenerate, monitoring the gradual recovery of this site will reveal much about; the vegetation structural units of the Darling Scarp Vegetation Complex, the impacts of a high intensity high frequency fire regime on this Vegetation Complex, and the natural mechanisms and disturbance opportunist species that will facilitate this recovery. In general this site (both north and south of Toodyay Rd.) complies very well with the representational landscape provided by Havel and Mattiske (2000) in Appendix 257 (att.) and as such provides a convenient opportunity to introduce participants to the flora and geology of the Darling Scarp. This landscape conforms well to that represented in Havel and Mattiske (2000) appendix D257. A site description summarising the known values of the site is attached. Reserve 2145/ Percy Cullen Oval - PRPBP Jarrah Forest Reference Site 2 (JF2) - 4 -

5 This is a 26 hectare reserve situated just west of the locality of Gidgegannup within, and managed by, the City of Swan. This site contains good representations of the landscape and flora of two vegetation complexes; these being Yarragil 1 and Dwellingup 2 (Havel and Mattiske 2000). Two reference points have been selected in this reference site using quadrats previously established as part of a comprehensive survey of this reserve (Bennett 2006). Quadrat data (Quadrats G105 and G108- see JF2 Map 2 att.) from Bennett s (2006) sites has been used for reference point descriptions in the attached site report for this reserve. In this manner, one photo point has been established at a quadrat within each of these two vegetation complexes, each of these within distinctive and interesting structural units. Quadrat G105 provides an accurate example of the ecological vegetation system (EVS) predicted by Havel and Mattiske (2000) for Dwellingup 2 Vegetation Complex within the northern part of the Jarrah Forest, i.e., JP4 = Upland ridges and spurs in the subhumid zone with gravely duplex soils and lateritic outcrops. Open forest of Eucalyptus marginata subsp. marginata and E. calophylla with second storey of Allocasuarina fraseriana, Banksia grandis and Persoonia elliptica. Shrub and herb storey consists of Adenanthos barbiger, Lechenaultia biloba, Hibbertia hypericoides and Nuerachne alopecurodea (Bennett 2006). Quadrat G108 provides an accurate example of different ecological vegetation system (EVS) predicted by Havel and Mattiske (2000) for the Yarragil 1Vegetation Complex within the northern part of the Jarrah Forest, i.e.: H16 = Minor valleys shallowly incised into the humid zone of the northern Darling Plateau with soils ranging from orange earths and humus podzols on the valley floor to red and yellow gravely duplex soils. Vegetation ranges from open woodland of Eucalyptus marginata subsp. thalassica, E. calophylla over a dense low shrub understorey through to wetlands dominated by Melaleuca preissiana, and Banksia littoralis and sedgelands dominated by Meeboldina scariosa and the introduced Typha orientalis (Bennett 2006). The vegetation condition for this reserve is estimated at 20% Very Good 60% Good 20% Degraded. The main impact on this reserve is Jarrah Dieback Phytophthora cinnamomi (currently under management) allowing a comparison of Dieback infested sites with sites relatively clear of this pathogen (Bennett 2006). This landscape conforms well to that represented in Havel and Mattiske (2000) appendix D251 (att.). A description summarising the known values of this site is attached. Noble Falls - PRPBP Jarrah Forest Reference Site 3 (JF3) This is a 46 hectare reserve vested with and managed by the City of Swan and situated just east of the locality of Gidgegannup within the City if Swan. This site contains good representations of the landscape and flora of two vegetation complexes, these being; Dwelling 4 and Murray 2 (Havel and Mattiske 2000) (JF3 Map1 att.). The Murray 2 section is comprised of major valleys moderately incised into the subhumid to arid zones of the northern Darling Plateau. Vegetation ranges from - 5 -

