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Rare plant recovery in Mallee woodlands.

Introduction

Semi-arid non-eucalypt woodlands (hereafter semi-arid woodlands) are an important component of the Victorian Mallee region. Semi-arid woodlands are characteristically dominated by trees other than eucalypts, notably Belah Casuarina pauper, Buloke Allocasuarina luehmannii, Slender Pine Callitris gracilis and Sugarwood Myoporum platycarpum (plant nomenclature follows Walsh and Stajsic 2007). Lower strata may be dominated by various grasses, forbs and cryptogams (notably lichens and mosses), or a variety of characteristic shrubs (e.g. Acacia spp., Senna spp.) (White et al. 2003). These woodlands once covered extensive tracts of the Mallee region, but today are restricted largely to the National Parks and Flora and Fauna Reserves (Connor 1966; Sluiter et al. 1997; White et al. 2003; Callister 2004).

Management history

Semi-arid woodlands have been cleared extensively for agriculture, timber harvesting (especially Slender Pine) and grazing. They have been further impacted by high populations of browsing and grazing animals, notably rabbits and kangaroos (Cohn and Bradstock 2000; Morcom 2000; Sandell et al. 2002; Sandell 2006). In 1977 and again in 1987, the Land Conservation Council recognised the severe and extensive depletion of these woodlands and the severe degradation of the remaining woodlands, and recommended their further reservation into what are now the Mallee National Parks and Reserves (Land Conservation Council 1977; 1987).

The composition of the remaining woodlands is substantially dependent on the local (site-specific) management history. Most remnant stands have been changed greatly following a century or more of fires (to which these woodlands are particularly susceptible), timber harvesting (especially Slender Pine), browsing and grazing by domestic, native and feral mammals, weed invasion and other novel intrusions into ecological processes (Gowans and Westbrooke 2002; Callister 2004; Gowans et al. 2005; Cheal 2009a, b; Gowans et al. 2010) such as wind-blown sand (Cheal et al. 2012). This wind-blown sand (a result of overgrazing and clearing) has been a problem since European settlement and continues today. It has the ability to 'bury' large areas of semi-arid woodland and mallee shrublands. Areas in HattahKulkyne and Wyperfeld National Parks have been replanted in the past in order to stabilise the shifting sands.

Soil disturbance has also been reduced through the removal of stock grazing, a key management focus in the parks soon after reservation. Additional browsing species currently include rabbits, hares, kangaroos and goats, and their numbers fluctuate as a result of control measures and climatic conditions (i.e. numbers decrease in drought periods and increase in wet periods when abundant feed is available).

Recovery and Restoration

Previous studies within these Mallee Parks and Reserves found that grazing-sensitive ground layer plants can recover quite rapidly with reduced grazing pressure (Sandell 2002; Cheal 2009a; Gowans et al. 2010), but recovery of woody perennial species such as shrubs and trees is more variable. Gowans et al. (2010) found a [greater than or equal to] 80% increase in mean species richness of the shrub layer in Pine-Buloke woodlands in Wyperfeld National Park, following stock removal and early control of browsers, notably rabbits, hares, goats and kangaroos.

Regeneration and/or recruitment events in the Mallee are sporadic (Batty and Parsons 1992; Sinclair 2005; Sandell 2006). Pre-conditions for both germination and establishment are largely unknown; however, it is thought that unusually heavy or prolonged rainfall is important to facilitate establishment and continued survival (Sinclair 2005; Sandell 2006). Successful regeneration of Belah has been observed where water accumulates in low-lying areas following heavy rainfall (Westbrooke 1998). Sugarwood regeneration also occurred following the establishment of the rabbit calicivirus in 1996 (Sandell 2002; Sandell et al. 2002; Cheal 2009b).

