The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) Assessment Report on the Sustainable Use of Wild Species (herein referred to as IPBES Sustainable Use Assessment) (IPBES, 2022c) represents one of the most comprehensive global efforts to document and quantify the rich socio-cultural heritage of human knowledge on species use. The assessment provides a best estimate of around 50,000 known species used by humans, of which there are 31,100 plants, 16,700 animals, and 1,500 fungi species. The Assessment acknowledges the conservativeness of these estimates. However, this caveat is not clearly mentioned in the Summary for Policymakers report. This may risk leading policymakers, scientists, and other report users to interpret these numbers as definitive rather than conservative, potentially undermining the ongoing efforts still needed to comprehensively document global species use.

In this Perspective paper, we examine the IPBES Sustainable Use Assessment in more detail, focusing on the methodology underlying the estimations of plant species use and identifying the associated knowledge gap. We contemplate shortfalls in current estimations, and showcase using case studies of different countries the potential of Indigenous, Local, and Traditional Ecological Knowledge (ILK & TEK) embedded within native language resources for filling such a knowledge gap. Finally, we discuss the challenges, solutions, risks and urgency to close the knowledge gap, and call for scientists, policymakers, Indigenous People and Local Communities and international knowledge hubs to collaborate to streamline native language resources at all levels of decision-making.

The IPBES Sustainable Use Assessment reviewed that humans collectively use around 31,100 plant species (IPBES, 2022b). Methodologically, the total estimates of utilized plants are aggregated across use categories such as food, medicine, raw material and feedstock, agricultural feed, timber and other social uses. Statistics on utilized plant species were extracted and compared across major global databases, such as the IUCN Red List of Threatened Species. The Kew Botanical Garden's State of the World Plants reports, and World Flora Online (IPBES, 2022c).

The total estimate for utilized plant species was taken from the 2016 Kew's State of the World's Plants Report, which recorded 31,128 utilized plant species (IPBES, 2022b; Kew Royal Botanic Gardens, 2016). This number was based on a list of ten large regional and purpose-specific datasets (Diazgranados et al., 2018). In 2020, three additional large datasets were added to the list, substantially increased the total record of useful plants to 40,283 species (Diazgranados et al., 2020). The increase of nearly 10,000 records of useful plant species—an additional one-quarter of the initial estimate—suggests that even the most comprehensive lists of utilized species knowledge are largely incomplete.

Large databases compiled from sources with coarse regional representativeness tend to result in regional knowledge gaps and underestimations of utilized plant species, especially in areas where data is less available. As a result, global resources such as Kew's databases are useful to provide a conservative overview of the global state of species use, with the nuances that such knowledge is likely underestimated in most regions. The comprehensiveness of global databases ultimately relies on the geographic and taxonomic representativeness of the source datasets. In some cases, these source datasets may have been compiled using smaller, area-specific lists, presenting scattered snapshots of species use knowledge in a specific region. Current progress indicates that much more knowledge is needed to account for the severe under-representations of species knowledge in the countries not covered by the large datasets. For instance, the Medicinal Plant Name Services (MPNS), the largest database of medicinal plants underlying Kew's global knowledge of utilized plant species, only considers two references of Vietnamese medicinal plants, each of which listed about 200 species (MPNS Resources V14, 2024), in contrast to at least 3,000 documented medicinal plant species used in the country (Vo, 2021).

The 2023 Kew's State of the World Plant and Fungi Report acknowledges this systematic and regional knowledge gap as plant “darkspots”—areas predicted to contain the most species unknown to science (Antonelli et al., 2023). The report identifies 32 plant darkspots worldwide, most of which are countries or regions located within biodiversity hotspots and areas with rich cultural heritage (Figure 1). The darkspots are home to plants unknown to science that potentially make up an estimated 15% of the total flora diversity (Ondo et al., 2024). The plant darkspots reflect both a lack of data collection effort and a lack of scientific knowledge of the rich biodiversity as well as the traditional knowledge contained within these locations.

