Calculates the Mixed Trophic Impacts of one species on another in the given ecosystem model following the algorithm of Ulanowicz and Puccia (1990). This considers both the direct and indirect trophic impacts.
Arguments
- x
a network object. This includes all weighte dflows into and out of each node. It must also include the "Living" vector that identifies the living (TRUE/FALSE) status of each node.
- zero.na
A logical parameter that specifies if NAs generated in the analysis should be reset to zero. The default is TRUE.
- balance.override
Mixed Trophic Impacts analysis builds on flow analysis and thus assumes the network model is at steady-state (inputs = outputs). Setting balance.override = TRUE allows the function to be run on unbalanced models, though this is unadvised.
Value
- G
output-oriented direct flow intensity matrix as in enaFlow, except oriented from row to column.
- FP
input-oriented direct flow intensity matrix similar to enaFlow; however, the calculation exclude respiration losses from the throughflow in the denominator to focus on NET production. Also, if the receiver compartment is not living, the flux intensity is set to zero.
- Q
direct net trophic impacts (G-t(FP)).
- M
Total (direct and indirect) tropic impacts of compartment i on j.
- Relations.Table
A table indicating the qualitiative pairwise relationships between the nodes as determined from the net (direct) and the mixed (integral) perspectives.
Details
This and other Ulanowicz school functions require that export and respiration components of output be separately quantified.
This analysis is similar in concept to the ENA Utility analysis.
Examples
data(troModels)
mti <- enaMTI(troModels[[6]])
attributes(mti)
#> $names
#> [1] "G" "FP" "Q" "M"
#> [5] "Relations.Table"
#>