Major Threats to Endangered Orchids of Victoria, Australia

Selbyana 26(1,2): 189-195. 2005. MAJOR THREATS TO ENDANGERED ORCHIDS OF VICTORIA, AUSTRALIA MICHAEL DUNCAN* Flora Ecology Research, Arthur Rylah Institute, Department of Sustainability and Environment, 123 Brown Street, Heidelberg, Victoria, Australia 3084. Email: [email protected] ANDREW PRITCHARD Department of Sustainability and Environment, 78 Henna Street, Warrnambool, Victoria, Australia 3280. FIONA COATES Flora Ecology Research, Arthur Rylah Institute, Department of Sustainability and Environment, 123 Brown Street, Heidelberg, Victoria, Australia 3084. ABSTRACT. Endangered terrestrial orchids in the public network of parks and reserves, on private land, along roadsides, and in small vegetation remnants in Victoria, Australia, face a range of threats. These include weed invasion, grazing by invertebrates and native and introduced herbivores, road maintenance, and small population size resulting from habitat fragmentation. In addition, these areas have been affected often and adversely by altered fire regimes or hydrology, introduced pathogens, mini ng and forestry activ ities, recreational activities, and site disturbance. Many species are under threat of illicit collection, and many suffer from inadequate public understanding of basic orchid biology, of conditions required for seedling recruitment, and of the need to maintain specific pollinators and mycorrhizal fungi. Key words: Orchidaceae, threats, endangered, Victoria, conservation INTRODUCTION facing terrestrial orchids in Victoria include land clearing, habitat fragmentation and small popu The state of Victoria, in the southeast corner lation size, weed invasion, grazing by inverte of Australia, contains a diverse orchid flora with brates and native and introduced herbivores, site more than 370 taxa recognized. Orchids are disturbance, mining, forestry, recreational activ among Victoria's natural treasures and must be ities, altered fire regimes or hydrology, and in counted among its most threatened assets (Back troduced pathogens, These threats are com house & Jeanes 1995). Almost half (170) of Vic pounded by a general lack of understanding torian terrestrial orchid taxa have a state conser about the biology of native orchids, their my vation status of rare (R), vulnerable (V), endan corrhizal associations, and the requirements of gered (E), or extinct (X), using criteria of the their pollinators. Unfortunately, these threats International Union for the Conservation of Na rarely occur in isolation. ture and Natural Resources, also known as the In the past 15 years, a number of people have World Conservation Union (IUCN 2001, TABLE undertaken assessments of the processes threat 1). The perilous status of such a large proportion ening the rarest orchids in Victoria (Beardsell & of our orchid flora reflects the serious and wide Muir 1992; Backhouse et al. 1999a, J 999b, ranging threats and threatening processes that 1999c; Berwick et al. 1999; Hill et al. 1999; adversely affect the quality and quantity of nat Ingeme & Backhouse 1999; Todd 2000; Craig ural vegetation. Although the problems being & Pritchard 2001a; Coates et al. 2002; Duncan faced by orchids are shared equally by other et al. 2003). In this paper, we describe a range threatened plants and animals, orchids have the of threats and threatening processes present in potential to act as flagship species, that is, to Victoria, using examples of threatened terrestrial highlight broader nature conservation and bio orchid populations. Based on DSE (2003), both diversity issues relating to a decline in the extent the state and national threatened status of a tax and quality of ecosystems. on are bracketed following the first mention of The major threats and threatening processes each orchid taxon. Many orchid taxa, which are yet to be formally described, are also yet to re ceive a national threatened status, Nomenclature * Corresponding author. follows that of Ross and Walsh (2003). 189 190 SELBYANA Volume 26(1,2) 2005 TABLE I. Summary of the conservation status of Vic cropping), less than 1 % of the pre-European torian orchids at the state and national level, Aus cover ofWBPG remains (NRE 1997). Tiny rem tralia, 2003. nants are restricted largely to roadsides, rail re serves, cemeteries, and unimproved paddocks Victoria Australia that have so far escaped cultivation and heavy DSE FFG EPBC grazing (Scarlett & Parsons 1993). Although ca. Conservation status (2003) (1988) (1999) 12% of Victoria is protected in national parks or Presumed extinct (X) 1 I 8 3 reserves, these include very little WBPG habitat. Endangered (E) 73 50 27 Thus most of the remaining fraction continues Vulnerable (V) 41 13 24 to be degraded by stock grazing, weed invasion, Rare (R) 45 2 o and site disturbance. The WBPG has a high lev TOTAL 170 73 54 el of endemism, with ca. 50% of orchid species Source: DSE (2003). occurring nowhere else (Rouse 2002). As a re Note: DSE = Victorian Department of Sustainability sult, 10 nationally threatened orchid species and Environment; conservation