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Australasian Plant Conservation

Originally published in Australasian Plant Conservation 21(3) December 2012 - February 2013, p 14-17

Sowing seeds: bridging the gap between ex situ collections and reintroduction

Lydia Guja1,2,*, Tom North1, David Taylor1, Joe McAuliffe1
1 Australian National Botanic Gardens, Canberra, ACT; 2 Centre for Australian National Biodiversity Research, Canberra, ACT; * Corresponding author email: Lydia.Guja@environment.gov.au

Small collection (1 - 499 seeds) case study: Mountain Cress (Drabastrum alpestre) occurs in three states in south-eastern Australia. In the Australian Capital Territory (ACT) it is known from only one location of c. 600 plants. The ACT Government and the ANBG are collecting, storing, and developing germination protocols for seeds of this threatened species. During the 2011/12 summer 80 seeds were collected. Future collections will increase conservation and recovery options. Photo: Colin Schofield ACT Parks and Conservation.

Minimal collection (500 – 999 seeds) case study: Ginninderra Peppercress (Lepidium ginninderrense) is threatened with only c. 406 plants remaining in the wild. The Seed Bank at the ANBG currently holds c. 950 seeds, separated by maternal line, representing the genetic diversity of the species. Propagation methods optimised at ANBG’s nursery ensure the best chance of reintroduction success. Translocation is planned with the New South Wales Office of Environment and Heritage. Photo: Joe McAuliffe ANBG.

Satisfactory collection (1000 – 9999) case study: Native Flax (Linum marginale) foundation seedlings ready for transfer to seed production areas (SPAs). The ANBG, Centre for Australian National Biodiversity Research (CANBR) and Greening Australia are collaborating, funded by the Caring for our Country program, to improve availability of seed for diverse restoration of threatened grasslands using SPAs. SPAs help minimise impacts of continued collecting on remnant vegetation, provide opportunity to research genetic implications of SPAs, and supply seed for restoration. Photo: Tom North ANBG.

Optimal collection (more than 10 000 seeds) case study: Brindabella Midge Orchid (Corunastylis ectopa) inflorescence. The ANBG, CANBR and ACT Government are collecting, storing, and developing germination protocols for seeds of three threatened ACT orchids. Orchids have high fecundity making collection targets achievable. However, seed germination relies on association with specific mycorrhizal fungi which must also be collected and stored. The project aim is future reintroduction and translocation. Photo: Mark Clements ANBG & CANBR.

Introduction

Seed banks provide an efficient means of ex situ conservation for a wide range of Australian native plants. The Australian National Botanic Gardens (ANBG) holds a large collection of native species in its conservation seed bank, and is playing a crucial role in holistic conservation projects. A key to successful reintroduction is an understanding of how an ex situ collection can be utilised to bridge the gap between the ‘freezer’ and a self sustaining plant population in the wild. This article aims to demonstrate that for each seed collection the options for use are dependent on the size, quality, and genetic diversity of the collection. We outline the actions required to achieve successful collection, storage and germination of seeds, propagation of plant material, and reintroduction or translocation of rare or threatened species. The role of the seed bank in integrated conservation management is highlighted and key lessons learned for the future are outlined.

Seed collections

A conservation seed bank consisting of quality collections is a strong foundation that can be utilised to achieve a number of conservation, management, and research outcomes. A good collection consists of:

  • records such as herbarium vouchers, geographic location, habitat type, and collection method associated with each accession
  • sampling in a random and even manner so that every plant has an equal chance of selection
  • genetic diversity maximised by sampling multiple parent plants (30-50) per population
  • quality ensured by collecting only viable, mature seeds
  • sustainability considered and only 10-20% of available seed collected
  • optimised utility through collection of more than10 000 viable seeds per collection.

Options for use

Small collection (1 - 499 seeds)

Very few options for conservation management are provided by small seed collections. A small collection limits the ability to:

  • conduct quality tests
  • develop germination protocols
  • re-test germination after storage
  • research seed biology
  • propagate plants.

