Animal-mediated pollination
is a particularly important interaction to understand in the
context of climate change, given that animal pollinators are
required by most of the world’s flowering plant species (Ollerton In this study, we use long-term data sets to examine whether pollinator
biodiversity could buffer plant–pollinator interactions against
climate change, by increasing and stabilising phenological synchrony
between apple (Malus x domestica Borkh.), a valuable fruit crop and
its wild pollinators. We use a 46-year time-series data set on the
bloom phenology of commercial apple in New York State, USA,
along with an independent data set on the phenology of wild bee
species that commonly visit apple flowers, which was collected over
the same time period in a broader region centred on the focal apple
orchard. First, we used contemporary data to select the key apple
visitor species and to test if there is phenological complementarity
among them. Second, we compared the empirical rate of phenological
advance over time between apple and its diverse set of pollinators,
in aggregate, to determine whether phenological mismatch is
occurring at the community scale. Third, we asked whether different
pollinator species showed different rates of phenological change
with respect to apple bloom over time. Such differential responses
to climate change could buffer aggregate function in this case, by
stabilising phenological synchrony over time. Finally, we conducted
a simulation analysis to explore the effect of pollinator species richness
on plant–pollinator phenological synchrony. We predicted that
increasing biodiversity would: (1) increase the phenological synchrony
between apple and its pollinators due to complementarity in
phenology across pollinator species, and (2) stabilise changes in synchrony
between apple and its pollinators through time, due to the
differential rates of phenological change over time across pollinator
species. We found that the phenologies of apple and its complete
community of 26 key pollinator species have largely shifted at similar
rates over 46 years of climate warming, and that asynchrony is
likely prevented by the varied rates of phenological change observed
among different pollinator species. The capacity of biodiversity to
buffer the effects of environmental change for plant–pollinator
interactions is supported by the simulation analysis, which shows
that high levels of bee diversity increase and stabilise phenological
synchrony through time.