Functions to calculate properties of fine/coarse roots within the soil, given root system parameters and soil layer definition.

## Usage

```
root_conicDistribution(Zcone, d)
root_ldrDistribution(Z50, Z95, d)
root_individualRootedGroundArea(VolInd, V, d, rfc)
root_specificRootSurfaceArea(specificRootLength, rootTissueDensity)
root_fineRootRadius(specificRootLength, rootTissueDensity)
root_fineRootHalfDistance(rootLengthDensity)
root_fineRootAreaIndex(
Ksoil,
krhizo,
lai,
specificRootLength,
rootTissueDensity,
rootLengthDensity
)
root_fineRootBiomass(
Ksoil,
krhizo,
lai,
N,
specificRootLength,
rootTissueDensity,
rootLengthDensity
)
root_rhizosphereMaximumConductance(
Ksoil,
fineRootBiomass,
lai,
N,
specificRootLength,
rootTissueDensity,
rootLengthDensity
)
root_fineRootSoilVolume(fineRootBiomass, specificRootLength, rootLengthDensity)
root_coarseRootSoilVolumeFromConductance(
Kmax_rootxylem,
VCroot_kmax,
Al2As,
v,
d,
rfc
)
root_coarseRootLengthsFromVolume(VolInd, v, d, rfc)
root_coarseRootLengths(v, d, depthWidthRatio = 1)
root_coarseRootSoilVolume(v, d, depthWidthRatio = 1)
root_horizontalProportions(poolProportions, VolInd, N, V, d, rfc)
```

## Arguments

- Zcone
A vector of depths (in mm) corresponding to the root cone tip.

- d
The width (in mm) corresponding to each soil layer.

- Z50
A vector of depths (in mm) corresponding to 50% of roots.

- Z95
A vector of depths (in mm) corresponding to 95% of roots.

- VolInd
Volume of soil (in m3) occupied by coarse roots per individual.

- V
Matrix of proportions of fine roots (cohorts x soil layers).

- rfc
Percentage of rock fragment content (volume basis) for each layer.

- specificRootLength
Specific fine root length (length of fine roots over weight).

- rootTissueDensity
Fine root tissue density (weight over volume at turgidity).

- rootLengthDensity
Fine root length density (length of fine roots over soil volume; cm/cm3)

- Ksoil
Soil saturated conductivity (mmol·m-1·s-1·MPa-1).

- krhizo
Rhizosphere maximum conductance per leaf area (mmol·m-2·s-1·MPa-1).

- lai
Leaf area index.

- N
Density of individuals per hectare.

- fineRootBiomass
Biomass of fine roots (g).

- Kmax_rootxylem
Sapwood-specific hydraulic conductivity of root xylem (in kg H2O·s-1·m-1·MPa-1).

- VCroot_kmax
Root xylem maximum conductance per leaf area (mmol·m-2·s-1·MPa-1).

- Al2As
Leaf area to sapwood area ratio (in m2·m-2).

- v
Vector of proportions of fine roots in each soil layer.

- depthWidthRatio
Ratio between radius of the soil layer with the largest radius and maximum rooting depth.

- poolProportions
Division of the stand area among plant cohorts (proportions).

## Details

`root_conicDistribution()`

assumes a (vertical) conic distribution of fine roots, whereas`root_ldrDistribution()`

distributes fine roots according to the linear dose response model of Schenck & Jackson (2002). Return a matrix of fine root proportions in each layer with as many rows as elements in`Z`

(or`Z50`

) and as many columns as soil layers.`root_coarseRootLengths()`

and`root_coarseRootLengthsFromVolume()`

estimate the length of coarse roots (mm) for each soil layer, including axial and radial lengths.`root_coarseRootSoilVolume`

estimates the soil volume (m3) occupied by coarse roots of an individual.`root_coarseRootSoilVolumeFromConductance`

estimates the soil volume (m3) occupied by coarse roots of an individual from root xylem conductance.`root_fineRootHalfDistance()`

calculates the half distance (cm) between neighbouring fine roots.`root_fineRootRadius()`

calculates the radius of fine roots (cm).`root_fineRootAreaIndex()`

estimates the fine root area index for a given soil conductivity and maximum rhizosphere conductance.`root_fineRootBiomass()`

estimates the biomass of fine roots (g dry/individual) for a given soil conductivity and maximum rhizosphere conductance.`root_rhizosphereMaximumConductance()`

is the inverse of the preceeding function, i.e. it estimates rhizosphere conductance from soil conductivity and fine root biomass.`root_fineRootSoilVolume()`

calculates the soil volume (m3) occupied with fine roots.`root_specificRootSurfaceArea()`

returns the specific fine root area (cm2/g).`root_individualRootedGroundArea()`

calculates the area (m2) covered by roots of an individual, for each soil layer.`root_horizontalProportions()`

calculates the (horizontal) proportion of roots of each cohort in the water pool corresponding to itself and that of other cohorts, for each soil layer. Returns a list (with as many elements as cohorts) with each element being a matrix.

## References

Schenk, H., Jackson, R., 2002. The global biogeography of roots. Ecol. Monogr. 72, 311–328.

Sperry, J. S., Y. Wang, B. T. Wolfe, D. S. Mackay, W. R. L. Anderegg, N. G. Mcdowell, and W. T. Pockman. 2016. Pragmatic hydraulic theory predicts stomatal responses to climatic water deficits. New Phytologist 212, 577–589.

## Examples

```
#Load example plot plant data
data(exampleforest)
#Default species parameterization
data(SpParamsMED)
ntree <- nrow(exampleforest$treeData)
#Initialize soil with default soil params
s <- defaultSoilParams(4)
#Calculate conic root system for trees
V1 <- root_conicDistribution(Z=rep(2000,ntree), s$widths)
print(V1)
#> [,1] [,2] [,3] [,4]
#> [1,] 0.385875 0.489125 0.125 0
#> [2,] 0.385875 0.489125 0.125 0
#Calculate LDR root system for trees (Schenck & Jackson 2002)
V2 <- root_ldrDistribution(Z50 = rep(200,ntree),
Z95 = rep(1000,ntree), s$widths)
print(V2)
#> [,1] [,2] [,3] [,4]
#> [1,] 0.6799879 0.2737911 0.03567632 0.01054468
#> [2,] 0.6799879 0.2737911 0.03567632 0.01054468
```