Reimagining the botanical biodiversity informatics landscape: Integrating physical vouchers and photographic vouchers maximises our knowledge of the world’s flora

Plant species occurrence records are the fundamental unit of botanical biodiversity informatics, informing ecology, taxonomy, and conservation. For centuries, these records have been represented by physical vouchers ─ plant specimens in herbaria ─ however, the recent emergence of photographic-based platforms such as iNaturalist has signalled a valuable new source of data. Although photographic voucher data are increasingly used in research and management globally, their universal acceptance is still unrealised, with concerns including identification accuracy and data biases. In Chapter 2 we organise an expert identification blitz to assess photographic voucher data quality, with fifty expert botanists finding an identification accuracy of 92.5% across 7,000 iNaturalist records of Western Australian plants. Chapter 3 presents a comprehensive data curation methodology for species list compilation for two of the oldest national parks in the world, finding that physical and photographic voucher integration facilitates the most comprehensive lists, and Chapter 4 uses these data to assess local extinctions and new arrivals in both regions. In Chapter 5, we build a Shiny application and R package that integrates physical and photographic vouchers to create place-based species lists using a novel data infrastructure approach. A comprehensive census of all described Australian plant species is conducted in Chapter 6, determining which species lack online published field photographs and explaining the spatial and taxonomic biases behind photographic documentation of plants, and Chapter 7 reports on the rapid progress made to address these data gaps. Chapter 8 reviews the new plant species that have been discovered via photographic vouchers on iNaturalist and Chapter 9 details the recent rediscovery of an extinct plant species via iNaturalist, with both providing recommendations for maximising discovery through collaborations between expert botanists and citizen scientists. This thesis presents compelling evidence for the complementary nature of physical and photographic vouchers, providing insights into the unprecedented opportunities for revolutionising our understanding of Earth’s flora that are offered by an integrative data approach. It presents a blueprint for maximising the quality and usefulness of photographic voucher data, and details the important paradigm shift that will shape the botanical biodiversity informatics landscape of the future.