Seasonal dynamics of flower production at a community scale
First, seasonal dynamics of flower production in this area were analyzed
using pooled data of all plots in each term. The number of flowering
species and the species diversity of floral compositions by
Shannon-Wiener’s H’ (based on the total flower number of
individual species) were compared among observation periods (early,
middle, late) and between years (2017, 2018). In the analyses, we
conducted the comparisons of all species, bee-visited species, and
fly-visited species, separately. In order to quantify the seasonal
dynamics of flowering species, furthermore, dissimilarity of floral
compositions was compared among seasons (early, middle, late) and
between years (2017, 2018) by non-metric multi-dimensional scaling
(NMDS), based on the Chao’s similarity index. These analyses were
performed using the Vegan package ver. 2.6-4 (Oksanen et al., 2022) and
the MASS package in R. The effects of season and year on floral
compositions were assessed by permutational multivariate analysis of
variance (PERMANOVA) using the adonis function.
Second, seasonal trends in the flower production of individual species
were analyzed at plot base by a generalized linear mixed model (GLMM)
with a Poisson error distribution and a log-link function, using the
package glmmTMB in R. In this analysis, we specifically targeted for
bee-visited and fly-visited plant species because of the dominance of
these types (see Results). In the GLMM, flower number of each species in
each plot was a responding variable, season, year, and pollination type
(bee-visited or fly-visited) were fixed effect variables, and plot and
species were set as random effect variables. In order to compare the
seasonal patterns of flower production between bee-visited and
fly-visited species, an interaction term between season and pollination
type was included in the GLMM.