Victorian Conservation Seedbank
The Victorian Conservation Seedbank is situated in the National Herbarium of Victoria (MEL) at Royal Botanic Gardens (RBG) Melbourne. It is the local arm of the international Millennium Seed Bank Project, an initiative of the Royal Botanic Gardens, Kew, in the United Kingdom. The Victorian Conservation Seedbank is part of a three-way partnership between RBG Melbourne, RBG Kew and Victoria's Department of Sustainability and Environment.
The Victorian Conservation Seedbank aims to collect high-quality seeds from native plant species within Victoria for long-term storage, research and restoration programs. The project mainly targets seed from rare or threatened species or those species found only in Victoria (endemics). Seeds are lodged for long-term storage at RBG Melbourne and the MSBP headquarters at Wakehurst Place in the UK.
The Millennium Seed Bank Project
The Seed Conservation Department of RBG Kew conceived the visionary Millennium Seed Bank Project as a large conservation project to mark the start of the new millennium. The project aims to conserve genetically diverse seed from 10 per cent of the world's approximately 240,000 species of seed-bearing plants, by the year 2010. These will be held as duplicate collections at Kew's seed bank facility at Wakehurst Place and in the country of origin. The initial goal has now been achieved and the project has moved on to the second phase; to conserve seed from a further 15 per cent of the world's seed-bearing plants by the year 2020.
About 50 countries worldwide have established partnerships with the MSBP. These partnerships are a means of adding new species to the Millennium Seed Bank itself as well as allowing research into seeds of species that may not have been collected or studied before. This will allow many species that were previously poorly known to be used in restoration programs.
In the early part of the MSBP a state-of-the-art seed bank facility was built at Wakehurst Place, an historic property near the town of Haywards Heath in West Sussex, England, about 70 km south of London. Here, all the seeds are stored in large walk-in vaults kept at -20ºC. It is also here that research into the many aspects of seed behaviour and longevity take place. Students come to this facility from around the world to study seeds for the purposes of conservation as well as for their economic importance.
Why do we need seed banks?
Life on earth is critically dependant on plants. They feed us and the other animals with which we share the planet. They provide us with medicine, fibre and timber, they maintain soil fertility and they oxygenate the air we breathe. But plant diversity is at a crossroads. Land degradation, urban expansion and climate change threaten plant species and whole plant communities, and ultimately ourselves.
While the plight of many of our threatened species and landscapes is becoming better understood, even if we could halt the threatening processes immediately, species would continue to decline. For many species the situation is critical and they seem doomed to extinction. There needs to be urgent action to preserve these species, and seed banks are a relatively easy, low-cost way to do this.
Of the approximately 3,200 native species in Victoria, nearly 800 are considered to be threatened; that is, they are in danger of becoming extinct in the next few decades. Obviously the risk for some species is higher than for others. Those that are restricted to the coldest environments on high mountain summits are likely to lose the little habitat they have to the effects of greenhouse gas-induced climate change. Similar threats face plants in areas prone to increasing salination or to those restricted to the outskirts of expanding towns or cities.
The aims of the Victorian Conservation Seedbank
Over the first five years of the project (2005–2010) seed collections from over 500 Victorian native plant species were incorporated into the Victorian Conservation Seedbank, and duplicated at the MSBP, contributing to the achievement of the MSBP goal of banking 10 per cent of the world's seed plant species by 2010. Rare, threatened and endemic species were targeted to ensure the long-term survival of our most at-risk plant species. We continue to support the MSBP in its endeavour to reach 25 per cent of the world's species seedbanked by 2020. While funding for VCS activities is now much constrained, our focus continues to be on threatened species, particularly those identified as being at risk from global warming (e.g. alpine and shallow-aquatic species).
As well as the seed collection, at least two pressed specimens (vouchers) of each species are also taken collected. One of these voucher specimens is retained in the National Herbarium of Victoria, and the other is sent to the MSBP. The vouchers are used as a permanent reference for the identity of each seed lot that is collected.
