Seedling establishment represents the final hurdle in the process of regeneration. The start of the seedling phase may be defined by the completion of germination. In most cases, this is marked by the extrusion of the radicle (root), which anchors the seedling in the soil, followed by the plumule (shoot), which grows towards the light. If the seed is buried, the plumule has to push its way through the soil to the surface, a process that expends energy from the seed's reserves. In most field experiments, the appearance of the shoot at the soil surface (emergence) is the first sign that germination has taken place and is usually taken as the starting point in demographic studies. However, although it is seldom measured, mortality between germination and emergence is probably quite high, especially if the seeds are emerging from any depth (See Section 7.3). The emerging seedling faces a new set of hazards. Whereas a lack of light, water or nutrient has little or no effect on seed survival, these become major causes of death in seedlings. The predators and pathogens that menaced the seed are replaced by a different set at the seedling stage.

Early growth of seedlings

The term ‘seedling’ is used very loosely in the literature to cover young plants generally, and it is seldom defined strictly, even within the contexts of individual studies (Fenner, 1987; Kitajima & Fenner, 2000). The main problem is defining the end point: when does a seedling cease to be seedling?