assessment of orchids cling to survival in this region, while another by the DSE, using IUCN 2001 criteria. two species are extinct. FFG = Victorian Flora and Fauna Guarantee Act For example, Pterostylis basaltica D.L. Jones 1988; orchids listed under the FFG. and M.A. Clem. (E), P. sp. aU. bicolor (E), P. EPBC = Commonwealth Environment Protection sp. aft'. cycnocephala (E), and P. sp. aU. mutica and Biodiversity Conservation Act 1999; orchids listed under the EPBe. (E) are all endemic to WBPG and were probably once widespread across the ecosystem. Today they occur together at the same single roadside DISCUSSION site, associated with a small, stony rise sur rounded by farmland (Ingeme & Backhouse In surveying the threats currently facing na J 999, Duncan et a1. 2003). Two of these taxa (P. tive orchids in Victoria, Australia, we found a sp. aU. cycnocephala and P. sp. aff. mutica) oc variety of factors but list the following as most cur nowhere else, while P. basaltica occurs on significant. a second stony rise further along the same road side, and P. sp. aff. bicolor also occurs in an Land Clearing and Habitat Fragmentation unimproved paddock more than 100 km away. The roadside site is less than 0.5 ha in area, and Habitat destruction is the single greatest threat within this site, all four species are restricted to to the Victorian orchid flora (Backhouse & the moss beds and shallow soils associated with Jeanes 1995). In little more than 150 years of the edges of exposed basalt rocks. European settlement, the natural vegetation in Protection of this site is critical. Until recently Victoria has been altered enormously. Land there was opportunistic grazing of the roadside clearing of more than 60% of the state for ag by stock from surrounding farmland. Also a po riculture and urban development has greatly re tential exists for fertilizer drift or run-off from duced the extent of many habitats. For example, these properties, as well as herbicide drift asso early settlers grazed their stock extensively on ciated with weed spraying along the road. This Victoria's native grasslands and grassy wood roadside also forms part of a strategic firebreak lands and forests. They cut down the trees for in the district and as a result has been burnt an housing and mining during the gold rush of the nually by volunteers for the last 30 years. The 18505, and then "improved" the pasture by in timing of this management practice appears to troducing exotic grasses and applying fertilizers. have fortuitously favored native species over Unfortunately some of these habitats were also weeds. the most orchid-rich, and today they contain the highest proportion of threatened species. Woolly Tea-Tree Scrub Woolly Tea-Tree Scrub (WTTS), dominated Western Basalt Plains Grassland by a dense overs tory of Leptospermum laniger The Western Basalt Plains Grassland (WBPG) um (Sol. ex Aiton) Sm., was once widespread in has a flora unique within Victoria. While mem swamps and along watercourses on moist, black, bers of the Myrtaceae, Mimosaceae, and Epa peaty, alkaline soils in coastal areas of southern cridaceae families dominate ecosystems across Victoria (Coates et al. 2002, Duncan et al. much of the state, the WBPG is dominated by 2003). This habitat is well suited to agriculture. Poaceae and Asteraceae families, with trees and As a result, what must once have been contin shrubs restricted to water courses and rocky out uous populations of the nationally threatened or crops (Rouse 2002). As a result of clearing this chids-Corybas sp. aU. diemenicus (E), Pter fertile land for agriculture (principally grazing or astylis sp. aff. furcala (V), and P. tenuissima SECOND IOCC PROCEEDINGS 191 Nicholls (V)-are now widely scattered, isolated diata D. Don), can cause significant changes to populations. Only isolated pockets of WTTS re the vegetation structure and hydrology of !lites. main, commonly as small stands in the wettest corners of active grazing paddocks. Draining Altered Fire Regimes and clearing have led to a highly fragmented dis tribution across ca. 600 km of Victoria's south Fire is a major environmental factor in Aus ern coastline. For example, C. sp. aff. diemeni tralia, and major habitats for terrestrial orchids cus is only known from six populations, sepa are burnt regularly (Jones 1988). A critical fac rated by a minimum of ca. 80 km. These pop tor is the timing and frequency of fires (Back ulations are now almost certainly genetically house & Jeanes 1995). Most Victorian orchids isolated. In addition, because of the small size have evolved in a pattern of summer (Decem of these habitat fragments, these orchids are ex ber-February) fires, occurring when most orchid posed to a range of other threats (particularly species are dormant. In many areas, however, weed invasion, site disturbance, and altered hy this fire pattern has been altered or replaced with drology). As a result, the thick L. lanigerum a no-fires regime, particularly close to urban ar overstory is highly degraded at two sites.

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