Semi-arid vegetation is necessarily slow-growing. Low mean annual rainfall reduces growth rates and variable and unpredictable rainfall patterns make plant establishment a rare and unreliable event for many plant species, including the dominant trees and shrubs. Consequently, ecological impacts have very long-lasting consequences. For example, many of the surviving Buloke trees most likely predate the arrival of rabbits in the 1860s (Castle 1989; Raymond 1990; Sluiter et al. 1997; Williams et al. 2004a, b). Recognisable (but degraded) Buloke Woodlands still exist, even though there has been scant regeneration for a century and a half. The corollary of this tolerance to adverse ecological management is that recovery is also slow and extended. Immediate reversal of a degrading process (such as high grazing pressure) does not produce rapid recovery of woodland that is original or in good condition. It may take many decades, and an accumulation of rare stochastic circumstances (such as cooler summers with extended rainfall) before degraded communities approach undisturbed condition states.

Climate

Droughts in north-western Victoria may be both seasonal and over much longer periods. Seasonal drought is a characteristic feature of the regional environment, with marked water deficits from December to April-May (White et al. 2003). A longer-term pattern of drought may be superimposed on this annual pattern, such as the recent rainfall deficit of the decade that finished in 2010-2011 (Fig. 1, Australian Bureau of Meteorology 2012). Seasonal drought is part of the regional landscape and rarely has long-term repercussions on the current flora and vegetation (White et al. 2003). Longer-term drought can have dramatic adverse impacts on the survival and regeneration of long-lived species. Decadal drought has been suggested as a reason for the recent widespread deaths of Slender Pines in the western Murray Sunset National Park (Cheal et al. 2007). Of course, drought is largely unmanageable (i.e. there is scant management response that ameliorates drought) with the possible exception that, to a certain extent, herbivore control and the associated reduction in browsing and grazing pressure mimic a good season in its impacts on the local vegetation and flora (Cheal et al. 2007).

Recently, in 2010 to 2012, two unseasonably mild and damp summers have occurred (Fig. 1; Australian Bureau of Meteorology 2012). Moister summers are very rare (maybe once every 20 to 30 years), but may be essential for the regeneration of many of the local plant species. The above-average rainfall in 2011 provided a unique opportunity to determine differing rates of regeneration across the semi-arid woodlands of the Mallee.

In the past, heavy grazing by rabbits, hares, goats, stock and kangaroos prevented plants from taking advantage of these occasional climatic conditions favourable to regeneration. However, concerted efforts to control these mammalian grazers and browsers (Sandell et al. 2002; Sandell 2002; Cheal 2009a; Gowans et al. 2010) have culminated recently in an extended period of reduced impact, putatively providing the essential pre-conditions for regeneration of many species which had become rare after decades (more than a century) of adverse management.

Methods

As part of a project assessing the quality of remnant semi-arid woodlands in north-western Victoria, field surveys were conducted in January and February 2012. Surveys were restricted to the Wyperfeld, Hattah-Kulkyne and Murray-Sunset National Parks and Yarrara Flora and Fauna Reserve (Figs. 2 and 3) and were restricted to sites that supported semi-arid woodland or that were believed to have formerly supported semi-arid woodland. Data collected during the survey were largely habitat structural aspects (e.g. tree density, cover of various vegetation strata), with very few floristic data, mostly tree and larger shrub species. The methods used during the survey, the number of sites visited and other background to the regional survey are available in Kenny et al. (2012). The species discussed below were incidental records, noted and collected when assessing sites for the target project. The project report is available from the Mallee CMA and Parks Victoria.

During these surveys 28 species listed on the Department of Environment and Primary Industries' (DEPI's) Advisory List of Rare and Threatened Species (DSE 2005) were found. These species are individually and briefly discussed below.

Results

Most threatened species are found in low abundance and often their distributions and abundances have been impacted negatively by extensive clearing, browsing and grazing in the region. As a result, they are represented sparingly in survey data sets. The current survey returned more than 115 records of rare or threatened species--a surprisingly high number (Table 1), particularly as rare or threatened species were not targeted. Easting/northing was determined by GPS unit, datum GDA 94, zone 54.

Abutilon otocarpum Desert Lantern

DEPI list: vulnerable.

