Botanic gardens are vital for delivering the Kunming‐Montreal global biodiversity framework

As we travel further into the Anthropocene, with the biodiversity crisis and climate change becoming ever more acute, the Kunming-Montreal global biodiversity framework (GBF) may well offer our last hope of preserving a diverse and fully functioning biosphere. Adopted by the Conference of the Parties to the UN Convention on Biological Diversity in December 2022, the GBF1 states that “Biodiversity is fundamental to human well-being, a healthy planet, and economic prosperity for all people, including for living well in balance and harmony with Mother Earth.” Its mission is to take urgent action to reverse biodiversity loss and put nature on a path to recovery, for the benefit of people and the planet a concept captured in the conference of the parties headline of an “ecological civilisation—building a shared future for all life on Earth.” We cannot establish an ecological civilisation without plant biodiversity. Plants, and other photosynthetic organisms, create and maintain the breathable atmosphere that sustains almost all forms of life on Earth. They are at the base of virtually all food chains, including our own, and our daily lives depend in a thousand ways on plant diversity at the ecosystem, species and genetic levels. It is therefore of the utmost priority that we protect and ensure the survival of plant diversity for the health and integrity of the biosphere and for the quality of life of future generations. Carrying the maximum possible plant biodiversity through the current ecological crises requires highly strategic, international efforts combining both in situ and ex situ conservation. It was often suggested in the past that the best way of securing the long-term survival of threatened species was through in situ conservation in well-placed protected areas. Today, however, the impacts of anthropogenic climate change, invasive species and novel pests and diseases threaten many of the most important biosphere reserves and other significant protected areas. Furthermore, climate change is already driving significant shifts in the actual and potential range of many species, an effect set to increase. It is now imperative that in situ and ex situ conservation are tightly integrated and that we accelerate efforts to repair damaged ecosystems through the UN Decade of Ecological Restoration2 and related initiatives. This paper explores the essential contribution of botanic gardens, arboreta and other plant diversity collections to these global challenges. It explores how these institutions must rapidly evolve and expand to take on new roles in the preservation of plant diversity and a green planet.3, 4 Three strategic priorities are identified and recent progress toward them is described for two megadiverse countries, China and South Africa. The international community of botanic gardens is increasingly active in ecological restoration, the development of green cities and other components of the GBF. For a future world rich in plant biodiversity, botanic gardens are essential but they are not sufficient. By this I mean that without the expertise and living collections of plant diversity at the heart of every botanic garden it will be impossible to protect plants from the extinction crisis, but that many other players will be required to ensure their future. Even when working as a well-coordinated international community, as botanic gardens do, they alone cannot scale up the propagation of plant diversity to meet the demands of establishing an ecological civilisation or delivering the vision of the UN Decade on Ecological Restoration. Botanic gardens are commonly seen by their visitors and the wider public simply as attractive, verdant places that are enjoyable to visit. This perception is not wrong but misses the hidden depths captured in the deeper definition offered by Wyse Jackson5 who proposed that “A botanic garden is an institution holding documented collections of living plants for scientific research, conservation, display and education.” The essence of such institutions stems from their people and their combined expertise in three distinct scientific endeavours: horticulture, systematics and science education. The science of horticulture, as practiced in botanic gardens, requires the ability to obtain seed, cuttings or other living material from the full spectrum of wild plant diversity and to successfully bring plants into cultivation, often for the first time.4, 6 The skills and expertise required for this go far beyond the normal practices of civic horticulture but this is not widely recognised or adequately rewarded as a career. The careful experimentation and discoveries needed to bring new plants into cultivation and to propagate them are rarely celebrated and often go unrecorded outside the “gray” literature. An important exception is the journal Sibbaldia, an open access journal that provides an opportunity for horticulturists and others in botanic gardens worldwide to share their expertise in maintaining and managing living collections.7 For the future, a much wider appreciation of the remarkable achievements of botanic garden horticulturists in saving threatened species from extinction is needed. Taxonomists and systematic biologists in botanic gardens and other scientific institutions are the gatekeepers to plant biodiversity. Without their ability to define and differentiate between the estimated 400,000 species of land plants and their subspecific variants, it is impossible to engage