compute_tracer: Calculate tracers, e.g., trophic level

In ecostate: State-Space Mass-Balance Model for Marine Ecosystems

Calculate tracers, e.g., trophic level

Description

Calculate how a tracer propagates through consumption.

Usage

compute_tracer(
  Q_ij,
  inverse_method = c("Penrose_moore", "Standard"),
  type_i,
  tracer_i = rep(1, nrow(Q_ij))
)

Arguments

Q_ij	Consumption of each prey i by predator j in units biomass.
inverse_method	whether to use pseudoinverse or standard inverse
type_i	character vector indicating whether a taxon is "hetero", "auto", or "detritus"
tracer_i	an indicator matrix specifying the traver value

Details

Trophic level y_i for each predator i is defined as:

\mathbf{y = l Q^* + 1}

where \mathbf{Q*} is the proportion consumption for each predator (column) of different prey (rows). We identify primary producers as any taxa with no consumption (a column of 0s), and assign them as the first trophic level.

More generically, a tracer might be used to track movement of biomass through consumption. For example, if we have a tracer x_i that is 1 for the base of the pelagic food chain, and 0 otherwise, then we can calculate the proportion of pelagic vs. nonpelagic biomass for each taxon:

\mathbf{y = l Q^* + x}

This then allows us to separate alternative components of the foodweb.

Value

The vector

\mathbf{y_i}

resulting from tracer

\mathbf{x_i}

ecostate documentation built on April 3, 2025, 5:25 p.m.