Fuchsia excorticata (J.R.Forst. et G.Forst.) L.f. (Kōtukutuku, Onagraceae) is a gynodioecious and bird pollinated tree, with females reliant on pollinators, while hermaphrodites can self‐pollinate. Females are important for population persistence as only they produce female offspring, and all their seed is the product of cross‐pollination so not subject to inbreeding depression. A lack of young female trees would suggest low frequencies of cross‐pollination, potentially due to the widespread decline of the species’ main pollinators, Prosthemadera novaeseelandiae (Tūī) and Anthornis melanura (Korimako). This study aimed to examine gender ratios and how trunk diameter varied with gender, alongside examining the frequency of pollen deposition on stigmas of female F. excorticata for two populations in the Dunedin region, Frasers Gully and Bethune's Gully. Females represented 34% of trees, with no significant difference between sites. This sex ratio was comparable to previous studies. There was no significant difference between genders in trunk diameter at either site. Pollen deposition levels were low on the whole, with less than half of sampled female flowers carrying pollen, although this was comparable to other studies. Conspecific pollen covered on average 6.99% of the stigmatic surface for female flowers and was significantly higher at Bethune's Gully compared to Frasers Gully. This suggests pollination effectiveness may differ between these two sites, leading to lower female recruitment in future at Frasers Gully. Specific planting of female trees and predator trapping to increase the pollination services provided by native birds would help ensure that female Fuchsia excorticata are able to persist in these populations.
Christensen et al. (Sun,) studied this question.