McCutcheon's Grevillia (Grevillia maccutcheonii) Interim Recovery Plan 2003-2008

Interim Recovery Plan No. 144
Gillian Stack, Andrew Brown and Val English
Department of Conservation and Land Management, WA, 2003

1. Background

History

Grevillea maccutcheonii was first collected from southeast of Busselton prior to 1992 by G. Robertson who had not seen the species elsewhere in the area. A specimen was given to a former employee of The Department of Conservation and Land Management (DCLM), G. McCutcheon who recognised it as an undescribed species and collected the type specimen in November 1993.

Despite comprehensive surveys in the area conducted between 1992 and 1994 by DCLM staff (Gibson et al. 1994) and floristic records for the area dating back to the turn of the century the site of the original collection is the only known location of the species.

In 1993, Grevillea maccutcheonii was known from 27 plants, five on a road reserve and 22 on adjoining private property. During a survey of the population in September 1994 none of the private property plants were located and it was noted that the area was being grazed by cattle. The landowner volunteered to remove the cattle, and the site, which was purchased by DCLM in 1999, is being monitored for regeneration of the species.

A number of seedlings have germinated in the area of the wild population since 1995, often in response to accidental or managed disturbance. Seedlings that appeared in areas of high threat such as in a drain alongside the road have been carefully removed and translocated to more secure ground. Steps have also been taken to protect seedlings from fungal attack and insect predation. Deaths of some juvenile and mature plants have occurred, from natural attrition, roadworks, drought and disease. There are currently a total of 13 mature plants and 20 seedlings at the wild population. Experimental translocations were undertaken in 2000, 2001 and 2002, with plants going into two recently acquired Nature Reserves. A number of other threatened ironstone species are also being translocated into the same Nature Reserves which were purchased for this purpose.

Apart from plants in BGPA and several private native gardens, Grevillea maccutcheonii is not known to be in cultivation. However, its compact habit, beautiful foliage, colourful flowers and extended flowering period would make it an attractive native plant for the nursery trade.

Description

Grevillea maccutcheonii is a dense tall shrub to two metres tall. It has attractive large red flowers and distinctive flattened three-lobed leaves that encircle the stem. The species is distantly related to G. manglesioides but differs in having completely glabrous vegetative and floral organs, and rigid, stem-clasping leaves and larger flowers. Flowering has been recorded between May and December, peaking in July to November.

Distribution and habitat

Grevillea maccutcheonii was probably once found in a tall mixed shrubland but this is now hard to confirm as its remaining habitat is now very degraded. Soils are shallow red brown clay associated with the highly restricted southern ironstone formations found at the base of the Whicher Range, a Critically Endangered habitat currently listed as a Threatened Ecological Community (TEC) and known as 'Shrublands on southern Swan Coastal Plain Ironstones' (English 1999). In this area the single known population grows on a one metre high mound of soil which was probably left following early road construction works. During winter months the mound is surrounded by water.

The ecological community 'Shrublands on southern Swan Coastal Plain Ironstones' in which Grevillea maccutcheonii occurs is also ranked Critically Endangered (English 1999). There are a total of 13 occurrences of this plant community located on seasonally inundated ironstone wetlands on the Swan Coastal Plain near Busselton.

Much of the species' diversity in the ironstone community comes from annuals and geophytes. Common native species are Kunzea aff. micrantha, Pericalymma ellipticum, Hakea sp. Williamson, Hemiandra pungens, Viminaria juncea, Aphelia cyperoides and Centrolepis aristata (Gibson et al. 1994).

Biology and ecology

The life span of this species is unknown, but flowering has been noted to occur on cutting grown plants in approximately two years. It is likely to take longer for seedlings. Seed is probably dehisced soon after maturity as this is typical of grevillea species. Longevity of the seed is unknown, but seed viability tends to be good (75-80% - unpublished data A. Cochrane ¹).

The species is a disturbance opportunist with seedlings appearing on a road reserve in grader spoil, and in response to deliberate disturbance at the base of a dead mature plant.

Grevillea maccutcheonii is moderately susceptible to the plant pathogen Phytophthora cinnamomi which has been recorded from Subpopulation 1t. The occurrence of the species in soils that are seasonally waterlogged may predispose the plants to the infection.

Threats

Grevillea maccutcheonii was declared as Rare Flora in August 1994 and ranked as Critically Endangered (CR) in September 1995. It currently meets World Conservation Union (IUCN, 2000) Red List category 'CR' under criteria B1ab(iii,v)+2ab(iii,v); C2a; D due to it being known from a single location, a continuing decline in the quality of habitat and number of mature individuals and population size estimated to be fewer than 50 mature individuals. G. maccutcheonii has specific habitat requirements and is naturally geographically restricted to the ironstone formations near Busselton. This soil type has been massively impacted by vegetation clearing in the past. The main continuing threats are weed invasion, rabbit grazing, disease, fire, road maintenance, chemical drift and degraded habitat.

