BackgroundHere we present preliminary results from the first three years of a long-term bee survey conducted at a 3,840-ha private conservation property in the northern Sapphire Mountains and Bitterroot River Valley, and a pilot study at an associated 80-ha property in the Swan River Valley, Missoula County, Montana, USA. The survey includes hand-net, bowl-trap, and blue-vane trap collections. The resulting checklist comprises 229 bee species and morphospecies within 5 families, 38 genera and 91 subgenera. Of the total species in the list, 34 of them represent first state records Montana. This survey expands the number of bee species recorded in Montana to 366. Included in these species is Megachile (Eutricharaea) apicalis Spinola, showing a range expansion for this introduced bee.New informationWe present new distributional records for 34 bee species, including Megachile (Eutricharaea) apicalis Spinola, an introduced bee that was discovered to be resident in North America in 1984 in Santa Barbara County, California. This species has since expanded its range in the across the west, but had not been previously recorded in Montana.

1. Recent declines in wild bee populations have led to increases in conservation actions and monitoring of bee communities. Pan traps are a commonly used sampling method for monitoring bee populations due to their efficiency and low cost.However, potential biases inherent in different sampling techniques may result in misleading characterizations of bee communities across space and time.2. In this paper, we examined how bee communities sampled using pan traps and aerial nets changed seasonally, and if they were affected by the availability of floral resources.3. We found strong seasonal changes in the abundance, but not the richness, of bees captured in pan traps. Notably, we captured the fewest bees during weeks in spring when most flowering plant species were in bloom, suggesting that floral resource availability influences pan trap captures. We also compared patterns of bee abundance in pan traps to those captured by aerial netting. Bee richness in pans and nets was positively correlated, but relative abundances in pan and net samples were dominated by different bee genera. Furthermore, most genera decreased in pans with increasing floral richness, but patterns were mixed for nets. When using presence/absence data, rather than abundance, community composition was more similar between netted and pan-trapped bee communities and changed less substantially across the floral richness gradient. 4. Overall, these differences led to sampling substantially different bee community compositions in pan traps versus nets, especially when using abundance-based methods to characterize the bee community. By examining multiple years of intensive seasonal sampling of plant and bee communities, we document potential pitfalls with methods commonly used to sample bee communities.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

The effects of altered nutrient supplies and herbivore density on species diversity vary with spatial scale, because coexistence mechanisms are scale dependent. This scale dependence may alter the shape of the species–area relationship (SAR), which can be described by changes in species richness (S) as a power function of the sample area (A): S = cAz, where c and z are constants. We analysed the effects of experimental manipulations of nutrient supply and herbivore density on species richness across a range of scales (0.01–75 m2) at 30 grasslands in 10 countries. We found that nutrient addition reduced the number of species that could co‐occur locally, indicated by the SAR intercepts (log c), but did not affect the SAR slopes (z). As a result, proportional species loss due to nutrient enrichment was largely unchanged across sampling scales, whereas total species loss increased over threefold across our range of sampling scales.

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