Seeds are obtained from a single population at one site only, and the abundance and sampling methods are recorded at the time of collection.
We also aim to conduct scientific projects based around seed and/or fruit morphology, or seed germination responses of particular plant species or families. Our current project is a study of seeds, fruit, germination and seedling morphology in Australian species of Melicytus (family Violaceae). The results of this research will be used in conjunction with other data to reassess the taxonomy of the genus Melicytus in Australia.
Collecting and processing seeds
We collect seeds from all over Victoria – from the Mallee area, where plants flower and fruit first, to the Alps where they generally flower and fruit much later. Our main collecting season is about six months long, starting in the warmer drier regions and ending in the highest parts of the Alps. For those plants that hold their seeds in woody capsules for many years – such as species of Eucalyptus, Banksia, Hakea and Callistemon – we can collect seed at any time of year.
After the seeds have been collected they are returned to our laboratory where they are cleaned, counted and dried. Seeds go immediately into a drying cabinet set at 15ºC and 15 per cent relative humidity to dry them to about 5 per cent moisture content, an essential part of long-term seed storage. The seeds are then cleaned using various techniques including sieves (for separation based on size) and a zig-zag aspirator (for separation based on weight). Germination trials are conducted on all seed lots with the aim of achieving greater than 75 per cent germination for all species. For species with deeply dormant seeds, various techniques to break dormancy are used. Seedlings produced in our germination trials are grown on and many have been used for ex situ conservation in the Melbourne Gardens' Rare and Threatened Species Collection.
When the seeds have been dried they are counted and each seed lot is split into two equal parts and sealed in air-tight foil bags. The bags are then put in long-term storage in a freezer at -20ºC, one in the UK and one here at RBG Melbourne. It has been shown that under these conditions most seeds can be stored for a century or more. The seeds will be accessed every five years for further germination trials or when needed to produce plants for restoration projects to bolster wild populations.
Conservation and restoration
There is no point collecting seeds and placing them in seed banks if these seeds cannot be converted into growing plants for use in ex situ and in situ conservation and restoration programs. Seeds preserved in long-term seed banks have already, and will continue to be, used in such a way around the world. In Victoria we have restoration projects involving endangered plant species including Nematolepis wilsonii, Swainsona recta, Prostanthera galbraithiae and several species of terrestrial orchid. Other threatened species will be added to this growing list.
Many of these species have seeds with built in dormancy or very specialised germination protocols. Making a high-quality seed collection is only the first step in an integrated program for plant conservation and restoration. Developing techniques for seed germination and seedling growth are critical if plants are to be returned to the wild. This type of work is done routinely by staff at the Victorian Conservation Seedbank on seeds of all species collected.
For restoration work to be successful it is necessary for the new site to be a close match for the original site where the seeds (and/or cuttings) were collected. For this reason, comprehensive data on the original site is recorded at the time of collection. This includes a GPS reading of position and altitude, locality description, soil type, habitat type and a list of associated species. The collection should preserve a high degree of the species' biodiversity by sampling from as much of the population as possible.
How do seed banks work?
By using techniques developed at research institutions around the world, often focusing on critical crop species, we now have the capability to store seeds of many plant species for decades or even centuries without losing their viability. These are the species said to have 'orthodox' seeds and constitute about 90 per cent of all seed-bearing plants.
Researchers have shown that by reducing the water content of these seeds to very low levels (around 5 per cent), they may be stored at sub-zero temperatures (usually around -20ºC), which drastically slows down the chemical processes that naturally lead to loss of seed viability.
Many Australian plants produce seeds that have complex dormancy systems that require critical cues from the environment before they will germinate. Typically, these cues follow seasonal climatic extremes, or bushfires or floods, but may also be simple weathering of hard seed coats, or subtle combinations of these factors. Without an understanding of these requirements, we cannot reasonably hope to reinstate lost or seriously depleted wild plant populations. Research into these processes is currently taking place in seed banks around the world.