Senescence

The loss of biomass due to senescence $S_{t s}$ [kg ha⁻¹] is defined as follows:

\begin{aligned} S_{t s} & = (1 - {(1 - α_{S E N})}^{1 / 30.44}) \cdot S E N_{t} \cdot max ({(\frac{s l a_{s}}{ϕ_{s l a}})}^{β_{S E N, s l a}}, 0.5) \cdot B_{t s} \\ S E N_{t} & = {\begin{cases} 1 & if S T_{t} < ψ_{S E N, S T_{1}} \\ 1 + (ψ_{S E N max} - 1) \frac{S T_{t} - ψ_{S E N, S T_{1}}}{ψ_{S E N, S T_{2}} - ψ_{S E N, S T_{1}}} & if ψ_{S E N, S T_{1}} < S T_{t} < ψ_{S E N, S T_{2}} \\ ψ_{S E N max} & if S T_{t} > ψ_{S E N, S T_{2}} \end{cases} \\ S T_{t} & = \sum_{i = t mod 365}^{t m a x} max (0 ° C, T_{i}) \end{aligned}

The monthly senescence rate defined by $α_{S E N}$ is converted to a daily senescence rate in the first equation.

$α_{S E N}$ senescence rater per month [-]
$ϕ_{s l a}$ reference value for the trait specific leaf area [m² g⁻¹]
$β_{S E N, s l a}$ scales the influences of the specific leaf area on the senescence rate [-]
$ψ_{S E N, S T_{1}}$ when the senescence starts to increase [°C]
$ψ_{S E N, S T_{2}}$ when the senescence reaches the maximum senescence rate [°C]
$ψ_{S E N max}$ maximum senescence rate [-]

when the senescence starts to increase ψ_SEN_ST₁	775
when the senescence reaches the maximum senescence rate ψ_SEN_ST₂	3000
maximum senescence rate ψ_SENₘₐₓ	2

reference value for the trait specific leaf area ϕ_sla	0.009
scale the influences of the specific leaf area on the senescence rate β_SEN_sla	0.3

julia

senescence!(; container, ST, total_biomass)

Calculate the biomass that dies due to senescence.

julia

initialize_senescence_rate!(; container)

Intialize the basic senescence rate based on the specific leaf area.

julia

seasonal_component_senescence(; container, ST)

Seasonal factor for the senescence rate.

Senescence ​