Often available only in native language resources, ILK & TEK hold vast, untapped potential for Indigenous People and Local Communities (IPLCs) protagonism in uncovering more knowledge of species use. Languages are repositories of important biodiversity knowledge; for instance, medicinal plant knowledge is often linguistically unique (Cámara-Leret and Bascompte, 2021). At the same time, biodiversity (including plant diversity) and human languages are interconnected, and both are facing critical threats (Anderson et al., 2022). Estimates suggest that half of the languages currently spoken in the world are disappearing by the end of the century (Harrison, 2008). Language loss ultimately results in the loss of knowledge and values of nature that reciprocally sustain biodiversity (Anderson et al., 2022). By valuing and preserving native languages, we protect the rich tapestry of the world's cultural heritage and ensure that future generations inherit a world that is linguistically, culturally and biologically diverse. The IPBES Methodological Assessment of the Diverse Values and Valuation of Nature (IPBES, 2022a) recognizes a policy and knowledge gap in articulating and coordinating efforts into language revitalization, and biodiversity studies and inventories. Thus, the well-documentation of ILK & TEK can simultaneously enhance current scientific knowledge of utilized species, safeguard traditional knowledge, and support the revitalization of human languages.

Here, we present the approaches to managing ILK & TEK in the context of utilized plant species of five countries—India, Vietnam, Brazil, Mexico, and Türkiye (Figure 1). These countries are among those with the highest knowledge gap in utilized plant species in Asia, Latin America, and Europe (Ondo et al., 2024), and where new plant species are most rapidly scientifically discovered (Cheek et al., 2020). Additionally, they represent diverse biogeographic zones, linguistic contexts, and levels of ethnobotanical documentation.

We adopted a collaborative, expert-informed comparative case study approach (Yin, 2017). Through the IPBES fellow network—an international network of outstanding, interdisciplinary early-career researchers working on biodiversity issues—we assembled a team of researchers with context-specific expertise of the five countries. Each author conducted a country-specific scoping review of native language resources and scientific literature, including national and regional ethnobotanical databases, peer-reviewed studies, and digitized traditional manuscripts, drawing on individual and external expert knowledge where necessary. For example, the author responsible for the India case was directly involved in the management of plant use databases; in other cases, the authors may need to consult leading experts in the country. The method was intentionally designed to be flexible to accommodate unique differences in documented plant-use knowledge and each country's progress in standardizing native-language data. Since there is no publicly accessible statistics on the number of utilized plant species by country and use, except for food, we cannot provide a structured comparison of the potential of native language resources to the global databases for most case studies. Nevertheless, this approach enabled us to highlight qualitatively the potential contributions of ILK & TEK embedded in native resources, and to identify the challenges to their standardization into global knowledge of utilized plant species (Figure 1 and Table 1).

Our case studies confirm the limitations in existing global databases of utilized plant species, with a vast knowledge gap in utilized plant species in plant biodiversity darkspots that warrants serious consideration. For instance, Türkiye's case study identifies more than 1,000 edible plant species, whereas Kew's global database includes only 300–500 species (Kew Royal Botanic Gardens, 2020). These case studies point to the undeniable potential of ILK & TEK in elevating scientific knowledge of plants useful to humans, which is often already richly embedded within native oral and written resources. It is crucial to improve access and usability of the rich ILK & TEK at the global level, by enhancing efforts to mainstream, document, and standardize this knowledge. Efforts in countries like India, Türkiye, and Mexico exemplify progress in harnessing, digitalizing, and generating databases of ILK & TEK, offering models for other countries where such work is still nascent, such as Vietnam and Brazil.

