Conservation Biology Research

• Introduction
• Conservation Research
• Plant Translocation
• Target Species
• Case Study
• Further Information
• Selected Publications

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Introduction

Nearly 24% of South Australia's vascular plants are considered to be under some degree of threat in the wild. Unless appropriate remedial action is taken, many of these threatened species could be at risk of becoming extinct within our lifetimes. However, because these species are so diverse, and the threats to their survival are so varied, their conservation management is rarely straightforward or obvious.

There is an urgent need to develop some basic knowledge about these plants and the reasons for their endangerment, so that sound management decisions can be made to ensure their future sustainability. With this aim in mind, the Botanic Gardens of Adelaide has been involved in conservation biology research for nearly 20 years. The studies are focussed on improving our understanding of the biology and ecology of the threatened flora of South Australia, so that recovery and management plans for these species are better informed by accurate scientific knowledge.

Conservation Research

The populations of many endangered species are small and fragmented, often being restricted to roadsides or small scrub patches in largely cleared agricultural regions of the State. Much of our research is focussed on the delineation of threats to a species' ongoing sustainability, and how these may be overcome to improve population management. Studies of reproductive biology and seed bank dynamics can tell us whether factors associated with fecundity or seed dispersal are limiting recruitment of the next generation. Studying responses of threatened species to fire informs us about regeneration mechanisms and safe fire frequencies. Genetic studies unveil issues associated with clonality or inbreeding in small populations.

Plant Translocation

For some endangered species, augmentation of existing populations or the construction of new populations by translocation (deliberate transfer of plants from an ex situ collection to an existing or new location in the wild) may be considered appropriate. This is usually preceded by trial translocations, which are a useful tool for refining procedural and technical details for large scale translocations. Studies on propagation physiology may also form part of this research. Recently, translocation was used to successfully augment a wild population of Acacia whibleyana by 25%, thereby broadening the age distribution of plants in the population and boosting fecundity.

Target Species

The plants targeted for research represent some of the State's most critically endangered species. Some of the species currently under study include two wattles (Acacia cretacea and A. whibleyana), two daisies (Acanthocladium dockeri and Brachyscome muelleri), a raspwort (Haloragis eyreana), several terrestrial orchids (Caladenia behrii, Pterostylis arenicola, Pterostylis 'Halbury') and a grass (Lachnagrostis limitanea).

Case Study

Spiny Daisy (Acanthocladium dockeri) is a critically endangered shrub occurring in five roadside populations in the arable Mid-North of South Australia. Each population is relatively small and compact in structure and the total number of remaining plants has been estimated at less than 3000. Our research showed that even though plants flowered prolifically, very few viable seeds were produced due to low pollen viability. No regenerating seedlings were observed in any population, raising the possibility that genetic diversity within each population was likely to be low.

We carried out a series of genetic tests which confirmed that each natural population consists of a single, distinct, genetic clone, proliferating vegetatively by root suckering. This means, in effect, that there are only five genetically distinct plants left in the wild. The loss of any one population would result in a 20% reduction in the genetic diversity remaining within the species. Thus, despite the seemingly large number of plants remaining, this species is in urgent need of active conservation management.

Further research showed that introduced white snails were a severe threat to plant survival and vigour in most populations, causing death to shoots and whole plants by ringbarking stems during autumn and winter. Fire was found to destroy the resident snail population, giving plants a temporary reprieve from grazing damage for up to three years post-fire. Spiny Daisy was able to tolerate a burn by resprouting successfully after a bush fire. Weeds were present in all populations and presented a potential threat to population regeneration and expansion by competing for resources.

These result led to the recommendation that all five remaining clones be preserved in their respective habitats, ensuring each population is secure and local threats (snails, weeds) are eliminated or controlled. Snails could be controlled on a small scale by baiting, but if numbers were excessive, burning could be used to provide a successful longer term control strategy.

Micropropagation techniques were developed and several new populations have been initiated through translocation to spread risk and enhance population security. Regular and ongoing snail baiting and weed control are occurring at each population as part of local site management of the species. Further research is currently in progress to assess the potential consequences of mixing genotypes from different populations together.

Further Information

For further information regarding Conservation Biology Research at the Botanic Gardens of Adelaide, please contact the Senior Biologist Dr. Manfred Jusaitis , Phone: (61 8) 8222 9306.

Selected Publications

Jusaitis M and B Sorensen (1993). Germination of Pterostylis arenicola - an endangered greenhood orchid from South Australia. The Orchadian 11: 18-22.

Jusaitis M (1995). In vitro propagation of Phebalium equestre and P. hillebrandii (Rutaceae). In Vitro Cellular and Developmental Biology-Plant 31: 140-143.

Sorensen B and M Jusaitis (1995). Seed germination of endangered South Australian plants. Proceedings of the International Plant Propagators' Society 45: 86-92.

Jusaitis M. (1997) Experimental translocations: implications for the recovery of endangered plants. In: Conservation into the 21st Century (Proceedings of the 4th International Botanic Gardens Conservation Congress, Perth, Western Australia). (eds D.H. Touchell, K.W. Dixon, A.S. George and A.T. Wills) pp. 181-196. Kings Park and Botanic Garden, Western Australia.

Lee TC and M Jusaitis (2000). Micropropagation of Haloragis eyreana Orch. (Haloragaceae) using field material. Botanic Gardens Micropropagation News 2(4): 50-51.

Jusaitis M, B Sorensen and L Polomka (2003). Reproductive biology of the endangered Brachyscome muelleri (Asteraceae), an endemic herb of Eyre Peninsula, South Australia. Australian Journal of Botany 51: 179-188.

Jusaitis M, L Polomka and B Sorensen (2004). Habitat specificity, seed germination and experimental translocation of the endangered herb Brachyscome muelleri (Asteraceae). Biological Conservation 116: 251-266.

Jusaitis M (2005). Translocation trials confirm specific factors affecting the establishment of three endangered plant species. Ecological Management & Restoration 6: 61-67.

Feuerherdt L, S Petit and M Jusaitis (2005). Distribution of mycorrhizal fungus associated with the endangered pink-lipped spider orchid (Arachnorchis (syn. Caladenia) behrii) at Warren Conservation Park in South Australia. New Zealand Journal of Botany 43: 367-371.

Jusaitis M and M Adams (2005). Managing low genetic diversity in Acanthocladium dockeri. Australasian Plant Conservation 13(4): 26-27.

Jusaitis M and M Adams (2005). Conservation implications of clonality and limited sexual reproduction in the endangered shrub Acanthocladium dockeri (Asteraceae). Australian Journal of Botany 53: 535-544.

Jusaitis M (2007). Response of the endangered grassland plant Acanthocladium dockeri to fire. Australasian Plant Conservation 15(3): 20-21.

Jusaitis M and B Sorensen (2007). Successful augmentation of an Acacia whibleyana (Whibley Wattle) population by translocation. Australasian Plant Conservation 16(1): 23-24.

Jusaitis M and L Polomka (2008). Weeds and propagule type influence translocation success in the endangered Whibley Wattle, Acacia whibleyana (Leguminosae: Mimosoideae). Ecological Management & Restoration 9: 72-75.

Jusaitis M (2008). Flowering and seed production in the endangered Spiny Daisy, Acanthocladium dockeri. Australasian Plant Conservation 17(1): 14-15.