TABLE 1.
Overview over the single steps involved in calculating energy flux with the adapted food‐web energetics approach
| Step | Question | Options (how to get it) | Status | Minimum requirements | Example references |
|---|---|---|---|---|---|
| 1. Community assessment | Who is there and how much? | Sample, assemble based on literature information. | Essential | Overall biomass and relative abundance (alternatively, only identity of trophic nodes and metabolic losses measured for each one). Taxonomic/functional resolution depends on the topological resolution (below). | Sousa et al. (2019), Decaëns (2021) |
| 2. Energy loss – metabolic demand | What energy do they need to sustain themselves? | Measure (rarely possible) or estimate based on literature data or regressions. | Essential | Metabolic demand of the present organisms. Literature regressions based on organism type, body mass and temperature well available. | Brown et al. (2004), Hillebrand et al. (2009), Ehnes et al. (2011) |
| 3. Body mass | How heavy are they? | Measure or infer from literature. | Useful for metabolic rates and passive preferences (relative resource availability) | None. Helpful for several steps (see Table 2). | Sohlström et al. (2018), Ruiz‐Lupión et al. (2019), Ärje et al. (2020) |
| 4. Topology | Who eats whom? | Assess or assemble based on available information (feeding type, functional traits). | Essential | A simple food chain with at least two nodes. | Gravel et al. (2013), Eitzinger et al. (2019), Hines et al. (2019), Sousa et al. (2019) |
| 5. Preferences | Relative consumption of resources? | Assess or infer based on relative resource availability, or functional traits. | Essential | Either assume all resources are consumed equally, or assume passive (density dependent) preferences, or provide additional information on active consumer preferences. | Gauzens et al. (2021), Pollierer and Scheu (2021) |
| 6. Assimilation efficiency | Fraction of consumed energy available to consumer? | Assess or take from literature. | Essential | Resource type required (animal, plant, detritus, etc.). Available from the literature. | See Table 3 |
For each step, the table outlines what the step is necessary for (Question), what are the options for achieving the required input information (Options), whether this step/information is absolutely necessary (status), what are the minimum requirements, and it provides example references helping with the decisions or pointing towards methods and literature resources to infer the input information. This table was inspired by figures in Jochum and Eisenhauer (2021) and Barnes et al. (2018).