Autotrophic respiration

Overview

Gross primary production ($\text{GPP}$) provides the carbon input to the system. A fraction of this carbon is released back to the atmosphere through autotrophic respiration $R_a$, which is represented as the sum of two terms: maintenance respiration $R_m$ (the carbon cost of maintaining existing plant tissues) and growth respiration $R_g$ (the carbon cost of producing new plant tissues).

\[\begin{equation} R_a = R_m + R_g \end{equation}\]

The remaining carbon is the net primary production ($\text{NPP}$), which is then allocated to the different plant components.

\[\begin{equation} \text{NPP} = \text{GPP} - R_a \end{equation}\]

abstract type AbstractAutotrophicRespiration{NF} <: Terrarium.AbstractProcess{NF}

subtypes(Terrarium.AbstractAutotrophicRespiration)

1-element Vector{Any}:
 PALADYNAutotrophicRespiration

PALADYN autotrophic respiration model

struct PALADYNAutotrophicRespiration{NF} <: Terrarium.AbstractAutotrophicRespiration{NF}

variables(PALADYNAutotrophicRespiration(Float32))

Variables
├─ Prognostic: 
├─ Auxiliary: 
├── autotrophic_respiration [kg m^-2 s^-1] on XY{Center, Center, Nothing} of the canopy domain
├── net_primary_production [kg m^-2 s^-1] on XY{Center, Center, Nothing} of the canopy domain
├─ Inputs: 
├── gross_primary_production [kg m^-2 s^-1] on XY{Center, Center, Nothing} of the canopy domain
├── leaf_respiration [kg m^-2 s^-1] on XY{Center, Center, Nothing} of the canopy domain
├── ground_temperature [°C] on XY{Center, Center, Terrarium.Coordinate{typeof(lastindex), Center}} of the ground domain
├─ Namespaces:

This implementation follows the autotrophic respiration scheme of PALADYN [21].

Maintenance respiration

Maintenance respiration is computed as the sum of leaf, stem, and root respiration

\[\begin{equation} R_m = R_{\text{leaf}} + R_{\text{stem}} + R_{\text{root}} \end{equation}\]

where $R_{\text{leaf}}$ is the dark respiration computed by the photosynthesis scheme, and $R_{\text{stem}}$ and $R_{\text{root}}$ are each computed from the corresponding tissue carbon pool and their assigned C:N ratios,

\[\begin{equation} R_{\text{stem}} = r_{10} \, f(T_{\text{air}}) \, \frac{C_{\text{stem}}}{a_{ws} \, \text{CN}_{\text{sapwood}}}, \qquad R_{\text{root}} = r_{10} \, f(T_{\text{soil}}) \, \phi \, \frac{C_{\text{root}}}{\text{CN}_{\text{root}}} \end{equation}\]

where $r_{10}$ (resp10) is the tissue respiration rate at 10 °C per unit nitrogen (kgC/kgN/day, converted to per second), $a_{ws}$ is the ratio of total to respiring stem carbon, $\phi$ is the phenology factor, and $f(T)$ is the temperature factor. All fluxes are in kgC/m²/s.

The temperature factor is a modified Arrhenius equation [28],

\[\begin{equation} f(T) = \exp\left(308.56 \left(\frac{1}{56.02} - \frac{1}{T + 46.02}\right)\right), \end{equation}\]

where $T$ is the air or soil temperature in °C; $f(10\,°\text{C}) = 1$.

The vegetation carbon $C_{\text{veg}}$ is a single prognostic pool. The tissue pools are diagnosed from it with the allometry of [21] (see compute_leaf_carbon, compute_root_carbon, and compute_stem_carbon), with the balanced leaf area index $\text{LAI}_b = C_{\text{veg}} / (2/\text{SLA} + a_{wl})$,

\[\begin{equation} C_{\text{leaf}} = C_{\text{root}} = \frac{\text{LAI}_b}{\text{SLA}}, \qquad C_{\text{stem}} = a_{wl} \, \text{LAI}_b \end{equation}\]

so that $C_{\text{leaf}} + C_{\text{root}} + C_{\text{stem}} = C_{\text{veg}}$, and stem and root respiration are proportional to $C_{\text{veg}}$.

Growth respiration

Growth respiration is taken as a fixed fraction of the carbon available after maintenance respiration

\[\begin{equation} R_g = 0.25 \cdot (\text{GPP} - R_m) \end{equation}\]

Methods

compute_f_temp(autoresp, T_air, T_soil)

compute_resp10(autoresp)

compute_Rm(
    autoresp,
    vegcarbon_dynamics,
    traits,
    T_air,
    T_soil,
    Rd,
    phen,
    C_veg
)

compute_Rg(autoresp, GPP, Rm)

compute_Ra(
    autoresp,
    vegcarbon_dynamics,
    traits,
    T_air,
    T_soil,
    Rd,
    phen,
    C_veg,
    GPP
)

compute_NPP(autoresp, GPP, Ra)

Process interface

compute_auxiliary!(
    state,
    grid,
    autoresp::PALADYNAutotrophicRespiration,
    vegcarbon::Terrarium.AbstractVegetationCarbonDynamics,
    phenology::Terrarium.AbstractPhenology,
    traits::PlantTraits,
    atmos::Terrarium.AbstractAtmosphere
)

Kernel functions

compute_autotrophic_respiration(
    i, j, grid, fields,
    autoresp::AbstractAutotrophicRespiration,
    vegcarbon::AbstractVegetationCarbonDynamics,
    atmos::AbstractAtmosphere,
    args...
)

compute_autotrophic_respiration!(
    out,
    i,
    j,
    grid,
    fields,
    autoresp::Terrarium.AbstractAutotrophicRespiration,
    args...
)

References