6 Woodland of Eucalyptus patens, E. rudis Melaleuca rhaphiophylla on valley floors to Woodland of E. wandoo and E. calophylla on slopes. The understory consists of Lepidosperma squamatum, Hypocalymma angustifolium, Astartea fascicularis, on valley floor to Hakea lissocarpha, Baeckea camphorosmae, and Gastrolobium calycinum, on slopes. Wooroloo Brook runs through the base of this vegetation complex (Molloy 2007). The Dwellingup 4 section is comprised of upland ridges and spurs in the subhumid zone with gravely duplex soils and lateritic outcrops. Open forest of Eucalyptus marginata subsp. thalassica and Corymbia calophylla with a weakly developed second storey of Allocasuarina fraseriana, and Banksia grandis. The understorey consists of, Xanthorrhoea gracilis, Leschenaultia biloba, Hibbertia hypericoides and Nuerachne alopecurodea (Molloy 2007). Woodman (2004), in a report for the City of Swan, described and mapped 11 different structural units for this reserve. The photo reference point is situated on a structural unit described by Woodman (2004) as "Low open forest to low dense woodland of Rock Sheoak Allocasuarina huegeliana over shrubland to low shrubland of mixed species Xanthorrhoea preissii, Hovea pungens and Chelianthes austrotenuofolia on sand over exposed granite". This site been selected as it is a prominent structural unit within the Northern Jarrah Forest. This site is in Good condition with some weed intrusion. The canopy of Rock Sheoak is still open and underdeveloped. It appears that this canopy is recent regeneration (5+ years) after having been totally removed by an intensive fire or series of fires. The condition of this site appears to be improving and should continue to further improve in the absence of further intense fires (Molloy 2007). This landscape conforms well to that represented in Havel and Mattiske (2000) appendix D261. A description summarising the known values of this site is attached. FR Berry Reserve - PRPBP Jarrah Forest Reference Site 4 (JF4) This is a 214 hectare reserve situated just west of the locality of Gidgegannup within the City if Swan. This site contains good representations of the landscape and flora of three vegetation complexes, these being; Murray 2 (My2), Helena 2 (He2) and Dwellingup 2 (D2) (Havel and Mattiske 2000) (JF4 Map1 (att.). The Murray 2 section is previously described under the Noble Falls Reserve description (above) and the Dwellingup 2 section is previously described under the Reserve 2145/Cullen Oval description. The Helena 2 section is comprised of an upland mosaic of open forest of Eucalyptus marginata subsp. thalassica-corymbia calophylla and woodland of Eucalyptus wandoo with some Eucalyptus accedens and Eucalyptus rudis on the deeper soils ranging to closed heaths and lithic complex on shallow soils associated with granite on steep slopes of valleys in semiarid and arid zones. Woodman (2004), in a report for the City of Swan, described and mapped 13 different structural units for this reserve (JF4 Map 3 (att.)

7 The two photo reference points chosen for this reserve are both situated in the Murray 2 Vegetation Complex (Havel and Mattiske 2000) (JF4 Map 2 (att.). The first reference point (FRB 1) is situated in a structural unit of open woodland dominated by Eucalyptus accedens and Eucalyptus wandoo interspersed with some Eucalyptus marginata subsp. thalassica and Corymbia calophylla, over a shrubland mosaic of low shubland of Xanthorrhoea preissii, Hypocalymma angustifolia, Luecopogon pulchellus, Grevillia bipinnatafida and Phyllanthus calycinus on shallow soils. The second photo reference point (FRB 2) is situated in a structural unit of a granite outcrop community (Lithic complex) of Stypandra glauca, Hibbertia aurea, Borya sphaerocephala, Chelianthes austrotenuofolia, Stylidium spp. Cyanicula cericia, Nuerachne alopecurodea with an emergent low shubland of Hypocalymma angustifolia, Luecopogon propinquus, Calothamnus sanguineous, Grevillia bipinnatafida and Phyllanthus calycinus. Surrounding taller shrublands are dominated by Grevillea endlicheriana, Calothamnus quadrifidus, Trymalium ledifolium Leptospermum erubescens, Dryandra squarrosa subsp. squarrosa and Hakea trifurcata. The general condition of this reserve is generally very good to excellent showing only some minor weed intrusion some evidence previous intense fire (probably 10+ years ago) and minor vehicle damage (Molloy 2007). This landscape conforms well to those represented in Havel and Mattiske (2000) appendices; D246 for Dwellingup 2, D259 for Murray 2, and D260 for Helena 2. A description summarising the known values of this site is attached

8 References Bennett, E., 2006, Flora and Vegetation Reserve 2145 and Percy Cullen Oval Gidgegannup. A report prepared for the City of Swan. Bennett Environmental Consulting Pty. Ltd., Kalamunda Commonwealth of Australia, Australian Native Vegetation Assessment National Land and water Resources Audit, Canberra Australia Copp, I., Geology and Landforms of the South-West. Department of Conservation and Land Management. Perth WA Erickson, R., George, A.S., Marchant, N.G. and Morcombe, M.K., Flowers and Plants of Western Australia. Reed Books Pty Ltd. Sydney NSW. Havel, J.J., Conservation in the Northern Jarrah Forest. The Jarrah Forest: a complex Mediterran ean Ecosystem, eds. Dell, B., Havel, J.J., and Malajczuk, N. Klewer Pulishers, Dordrecht. Havel, J.J., and Mattiske, E.M., Vegetation Mapping of South West Forest Regions of Western Australia. A report prepared for the Department of Conservation and Land Management and Environment Australia. Mattiske Consulting Pty. Ltd. Perth Western Australia. Markey, A., Floristic Survey of the northern Darling Scarp. Unpublished report to the Department of Conservation and Land Management, the Department of Environmental Protection and the Western Australian Conservation Council (Inc.) for the Australian Heritage Commission. May, J. E., and McKenzie, N. L., Jarrah Forest, Bioregional Summary of the 2002 Biodiversity Audit for Western Australia. Department of Conservation and Land Management, Perth WA. Molloy, S., (2007) Jarrah forest reference site field notes. Northern Transect. Unpublished Western Australian Herbarium, FloraBase - The Western Australian Flora. Department of Environment and Conservation. accessed October Woodman Environmental Consulting Pty. Ltd., City of Swan Local Biodiversity and Green Plan, Flora and Fauna Assessment, Assessment of Corridor Plan, and Assessment of Priorities for further Investigation, RFQ Q22/03/TA. A report for the City of Swan