  • Weed invasion and competition is a major threat to both the natural and translocated populations. Weeds suppress early plant growth by competing for soil moisture, nutrients and light. They also exacerbate grazing pressure and increase the fire hazard due to the high fuel loads that are produced annually by many grass weed species. Narrow linear populations such as road reserves have little buffering, and are severely affected by weed invasion from adjacent cleared land. The translocated populations are being planted into areas previously cleared for agriculture and presently being rehabilitated.
  • Grazing by rabbits has impacted on G. maccutcheonii populations. In addition to direct grazing, rabbits also encourage invasion of weeds through soil digging, addition of nutrients to soil, and introduction of weed seeds. The high level of palatable weeds in the area of populations and in adjacent farming properties attract herbivorous animals, which are often unselective in their grazing.
  • Disease is a serious threat to all populations. Phytophthora cinnamomi is a plant pathogen that causes root rot which results in the plant dying of drought stress. G. maccutcheonii has been found to be moderately susceptible to dieback caused by P. cinnamomi (personal communication C. Crane ²).
  • Inappropriate fire regimes would impact the viability of populations as seeds of Grevillea maccutcheonii are likely to germinate following fire. If this is the case, the soil seed bank would rapidly be depleted if fires recurred before regenerating or juvenile plants reached maturity and replenished the soil seed bank. Fires also generally stimulate the germination of weeds which have infested the habitat of the natural population.
  • Degraded habitat represents a threat to all populations. The lack of associated native vegetation makes it more likely that pollinators will be infrequent or absent. In addition, the lack of available habitat for recruitment is of concern. Part of the natural population occurs on a narrow road reserve with cleared land beyond.
  • Strong wind is a threat to Populations 1b and 1t due to a lack of protective natural vegetation. Wind can physically damage adult plants, increase soil moisture loss and dislodge enough material to smother small plants. Planting of windbreaks has commenced.
  • Road maintenance threatens Population 1a and its habitat. Associated threats include grading, chemical spraying, construction of drainage channels and the mowing of roadside vegetation. Several of these actions also encourage weed invasion.
  • Competition: There are several competing native species growing with Grevillea maccutcheonii the dominant ones being Melaleuca incana, Viminaria juncea, Hakea sp. Williamson, Kunzea aff. micrantha, Loxocarya magna, Juncus microcephalus, Acacia sp. and Dryandra nivea subsp. uliginosa. These may need to be pruned to reduce competition.

¹ Anne Cochrane, Manager, DCLM's Threatened Flora Seed Centre
² Colin Crane, Phytophthora researcher, DCLM's Science Division

Summary of population information and threats
Pop. No. & Location Land Status Year/No. plants Condition Threats
1a. SE Busselton Shire Road Reserve 1993 8
2000 14 (ca 300)
Moderate Weed invasion, grazing, disease, inappropriate fire regimes, degraded habitat, road maintenance activities, competition, chemical drift
1b. SE Busselton Nature Reserve 1993 22
1994 0
Moderate Weed invasion, grazing, disease, inappropriate fire regimes, degraded habitat, chemical drift
1t. SE Busselton Nature Reserve 2000 300
2001 ? [147]
  Weed competition, grazing, disease, inappropriate fire regimes, degraded habitat, strong wind, chemical drift
2t. SE Busselton Nature Reserve 2000 48
2001 ? [21]
  Weed competition, grazing, disease, inappropriate fire regimes, degraded habitat, chemical drift

Numbers in ( ) = number of juveniles. Pop.t = translocated population. [ ] = additional plantings.

Critical habitat

Critical habitat is habitat identified as being critical to the survival of a listed threatened species or listed threatened ecological community. Habitat is defined as the biophysical medium or media occupied (continuously, periodically or occasionally) by an organism or group of organisms or once occupied (continuously, periodically or occasionally) by an organism, or group of organisms, and into which organisms of that kind have the potential to be reintroduced. (Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)).

The critical habitat for Grevillea maccutcheonii comprises:

  • the area of occupancy of the known population;
  • occurrences of similar habitat currently containing translocated plants of this species (these may in time become self-sustaining populations);
  • areas of similar habitat within 200 metres of wild and translocated populations, i.e. shallow red brown clay associated with ironstone (these provide potential habitat for natural range extension);
  • corridors of remnant vegetation that link wild and translocated populations (these are necessary to allow pollinators to move between populations and are usually road and rail verges);
  • the local catchment area (the species occurs in a winter-wet habitat dependent on the maintenance of local surface and ground water hydrology); and
  • additional occurrences of similar habitat that do not currently contain the species but may have done so in the past (these represent possible translocation sites).

Habitat critical to the survival of the species, and important populations

Given that Grevillea maccutcheonii is listed as Critically Endangered it is considered that all known habitat is habitat critical. In addition, all populations, including future translocated populations, are or will be considered important to the survival of the species.

Benefits to other species/ecological communities

Recovery actions implemented for Grevillea maccutcheonii will improve the status of the Critically Endangered TEC 'Shrublands on southern Swan Coastal Plain Ironstones' in which it occurs.

International Obligations

This plan is fully consistent with the aims and recommendations of the Convention on Biological Diversity, ratified by Australia in June 1993, and will assist in implementing Australia's responsibilities under that Convention. However, as Grevillea maccutcheonii is not listed under any international agreement, the implementation of other international environmental responsibilities is not affected by this plan.

Role and interests of indigenous people

There are no known indigenous communities interested or involved in the management of areas affected by this plan. Therefore no role has been identified for indigenous communities in the recovery of this species.

Social and economic impacts

The implementation of this recovery plan is unlikely to cause significant adverse social and economic impacts. All populations occur in Nature Reserves or along road reserve.

Evaluation of the Plans Performance

The Department of Conservation and Land Management (DCLM), in conjunction with the South West Region Threatened Flora Recovery Team will evaluate the performance of this IRP. The plan is to be reviewed within five years of its implementation. Any changes to management / recovery actions will be documented accordingly.

Guide for decision-makers

Section 1 provides details of current and possible future threats. Any on-ground works (clearing, firebreaks, roadworks etc) in the immediate vicinity of Grevillea maccutcheonii will require assessment. On-ground works should not be approved unless the proponents can demonstrate that they will not have an impact on the species, its habitat or potential habitat, or on the local surface hydrology such that drainage in the habitat of the species would be altered.