New Records: Five new localities, two with 100+ plants; all within former range. Representative Locality: 501668 / 6213467 Specimens: Lodged with the ARI Herbarium. Implications: None; current status is supported. The plant is not widespread. It occurred in two localised populations of no more than 100 plants each, on otherwise unremarkable sites on low rolling dunes in former woodland. The plant is probably subject to heavy browsing in 'normal' seasons and reasonably considered threatened in Victoria. It is not considered threatened elsewhere in Australia. The seeds are capable of long-term storage in a soil seed bank. Previous germination experiments under 'fresh' and seed heated trials resulted in no germination (Ooi et al. 2009).

Acacia colletioides Wait-a-while

DEPI list: rare.

New Records: Three new localities, with few plants at each; all within former range. Representative Locality: 561450 / 6177402 Implications: None; current status is supported. In Victoria, Wait-a-while is restricted to the northern Mallee, where it is uncommon but concentrated in non-mallee sites (i.e. non-eucalypt sites, which are only exceptionally burnt). In spite of its spiny nature, it appears to be relatively palatable. For many years the more common Spine Bush Acacia nyssophylla was confused with Wait-a-while. All records of Wait-a-while before the mid-1980s are suspect and should be checked; it is suspected that many may be re-determined as A. nyssophylla.

Amyema linophylla Buloke Mistletoe (front cover)

DEPI list: vulnerable.

New Records: Fewer than five new records, all within former range.

Representative Locality: 534811 / 6194098 Implications: None; current status is supported. The plant is not widespread and is largely an obligate parasite on Buloke Allocasuarina luehmannii and Belah Casuarina pauper in Victoria, although it is occasionally recorded on other hosts (Marriott 2012). Both Buloke and Belah are greatly reduced in abundance and heavily browsed (as is Buloke Mistletoe itself) wherever the foliage is accessible to kangaroos or domestic stock.

Atriplex acutibractea subsp. acutibractea Pointed Saltbush

DEPI list: vulnerable and listed under the Flora and Fauna Guarantee Act 1988. New Records: One new locality, with approximately five plants, a major outlier from its (former) known range in Victoria (Nowingi to Mildura).

Representative Locality: 508817 / 6203488 Specimens: Lodged with the ARI Herbarium and the National Herbarium of Victoria (MEL).

Implications: None; current status is supported. The plant is not widespread. This is the first (and only) one of the recent Victorian records from a park or similarly protected reserve. In Victoria the species is associated with Oil Mallee Eucalyptus oleosa, Narrow-leaf Mallee E. leptophylla, White Mallee E. gracilis and Grey Mallee E. socialis, usually on slightly saline soils.

Convolvulus clementii Desert Bindweed

DEPI list: vulnerable.

New Records: Two new records, all within the former range.

Representative Locality: 511810 / 6184943 Specimens: Lodged with the ARI Herbarium and the National Herbarium of Victoria (MEL).

Implications: Review current status. This species may be less threatened than the current designation 'vulnerable' implies. This species is only recently recognised for Victoria (Johnson 2001) and is under-collected and previously overlooked. Its habitat seems to be tightly restricted to heavy soil flats in the far north-west of the state and it is uncommon to locally common. Its distribution in Victoria is poorly known, as it has only recently been distinguished from C. erubescens. In NSW, it is described as mostly found on flat areas, such as dune swales and claypans subject to seasonal inundation, in areas of open grassy woodland.

Eremophila oppositifolia Twin-leaf Emubush

DEPI list: rare.

New Records: Six new records, all within the known range in Victoria.

Representative Locality: 556392 / 6177413 Implications: None; current status is supported. The plant is not widespread, but may be locally common (particularly in high quality semi-arid woodlands).

Eremophila scoparia Silvery Emu-bush DEPI list: rare.

New Records: One new locality, some distance from former records, which are concentrated in the far north-east of the Sunset Country, immediately west of Mildura.

Representative Locality: 586686 / 6171660

Implications: None; current status is supported. Silvery Emu-bush is not widespread. This record is a notable range extension and, unlike most other Victorian occurrences, in a secure reserve.

Eriochlamys behrii Woolly Mantle DEPI list: rare.

