Reproductive effort and success in Bombax ceiba L. in a tropical forest of Mizoram, Indo-Burma region of North-East India

Abstract

Ecologically, the interaction between plant and pollinators is mutually beneficial for the survival and adaptability. It leads to a higher level of fitness of both interacting partners. Birds play significant roles in plant reproduction and the fitness of ecosystem in tropical forest. This study was carried out with the objective to analyze legitimate floral visitors of Bombax ceiba Linn. in tropical forests of Indo-Burma region of India in relation to pollen production and mating system. The study was performed at two different locations, namely Bethlehem Vengthlang (23°43′N latitude and 92°43′E longitude) and Tanhril (43° 37’ N latitudes and 38° 39’ E longitudes). Both study sites are located 30 km apart from each other. Analysis revealed that the pollination in B. ceiba was mostly carried out by the birds, and the flowers were visited and foraged by thirteen (13) species of birds belonging to five families of the order of Passeriformes. One species of squirrel (Funambulus sp.) was also recorded visiting the flowers of B. ceiba. Study on mating-system evaluation revealed that the B ceiba is an outcrossing tree species, requiring the services of adequate pollinators for successful pollination and reproductive fitness. However, geitonogamy was partly functional. The index of self-incompatibility (ISI) value exposed that the species is mostly self-incompatible. All the species of birds were efficient pollinators for B. ceiba in the present study sites. The fruit and seed sets following natural pollination are fairly high compared with other bird-pollinated species. High pollen-production capacities per flower and per tree along with the high visitation of bird pollinators would have promoted the maximum reproductive success in B. ceiba. This also depicts that the species does not have the problem of pollen and resource limitations in Indo-Burma region of North-East India. B. ceiba tree is often used in urban forestry, and these results can be used for a comparative study of natural and human-altered ecosystems.