Data from: Pollinator competition and the contingency of nectar depletion during an early spring resource pulse

Concerns about competition between pollinators are predicated on the
assumption of floral resource limitation. Floral resource limitation,
however, is a complex phenomenon involving the interplay of resource
production by plants, resource demand by pollinators, and exogenous
factors — like weather conditions — that constrain both plants and
pollinators. In this study, we examine nectar limitation during the mass
flowering of rosaceous fruit trees in early spring. Our study is set in
the same region as a previous study that found extremely severe nectar
limitation in summer grasslands. We use this seasonal contrast to evaluate
two alternative hypotheses concerning the seasonal dynamics of floral
resource limitation: either (H1) rates of resource production and
consumption are matched through seasonal time to maintain a consistent
degree of resource limitation or (H2) a mismatch of high floral resource
production and low pollinator activity in early spring creates a period of
relaxed resource limitation that intensifies later in the year. We found
generally much lower depletion in our study compared to the near 100%
depletion found in the summer study, but depletion rates varied markedly
through diel time and across sampling days, with afternoon depletion rates
sometimes exceeding 80%. In some cases, there were also pronounced
differences in depletion rate across simultaneously sampled floral
species, indicating different degrees of nectar exploitation. These
findings generally support the seasonal mismatch hypothesis (H2) but
underscore the complex contingency of nectar depletion. The challenge of
future work is to discern how the fluctuation of resource limitation
across diel, inter-diel, and seasonal time scales translates into
population-level fitness outcomes for pollinators.