Multidimensional biases, gaps and uncertainties in global plant occurrence information

Abstract

Plants are a hyperdiverse clade that plays a key role in maintaining ecological and evolutionary processes as well as human livelihoods. Glaring biases, gaps, and uncertainties in plant occurrence information remain a central problem in ecology and conservation, but these limitations have never been assessed globally. In this synthesis, we propose a conceptual framework for analyzing information biases, gaps and uncertainties along taxonomic, geographical, and temporal dimensions and apply it to all c. 370,000 species of land plants. To this end, we integrated 120 million point-occurrence records with independent databases on plant taxonomy, distributions, and conservation status. We find that different data limitations are prevalent in each dimension. Different information metrics are largely uncorrelated, and filtering out specific limitations would usually lead to extreme trade-offs for other information metrics. In light of these multidimensional data limitations, we critically discuss prospects for global plant ecological and biogeographical research, monitoring and conservation, and outline critical next steps towards more effective information usage and mobilization. We provide an empirical baseline for evaluating and improving global floristic knowledge and our conceptual framework can be applied to the study of other hyperdiverse clades.

Biomes as evolutionary arenas: Convergence and conservatism in the trans‐continental succulent biome

“…Possibilities might include high‐resolution global maps of crassulacean acid metabolism photosynthesis, annual versus perennial plant life history, plant growth forms including lianas and geoxyles, C 4 grasses, leaves with drip tips, sclerophyly, deciduousness and spinescence; there are many options. A complication with this approach is spatial biases in available species occurrence data (Meyer et al, 2016), but as we show, this problem can be circumvented by species distribution modelling, and occurrence data are rapidly expanding. A logical next step would be to map not just occurrences of functional traits, but also their abundance, based on global plot data (Oliveira‐Filho et al, 2013).…”

“…Second, stem succulents can occur on azonal landscape features such as inselbergs, termitaria (Moe et al, 2009), and rocky outcrops that are less fire‐prone than surrounding savannas (Cousins & Witkowski, 2012; Pérez‐García et al, 2012; Thomas, 1991). Third, while much digitized species occurrence data are available, some regions, such as India and north‐east Africa, are significantly under‐represented (Meyer et al, 2016). Finally, a handful of stem succulents ( c. 15 species) are known from more mesic areas outside of the succulent biome, perhaps reflecting the difficulties associated with how to define succulents in general, and stem succulents in particular (Eggli & Nyffeler, 2009; Ogburn & Edwards, 2010).…”

“…grid cell, two by varying the grid cell sizes to 0.1° and 0.5°, and one by counting unique species rather than genera. Since the global distribution of stem succulent richness on these maps was strongly influenced by the spatial sampling bias of the GBIF data (Meyer, Weigelt, & Kreft, 2016; which accounted for c. 75% of the data), we modelled the distribution of stem succulents, rather than using it directly in further analyses. The four richness maps were used to generate four independent models, but since the results are highly similar (Supporting Information Figures S1–S4), we discuss the methods and results in detail only for the 0.25° genus map.…”

Widespread sampling biases in herbaria revealed from large‐scale digitization

“…Meyer et al . () evaluated worldwide terrestrial plant occurrence data using 120 million records from the Global Biodiversity Information Facility (GBIF; Edwards et al ., ). Their analyses revealed large taxonomic gaps in global plant occurrence data (< 25% of species of land plants were sampled); extensive spatial gaps across regions that harbor high concentrations of plant diversity, especially in Asia, Central Africa, and Amazonia; and strong temporal discontinuities in occurrence records across decades, all of which can hamper inferences about the effects on plants of recent and future environmental change.…”

“…Although Meyer et al . 's () study represents the most comprehensive effort to assess biases in plant collections at a global scale to date, the vast majority of herbarium collections have not been digitized, and of those that have been, many are unavailable, in whole or in part, on GBIF. Thus, Meyer et al .…”