Can botanic gardens conserve all of the world’s rare and threatened plant species?
Plants are essential for human and other animal life on Earth in that they capture energy from the sun and convert it into food in the form of their seeds, leaves and roots. Human life is further sustained by the medicines, building materials and fuel that plants provide. Plants are central to many ecological processes such as climate regulation (including carbon dioxide absorption), soil fertility and the purification of both water and air. In spite of their importance, more than 80,000 seed-bearing plant species (20% of the total) are currently under threat (Brummitt et al., 2015). This threat of extinction is largely due to habitat degradation, invasive alien species and over-exploitation, and is likely to be exacerbated by climate change. Furthermore, this threatened plant diversity will be essential to solving some of this century’s major challenges in the areas of food security, energy availability, water scarcity, climate change and habitat degradation.
It is estimated that humans have modified more than 50% of the world’s land surface (Hooke et al., 2012), with approximately 40% given over to agriculture and livestock management. For plants with natural distributions that fall within these transformed areas, ex situ conservation or active human management may be the only way they can survive.
Even in national parks and wilderness areas not significantly altered or actively managed by people, plant populations may be vulnerable – particularly to invasive species, pests, diseases and a changing climate.
Botanic gardens offer the opportunity to conserve and manage a wide range of plant diversity ex situ, and in situ in the broader landscape. The rationale that botanic gardens have a major role to play in preventing plant species extinctions through integrated plant conservation action is based on the following assumptions:
- There is no technical reason why any plant species should become extinct. Given the array of ex situ and in situ conservation techniques employed by the botanic garden community (seed banking, cultivation, tissue culture, assisted migration, species recovery, ecological restoration, etc.) we should be able to avoid species extinctions.
- As a professional community, botanic gardens possess a unique set of skills that encompass finding, identifying, collecting, conserving and growing plant diversity across the entire taxonomic spectrum.
Botanic gardens are a diverse community, fulfilling multiple objectives including attracting visitors, public education, scientific research, horticulture, and conservation. They have the potential to maximise their plant conservation impact by prioritising plant conservation action, becoming better organised as a professional community, and effectively communicating their role and objectives in plant conservation to policy makers, funders, and the general public.
Botanic Gardens Conservation International (BGCI) is a membership organisation, representing botanic gardens in more than 100 countries around the world. We aim to support and empower our members and the wider conservation community, including ordinary citizens, so that our knowledge and expertise can be applied to reversing the threat of extinction facing plants. Our vision is a world in which plant diversity is valued, secure, and supporting all life, and our mission is: “To mobilise botanic gardens and engage partners in securing plant diversity for the well-being of people and the planet” (Smith, 2018).
In this paper I will set out how we will achieve this mission through the establishment and promotion of a botanic garden-centred Global System for the conservation and management of plant diversity that aims to collect, conserve, characterise and cultivate samples from all of the world’s rare and threatened plants as an insurance policy against their extinction in the wild and as a source of plant material for human innovation, adaptation and resilience.
The concept of a rational, cost-effective Global System
The Global System approach is exemplified by the endeavours of the global crop research community. Despite its importance to food security, much of the world’s crop diversity is neither safely conserved, nor readily available to scientists and farmers who rely on it to safeguard agricultural productivity. Crop diversity is being lost, and with it the biological basis of our food supply. Given the urgent need to achieve food security in the face of a changing climate and burgeoning human population, the crop research community has developed the concept of a cost-effective, rational Global System for the conservation and sustainable use of plant genetic resources in food and agriculture. This Global System, established by the Food and Agriculture Organisation of the United Nations (FAO, 2011), comprises elements of policy, planning, a review process, physical infrastructures, human resources, germplasm collections and data. It consists of:
- The International Treaty on Plant Genetic Resources for Food and Agriculture (PGRFA),
- The Global Plan of Action for PGRFA,
- A review process (State of the World’s PGRFA),
- A network of international institutions and crop collections,
- A global portal of accession-level data (Genesys),
- A universal gene bank information management system (GRIN Global),
- Advanced bioinformatics tools that allow users to mine crop characterisation data (DIVSEEK).
Compared to the botanic garden community, the crop community is highly centralised around the FAO and the 11 multilateral germplasm collections in the gene banks of the Consultative Group on International Agricultural Research (CGIAR). Likewise, the International Treaty – in theory at least – facilitates access to material and data between national gene banks, multilateral gene banks and users. No such centralised, multilateral infrastructure exists for botanic gardens. Nevertheless, there are strong parallels with the policy, infrastructural and collections frameworks that exist in the botanic gardens community.
