Background

The absence of soil is the defining characteristic of the first stage of primary succession. Therefore the development of soil is a crucial aspect of primary succession. Because soil development is a product of both physical and biological processes, it links the abiotic and biotic variables that drive primary succession (Matthews, 1992). In Chapter 2 we discussed how various physical disturbances alter substrate stability, texture and fertility. In this chapter we will explore how these and other environmental variables govern soil formation and how soil properties such as water-holding capacity and nutrient content vary with succession. We will then examine how such processes as nitrogen fixation and decomposition influence organic matter accumulation. We conclude with a discussion of the spatial variability in soil development during primary succession. Throughout, we will contrast soil development among different types of primary succession and along physical gradients while looking for the level of specificity at which generalizations are possible. For readers that want a more thorough coverage of pedogenesis (soil formation), we refer them to other sources (Stevens & Walker, 1970; Swift et al., 1979; Birkeland, 1984; Killham, 1994; Paton et al., 1995; Wood, 1995; Coleman & Crossley, 1996; Brady & Weil, 1998). Our intent here is to establish the importance of soil development in the context of primary succession.

The types of soil and the rates at which they form are critical in determining the rates and trajectories of primary seres as well as their community and ecosystem properties.