The study of the determinants of biomass pyramids (i.e., the patterns of biomass of organisms at different trophic levels of an ecosystem) within and across ecosystems is an enduring endeavor in the ecological sciences (Gripenberg and Roslin, 2007; Gruner et al., 2008). This classic ecological problem still fascinates ecologists worldwide and the lively debate on this question is an attestation of the complexity of ecological systems. The ecological literature reveals two main perspectives for predicting biomass pyramids; one perspective emphasizes the role of resources such as inorganic nitrogen (N) and phosphorus (P) or primary producers in determining the biomass of higher trophic levels, and the other perspective emphasizes the role of consumers such as herbivores and predators in determining the biomass of lower trophic levels (Oksanen and Oksanen, 2000; Gruner et al., 2008).
The resource-based hypothesis states that organisms are resource-limited, and therefore resources determine the shape of biomass pyramids (Elton, 1927; Lindeman, 1942; White, 1978; McQueen et al., 1986). Consistent with Elton's (1927) perspective, Lindeman (1942) and others (e.g., White, 1978; McQueen et al., 1986) argued that inorganic nutrients and solar radiation limit plant growth and subsequently the potential transfer of energy and nutrients from lower trophic levels to higher trophic levels in ecosystems. This bottom-up perspective has been expanded to consider the role of plant defense in limiting herbivory (Strong, 1992; Polis and Strong, 1996; also, see Chapter 8 and Chapter 13).
In contrast, the consumer-based hypothesis (i.e., Hairston Smith Slobodkin (HSS) Hypothesis) states that organisms are consumer-regulated, and therefore higher-level consumers determine biomass pyramids (Hairston et al., 1960). Oksanen et al. (1981) further developed the consumer-regulated framework by developing the exploitation ecosystem hypothesis (EEH), which suggests that top-down control of ecosystems will vary along environmental gradients. Top-down perspectives gained additional support through Carpenter et al.'s (1985) empirical evidence of trophic cascades, whereby top predators have indirect positive effects on non-adjacent trophic levels.