Nevertheless, two important challenges persist. First, ILK & TEK often lack a formal recognition in scientific endeavors and policy decision-makings. Increasing awareness through communication and mainstreaming of ILK & TEK-related knowledge gaps, including those identified in global initiatives such as IPBES (IPBES, 2022a,c), can help stakeholders recognize the value of ILK & TEK. Second, linguistic barriers remain a critical constraint. In some cases, the use of rare or minority languages impedes integration into standardized databases. In others, established databases are only available in the dominant national languages (e.g., Spanish, Turkish, and Vietnamese), limiting broader accessibility. To overcome this challenge, it is imperative that ILK & TEK data collection and standardization processes involve multi-stakeholder collaborations, including traditional ecological knowledge holders, local researchers, policymakers and international initiatives, with the explicit aim to empower IPLCs by helping them steward their biocultural heritage and not the opposite (Arias-Arévalo et al., 2023). Crucially, such efforts must be grounded in the principles of Free, Prior, and Informed Consent to ensure that the rights, agency, and benefits of knowledge holders are respected. In doing so, ILK & TEK can be made more accessible and actionable across spatial scales and governance contexts, while safeguarding ethical standards and community sovereignty.

Immediate actions and strategies to revitalize ILK & TEK are crucial, given the rate at which languages and biodiversity, including ethnobotanical knowledge, are being lost (Copete et al., 2023). For example, researchers in the Ixcatec indigenous region in Oaxaca, Mexico document more than 500 useful plant species and create a game in the almost extinct local Ixcatec language, a photo contest and other activities, aiming at motivating young people in the community to rescue, value and transmit this knowledge to the wider community (Aguilar et al., 2016). Art expressions, traditional celebration enhancement and oral documentation of stories are examples of creative approaches to incentivize and foster IPLCs protagonism and stewardship for nature conservation.

Overlooking the systemic knowledge gap on utilized plant species can potentially risks introducing biases into scientific analyses and policy implications. For example, Pironon et al. (2024) in a comprehensive global study, mapped plant use by integrating 12 databases and over 11 million geo-referenced records for 35,687 species. They found no higher concentrations of documented plant use in Indigenous territories compared to adjacent non-Indigenous areas, attributing this to the historical displacement of Indigenous People from their original land. While plausible, an alternative explanation lies in uneven data availability—particularly in megadiverse, culturally rich regions—potentially skewing results. Although the authors noted lower data occurrences in these areas, they did not fully consider how these data gaps may critically undermine meaningful comparisons of utilized plant species richness between Indigenous and non-Indigenous regions. Furthermore, such systematic knowledge gap can also lead to far-reaching and serious consequences, including underestimating the values of nature contributions to humans; misguiding conservation priorities and inequitable policy decisions away from diverse and culturally significant regions that are not well-documented; unaware of the erosion of biocultural heritage that are parts of IPLCs identities, which weaken their rights and claims to land and knowledge systems; and a loss of opportunity to leverage the sustainable use of a diverse range of species in support of the multi-dimensional and interconnected global sustainable goals, including poverty, sustainable food system, and climate change.

To conclude, filling in the global knowledge gap of utilized plant species requires substantial efforts to illuminate plant darkspots (Ondo et al., 2024). This is challenging, as these darkspots are often countries in the Global South with rich biological and cultural diversity but severely lack resources to implement sufficient monitoring and data collection efforts. Filling this knowledge gap therefore partially requires enhancing biodiversity funding for the region, a goal aligned with the Kunming-Montreal Global Biodiversity Framework (CBD, 2022). At the same time, the rich knowledge embedded within ILK & TEK systems offers a valuable opportunity to leverage existing knowledge of utilized species, by making good use of available oral and written native language resources while strictly adhering to the principles of fair and equitable benefit sharing (CBD, 2022). These knowledge systems need to be standardized and preserved at the national level and streamlined into global data facilities, such that ILK & TEK can be used as a common pool of knowledge in favor of biodiversity, nature's contributions to society and sustainable development. Countries must recognize that ILK & TEK of utilized species is not only a crystallization of past knowledge, but also a sustainable investment opportunity for the future, including the potential to significantly expand the nation's inventory of nature's contributions to people, such as the economic development of new bioeconomy, technology, and innovation. For example, utilized plant knowledge has contributed to a 7-time increase in the export values of non-timber forest products of Vietnam in just a decade (NBCA, 2022). Existing global efforts to document and digitize knowledge on utilized species, such as the IPBES Sustainable Use Assessment and the rich body of literature it was built upon, serve as a strong foundation—one that countries can further strengthen by supporting the systematic integration and standardization of ILK & TEK deeply embedded in native language resources.