meaningfully with our planet's rich green inheritance. The fundamental importance of taxonomy6, 8 was fully appreciated in Target one of the Global Strategy for Plant Conservation (GSPC) for 2011–2020 which called for “an online flora of all known plants.” Thanks to the efforts of a consortium of more than 50 botanic gardens, arboreta, museums and other data providers this has effectively been achieved through the World Flora Online.9 As GSPC Target 2 also recognised, we cannot begin to know which plants require the most urgent attention without an assessment of their conservation status. While many plant species remain to be assessed, recent years have seen outstanding progress in conservation status assessments for the world's trees.10, 11 However, threat assessments are needed for all plants regardless of their life-form. Bringing plants into cultivation in botanic gardens also underpins and enables research into their specific properties and values, for example, as medicines, edible crops or their wild relatives, biofuels or innovative materials offering alternatives to those derived from petrochemicals.12-14 The third strand of botanic garden science, public education, citizen science and outreach is a significant strength of most botanic gardens, including many that lack the capacity for active programmes of research and conservation.6 These efforts are essential to engage with wider society to engender a greater appreciation of the role of plants in the biosphere and their importance for future human prosperity. These three scientific endeavours are not be found exclusively in botanic gardens there are, for example, important systematic biology programmes in some universities and research institutes that do not hold living plant collections, but significant strengths in all three only occur in botanic gardens and arboreta. Consequently, only such collections-based institutions benefit fully from the interplay between horticulture, systematics and science education which makes them such distinctive centres of expertise. Developing their living collections as elements of a global ex situ meta-collection15 of plant diversity distributed across botanic gardens located in every terrestrial biome and major ecosystem. A determined drive toward integrating the accession information from collections management databases will enable all significant botanic garden holdings to be viewed and analysed together. This will underpin the second strategic priority. Urgently targeting the collection of genetically diverse plant material to increase representation in living collections, seed banks and seed orchards to enable widely distributed ex situ collections to provide a secure source of plant material to back up in situ conservation and support ecological restoration. Priority must be given to the most threatened species and places experiencing rapid ecological degradation. We already know which tree species require the most urgent action but need to accelerate the assessment of all other plants to identify those of greatest concern. To achieve a massive expansion in the scale of cultivation and propagation of genetically diverse plant material of known provenance to meet current and future demand for ecological restoration and in situ reinforcement plantings in the wild. The scale of the nurseries and seed orchards required to meet this demand will always be greater than can be met by the world's botanic gardens no matter how closely they work together. The best pathway to success is to see botanic gardens as the key resource centres providing access to industrial-scale growers from forestry and land management organisations, commercial growers and any other partners able to finance and facilitate the large-scale propagation of high-quality plants. Together, these strategic priorities require unprecedented effort matched by significant financial investment to enable botanic gardens to unleash their potential to underpin an ecological civilisation. Challenging though this will be, significant progress is already being made and two mega-diverse countries illustrate the way forward. China has almost 200 botanic gardens after several decades in which their numbers have increased rapidly. Among them, they have 60% of China's 35,784 higher plant species in cultivation.16 In 2021 the Government of China announced its intention to develop a system of 10 to 12 National Botanical Gardens (CNBGs) distributed across its major climatic and vegetation zones and tasked with leading the integration of ex situ conservation and complementary in situ conservation in China's protected areas. The first two to be recognised were the National Botanical Garden in Beijing and the South China National Botanical Garden in Guangzhou. Substantial investment in the CNBGs will see them expand their living collections to protect the most threatened species, carry out high-level research supporting conservation and sustainable use of plant resources whilst showcasing the exceptional plant diversity of China and engaging in public education.16 By 2050, the aim is that CNBGs will provide ex situ protection for more than half of all native plant species including over 85% of the national Key protected species and all 156 plant species with extremely small populations (PSESP).17 China's State Council explicitly charged the CNBGS with exploring green development and working toward the global ecological civilisation envisaged in the Kunming-Montreal GBF. The evaluation and recognition of further CNBGs is actively underway. South Africa shows many