Despite the accelerating pace of biodiversity data collection, just 42% of nations have expanded their scientific understanding of bird species distributions in the last decade, according to a study by Ruth Oliver and Walter Jetz at Yale University's Center for Biodiversity and Global Change, and colleagues, publishing August 10th in the open-access journal PLOS Biology.
The researchers developed two new metrics — the Species Status Information Index (SSII) and the Species Sampling Effectiveness Index (SSEI) — to assess the geographic coverage of biodiversity data and the effectiveness of scientists' sampling efforts. They then applied these metrics to over 450 million occurrence records for over 31,000 terrestrial vertebrate species added to the Global Biodiversity Information Facility (GBIF) between 1950 and 2021. "These maps can offer guidance on where best to direct efforts of citizen scientists and government agencies to monitor biodiversity status and trends," says Jetz.
The authors found that the rapid growth in the number of records over the past 20 years has not led to matching increases in data coverage for all species and geographic regions. For example, although birds have consistently had the highest number of new records, their global coverage (SSII) only exceeded those of other taxa in the 1980s, while sampling effectiveness (SSEI) has rapidly declined since the early 2000s. Regions with the most complete biodiversity records include the United States, Europe, South Africa, and Australia. However, the SSII in some of these regions has stagnated in the last decades, while data coverage has grown in Asia, South America, and Northern Africa.
The study is the first global assessment of trends in biodiversity data coverage and sampling effectiveness for terrestrial vertebrates and presents a framework for assessing where additional sampling is most critical. Although citizen science initiatives have played an invaluable role in increasing survey effort in recent decades, the authors say that citizens' efforts could be better targeted to address taxonomic and geographic knowledge gaps. "It's amazing how much we still don't know about the biodiversity around us," Oliver notes.
