Evolutionary-Economic Principles as Regulators of Soil Enzyme Production and Ecosystem Function

Extracellular enzymes are ubiquitous in soil environments. Produced by microorganisms and plant roots, these enzymes serve a dual function of degrading complex organic material into simpler forms and acquiring resources for the enzyme producer (Burns 1982; Sinsabaugh 1994). Without extracellular enzymes, microbes and plants would be unable to obtain resources from complex compounds, and cycles of carbon (C) and nutrients would grind to a halt. Researchers have been measuring and interpreting soil enzyme activities for over 100 years (Eriksson et al. 1974; Skujins 1976). Although extracellular enzymes are clearly important for soil function, the factors regulating enzyme production remain unclear. For example, the mechanisms that determine the composition, timing, spatial location, and quantity of extracellular enzyme production in soil are still poorly known (Wallenstein and Weintraub 2008). Better knowledge of these mechanisms would improve our ability to predict how soil biogeochemical cycles will respond to changes in the environment. Increasing global temperatures, land use change, nutrient deposition, and invasive species are prominent examples of global changes that currently affect soil ecosystems (Trumbore 1997; Swift et al. 1998; Ehrenfeld 2003).