parallels in its strategic development of the national botanic gardens managed by the South African national biodiversity institute (SANBI). These have continued to evolve since Willis18, 19 reported on the response to the Global Strategy for Plant Conservation8 and the International Agenda for Botanic Gardens in Conservation20 of the then eight national botanical gardens. In 2020, the South African Minister of Forestry, Fisheries and the Environment published the South African national botanical garden expansion strategy 2019–2030, which aims, in response to the GBF, to establish at least one national botanical garden in each of the seven provinces of South Africa and a botanical or demonstration garden for each biome of the country21 (South African government gazette December 2020). SANBI now manages 11 national botanic gardens located in all but one province. In addition to these, South Africa has other significant botanic gardens, including the oldest in Africa, Durban Botanic Garden, founded in 1849, which recently celebrated its 175th anniversary. China and South Africa are active participants in a global community of around 3000 botanic gardens and are closely engaged with Botanic Garden Conservation International (BGCI), which works to mobilise botanic gardens and engage partners in securing plant diversity for the well-being of people and the planet. BGCI and partners have accelerated the red list assessment of the world's 60,000 tree-threatened tree species11 with only about 10% still requiring assessment. The rapid progress made through the global tree assessment supports targeted conservation programmes and identifies which species need to be protected in ex situ collections. BGCI also maintains a series of online resources including PlantSearch,22 for living collections accession information, which enables gap analysis of current collections to define future priorities and policies at institutional, national, regional and global levels. For ex situ plant collections to become a global meta-collection will require many more institutions to upload their accession information because large areas of the world currently appear data deficient when they are not, the information is simply not available in global information systems. Compared to most of the other challenges, making existing accession data available and applied to the development of priorities for action should be straightforward. Scaling up the production and provision of high-quality, wild-origin plant material for everything from ecological restoration and urban greening to plant-based adaptation to climate change is the greatest challenge to the botanic gardens community. Achieving the GBF will require botanic gardens to expand their horizons far beyond their present-day physical boundaries through new partnerships with key players and agencies engaged in every aspect of land management around the world. Despite the fundamental importance of plants for the healthy functioning of the biosphere, the priority they are accorded and the resources currently allocated for their conservation are woefully inadequate. In the United States, for example, Havens et al. noted that in 2011 plants accounted for 57% of species on the federal endangered species list but received less than 3.86% of federal expenditure on endangered species.23 Resource constraints were also identified as an obstacle to progress in the 2020 Plant Conservation Report which assessed progress under the GSPC.24 Nevertheless, the same Report documented significant achievements in countries around the world and it is clear that many institutional budgets are being deployed in support of plant conservation. A more complete assessment of the status of the more than 300,000 plant species that are not trees is an enormous challenge that will only be achievable by prioritising those plants most obviously at risk, such as the medicinal plants, succulents and orchids that are the target of the illegal wildlife trade.25 It will also be important to engage with experts such as those brought together in the World Flora Online Taxonomic Expert Networks.26 However, the second strategic priority, increasing representation in living collections must move forward in parallel with the assessment of threatened status and, at national and regional levels, in those ecosystems which are most at risk. Meeting the future needs for plant diversity requires new partnerships with different kinds of agencies beyond those traditionally involved with botanic gardens. For example, new and strengthened relations with provincial and city authorities and the Forestry and Grassland Administration are built into the CNBG system. Engagement with a greater diversity of partners than is traditional for botanic gardens is also at the heart of the development of The Global Biodiversity Standard (TGBS)27 by BGCI, Conservation International, CIFOR-ICRAF, Ecosia, the IUCN Species Survival Commission, the Plan Vivo Foundation, Reforest’Action, 1t.org and the Society for Ecological Restoration. While the creation of an ecological civilisation lies in the future, the way towards it and the vital part botanic gardens must play are becoming clear. Stephen Blackmore: development of ideas and concepts, preparation of original manuscript. This paper, based on my presentation at the eighth Global Botanic Gardens Congress, Singapore 6–9 August 2024, is dedicated to the founding director of BGCI, my professor and mentor, Vernon Hilton Heywood (1927–2022). Not applicable.

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