New Records: One new locality, within the former range.

Representative Locality: 556398 / 6128871

Implications: Review current status. Recent taxonomic revision (Walsh 2007) has segregated the more southern populations as a new species, Eriochlamys squamata. Nevertheless, E. behrii remains common in suitable habitat (the upper margins of saline boinkas and seasonal lakes).

Jasminum didymum subsp. lineare Desert Jasmine

DEPI list: vulnerable.

New Records: Four new records, within former range.

Representative Locality: 539840 / 6191161

Specimens: Lodged with the ARI Herbarium Implications: None; current status is supported. In Victoria, Desert Jasmine is largely (but not wholly) restricted to high quality semi-arid woodland stands, which are also rare in occurrence.

Maireana georgei Slit-wing Bluebush

DEPI list: vulnerable.

New Records: Two new localities, each with probably <10 plants, all within the known range in Victoria.

Representative Locality: 499061 / 6195895

Implications: None; current status is supported. The plant is widespread and yet nowhere common. It appears to be restricted to heavier, more fertile sites, supporting either grassland or open woodland (the focus of former licensed grazing). It is one of the most palatable Maireana species (Cunningham et al. 1981) and populations may increase over time (assuming continuing grazing/browsing control).

Maireana sedifolia Pearl Bluebush (Fig. 4) DEPI list: rare.

New Records: One new locality, within its known range in Victoria. Representative Locality: 512182 / 6190133 Implications: None; current status is supported. In Victoria, Pearl Bluebush is largely restricted to heavier soils that are relatively fertile (and were thus preferentially alienated and cleared) in the north-west. It may be locally dominant, in small patches. This long-lived perennial is moderately valuable as forage, particularly in dry times (Cunningham et al. 1981), but only rarely germinates and establishes from seed (Noble 1977; Crisp 1978; Tupper and Muller 1985). Populations may slowly increase over (extended) time, assuming continuing grazing/ browsing control.

Maireana triptera Three-wing Bluebush

DEPI list: rare.

New Records: Twelve new records, within known range.

Representative Locality: 508817 / 6203488 Specimens: Lodged with the ARI Herbarium. Implications: None; current status is supported. This small shrub may be locally common (i.e. it usually occurs as small stands of relatively high density but small total area, < 1 ha). Stands are few enough that a Viclist status of 'rare' is reasonable. Moles et al. (2003) found seed viability almost halved after a year buried in the soil; a curious observation, in contrast with recorded recurrences in sites after a good rainy season, despite previous lack of records.

Marsdenia australis Doubah

DEPI list: vulnerable.

New Records: Two new records, all within former range.

Representative Locality: 539428 / 6191659

Specimens: Lodged with the ARI Herbarium. Implications: None; current status is supported. In Victoria, Doubah is largely (but not wholly) restricted to high quality semi-arid woodland stands, most of which have been cleared for agriculture. Doubah is also vulnerable to being browsed. Doubah is scattered but widespread throughout Central Australia and subject to increasing attention as a bush food, for which purpose it is already being commercially cultivated (Olive 2011).

Phyllanthus lacunellus Sandhill Spurge

DEPI list: rare.

New Records: Two new records, approximately 25 plants in each locality, in expected habitat (sandy rises within woodland) for Sandhill Spurge.

Representative Locality: 508263 / 6213718

Specimens: Lodged with the ARI Herbarium. Implications: None; current status is supported. Germination trials from samples collected in Western Australia found germination only in 'Autumn' conditions (Graham et al. 2004). No individuals were found at the sites from where seeds were collected, suggesting a long-term soil seed store. Only three individuals germinated (Graham et al. 2004).

Ptilotus sessilifolius Crimson Tails

DEPI list: poorly known.

New Records: One new locality, within known range in Victoria.

Representative Locality: 630231 / 6160159

Implications: Little; current status is supported. Crimson Tails is not well known in Victoria, although reported as common elsewhere (Cunningham et al. 1981). It is likely to have been overlooked previously and may have suffered from former browsing.

