Community growth adjustment by environmental and seasonal factors

The functions limit the growth of all plant species without any species-specific reduction:

The growth is adjusted for environmental and seasonal factors $E N V_{t x y}$ [-] that apply in the same way to all species:

E N V_{t x y} = R A D_{t x y} \cdot T E M P_{t x y} \cdot S E A_{t x y}

with the radiation $R A D_{t x y}$ [-], temperature $T E M P_{t x y}$ [-], and seasonal $S E A_{t x y}$ [-] growth adjustment factors.

Radiation influence

The growth reducer due to too much radiation $R A D_{t x y}$ [-] is described by:

R A D_{t x y} = max (min (1, 1 - γ_{R A D, 1} \cdot (P A R_{t x y s} - γ_{R A D, 2})), 0)

$γ_{R A D, 1}$ controls the steepness of the linear decrease in radiation use efficiency for high $P A R_{t x y}$ values [ha MJ⁻¹]
$γ_{R A D, 2}$ threshold value of $P A R_{t x y}$ from which starts a linear decrease in radiation use efficiency [MJ ha⁻¹]

Visualization

steepness of the reduction γ_RAD_1	4.45e-6
PAR at which the growth is reduced γ_RAD_2	50000

API

GrasslandTraitSim.radiation_reduction! Function

julia

radiation_reduction!(; container, PAR)

Reduction of radiation use efficiency at high radiation levels.

source

Temperature influence

The growth reduction factor due to too low or too high temperature $T E M P_{t x y}$ [-] is described by:

T E M P_{t x y} = {\begin{cases} 0 & if T_{t x y} < ω_{T E M P, T_{1}} \\ \frac{T_{t x y} - ω_{T E M P, T_{1}}}{ω_{T E M P, T_{2}} - ω_{T E M P, T_{1}}} & if ω_{T E M P, T_{1}} < T_{t x y} < ω_{T E M P, T_{2}} \\ 1 & if ω_{T E M P, T_{2}} < T_{t x y} < ω_{T E M P, T_{3}} \\ \frac{ω_{T E M P, T_{4}} - T_{t x y}}{ω_{T E M P, T_{4}} - ω_{T E M P, T_{3}}} & if ω_{T E M P, T_{3}} < T_{t x y} < ω_{T E M P, T_{4}} \\ 0 & if T_{t x y} > ω_{T E M P, T_{4}} \end{cases}

Equation are from Jouven et al. (2006) and theses are based on Schapendonk et al. (1998).

$ω_{T E M P, T_{1}}$ minimum temperature for growth [°C]
$ω_{T E M P, T_{2}}$ lower limit of optimum temperature for growth [°C]
$ω_{T E M P, T_{3}}$ upper limit of optimum temperature for growth [°C]
$ω_{T E M P, T_{4}}$ maximum temperature for growth [°C]

Visualization

minimum temperature for growth ω_TEMP_T1	4
lower limit of optimum temperature for growth ω_TEMP_T2	10
upper limit of optimum temperature for growth ω_TEMP_T3	20
maximum temperature for growth ω_TEMP_T4	35

API

GrasslandTraitSim.temperature_reduction! Function

julia

temperature_reduction!(; container, T)

Reduction of the growth if the temperature is low or too high.

source

Seasonal effect

The seasonal growth adjustment factor $S E A_{t x y}$ [-] is desribed by:

\begin{aligned} S E A_{t x y} & = {\begin{cases} ζ_{S E A min} & if S T_{t x y} < 200 ° C \\ ζ_{S E A min} + (ζ_{S E A max} - ζ_{S E A min}) \cdot \frac{S T_{t x y} - 200 ° C}{ζ_{S E A, S T_{1}} - 400 ° C} & if 200 ° C < S T_{t x y} < ζ_{S E A, S T_{1}} - 200 ° C \\ ζ_{S E A max} & if ζ_{S E A, S T_{1}} - 200 ° C < S T_{t x y} < ζ_{S E A, S T_{1}} - 100 ° C \\ ζ_{S E A min} + (ζ_{S E A min} - ζ_{S E A max}) \cdot \frac{S T_{t x y} - ζ_{S E A, S T_{2}}}{ζ_{S E A, S T_{2}} - ζ_{S E A, S T_{1}} - 100 ° C} & if ζ_{S E A, S T_{1}} - 100 ° C < S T_{t x y} < ζ_{S E A, S T_{2}} \\ ζ_{S E A min} & if S T_{t x y} > ζ_{S E A, S T_{2}} \end{cases} \\ S T_{t x y} & = \sum_{i = t mod 365}^{t} max (0 ° C, T_{i x y} - 0 ° C) \end{aligned}

This empirical function was developed by Jouven et al. (2006).

$ζ_{S E A, S T_{1}}$ threshold of the yearly accumulated temperature, above which the seasonality factor decreases from $ζ_{S E A max}$ to $ζ_{S E A min}$ [°C]
$ζ_{S E A, S T_{2}}$ threshold of the yearly accumulated temperature, above which the seasonality factor is set to $ζ_{S E A min}$ [°C]
$ζ_{S E A min}$ minimum value of the seasonal effect [-]
$ζ_{S E A max}$ maximum value of the seasonal effect [-]

Visualization

ζ_ST₁	775
ζ_ST₂	1450
minimum value of the seasonal effect ζ_SEAmin	0.7
maximum value of the seasonal effect ζ_SEAmax	1.3

API

GrasslandTraitSim.seasonal_reduction! Function

julia

seasonal_reduction!(; container, ST)

Adjustment of growth due to seasonal effects.

source

Community growth adjustment by environmental and seasonal factors ​

Radiation influence ​

Visualization ​

API ​

Temperature influence ​

Visualization ​

API ​

Seasonal effect ​

Visualization ​

API ​

Community growth adjustment by environmental and seasonal factors

Radiation influence

Visualization

API

Temperature influence

Visualization

API

Seasonal effect

Visualization

API