ABSTRACT
The role of fungi in primary production goes beyond making nutrients available to plants. There are intimate associations between the photosynthesizing components of the ecosystem and fungi, many of which are symbiotic. Such interactions between fungi and other organisms enhance nutrient availability for primary production and include mycorrhizae and associated rhizospheric microbial communities. In addition, some of these synergistic interactions between plants and fungi are involved in the prevention of plant disease and inhibiting herbivory. The latter is an important trait of endophytes, and has economic importance. In the form of lichens, the whole symbiotic association among fungi, algae, and bacteria is involved in primary production. Here, as we saw in the last chapter, the fungal partner acts as a supportive network for photosynthetically active algae and bacteria. In the mycorrhizal habit, fungi form a close association with plant roots and are physiologically and morphologically adapted to assist in the transport of nutrients into root systems. The diversity of mycorrhizal morphologies, the range of fungal taxa associated with mycorrhizal associations, and their range of degrees of dependency upon the association has led scientists to investigate their biology and ecology for more than 100 years. Indeed, Setälä’ et al. (1998) accumulated evidence to show that the diversity of organisms in soil has significant effects on primary production, especially when the number of trophic levels is low. They also suggest that the inclusion of ectomycorrhizae into the models of diversity and function of forested systems is of fundamental importance in understanding the mechanisms regulating primary production. As endophytes, fungi can be important in defending plants against herbivory, thus indirectly influencing primary productivity by negating or minimizing plant biomass loss through grazing. In addition to these direct effects of fungi on regulation of primary production, fungi are important in regulating the individual fitness of a plant or animals, and thus can influence the standing of individual species within a community and the community composition. These indirect effects will be explored in greater depth in Chap. 5. Table 3.1 shows the ecosystem services promoted by fungi that will be discussed in this chapter.
