land-cover change is an important ingredient in the larger problem of global environmental change. Land-use patterns, driven by a variety of social processes, result in land-cover changes that affect biodiversity, water and radiation budgets, trace-gas emissions, and other factors that, cumulatively, alter the global climate and biosphere. Most research on global environmental change has focused on the causes and impacts of global climate change and ozone depletion, with less attention to biodiversity trends. Land-use and land-cover studies have been entrained in this work only secondarily, for example, to calculate the rate of loss of tropical forests or to assess habitat fragmentation. Land-use and land-cover change is gaining recognition as a key driver of environmental change. The re-W. E. Riebsame is an associate professor in the Department of Geography, University of Colorado, Boulder, CO 80309. W. J. Parton is a professor in the Department of Rangeland and Ecosystem Science, K. A. Galvin is a research scientist at the Natural Resource Ecology Laboratory, I. C. Burke is an associate professor in the Department of Forest Sciences, L. Bohren is a research associate in the Department of Industrial Science, R. Young is a professor emeritus in the Department of Agricultural and Resource Economics, and E.

Most research on pollination has focussed on a subset of insect taxa within a narrow time window during daylight hours. As a consequence, we have a limited understanding of the diversity and activity of flower visitors during the night or belonging to taxa other than bees or syrphid flies. Here, we quantified the abundance and species richness of flower visitors in ruderal meadows over repeated 24‐h cycles (i.e. day and night), and identified abiotic factors influencing these patterns. From the plant perspective, we investigated the likelihood of being visited by an insect across a 24‐h cycle. Activity of flower‐visiting insects never dropped to zero over 24‐h. During the day, non‐syrphid Diptera and Hymenoptera were the most abundant, and species‐rich groups of flower visitors, Lepidoptera and Coleoptera during night. While two of the seven most frequently visited plant species were most likely to be visited during the day, five also had a high likelihood to be visited during the night. The abundance and species richness of flower visitors was positively related to temperature during both the day and the night, whereas there was only a positive relationship with brightness during the day. We conclude that non‐syrphid Diptera and nocturnal flower visitors are currently underappreciated. As the latter seem to respond differently to abiotic factors compared to diurnal species, they may potentially increase response diversity and resilience of plant‐pollinator communities. There is an urgent need to improve our understanding of their ecological role and potential decline due to global change.

Climate and land-use changes are main drivers of insect declines, but their combined effects have not yet been quantified over large spatiotemporal scales. We analysed changes in the distribution (mean occupancy of squares) of 390 insect species (butterflies, grasshoppers, dragonflies), using 1.45 million records from across bioclimatic gradients of Switzerland between 1980 and 2020. We found no overall decline, but strong increases and decreases in the distributions of different species. For species that showed strongest increases (25% quantile), the average proportion of occupied squares increased in 40 years by 0.128 (95% credible interval: 0.123–0.132), which equals an average increase in mean occupancy of 71.3% (95% CI: 67.4–75.1%) relative to their 40-year mean occupancy. For species that showed strongest declines (25% quantile), the average proportion decreased by 0.0660 (95% CI: 0.0613–0.0709), equalling an average decrease in mean occupancy of 58.3% (95% CI: 52.2–64.4%). Decreases were strongest for narrow-ranged, specialised, and cold-adapted species. Short-term distribution changes were associated to both climate changes and regional land-use changes. Moreover, interactive effects between climate and regional land-use changes confirm that the various drivers of global change can have even greater impacts on biodiversity in combination than alone. In contrast, 40-year distribution changes were not clearly related to regional land-use changes, potentially reflecting mixed changes in local land use after 1980. Climate warming however was strongly linked to 40-year changes, indicating its key role in driving insect trends of temperate regions in recent decades.

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