Radyera farragei Desert Rose Mallow

DEPI list: vulnerable.

New Records: Two new records and approximately five plants.

Representative Locality: 512085 / 6184575 Specimens: Lodged with the ARI Herbarium and the National Herbarium of Victoria (MEL).

Implications: None; current status is supported. Desert Rose Mallow is rarely recorded, and usually only after extended summer rains (as occurred in 2011-2012; Browne 1986).

Rhagodia ulicina Spiny Goosefoot

DEPI list: rare.

New Records: Twenty-four new localities, all within its known range in Victoria. Representative Locality: 573762 / 6165291 Implications: Review current status. Spiny Goosefoot is not widespread, but may be locally common. It was formerly confused with forms of Chenopodium desertorum or Rhagodia spinescens, and thus there are relatively few records (and all of these are relatively recent).

Rhyncharrhena linearis Purple Pentatrope

DEPI list: vulnerable.

New Records: One new record, approximately five plants (difficult to count 'plants' as this species suckers freely) in standard habitat (disturbed Belah Woodland). Representative Locality: 506760 / 6177745 Specimens: Lodged with the ARI Herbarium. Implications: None; current status is supported. Purple Pentatrope is palatable and vulnerable to being browsed.

Sarcozona praecox Sarcozona

DEPI list: rare.

New Records: Eleven localities added, all within the known range in Victoria.

Representative Locality: 539428 / 6191659

Implications: Review current status. Sarcozona is widely scattered throughout the northern Mallee, but is rarely locally abundant. This species is often confused with Carpobrotus and Disphyma species, so it may be more common than the 300+ records imply.

Sclerolaena patenticuspis Spear-fruit Copperburr (Fig. 5)

DEPI list: vulnerable.

New Records: Two new locality records, within known range.

Representative Locality: 512058 / 6193869 Specimens: Lodged with the ARI Herbarium and the National Herbarium of Victoria (MEL).

Implications: Review current status. Spear-fruit Copperburr is not widespread. It occurs in a few localised populations, but with substantial numbers of individuals. The plants are probably subject to heavy browsing in more typical seasons and Spear-fruit Copperburr was formerly considered threatened. As with other (mildly) palatable Sclerolaena species, it is likely to have benefitted from a couple of benign summer seasons (2010-11 and 2011-12) and a dramatic reduction in browsing pressure.

Sida fibulifera Pin Sida

DEPI list: vulnerable.

New Records: More than five records, all within former range.

Representative Locality: 515157 / 6209843 Specimens: Lodged with the ARI Herbarium and the National Herbarium of Victoria (MEL).

Implications: Review current status. Pin Sida is not widespread in the state, but is widespread in the Millewa region (especially now that browsing pressure has been reduced). In this study it occurred in many (former) woodland quadrats and with substantial numbers of individuals. The plant is probably subject to heavy browsing in more typical seasons and was formerly considered threatened. As with other palatable Sida species, it is likely to have benefitted from the recent benign summer seasons (2010-11 and 2011-12) and a dramatic reduction in browsing pressure. The seed, although of low viability (13% viable), maintained viability after a year in soil (10%, Moles et al. 2003). Pin Sida likely maintains a long-term viable seed store.

Sida intricata Twiggy Sida

DEPI list: vulnerable.

New Records: More than five new records, all within former range.

Representative Locality: 514855 / 6191538 Specimens: Lodged with the ARI Herbarium. Implications: Review current status. As with Pin Sida, Twiggy Sida is not widespread in the state, but is widespread in the Millewa region. In this study, it occurred in many (former) woodland quadrats and with substantial numbers of individuals. The plant is probably subject to heavy browsing in more typical seasons and was formerly considered threatened. As with other palatable Sida species, it is likely to have benefitted from the recent benign summer seasons (2010-11 and 2011-12) and a dramatic reduction in browsing pressure.

Sida spodochroma Limestone Sida

DEPI list: vulnerable and listed under the Flora and Fauna Guarantee Act 1988 (there is a current Action Statement, DSE 2003). New Records: More than five records, all within former range.

