Pollen

: The missing data in floral resource projects

Abstract

Pollen is an important floral resource that has largely been ignored in favour of sampling nectar. Although nectar is an important source of carbohydrate, pollen provides the protein, sterols and lipids needed for many pollinator species. I quantified the floral longevity of 73 common UK farmland species and calculated their pollen production per 24 hours. Working on three farms in Somerset, the pollen productivity of each farm was measured between March and October. This was done by combining the floral longevity of each farmland plant species with published data on the farm’s phenology and a combination of new and unpublished data on the total amount of pollen produced by each plant species. The mean floral longevity of the 73 plant species was 2.58 days ±1.4 SD, with a range of 1-8.1 days. The amount of pollen and nectar produced by plants is broadly correlated, although there are some outliers that do not follow this trend. Many of the weedy species such as Taraxacum officinale produce high quantities of pollen and nectar throughout the year, providing much needed floral resources for pollinators. Species like Salix spp. produce high quantities of pollen and nectar, however they only produce this for a short period of time, so overall their contribution to floral resources over the flowering season is small. Farmland pollen availability shows a strongly seasonal pattern, peaking in April, followed by a gap in June, before peaking again in July and August, then drops off rapidly. Two habitat types provide the highest quantities of pollen and nectar at the unit area level; hedgerows and woodland, however at the farm-scale, pasture provides the largest amount of pollen and nectar. This research expands on the poorly understood aspects of pollen availability and floral longevity of UK farmland species and is the first comprehensive database on daily pollen production of species.

Date of Award	20 Jun 2023
Original language	English
Awarding Institution	University of Bristol
Supervisor	Jane Memmott (Supervisor)