Mirranie Barker and Stephen Barry
Environmental Protection Agency, Queensland
This document is an update of the recovery plan prepared by Stephen Barry (2000) for the endangered plant the Isis tamarind Alectryon ramiflorus. It provides information on the biology and ecology of the species and identifies a range of recovery actions. It also sets out a research and monitoring program on which to base effective management decisions for the future conservation and down listing of the species from endangered to vulnerable.
A. ramiflorus is listed as endangered under the Queensland Nature Conservation (Wildlife) Regulation 1994 and the Commonwealth Environment Protection and Biodiversity Conservation Act 1999, and is listed as 2E by Briggs and Leigh (1995). A. ramiflorus is known from a main population of at least 37 plants in the Cordalba Forest Reserve and from four smaller populations of one to three plants growing in roadside or riverine remnants near Childers, Queensland.
A. ramiflorus belongs to the family Sapindaceae. It is locally known as the Isis tamarind.
Individual trees may be single or multi-stemmed, often branching low to the ground, reaching 16m in height. The species readily forms adventitious shoots where aerial stems are damaged or come in contact with the soil surface. The outer bark is soft and flaky and light brown in colour; the older branches have numerous prominent lenticels whilst the young branches and leaf axes have pale brown hairs. Leaves are highly variable or polymorphic, especially in juvenile and adventitious shoot stages, when they are sometimes bipinnate (four to18 leaflets in mature leaves, 24 38 in juvenile leaves). The arrangement of the leaflets is sub opposite or alternate, with the rachis extending beyond the leaflets; the leaf stalk has a small swelling at the junction with the stem. Individual leaflets are lobed or pinnate, with rounded or notched tips. The inflorescences grow in clusters of two to seven and are borne on older branches or sometimes on the younger shoots; individual flowers are small (3-3.5mm diameter), pale green and without petals; stamens six to eight, ovary one, two to three lobed; borne in spring and summer. The fruits are green, usually two lobed and five to six by nine millimetres; take three months to ripen; seeds are brownish and half-enclosed by a red aril. Distinctive features of the species are the variable and polymorphic leaves and leaflets and the clustering of inflorescences on the older branches of the tree.
The reproductive biology of A. ramiflorus is not well understood. Plants sucker from the base, if damaged, or from prostrate above ground stems, which come in contact with the surface soil, producing a multi-stemmed habit. The somewhat clumped distribution of individuals in the Cordalba population suggests that seed dispersal is poor or plants may reproduce asexually by root suckering.
Observations taken over the last decade suggest that flowering and fruiting behaviour in A. ramiflorus is very limited or highly variable from year to year and between adult plants. Where flowering does occur, the flowers typically form in mid-summer and are often aborted before developing to an early fruiting stage. This may be associated with the lack of suitable pollination vectors owing to the fragmentation of the available habitat. The showy red aril of the fruit suggests the seed is dispersed by birds or possibly by ants.
The location of 80+ seedlings under an adult tree at Cordalba indicates that germination and initial growth may not be a limiting factor. This high initial establishment rate occurred even after 8.3kg (wet weight) of seeds had been removed. Seedling mortality was high with only a few seedlings surviving the relatively hot and dry summer conditions. Seedling dispersal was poor with all seedlings recorded within a five-metre radius of the parent trees. Production of viable fruit appears to be limited to a few individuals in a population, only one adult being responsible for all the ex situ propagated seedlings. Preliminary genetic investigations indicate that there is no variation between the sole parent plant and its seedlings (Robinson 2001).
Current population size
In late 1999 there were 69 individuals, 26 of these being considered sexually mature. Trees with a stem diameter at breast height (dbh, measured at 1.3m height) of at least 6cm were considered to be mature, as this was the minimum stem width recorded for flowering individuals. Table 1 shows the number of plants per site.
A survey in 1991 found that many A. ramiflorus plants were in poor health due to drought stress, the identification of some individuals being difficult due to lack of leaves. Another survey in July 1994 reassessed tree survival and found that all adult trees of A. ramiflorus >10cm dbh had survived with four of the original fifteen younger trees unable to be relocated and presumed dead. The total population of 32 plants was recorded, three more than had previously been recorded in the 1991 census.