A Global System for botanic gardens
Following the example of the crop conservation community, a botanic garden-centred Global System for the conservation and management of plant diversity aims to collect, conserve, characterise and cultivate samples from all of the world’s rare and threatened plants as an insurance policy against their extinction in the wild and as a source of plant material for human innovation, adaptation, and resilience. This Global System comprises the following components:
- A global policy framework: the Convention on Biological Diversity,
- A global action plan: the Global Strategy for Plant Conservation,
- A review process: the Global Partnership for Plant Conservation,
- A collections infrastructure comprising an international network of botanic gardens and their living collections,
- A global portal of plant collection data,
- An array of data sources providing access to phenotypic and genotypic data enabling conservation and use of the collections for human development and well-being,
- A range of tools, resources and activities that aims to increase awareness and participation in plant conservation resulting in wide reaching benefits for society.
Most of the policy, planning and review architecture already exists, as indicated above. In addition, BGCI itself sits at the centre of a network of more than 3,000 botanic gardens in over 100 countries around the world (Figure 12.1), which includes the following:
Kew’s Millennium Seed Bank, the Royal Botanic Garden, Sydney’s Plant Bank, and Kunming Institute of Botany’s Gene Bank of Wild Species are the largest, most sophisticated seed banks in the world. The sector is equally strong in glasshouse and horticulture infrastructures and is more than adequately served with micro-propagation facilities and molecular laboratories. The botanic garden community’s most comprehensive data source on garden facilities and foci is BGCI’s GardenSearch, a web-based directory of the world’s botanic gardens comprising information on 3,571 botanic gardens and arboreta worldwide.
Comprehensive living plant collections
These cover at least a third of total known plant diversity. BGCI’s PlantSearch database (BGCI, 2019) includes 1,398,542 collection records, representing 556,338 taxa, at 1,119 contributing institutions around the world. A recent study (Mounce et al., 2017) found that that the botanic gardens included in PlantSearch manage at least 105,634 species, equating to 30% of all vascular plant species, 57% of vascular plant genera and an astonishing 93% of all vascular plant families. These collections include over 41% of known threatened species. There are, of course, caveats such as the fact that accession records are not always up to date or accurately named. However, this can be balanced against the fact that PlantSearch itself is not comprehensive, covering only about 40% of all botanic gardens.
Well-curated data sources
BGCI’s PlantSearch database is the most comprehensive register of the names of plants grown in botanic gardens. However, although it indicates which species are grown where, it does not enable the user to identify a specific collection that might be useful in plant conservation or for research. Therefore, the most pressing need is that PlantSearch becomes a portal to individual accessions and their data held in specific botanic gardens and ultimately becomes a means by which gardens can exchange material for conservation purposes in much the same way that the zoo community uses its International Species Information System (now called Species360) as a stud book for captive breeding (Conde et al., 2011). PlantSearch 2.0, which will trial this approach, will be launched in 2020. BGCI also manages ‘ThreatSearch’, the most comprehensive consolidated list of plant threat assessments in the world. This database comprises, global, regional and national assessments, and currently includes over 300,000 assessments covering >180,000 taxa, and enables botanic gardens to identify the world’s rarest and most threatened plant species so that they can give these species top priority.
BGCI’s role in building and co-ordinating the Global System
Sitting at the centre of a network of botanic gardens in 100 countries, including the largest and most influential gardens in our sector, BGCI and its regional and national partners are in a prime position to promote a more efficient, cost-effective and rational approach to plant conservation in botanic gardens. BGCI has strategic partnerships with national associations of botanic gardens, such as the Center for Plant Conservation in the USA and the Chinese Union of Botanical Gardens in China. We have similar partnerships with regional associations such as the European Consortium of Botanic Gardens, the South East Asian Botanic Garden Network and the African Botanic Garden Network. Building on the objectives outlined in BGCI’s Strategic Plan (BGCI, 2015), we can mobilise botanic gardens in four ways, by:
1. Leading and advocacy: We will provide leadership to the botanic gardens sector, and promote the role of botanic gardens to policymakers and funders in delivering the Global Strategy for Plant Conservation (2010). This is already happening as an increasing number of countries incorporate the Global Strategy into their National Biodiversity Strategies and Action Plans (Sharrock et al., 2014). In addition, through our strong links with the UN, botanic gardens are already recognised as playing an important role in the conservation and use of plant genetic resources in agriculture (FAO, 2011) and forestry (FAO, 2014). BGCI’s International Advisory Council, which currently comprises directors from 30 botanic gardens on six continents, is the closest approximation to a global leadership forum that the botanic gardens sector has. This body speaks with one voice on the primary importance of plant conservation in our sector.
