The Status and Function of Ericoid Mycorrhizal Systems

Abstract

While ecologists have recognised the association between plants of the order Ericales and nutrient impoverished soils, it has been customary for them to emphasise above-ground features when considering the attributes which may confer success upon its constituent families and their close relatives. Specht (1979), for example, described the heathlands of the world as being defined by the presence of the families Ericaceae, Empetraceae, Epacridaceae, Diapensiaceae and Prionotocaeae, all of which were characterised by their possession of an evergreen sclerophyllous habit. Sclerophylly may, as pointed out by Specht and Rundel (1990), be a product of low nutrient availablity, since it is inevitable that as supplies of the major elements nitrogen (N) and phosphorus (P) decline, increasing proportions of fixed carbon are diverted from functional to the structural components cellulose, lignin and its phenolic precursors. However, the consequences of these above-ground modifications for the quality of the resources derived from them in the form of litter, and the relationship between the quality of substrates and the attributes required for mobilisation of their sequestered nitrogen and phosphorus have received relatively little attention.