Pollen richness, diversity, and composition
Pollen richness and diversity were calculated separately for each bee
species in a day at a given period and site. Pollen richness represents
the number of plant families or morphotypes present in the daily
collection of pollen by individual colonies. Pollen diversity included
richness, but also accounted for the relative abundance of each pollen
type. To estimate diversity, we calculated Simpson Diversity Index (1-D)
which is constrained between 0 and 1, where 1 indicates greatest
diversity. Diversity was calculated using the ‘diversity’ function in
the ‘vegan’ package (Oksanen et al., 2019) in R (R. Core Team, 2013). We
used the linear mixed model (proc mixed in SAS v. 9.4) described in the
flower constancy section to determine the impact of bee species, time
period, site, and their two-way interactions on pollen richness and
pollen diversity.