title: Counting complete? Finalising the plant inventory of a global biodiversity hotspot.
abstract: The Cape Floristic Region-the world's smallest and third richest botanical hotspot-has benefited from sustained levels of taxonomic effort and exploration for almost three centuries, but how close is this to resulting in a near-complete plant species inventory? We analyse a core component of this flora over a 250-year period for trends in taxonomic effort and species discovery linked to ecological and conservation attributes. We show that >40% of the current total of species was described within the first 100 years of exploration, followed by a continued steady rate of description. We propose that <1% of the flora is still to be described. We document a relatively constant cohort of taxonomists, working over 250 years at what we interpret to be their 'taxonomic maximum.' Rates of description of new species were independent of plant growth-form but narrow-range taxa have constituted a significantly greater proportion of species discoveries since 1950. This suggests that the fraction of undiscovered species predominantly comprises localised endemics that are thus of high conservation concern. Our analysis provides important real-world insights for other hotspots in the context of global strategic plans for biodiversity in informing considerations of the likely effort required in attaining set targets of comprehensive plant inventories. In a time of unprecedented biodiversity loss, we argue for a focused research agenda across disciplines to increase the rate of species descriptions in global biodiversity hotspots.
authors.affiliation: Department of Conservation Ecology and Entomology, Stellenbosch University, Stellenbosch, Western Cape, South Africa; Institute of Landscape and Plant Ecology, University of Hohenheim, Stuttgart, Germany; South African Environmental Observation Network Fynbos Node, Cape Town, Western Cape, South Africa.
authors.forename: Martina
authors.initials: M
authors.lastname: Treurnicht
authors.affiliation: Kirstenbosch Research Centre, South African National Biodiversity Institute, Cape Town, Western Cape, South Africa; Statistics in Ecology, Environment and Conservation, Department of Statistical Sciences, University of Cape Town, Cape Town, Western Cape, South Africa.
authors.forename: Jonathan F
authors.initials: JF
authors.lastname: Colville
authors.affiliation: Microsoft Research , Redmond , WA , United States of America.
authors.forename: Lucas N
authors.initials: LN
authors.lastname: Joppa
authors.affiliation: Centre for Biodiversity Conservation, Kirstenbosch Botanical Gardens, Table Mountain Fund (WWF-SA) , Cape Town , Western Cape , South Africa.
authors.forename: Onno
authors.initials: O
authors.lastname: Huyser
authors.affiliation: Compton Herbarium, South African National Biodiversity Institute, Cape Town, Western Cape, South Africa; Research Centre for Plant Growth and Development, University of KwaZulu-Natal, Pietermaritzburg, KwaZulu-Natal, South Africa.
authors.forename: John
authors.initials: J
authors.lastname: Manning
keywords: Bio-inventory; Botanical exploration; Cape Floristic Region; Plant conservation; Plant species description; Species accumulation; Species discovery; Species inventory; Taxonomic effort