Fifteen forms of biodiversity trend in the Anthropocene

• There are extensive human-caused impacts on the biosphere and we consider their effect on biodiversity.
• Different human impacts have opposite results, and assessments to date have found contradictory results.
• We suggest that this is due to the need to unpack biodiversity trends by scale and type of biodiversity.
• We identify 15 distinct biodiversity trends and summarize what is and is not known about them to date.
• We also show that community trends contain high variability in outcome for individual species.

Humans are transforming the biosphere in unprecedented ways, raising the important question of how these impacts are changing biodiversity. Here we argue that our understanding of biodiversity trends in the Anthropocene, and our ability to protect the natural world, is impeded by a failure to consider different types of biodiversity measured at different spatial scales. We propose that ecologists should recognize and assess 15 distinct categories of biodiversity trend. We summarize what is known about each of these 15 categories, identify major gaps in our current knowledge, and recommend the next steps required for better understanding of trends in biodiversity.