Representative Locality: 509880 / 6215823

Specimens: Lodged with the ARI Herbarium. Implications: Review current status and revise the Action Statement. Limestone Sida is not widespread in the state nor in the region, and is far less common than the above-listed Sida species. According to the Action Statement (DSE 2003), only eight small populations had been found on limestone soils in the Red Cliffs-Cardross area, within 10.5 km of each other. In the Millewa area, Limestone Sida is largely restricted to areas where limestone approaches, or outcrops at, the surface. Limestone Sida occurred in a few (former) woodland quadrats and was occasionally locally common. The plant is probably subject to heavy browsing in more typical seasons and was formerly considered threatened.

Tecticornia triandra Desert Glasswort

DEPI list: rare.

New Records: One new locality, somewhat removed from its (former) known range in Victoria (old river terraces west of Mildura and Rocket Lake).

Representative Locality: 575887 / 6166604

Implications: None; current status is supported. The plant is not widespread and has not been overlooked as it cannot reasonably be confused with any other species from the region.

Tragus australianus Small Burr-grass

DEPI list: rare.

New Records: More than 20 new records, each with anything between 1 and 50 plants, all within former range.

Representative Locality: 506760 / 6177745

Specimens: Lodged with the ARI Herbarium.

Implications: Review current status, as its abundance in the current study suggests that this species should no longer be considered rare or otherwise threatened. This year (2012) it was widespread in the north-western Millewa area and in most of the 137 sites surveyed. The local population in January 2012 was estimated at >50 000 plants. Low germination rates and similar rates at temperatures from 12[degrees]C to 28[degrees]C suggest the possibility of year-round establishment. One study revealed a high speed of germination with 50% of the seeds germinating on the first day (Jurado et al. 1992), suggestive of a disturbance responsive life form. Small Burr-grass is widespread throughout the arid and semi-arid areas of mainland Australia. In Victoria, Small Burr-grass is seasonal in occurrence and its abundance in 2012 is probably attributable to extended summer rainfall, combined with effective control over rabbit and kangaroo populations. In less benign seasons it is likely to retreat to a soil seed store.

Triraphis mollis Needle Grass

DEPI list: rare.

New Records: Six new localities, each with many individuals, all within the former known range in Victoria.

Representative Locality: 626751 / 6164520

Implications: None; current status is supported. The plant is not recorded in most seasons (Sandell 2003) and is (locally) common only after extended summer rains, as occurred in 2011 and 2012. It tolerates, or even benefits from, moderate soil disturbance (Cunningham et al. 1981).

Velleia arguta Grassland Velleia

DEPI list: rare.

New Records: Three new localities, all within the known range in Victoria. Representative Locality: 512085 / 6209220 Implications: None; current status is supported. In Victoria, Grassland Velleia is largely restricted to little-disturbed grasslands in the north.

Vittadinia eremaea Desert New Holland Daisy

DEPI list: none; 'rare' status is recommended. New Records: One new locality, with an unknown number of plants (suspected to be well over 50). Along with another record in the same season, from Ian Sluiter of Ogyris Consulting, this is the first specimen record for Victoria at the National Herbarium of Victoria (MEL). Specimens: Lodged with the National Herbarium of Victoria (MEL).

Implications: Assessment and inclusion recommended. Desert New Holland Daisy is widespread and locally common throughout arid Australia, but this year's records are the first specimen records for Victoria at MEL. Desert New Holland Daisy is relatively unattractive as forage (Read 1999) and appears to have only a short-term soil seed store (Moles et al. 2003). As a result, it is likely that these recent records in Victoria are as much in response to two relatively benign summers (2010-11 and 2011-12) as to reduced browsing pressures. Nevertheless, it is among the more distinctive of the Vittadinia species and unlikely to have been consistently overlooked in the past.

Discussion

There is always some inference and extrapolation in attributing causes to changes observed in the landscape. Data may help clarify and partially justify suggested causal connections but rarely provide absolute proof (i.e. with no uncertainty). Nevertheless, reasonable causal connections can still be determined as is the case with these new records of 28 rare and threatened species that inhabit semi-arid woodlands in the Victorian Mallee.

