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Sunbirds serve as major pollinators for various populations of Firmiana kwangsiensis, a tree endemic to South China

Huang, Zhi‐Huan, Luo, Wen‐Hua, Huang, Shi‐Xun, Huang, Shuang‐Quan
Journal of systematics and evolution 2018 v.56 no.3 pp. 243-249
Malvaceae, Nectarinia, birds, butterflies, calyx, ecology, endangered species, ex situ conservation, fruits, honey bees, leaves, limestone, nectar, pollen, pollinators, reproductive success, seed set, self-pollination, sugars, trees, wasps, China
Loss of local, effective pollinators may potentially limit plant reproductive success but the plant–pollinator interactions could be rescued if the plant does not reject other pollen vectors. Firmiana kwangsiensis H.H. Hsue (Malvaceae) is an endangered tree endemic to limestone areas in South China. Although its preservation status is listed as “critically endangered”, its reproductive ecology is little known. We compared floral visitors in three wild populations and one transplanted population. Such a comparison allows us to see whether the pollinator assemblage varies geographically and to examine the plasticity of plant–pollinator interactions, informing sustainable ex situ conservation. Our pollination experiments indicated that fruit/seed set in F. kwangsiensis largely depended on pollinator visits, and was greatly reduced under hand self‐pollination or exclusion of bird visits. Floral visitors included sunbirds, butterflies, and bees (honeybee and wasp) but their visitation frequency varied in the four populations. The sunbird Nectarinia jugularis was the major pollinator in the three wild populations, but was replaced by the other sunbird Aethopyga christinae in the ex situ population. This tree is showy, with orange‐red flowers blooming before the leaves emerge. The calyx tube accumulates a large volume of dilute nectar (sugar concentration was 9.5%) in the morning, rewarding sunbird pollinators. Our investigations indicated that sunbirds rather than insects served as a functional group of pollinators for this endangered species. Successful ex situ conservation of this type of plant needs to consider the availability of potential pollinators.