Pollination service provision
Urbanisation had
an
overall positive effect, although not statistically significant, on
pollination service provision (d = 0.20; 95% CI = [-0.10,
0.51]; p = 0.19). The heterogeneity of the effect sizes was large and
statistically significant (Qt = 1543.29, df = 115, P
< 0.001). The pollinator groups sampled in the studies that
estimated pollination service provision differed significantly in their
contribution to plant reproductive success (Fig. 5, Table 2). Honey bees
significantly boosted plant reproductive success (Fig. 5). Flowering
plants with radial flowers had an increased reproductive success with
increasing urbanisation
(Table
2, Fig. 5). The origin of plant species (native vs. non-native) did not
explain the effects of urbanisation on pollination services (Table 2).
Urbanisation had a positive effect, although not statistically
significant, on the pollination of both native and non-native plants
(Fig. 5). The five reproductive success indexes significantly explain
the effects of urbanisation on pollination (Table 2), with positive
responses in studies that estimated seed set and visitation duration;
positive
but not statistically significant responses for studies that measured
fruit set and visitation rate and negative responses, although not
statistically significant, for studies that evaluated the number of
flower visits (Fig. 5). In addition, the richness and abundance of
pollinators were not significantly related to pollination service
provision (Fig. S6, Table S4)