Chapter 9 - The role of symbioses in seedling establishment and survival

Summary

Introduction

Seedling establishment is one of the key processes that determines the structure and diversity of natural communities. There are many factors that contribute to seedling establishment as explored in Pickett et al. (1987) and this volume. To date, little attention has been paid to the effects of mycorrhizal fungi on seedling establishment. However, there are several compelling reasons to consider these symbiotic fungi. First, the vast majority of all land plant species form symbiotic associations with mycorrhizal fungi and seedlings of most species become colonized by these soil fungi immediately after germination and root formation (Newman, 1988; Read & Birch, 1988; Wang & Qiu, 2006). Second, seedlings usually receive mineral nutrients from mycorrhizal fungi and often show enhanced growth when colonized. In addition, several studies report that mycorrhizal fungi can protect seedlings against drought and the harmful effects of pathogenic soil fungi and heavy metals. Third, many mycorrhizal fungi are not host specific and can colonize a wide range of plant species (Molina et al., 1992; Smith & Read, 1997; Opik et al., 2006). Due to this lack of specificity, seedlings can quickly become integrated into hyphal networks that are usually already present and maintained by the surrounding vegetation. Hence, in this way, seedlings have immediate access to a cheap nutrient absorption machine in which they do not need to invest resources (Newman, 1988).