Formal protection of the large reserves in north-western Victoria was a consequence of the Land Conservation Council studies in the 1970s and 1980s (Land Conservation Council 1974, 1977, 1987). Domestic stock were not immediately removed from these reserves, but were gradually removed over the following 15 years or so. At the same time, control of introduced herbivores (notably rabbits) was introduced as a concerted planned campaign (Sandell 2006). Control measures were also extended to other herbivores, including kangaroos, as it became apparent that there could be scant woodland regeneration under continuing high grazing/browsing pressures (Sandell et al. 2002; Callister 2004; Parsons 2006; Cheal 2009a, b; Gowans et al. 2010). Currently, grazer/browser populations throughout much of the Mallee parks and reserves are maintained at significantly lower levels than at any time since park declaration.

Most of the rare and threatened plants discussed here are variously palatable to mammalian browsers/grazers (Cunningham et al. 1981; Sandell et al. 2002; Sinclair 2005). 'Palatability' is not an absolute characteristic. The likelihood of a plant being harvested by a herbivore depends on the amount of alternative forage (and thus indirectly on seasonal conditions). Nevertheless, in times of shortage, unpalatable plants may be edible (Beetham et al. 1987; Sandell 2003). Shortage of forage may be due to adverse seasonal conditions (such as droughts) or abundant competitors for the available forage, or some combination of these.

At least seven of the 28 rare or threatened species identified from the current study (Table 1) are probably most reasonably interpreted simply as further records of long-lived perennial species from within their known ranges (i.e. Acacia colletioides, Amyema linophylla, Eremophila scoparia, Jasminum didymum, Maireana sedifolia, Sarcozona praecox and Tecticornia triandra). Others may be misinterpretations of known distributional data (i.e. Eriochlamys behrii, Ptilotus sessilifolius and Rhagodia ulicina). However, most (all?) of the remainder can reasonably be interpreted as recovery (higher populations or wider distributions) following two benign seasons and extensive control of grazers/browsers. For some of these, population increases and extensive re-establishment are a dramatic change from former restricted ranges with few individuals (e.g. Atriplex acutibractea, the three Sida species, Tragus australianus and Triraphis mollis). Recovery of these rare plants in previous benign seasons was not recorded in previous studies (Parsons and Browne 1982; Cheal et al. 1992; Parsons 2006), but is clearly indicated for most of the species in the current study.

It appears that (partial) recovery of the suite of rare plants discussed in the current study can be attributable to two principal factors:

* two benign summers, with rainfall extending into the summers, and

* over two decades of herbivore control, culminating in historically low populations of rabbits and other herbivores throughout much of the study area.

Each of these factors, on its own, is insufficient to enable recovery of rare plants. But when benign summers coincide with effective herbivore control, dramatic recovery in rare herbs and sub-shrubs can be expected, and has been observed in early 2012. Management in semi-arid communities necessitates a long-term perspective and a sensitivity to adverse contexts before the resultant degradation becomes overwhelming and essentially irreversible.

Acknowledgements

Kate Bennetts, Judy Downe, Alison Oates and Dylan Osler assisted with field surveys. Keisha Atchison assisted with GIS mapping and Katie McClaren assisted with data entry. This work was commissioned and funded by the Mallee Catchment Management Authority through the Victorian Investment Framework initiative, Parks Victoria and the Victorian State Government. The authors are grateful for the support and foresight of Karen Nalder and Elizabeth Gosling (Mallee CMA) and Peter Sandell (Parks Victoria).

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Received 8 November 2012; accepted 11 April 2013

David Cheal (1,2), Claire Moxham (1), Sally Kenny (1) and Jessica Millet-Riley (1)

(1) Arthur Rylah Institute for Environmental Research, Department of Environment and Primary Industries 123 Brown Street, Heidelberg, Victoria 3084

(2) corresponding author; School of Science, Information, Technology & Engineering, University of Ballarat, PO Box 663, Ballarat, Victoria 3353

Table 1. Rare or threatened species recorded in the semi-arid
woodlands of north-western Victoria in 2012. 'Incidental' refers to
those species recorded outside recent quadrat-based surveys.
* indicates species which are also listed under the Flora and Fauna
Guarantee Act 1988.

