Introduction

In this module, we examine the complex issue of plant reproduction in tropical forests. It is complex because there is a huge variety of mechanisms. For example, many plant species have developed a relationship with a particular species of pollinator, such that only species is capable of pollinating the plant. This is particularly true of the >900 species of figs (Moraceae), many of which are pollinated by their own unique species of fig-wasp (Agaonidae; Chalcidoidea).

Pollination is only part of the reproduction process, which also includes seed set, dispersal, germination and establishment. Wind pollination and wind dispersal of seeds are relatively rare, although some important families, such as the Dipterocarpaceae, have winged seeds that can disperse a short distance from the parent tree. Many tropical trees encase their seeds in a fruit which attracts many different species, including birds and mammals. Some of these are seed predators, gaining nutrition from the seed or destroying the seed in the process of eating the fruit. Others swallow the fruit and seed, and then defecate the seed some distance from the parent tree.

Once on the ground, many seeds are predated. However, a few manage to germinate and they ten encounter a different set of problems as the seedling grows in the forest environment. Not all plants follow this patter, with epiphytes being a notable example. However, their seeds still need a suitable substrate to germinate, and must compete with other epiphytes as they grow.

This module is divided into three topics, all dealing with plant reproduction. The first topic addresses flowering and genetic neighborhoods. The second topic looks at seed set and seed dormancy. The third and final topic deals with vegetative reproduction and the growth and survival of seedlings.