calc_interaction_intensity: Calculates the interaction intensity of a food web using the... In lsaravia/EcoNetwork: Ecological network analyses including multiplex networks

 calc_interaction_intensity R Documentation

Calculates the interaction intensity of a food web using the metabolic theory and the interaction dimensionality

Description

The function uses the body mass in Kg of predator/consumer and prey/resources and the dimensionality of the interaction as source data, then the interacion intensity is estimated with all the coeficients from 1 as `alfa*xR*mR/mC`, where `alpha` is the search rate `xR` the resource density, `mR` the resource body mass and `mC` the consumer body mass. If available the resource density is not known (parameter `res_den`) you must set the column to a less than 0 value; and it will be estimated according to the equation S18 and supplementary figures 2i & j (individuals/m2 - m3)

Usage

```calc_interaction_intensity(da, res_mm, res_den, con_mm, int_dim, nsims = 1)
```

Arguments

 `da` data.frame with the interactions body mass and type of interaction dimensionality `res_mm` name of the column with the resource body mass mean `res_den` name of the column with the resource density in Individuals/m^2 in 2D or m^3 in 3D. If lower than 0 it uses the previously mentioned estimation. `con_mm` name of the column with the consumer body mass mean `int_dim` name of the column with the interaction dimensionality

Details

For detritus or sediment the resource mass mean is not known (parameter `res_mm`) it must be set as negative; and the resource body mass (kg) will be calculated using the equation S9 and supplementary figures 2c & d of the paper.

If the parameter 'nsims > 1 ' the function will estimate the variability on each interaction strength. It takes random values from a normal distribution with mean and standard deviation given by the Pawar's regressions for the slopes of allometric exponents.

Value

A data.frame based on `da` with the following fields added

• mR: if `res_mm<0` is the resource mass calculated with the equations from ref 1, if `res_mm>0` duplicates the value of `res_mm`

• xR: calculated resource density or the same value as in the input data.frame.

• alfa: calculated search rate.

• qRC: calculated trophic interaction strength as `alfa*xR*mR/mC` where `mC` is the consumer body mass.

References

1. Pawar, S., Dell, A. I., & Van M. Savage. (2012). Dimensionality of consumer search space drives trophic interaction strengths. Nature, 486, 485. https://doi.org/10.1038/nature11131

Examples

```## Not run:
g <- netData[[1]]

require(dplyr)

# build the data.frame with random values

set.seed(7815)
da <- as_long_data_frame(g) %>% dplyr::select(from:to) %>% mutate(con_mm=rlnorm(n(),5,2),res_mm=con_mm - 30 ,int_dim=sample(c("2D","3D"),n(),replace=TRUE), res_den = -999)

calc_interaction_intensity(da,res_mm,res_den,con_mm,int_dim, nsims=1)

## End(Not run)
```

lsaravia/EcoNetwork documentation built on Feb. 27, 2023, 6:43 a.m.