Scientific name              English name

Abutilon otocarpum           Desert Lantern
Acacia colletioides          Wait-a-while
Amyema linophylla            Buloke Mistletoe
Atriplex acutibractea        Pointed Saltbush
Convolvulus clementii        Desert Bindweed
Eremophila oppositifolia     Twin-leaf Emu-bush
Eremophila scoparia          Scotia Bush
Eriochlamys behrii (3)       Woolly Mantle
Jasminum didymum             Desert Jasmine
Maireana georgei             Slit-wing Bluebush
Maireana sedifolia           Pearl Bluebush
Maireana triptera            Three-wing Bluebush
Marsdenia australis          Doubah
Phyllanthus lacunellus       Sandhill Spurge
Ptilotus sessilifolius       Crimson Tails
Radyera farragei             Bush Hibiscus
Rhagodia ulicina             Spiny Goosefoot
Rhyncharrhena linearis       Purple Pentatrope
Sarcozona praecox            Sarcozona
Sclerolaena patenticuspis    Spear-fruit Copperburr
Sida fibulifera              Pin Sida
Sida intricata               Twiggy Sida
Sida spodochroma             Limestone Sida
Tecticornia triandra (5)     Desert Glasswort
Tragus australianus          Small Burrgrass
Triraphis mollis             Purple Needlegrass
Velleia arguta               Grassland Velleia
Vittadinia eremaea           Desert New Holland Daisy

Scientific name              DEPI list             Number of
                             Conservation status    records

Abutilon otocarpum           Vulnerable (1)            5
Acacia colletioides          Rare (2)                  3
Amyema linophylla            vulnerable            Incidental
Atriplex acutibractea        rare *                Incidental
Convolvulus clementii        vulnerable            Incidental
Eremophila oppositifolia     rare                      6
Eremophila scoparia          rare                      1
Eriochlamys behrii (3)       rare                      1
Jasminum didymum             vulnerable                4
Maireana georgei             vulnerable                2
Maireana sedifolia           rare                      1
Maireana triptera            rare                      12
Marsdenia australis          vulnerable                2
Phyllanthus lacunellus       rare                      2
Ptilotus sessilifolius       poorly known (4)          1
Radyera farragei             vulnerable                2
Rhagodia ulicina             rare                      24
Rhyncharrhena linearis       vulnerable                1
Sarcozona praecox            rare                      11
Sclerolaena patenticuspis    vulnerable                2
Sida fibulifera              vulnerable            Incidental
Sida intricata               vulnerable               > 5
Sida spodochroma             vulnerable *          Incidental
Tecticornia triandra (5)     rare                      1
Tragus australianus          vulnerable               > 20
Triraphis mollis             rare                      6
Velleia arguta               rare                      3
Vittadinia eremaea           New record            Incidental

(1) Vulnerable defined as 'not presently endangered but likely to
become so soon due to continued depletion; or occurring mainly on
sites likely to experience changes in land-use which could threaten
the survival of the species in the wild; or species whose total
populations are so low that recovery from local disturbance could
be unlikely'.

(2) Rare defined as 'rare in Victoria but not considered otherwise
threatened. This category does not necessarily imply that the species
is substantially threatened, but merely that there are relatively
few known stands'

(3) Note: whilst this species is listed in the Victorian Census
(2007) as rare, it is widespread and relatively common in
north-western Victoria.

(4) Poorly Known defined as 'suspected, but not definitely known, to
belong to categories rare, vulnerable or endangered'.

(5) formerly known as Pachycornia triandra.
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Title Annotation:Research Reports
Author:Cheal, David; Moxham, Claire; Kenny, Sally; Millet-Riley, Jessica
Publication:The Victorian Naturalist
Article Type:Report
Geographic Code:8AUST
Date:Jun 1, 2013
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