The results of further surveys of the Cordalba site undertaken in late 1996 to early 1997 and in late 1999, indicate that the population is increasing. The population contains plants of varying diameter and height with the majority of individuals having a diameter of less than 10cm. The increase in population size is consistent with the observation that the dry rainforest community at this site is expanding.
Natural regeneration at the other sites near Childers is minimal, especially compared to the regeneration occurring at the Cordalba site.
A. ramiflorus is known from a small main population within the Cordalba Forest Reserve - Zillman Scientific Area, 24km northwest of Childers, and from four additional sites closer to Childers, in southeast Queensland (Table 1). The four Childers sites are scattered remnant distributions of a once extensive "Isis Scrub" community. The original scrub has largely been cleared and the land is now grazed by cattle or farmed for sugar cane and small crops. No additional populations of the species have been located to date during botanical surveys in the Childers-Bundaberg-Goodnight Scrub district.
|Locality||Latitude||Longitude||Tenure||No. plants||No. of trees planted|
|Cordalba Forest Reserve||-25.1250||152.0583||State Forest Reserve, managed by QPWS||17 adult
|Francey Road||-25.2033||152.2758||Road Reserve, managed by Isis Shire Council||1 adult
|The Yards||-25.2375||152.2503||Road Reserve, managed by Isis Shire Council||3 adult||20|
|Helms Scrub||-25.2494||152.2625||Reserve (Refuse station), managed by Isis Shire Council||2 adult
|Smith Creek||-25.2708||152.3117||Freehold||3 adult||6|
A. ramiflorus is known to occur naturally from only five populations. Four of these populations only contain two to three individuals. Therefore all sites containing this species are considered critical.
Cordalba Forest Reserve
The Cordalba site has a small patch of araucarian microphyll vineforest, approximately 1.9ha in extent, situated on the western edge of the Cordalba Forest Reserve. The scrub community is bounded by cleared freehold land to the west and by mixed eucalypt open forest to the north, south and east. Relict eucalypt species within the scrub suggest the vineforest is currently expanding its local distribution. Recent fire history and the distribution of natural firebreaks have played a significant role in determining the balance between scrub and eucalypt forest development in this region.
The site extends eastwards from a ridgeline and typically has moderately inclined hill slopes and gullies. The surface soils are poorly drained, acidic (pH 5), pale brown, gravelly and sandy clays. The geology is mapped as phyric to microphyric olivine basalt. However, a surface rock fragment collected at the site was determined to be granitic in origin. The scrub has a low and uneven canopy (6-12m tall) with emergent trees to 25m. Floristic composition is typical of other "dry rainforest" communities in the district. A road and associated drainage works have caused local disturbance to the site and canopy gaps are readily colonized by the shrub Murraya ovatifoliolata and by lantana which forms dense thickets.
This site has been declared a scientific area under the Forestry Act 1959 and stock proof fencing has been erected and firebreaks constructed to protect the community from accidental disturbance, grazing and fire impacts.
The values associated with the Cordalba site have been recognised by its recent gazettal as a State forest scientific area. As part of the Southeast Queensland Regional Forest Agreement, the Cordalba State Forest has been re-gazetted as forest reserve. The designation as a scientific area under the Forestry Act is not a tenure, merely the designation by regulation as a special management area.
Francey Road, Smith Creek, "The Yards" and Helm's Scrub
The four Childers sites differ from the Cordalba site in that they all have red krasnozem soils. Three of the sites occur in alluvial areas (Francey Road, Helm's Scrub and Smith Creek) whereas the fourth is a west-facing moderately inclined hill slope and gully at the margin of the red soil plateau ("The Yards"). All four sites are fairly narrow linear strips (20-50m) of remnant araucarian microphyll vineforest in close association with eucalypt open forest communities (e.g. Queensland blue gum Eucalyptus tereticornis and narrow-leaved ironbark E. crebra). Varying degrees of disturbance (fire, grazing, thinning, etc.) have allowed a number of pioneer or weed species to establish, particularly at the Francey Rd, Helm's Scrub and "The Yards" sites (e.g. hickory wattle Acacia disparrima, lantana Lantana camara, guinea grass Panicum maximum, blady grass Imperata cylindrica var. major, pink periwinkle Catharanthus roseus and asparagus fern Asparagus densiflorus).
