Assessing the Functional Roles of Pollinators in Maintaining Plant Reproductive Success in the Afromontane Forests of the Mambilla Plateau

The functional roles of pollinators in supporting plant reproductive success in the Mambilla Plateau afromontane forests, one of Nigeria's most biodiverse plant communities, have not been empirically quantified, representing a significant knowledge gap with conservation implications. This study assessed pollinator diversity, visitation rates, pollen load analysis, and the consequences of pollinator exclusion on fruit and seed set in 10 common afromontane plant species in Mambilla Forest Reserve, Taraba State. For each plant species, pollinator visitation was recorded through systematic 30-minute observation sessions over 3 months, totalling 240 observation hours. Pollen loads were collected from the 10 most frequent visitor species and identified by palynological analysis. Pollination exclusion experiments using bagged inflorescences (open, insect-excluded, and hand cross-pollinated treatments) were conducted for each plant species. Forty-two pollinator species were recorded, comprising Hymenoptera (58%), Lepidoptera (24%), and Diptera (18%). Apis mellifera was the most frequent visitor overall but was not the most effective pollinator for 6 of 10 study species, where specialist native bees and moths showed higher pollen deposition rates. Fruit set in insect-excluded inflorescences was significantly lower than open-pollinated controls for all 10 species (mean reduction: 64%), confirming strong pollinator dependence. Two study plant species showed obligate dependence on specific moth species for successful seed set. The study provides the first empirical pollination ecology dataset for Mambilla Plateau flora and recommends pollinator habitat conservation as an integral component of the plateau's biodiversity management strategy.

Keywords: pollinators, reproductive success, afromontane, Mambilla Plateau, pollination ecology