Nonlinear trends in abundance and diversity and complex responses to climate change in Arctic arthropods

Significance Arthropods are excellent indicators for studying global change in the rapidly changing climate of the Arctic. We used the most comprehensive standardized dataset on Arctic arthropods to quantify diversity and abundance variation over 24 y in an area that is warming rapidly. Overall arthropod abundance and diversity showed opposing nonlinear trends, with a sharp increase in overall abundance in recent years. However, trends varied substantially among taxa and habitats and several groups declined in abundance. We found strong evidence of conditions outside the growing season and density-dependent feedbacks affecting abundance. Our results emphasize the need for a more integrated approach to investigating arthropod responses to environmental stressors at finer taxonomic resolution and by incorporating time-lagged effects.