Research highlights global plant diversity ‘darkspots’ where scientific efforts are urgently needed

An ambitious project led by scientists from the Royal Botanic Gardens, Kew, along with global partners, seeks to shed light on the planet’s “plant diversity darkspots”—regions teeming with biodiversity but where geographic and taxonomic data remain incomplete, leaving scientists in the dark about the wealth of plant diversity they contain.

The study, published in the journal New Phytologist, identified 33 global plant diversity darkspots with at least 14 (44%) of these in tropical Asia. With 3 in 4 of the planet’s undescribed plant species already threatened with extinction (State of the World’s Plants and Fungi 2023), these new data give scientists a useful tool for determining where to prioritize plant collection and conservation in this crucial decade for halting and reversing biodiversity loss.

The study involved predicting the number of plant species per “botanical country” (countries or close equivalents) that currently remain unnamed and unmapped. The researchers then examined where these darkspots coincided with the 36 recognized “biodiversity hotspots”—regions of rich and unique flora that are also under threat—as well as how socio-political and environmental factors may impact botanical expeditions and guide future taxonomic efforts.

Dr. Samuel Pironon, Lecturer in Conservation Biology at Queen Mary University of London, Honorary Research Associate at RBG Kew, and a lead author of the paper, says, “Resources to undertake new botanical expeditions or to digitize existing collections are limited, so prioritizing collecting efforts is vital. Our study provides a flexible framework to help accelerate the documentation of global plant diversity to inform conservation actions. Knowing where there are most species remaining unnamed and unmapped, of which many are likely to be threatened, is necessary for us to meet the 2030 targets of the Global Biodiversity Framework.”

In total, the work unveiled the presence of 33 darkspots: 14 of which span parts of the Asia-Tropical region, eight in South America, eight in the Asia-Temperate region, two in Africa and one in North America. Overall, Colombia, New Guinea, and China South-Central had the greatest combined descriptive and geographical data shortfalls globally, in decreasing order.

By continent, New Caledonia had the greatest combined shortfall for the Pacific; Western Australia for Australasia; New Guinea for Asia-Tropical; China South-Central for Asia-Temperate; Madagascar for Africa; Albania for Europe; Mexico Southwest for North America; and Colombia for South America. When considering different environmental and socio-economic scenarios, six botanical countries consistently came out as priority areas for focused collecting activities: Colombia, Myanmar, New Guinea, Peru, Philippines and Turkey.

New Guinea was the only darkspot not to overlap with a global biodiversity hotspot, but its exceptional biodiversity, which will increase further as the knowledge gaps are filled, may face rising threats from species overexploitation and the conversion of land to agriculture.

Ian Ondo, Senior Data Analyst at RBG Kew, Program Officer at the United Nations Environmental Programme World Conservation Monitoring Centre (UNEP-WCMC), and lead author of the paper says, “Recognizing and accounting for plant diversity darkspots is essential to achieving comprehensive conservation priorities. It ensures that critical areas are inclusive of underrepresented biodiversity and receive attention and protection, ultimately enhancing global efforts to maintain biodiversity.”

“Many species that are not yet described by science, are in fact well known by Indigenous and local communities” explains Dr. Kiran Dhanjal-Adams, Future Leader Fellow at RBG Kew.

“With the Kunming-Montreal Global Biodiversity Framework highlighting the importance of indigenous and local communities in conservation, we have the basis for strengthening partnerships and increasing our capacity to describe species in a way that can help raise conservation interest and funds to support local communities, as well as shedding light on new species.”

Five commitments to close biodiversity knowledge gaps

Arising from discussions at Kew’s 2023 State of the World’s Plants & Fungi Symposium, RBG Kew and Missouri Botanical Garden led the drafting of the “2030 Declaration on Scientific Plant and Fungal Collecting” which contains five commitments towards filling key knowledge gaps in plant and fungal diversity, through collaborative and targeted collecting and research activities. The five commitments include: 1) use evidence-based collection strategies, 2) strengthen local capacity, 3) collaborate across taxa and disciplines, 4) collect for the future, and 5) share the benefits.

The collection of biological specimens from the wild is a fundamental part of the natural sciences, and researchers all around the world continue to collect and preserve samples of different organisms to advance research and support conservation actions.

These scientific collections—which require special permits and must follow national and international legislations on access and benefit sharing—can help to identify new species, tell us how climate change is affecting the natural world, or yield new medicines and fuels. There is much unknown, particularly for fungi, with over 90% of the estimated 2.5 million species remaining as-yet-undescribed.

The Declaration, co-authored by contributors from 22 countries and already signed by over 800 individuals and organizations from 85 countries, remains open for signatories until the end of this year. It is a first step towards increased global and regional coordination of scientific collecting efforts. RBG Kew hopes that conversations will continue during and in between botanical and mycological congresses at international, regional, national and local levels to foster more decentralized and complementary efforts.

Professor Alexandre Antonelli, Director of Science at Royal Botanic Gardens, Kew, and senior author of the paper says, “As we head to CBD COP16 in Colombia, governments will be under scrutiny to determine what progress has been achieved towards the Kunming-Montreal Global Biodiversity Framework 2030 targets, what challenges remain and how they can be overcome.

“Comprehensive data on plants and fungi are an integral part of the solution, and filling knowledge gaps in darkspots represents a cost-effective way forward. If countries come together and implement these declaration commitments, we will be better able to address the grand challenges of biodiversity loss, climate change and food security.”