Biomass or growth? How to measure soil food webs to understand structure and function

Abstract

Food web links reflect the feeding rate of organisms and should thus capture the biomass production rate of the consumer. This information is rarely available for detrital food webs and has instead been inferred from biomass estimates to construct quantitative detrital food webs. Published method comparisons between biomass, growth and mineralisation show that microbial biomass is a poor predictor for process rates. This calls into question the current practise of parameterising soil detrital food webs. Emerging methods to estimate microbial growth rates and growth efficiencies are promising new avenues. If quantitative assessments of detrital food webs are revised by incorporating information that reflects the feeding rates of organisms, they could represent a powerful conceptual tool to investigate fundamental ecological theory, including how stability links to complexity and how function depends on the structure of whole food webs.