Systematic review of biodiversity monitoring shows gradual rise of scaleable and automated methods and inherent spatial and taxonomic biases

Global policy efforts to reverse biodiversity declines are hindered by a lack of clarity over how to measure biodiversity. The debate over the best ways to define biodiversity and which metrics to use has taken place in the absence of a clear, holistic view of how biodiversity has been, and is currently, measured. This gap has hindered us moving from discussion to action on conserving biodiversity. Here we track trends in biodiversity measurement, using a dataset of > 2400 papers across the last 22 years, identifying trends, biases, and gaps in the assessment of nine major taxonomic groups (Invertebrate, fish, aquatic mammal, terrestrial mammal, bird, herpetofauna, fungi, microbe and plant). We found proportional declines in invertebrate, but increases in fish, surveys over time, and fewer assessments of biodiversity in Africa and Oceania. Although we do find an increase in the use of high-throughput, scaleable methods such as eDNA and camera-traps, their uptake is more modest than might be expected and shows signs of having already plateaued. We argue that emerging technologies can, but remain underutilised in addressing the systematic biases in our understanding of biodiversity, and so in helping guide and track our progress towards restoring and saving biodiversity.