Effects of climate change on phenologies and distributions of bumble bees and the plants they visit

Abstract

Surveys of bumble bees and the plants they visit, carried out in 1974 near the Rocky Mountain Biological Laboratory in Colorado, were repeated in 2007, thus permitting the testing of hypotheses arising from observed climate change over the intervening 33‐yr period. As expected, given an increase in average air temperature with climate warming and a declining temperature with increasing elevation, there have been significant shifts toward higher elevation for queens or workers or both, for most bumble bee species, for bumble bee queens when species are combined, and for two focal plant species, with no significant downward shifts. However, contrary to our hypotheses, we failed to observe significant altitudinal changes for some bumble bee species and most plant species, and observed changes in elevation were often less than the upward shift of 317 m required to maintain average temperature. As expected, community flowering phenology shifted toward earlier in the season throughout our study area, but bumble bee phenology generally did not change, resulting in decreased synchrony between bees and plants. However, we were unable to confirm the narrower expectation that phenologies of bumble bee workers and community flowering coincided in 1974 but not in 2007. As expected, because of reduced synchrony between bumble bees and community flowering, bumble bee abundance was reduced in 2007 compared with 1974. Hence, climate change in our study area has apparently resulted primarily in reduced abundance and upward shift in distribution for bumble bees and shift toward earlier seasonality for plant flowering. Quantitative disagreements between climate change expectations and our observations warrant further investigation.

Specialty fruit production in the Pacific Northwest: adaptation strategies for a changing climate

“…Although, some studies have shown temporal mismatch between some flowering plants and pollinators due to climate change (Burkle et al 2013;Robbirt et al 2014), there is a knowledge gap regarding such phenological mismatches between pollinator-dependent agricultural crops and bees, and their impact on pollination (Settele et al 2016). The potential for such phonological mismatch is greater for native bees such as bumble bees that hibernate during winter and whose emergence in spring is dependent on prevailing temperatures during the hibernation period (Pyke et al 2016).…”

Enhanced reproductive success revealed key strategy for persistence of devastated populations in Himalayan food‐deceptive orchid, Dactylorhiza hatagirea

“…; Pyke et al . ), which in turn will severely affect the fitness of this species. It is very likely that some genetic variation is present in the populations, which is buffering against further loss of variation, and this might help preserve the potential for future adaptive changes.…”

Micro-climatic controls and warming effects on flowering time in alpine snowbeds

“…Moeller and Geber 2005), increasing flowering synchrony among snowbed species may lead to a release of pollen limitation, which is regarded as being particularly strong in alpine plants (García-Camacho and Totland 2009). However, given the complex interplays between species flowering and interannual variation of environmental factors (Forrest et al 2010), and the possibility of warming-induced decrease in seasonal synchrony between plants and pollinators (Pyke et al 2016), it is not yet possible to predict these indirect effects of climatic changes on plants forming alpine snowbed communities.…”