2. Leading and co-ordinating innovative and strategic projects achieving outcomes in plant conservation policy, practice and education: At the global level, BGCI leads and co-ordinates consortia of botanic gardens with specific expertise within the broader network. These include:
a. providing the secretariat for the Global Partnership for Plant Conservation which measures progress towards the GSPC targets (Plants 2020, 2010);
b. providing the secretariat to IUCN’s Global Tree Specialist Group and co-ordinating the Global Tree Assessment which aims to have assessed the threat status of all known trees by 2020 (Newton et al., 2015);
d. co-ordinating Global Conservation Consortia for exceptional taxa such as Magnolia, Acer, Rhododendron and Quercus;
f. co-ordinating and providing the secretariat for the Ecological Restoration Alliance of Botanic Gardens (ERA), a consortium that currently includes 40 botanic gardens carrying out more than 200 restoration projects across the globe (Shaw et al., 2015);
3. Building plant conservation capacity in botanic gardens and other sectors: BGCI’s website is already widely used by the botanic garden community as a source of information on running a modern botanic garden, particularly through the latest iteration of BGCI’s botanic garden manual (BGCI, 2016). However, we are working hard to augment this information with resources and tools covering specific disciplines, including red listing, seed conservation, tree conservation, ecological restoration, plant health and public engagement. In addition, BGCI currently provides training courses on plant conservation policy, red-listing, seed conservation, ecological restoration, nursery techniques and public engagement. These courses are aimed at supporting smaller botanic gardens but also professionals in other sectors such as foresters and national park managers.
4. Providing funding: BGCI is committed to accelerating our fundraising efforts in order to mobilise funding to deliver plant conservation projects and outcomes, prioritising smaller, resource-poor botanic gardens in biodiversity hotspots. Currently, BGCI disburses around ten times what it receives in subscriptions back into the botanic garden sector – primarily for plant conservation and education activities. Traditionally, this funding comes mainly from trusts and foundations. Over the next five years our aim is to double that funding by building a global botanic garden endowment fund that will be used to generate regular income to support botanic garden-centred plant conservation activities on the ground.
Accepting the challenge: the role of the botanic garden community
Notwithstanding our impressive array of resources as a global community, substantial investment will be required to build a fully functioning Global System that can prevent species extinctions in perpetuity. Perhaps the most important thing we need to do is to agree, as a professional community, that we are going to take on the challenge of plant species extinctions. Only by presenting a united front, and showing that commitment, are we going to convince policymakers and funders that we have a substantial role to play.
Secondly, we need to promote plant conservation action in botanic gardens. This activity is currently competing with the other functions of botanic gardens, particularly the need to increase visitor numbers and generate income. Plant conservation activities in botanic gardens can be substantial or limited and may include plant conservation policy, practice or education. What is important is that all botanic gardens do something – preferably plant conservation action, and with local relevance. Although botanic gardens currently grow or conserve 42% of threatened plant species, only about 10% of their collections effort is directed at rare and threatened species (Mounce et al., 2017).
Thirdly, we need to better co-ordinate our work, and focus botanic garden efforts on the gaps, i.e. making sure that we tackle the rarest, most threatened and most challenging species. Although we maintain a third of known plant diversity in our living collections and seed banks, there are major gaps in our collections, infrastructures, knowledge and expertise. Mounce et al. (2017) point out that, although 60% of temperate vascular plants are grown in botanic gardens, only 25% of tropical species are represented. This is largely due to the fact that 82% of botanic gardens are located in the Northern Hemisphere (Figure 12.1) and there is insufficient expertise and resources in the tropics. In addition, botanic gardens grow or conserve less than 5% of non-vascular plants (mosses, liverworts etc.) despite the fact that they are ecologically important and many of them are threatened.
Fourthly, we need to acknowledge that we cannot work in isolation. An ex situ seed or living collection is the means to an end, not the end in itself. The aim is to achieve self-perpetuating populations of plants out in the broader landscape. This means working in an integrated way with in situ conservationists (e.g. park managers, NGOs etc.), foresters, farmers and other sectors that manage transformed landscapes. Explicitly, this also means that botanic gardens need to go out beyond their garden walls, and learn new disciplines. A large number of botanic gardens already manage wild areas and native species assemblages so this is not a huge ideological leap. However, we haven’t always been good at working in partnership with other professional sectors.
Finally, we need to facilitate plant conservation action in broader society through stimulating public dialogue, creating opportunities for participation in local and global conservation efforts and through provision of education, tools and information. At the same time, we need to be careful that our plant conservation effort does not begin and end here. Currently, too many gardens argue that they are fulfilling their role by simply informing the public about the need for plant conservation. This approach conveniently ignores the fact that our sector has the technical skills that broader society does not have, and that with those skills comes responsibility.
The loss of plant diversity is the most urgent and important issue that botanic gardens need to address but it is not always seen as a priority given the multiple roles that botanic gardens are expected to fulfil. Botanic gardens, as a professional community, possess unique knowledge and skills to find, identify, conserve and manage plant diversity in the landscape and, for this reason, they need to show greater leadership in plant conservation. To be most effective the sector needs to organise itself in a rational and cost-effective way by sharing knowledge and enabling all botanic gardens to carry out effective plant conservation in their own geographic or taxonomic spheres. Botanic Gardens Conservation International and its national and regional partners are ideally placed to facilitate this approach.
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[*] This paper is an updated version of Smith, P.P. (2016). Building a Global System for the Conservation of all Plant Diversity: a Vision for Botanic Gardens and for Botanic Gardens Conservation International. Sibbaldia 14, 5-13.
[†] Botanic Gardens Conservation International.
 see http://www.bgci.org/threat_search.php