Sedge-Rich Eucalyptus Camphora Swamp
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Action Statement Flora and Fauna Guarantee Act 1988 No. 130 Sedge-rich Eucalyptus camphora Swamp Description and Distribution The only known occurrence of Sedge-rich Eucalyptus camphora Swamp is within the Yellingbo Nature Conservation Reserve, 50 km east of Melbourne in the Yarra Valley (SAC 1994). The community typically features a canopy of Mountain Swamp Gum Eucalyptus camphora of moderate cover (20-50%). Canopy height varies from about 6 to 25 metres (McMahon et al. 1991). The community varies in structure from open forest to woodland. The shrub stratum is sparse and dominated by Woolly Tea-tree Leptospermum lanigerum. In contrast the ground layer is comprised of a diversity of sedges, rushes, grasses Sedge-rich Eucalyptus camphora Swamp and forbs. Notable species include Fen Sedge Distribution in Victoria Carex gaudichaudiana, Tassel Sedge Carex [source: Flora Information System, DSE 2004a] fascicularis, Tall Sedge Carex appressa, Leafy Flat- sedge Cyperus lucidus and Soft Twig-sedge Baumea rubiginosa, Australian Gipsywort Lycopus australis, Current conservation status Ridged Knotweed Persicaria strigosa and Showy SAC (1994).....................................threatened (Vic.) Willow-herb Epilobium pallidiflorum. Sedge-rich Eucalyptus camphora Swamp has Where Sedge-rich Eucalyptus camphora Swamp is been listed as a threatened community under associated with well-defined streambeds or near the Flora and Fauna Guarantee Act 1988. permanent flowing water, Woolly Tea-tree forms a closed-shrub community with scattered emergent Reasons for conservation status Mountain Swamp Gum. Scented Paperbark In its final recommendation (SAC 1994), the Melaleuca squarrosa is co-dominant with Woolly Scientific Advisory Committee determined that Tea-tree in the lower reaches of ephemeral Sedge-rich Eucalyptus camphora Swamp is: tributaries. In these areas, Mountain Swamp Gum • only known from one site in Victoria has a cover of 5-20%. On sites subject to seasonal rather than permanent inundation, Variable Sword- • very rare in terms of the total area it covers sedge Lepidosperma laterale var. majus is • significantly prone to future threats which frequently co-dominant with sedges Carex spp. are likely to result in extinction of Sedge-rich Blackwood Acacia melanoxylon and Slender Eucalyptus camphora Swamp Tussock-grass Poa tenera are also found in these • in a demonstrable state of decline which is sites. Where Sedge-rich Eucalyptus camphora likely to result in extinction of Sedge-rich Swamp has been highly disturbed, Common Reed Eucalyptus camphora Swamp Phragmites australis dominates the ground layer. At these sites the canopy of eucalypts is very sparse or absent as a result of dieback. Comprehensive surveys provide evidence that • Altered water distribution patterns in the Sedge-rich Eucalyptus camphora Swamp is very swamp as a consequence of levee construction rare in terms of abundance and distribution. The in the 1950s (Pearce 1997, Craigie et al. 1998); total area occupied by Sedge-rich Eucalyptus • Sediment deposition, possibly as a consequence camphora Swamp is estimated to be 200ha (SAC of point (3) above (Carr 1998, Craigie et al. 1994). It is likely that the Sedge-rich Eucalyptus 1998). camphora Swamp was once widespread in valleys Over the last decade several hypotheses have been between Healesville and Macclesfield but has been advanced to explain eucalypt dieback within the markedly reduced in extent through clearing Yellingbo Nature Conservation Reserve. Initially (McMahon and Franklin 1993). dieback was attributed to exhaustion of carbohydrate reserves within the trees as a Major Conservation Objective consequence of psyllid infestation maintained by Bell Miners (Menkhorst and Middleton 1999, Objectives of this Action Statement McMahon et al. 1991). These authors • to refine our understanding of the distribution recommended removal of Bell Miners. and ecology of Sedge-rich Eucalyptus camphora Swamp Dieback in some parts of the Sedge-rich Eucalyptus camphora Swamp (e.g. Macclesfield Creek) may be • to determine the nature and impact of threats attributed to the psyllid-Bell Miner interaction (B. affecting Sedge-rich Eucalyptus camphora Quin, pers. comm.). However, dieback in the Swamp Cockatoo Swamp is not considered to be • to develop and implement effective associated with Bell Miners as large numbers of management techniques. these birds have not been recorded for this area (P. Long-term objectives Menkhorst pers. comm.). • protect, enhance and restore the extent and Kasel (1999) made a thorough study of the decline quality of Sedge-rich Eucalyptus camphora of Mountain Swamp Gum within the Yellingbo Swamp. Nature Conservation Reserve. She suggested that dieback