The Childers sites remain unprotected with varying degrees of disturbance and exposure to threatening processes. All four sites contain populations of A. ramiflorus of one to three adult plants only. The Francey Road site is situated within a road reserve and is threatened by routine road/bridge maintenance works including periodic burning and slashing. "The Yards" site is also situated on a road reserve. The Smith Creek site occurs on freehold land and has a remnant riparian corridor of microphyll vineforest surrounded by sugar cane crops and grazing land. The riparian corridor extends for a distance of several kilometres and, at the site, averages 30-50m in width. The Helm's reserve is an Isis Shire Reserve and the site of the refuse station for the Childers Township.
At all localities, the small remnant vine forest patches and individual A. ramiflorus trees are susceptible to a number of potential threatening processes including:
- further loss of habitat and continued fragmentation of existing patches increasing the susceptibility of the habitat and individual A. ramiflorus individuals to wind damage, insect predation and drought;
- competition from weeds, primarily lantana, asparagus fern, mother of millions and guinea grass, with minor weeds such as coral berry, wild tobacco and Brazilian nightshade;
- grazing and trampling of seedlings and juveniles by introduced and native animals such as cattle and wallabies;
- inappropriate fire regimes;
- low population size and a small number of reproductively successful individuals producing a restricted gene pool and a potential for inbreeding depression; and
- road maintenance and other local Government activities.
The Cordalba site is being managed by QPWS for the long-term survival of A. ramiflorus and its habitat. If required, controlled burning and control of weeds and introduced animals will be undertaken in the surrounding open forest. Twelve A. ramiflorus seedlings have been planted and are being monitored to assess survival.
Green Corps undertook a rehabilitation project for Helm's Reserve. They removed introduced weeds; replanted gaps with dry vine scrub species, including eight A. ramiflorus seedlings; controlled erosion; and provided visitor facilities. The Childers branch of Greening Australia Bush Care will monitor the site and co-ordinate any future activities.
The owners of the land containing the Smiths Creek population have agreed to participate in a Land for Wildlife scheme. Funding was gained through the WWF Rainforest Recovery Project and realignment of the existing fence, weed control and rainforest plantings were undertaken. Planting included six A. ramiflorus seedlings.
Official signage has been erected at the three reserve sites. The signs say "Environmentally Significant Area" and identify a contact number for persons to call before undertaking any work in the area.
A. ramiflorus has been successfully propagated and twenty seedlings have been planted at "The Yards" site and another six plants have been planted on another Childers Land for Wildlife property. It has also been established at a number of regional botanic gardens as well as a few private gardens in the Bundaberg-Childers area. All seedlings have been sourced from one adult tree.
- Improved conservation of other threatened and poorly known species in the study area including Quassia bidwillii, Cossinia australiana and an as yet undescribed Cupaniopsis sp. "Biggenden" for which there are currently fewer than 15 plants known (J. Randall pers. comm.).
- Greater protection and re-establishment of lowland "dry rainforest" remnants that have been seriously over-cleared in Queensland and northern New South Wales.
Use of A. ramiflorus by indigenous people has not been documented, although a related species, Alectryon tomentosus, has edible, pleasant-tasting fruit and the bark was used as a fish poison. Members of the Sapindaceae family often have edible or partially edible fruit and are known collectively as "native tamarinds" due to the flavour resembling that of the pod of the Indian tamarind (Tamarindus indica of the Caesalpiniaceae family).
Mirranie Barker gave a talk on the A. ramiflorus to the Gurang Land Council at Bundaberg in July 2002 and interest in this species was generated. Investigations are underway to find out if there were any occasions where elders used A. ramiflorus during their day-to-day activities. It is hoped that a working relationship will be developed with the Gurang Land Council to promote awareness, and co-operation in the management, of A. ramiflorus.
The organisations/people that would be affected by the implementation of recovery actions for A. ramiflorus are private landholders, the Isis Shire Council and Queensland Parks and Wildlife Service. Landholders with known populations of A. ramiflorus occurring on their property have been actively involved in the conservation of this species, as has the Isis Shire Council. It is expected that their level of dedication to the conservation of this species will continue. QPWS has an ongoing commitment to the conservation of this species in the Cordalba Forest Reserve and oversees the implementation of recovery actions.
There are no organisations or individuals going to be disadvantaged by the implementation of this plan.
The species is not listed under any international agreements.