Actions to increase the size and improve utility of a small collection include:

  • targeting more populations
  • alternative methods of sourcing seed
  • successive annual collections.

Minimal Collection (500 - 999 seeds)

Minimal seed collections provide limited options for conservation management and, therefore, limit the ability to:

  • establish effective germination protocols if the seeds have complex dormancy syndromes
  • propagate an adequate number of plants for translocation
  • provide alternative seed sources such as the establishment of seed production areas to increase seed availability.

Actions to increase the size and improve utility of a minimal collection are as for ‘Small Collection (1-499 seeds)’.

Satisfactory collection (1000 - 9999 seeds)

A seed collection of satisfactory size provides some options for conservation management and research. A satisfactory collection allows:

  • quality tests and germination re-testing
  • some limited research into seed biology and ecology
  • propagation of approximately a third of the collection.

A satisfactory collection may still restrict options for use and can limit the ability to:

  • research complex dormancy syndromes and develop germination protocols
  • propagate an adequate number of plants for  translocation.

Actions to increase the size and improve utility of a satisfactory collection are as for ‘Small Collection (1-499 seeds)’.

Optimal collection (more than 10 000 seeds)

An optimal collection is ideal for conservation management and research. A collection of 10000 or more seeds per species allows:

  • splitting of the collection into conservation (long term storage), active (short term storage for e.g. research or propagation), and duplicate collections (to mitigate against loss)
  • germination re-testing to monitor the effect of storage on seed survival and vigour
  • assessment of alternative storage methods if required
  • research into complex seed dormancy and development of germination protocols
  • optimisation of propagation methods
  • reintroduction of adequate numbers of plants.

Although a collection may be of optimal size it is still important to consider further actions that may be taken. Further actions can ensure that a collection is representative of a species, and that the germination requirements of the species can be met. Actions that can be taken to improve optimal collections include:

  • targeting more populations and parent plants to represent the range and genetic diversity of a species
  • identifying, collecting, and storing other materials that may be required for germination or establishment e.g. mycorrhizal fungi for orchids or seeds of host plants for parasitic species.

Planning

Planning is key to optimal seed collections and reintroductions. For every collection it is important to:

  • identify the purpose of the collection e.g. conservation, restoration or research
  • plan to make conservation collections before only a few plants remain in the wild and only a few seeds can be collected or collection impacts the viability of the wild population
  • research the target species (ecology, biology, taxonomy and flowering and fruiting phenology) to inform collection and propagation procedures
  • plan for associated research e.g. recalcitrance, complex dormancy, or symbiotic relationships
  • monitor and evaluate conservation or restoration in the long term
  • communicate results and lessons learned to inform future actions.

Bridging the gap

Key lessons learned from collaborative projects aimed at bridging the gap between the ‘freezer’ and a self sustaining plant population in the wild are:

  • an ideal collection that provides options for conservation, reintroduction and research is 10 000 seeds or more, collected from multiple populations to represent the range and genetic diversity of a species
  • the impact of wild seed collection on remnant populations may be reduced by using foundation collections from the wild to establish seed production areas and increase seed availability
  • refining germination protocols and horticultural techniques at the outset will help determine the best method, and increase success, of reintroduction
  • improved knowledge of the biology, ecology, and genetics of a species is required to guide further research and activities aiming to restore viable plant populations.

Further reading

Offord, C. A. and Meagher, P. F. (Eds.). (2009). Plant Germplasm Conservation in Australia. Strategies and Guidelines for Developing, Managing and Utilising Ex Situ Collections. Australian Network for Plant Conservation Inc., Canberra.

Smith, R. D., Dickie, J.B., Linington, S.H., Pritchard, H.W. and Probert, R.J. (Eds.). (2003). Seed Conservation: Turning Science into Practice. The Royal Botanic Gardens Kew, Great Britain.

Acknowledgements

Many people are involved in these conservation projects and their contributions are greatly appreciated.

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