along the Cockatoo Creek was related to Decline and Threats water stress (i.e. seasonal water deficit), nitrogen- enrichment, increasing soil salinity or a Eucalypt Dieback combination of these factors (Kasel 1999). The community is threatened by eucalypt dieback. McMahon et al. (1991) considered that dieback Lack of eucalypt regeneration could result in destruction of the eucalypt canopy. There is little evidence of natural regeneration of The Cockatoo Swamp supports the largest stand of Mountain Swamp Gum at Yellingbo (Pearce 1997, this community within the reserve and McMahon G. Carr pers. comm.). Death of adult trees and Franklin (1993) estimated that 30% of the coincides with changes in the understorey of canopy was affected by dieback. Since 1991 a Sedge-rich Eucalyptus camphora Swamp (Carr further 12% of the Swamp has suffered dieback 1998). Pearce (1997) considers that the with weed species invading the understorey (Carr development of replacement stands of Mountain 1998). Swamp Gum is of paramount importance for the Eucalypt dieback within the Yellingbo Nature conservation of the endangered Helmeted Conservation Reserve represents a severe site-level Honeyeater Lichenostomus melanops cassidix. Lack response to a range of complex, interacting of suitable sites for establishment, grazing from landscape management issues. Potential native and feral vertebrates and competition from contributing factors include: native (e.g. Common Reed) and exotic plant species are all likely to play a role in the failure of • Nutrient imbalances in trees brought about by Mountain Swamp Gum to re-establish within the anthropogenic input of nutrients from Yellingbo Nature Conservation Park – but perhaps surrounding agricultural activities (Kasel 1999). the most basic determinant of all these ecological Elsewhere, high nitrogen levels in eucalypt changes, including the death of dominants and the leaves have been shown to correlate with inability of Eucalyptus camphora to regenerate, is increased insect populations leading to anthropogenic nutrient enrichment, particularly eucalypt dieback (e.g. Fox and Macauley 1977, nitrification. Atkinson 1990, Landsberg 1990) The potential for the introduced Honeybee Apis • High numbers of Bell Miners Manorina mellifera to alter pollination patterns from melanophrys that aggressively exclude psyllid- outbreeding to inbreeding and thus the genetic eating birds leading to high numbers of sap- quality and absolute quantity of Mountain Swamp feeding psyllid insects (Loyn et al. 1983). 2 Gum seed should not be discounted (Paton 1993, Survey Horskins and Turner 1999). The vegetation of the Reserve was surveyed by McMahon et al. (1991). Carr (1998) made a brief Weeds study of the Mountain Swamp Gum dieback. Thirty one percent of plant species represented in Craigie et al. (1998) assessed proposed works to the Yellingbo Nature Conservation Reserve are ameliorate the effects of hydrological processes on naturalised aliens with the potential to seriously vegetation dieback at Cockatoo Swamp. Some degrade or even eliminate the indigenous mapping of dieback in relation to sediment depth vegetation of the reserve (McMahon et al. 1991). is on-going (B. Quin pers. comm.) This relatively high composition of weeds is probably a consequence of the linear nature of the Research Reserve and a history of considerable site There has been no formal research into the modification, including eutrophication vegetation community dynamics (e.g. vegetation (nitrification). Weed species comprise about 15% change over time, recruitment processes etc.) of of total plant species of the Sedge-rich Eucalyptus the Sedge-rich Eucalyptus camphora Swamp. camphora Swamp. The main weed species of concern to Sedge-rich Eucalyptus camphora Swamp Site Management are Grey Sallow Salix cinerea, Great Reed-mace Management of the Sedge-rich Eucalyptus Typha latifolia, Reed Canary-grass Phalaris camphora Swamp has included weed removal and arundinacea, Reed Sweet Grass Glyceria maxima, coppice treatments of some trees and shrubs (B. Creeping Buttercup Ranunculus repens, Lesser Quin, J. Bye pers. comm.). Between 1978 and 1987 Spearwort Ranunculus flammula and Cut-grass approximately 80 000 trees and some shrubs were Leersia oryzoides (McMahon et al. 1991, Carr 1998, planted in the Yellingbo Nature Conservation G. Carr pers. comm.). Reserve (Backhouse 1987). Planting continued through the following decade, with rehabilitation Wider conservation issues efforts receiving a boost recently from ‘Green The Helmeted Honeyeater and the Leadbeater's Corps’ teams. In the last few years, approximately Possum Gymnobelideus leadbeateri, are found 10 000 seedlings of 15 tree and shrub species have within the Sedge-rich Eucalyptus camphora Swamp been planted per year. Some fencing has been and are