Long-term declines in insect abundance and biomass in a subalpine habitat

Recent reports of insect declines have caused concern among scientists and the public. Declines in insect abundance and biomass are ubiquitous across many climatic zones and have been largely attributed to anthropogenic land use intensification and climate change. However, there are few examples of long-term continuous data in relatively undisturbed environments, as opposed to agricultural landscapes. We sampled insects weekly from 1986 to 2020 in a protected subalpine meadow in Colorado, which is embedded in an undisturbed natural landscape. During the study period, summers became warmer, while winters became drier. Insect biomass declined by & SIM;47% and abundance declined by & SIM;61.5% over the last 35 years. Insect declines occurred in concert with changes in climate, as some climate factors were correlated with insect abundance and biomass. Specifically, insect abundance was lower during years with less summer precipitation and winter snowfall, and to a lesser degree with warmer temperatures. In subalpine systems, changes in precipitation and warmer temperatures are expected to continue under climate change; thus, continued insect declines might be expected even in relatively undisturbed habitats.