compute_tracer {ecostate} | R Documentation |
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}