Species-specific growth adjustment - Soil water

The water stress growth reducer $WA{T}_{ts}$ [-] is defined as:

$$\begin{array}{rl}WA{T}_{ts}& =\{\begin{array}{ll}0& \text{if }{W}_{p,t}=0\\ 1/(1+\exp (-{\beta }_{W,RSA}\cdot (W_{p,t}-x_{0,W,RSA})))& \text{if }0<W_{p,t}<1\\ 1& \text{if }{W}_{p,t}>=1\end{array}\\ x_{0,W,RSA}& =\frac{1}{{\beta }_{W,RSA}}\cdot (-{\delta }_{W,RSA}\cdot (TRS{A}_{ts}-(\frac{1}{{\delta }_{W,RSA}}\cdot \log \left(\frac{1-{\alpha }_{W,RSA,05}}{{\alpha }_{W,RSA,05}}\right)+{\varphi }_{RSA})))+0.5\\ TRS{A}_{ts}& =\frac{B_{B,ts}}{B_{ts}}\cdot rs{a}_s\\ W_{p,t}& =\frac{W_t-PWP}{WHC-PWP}\end{array}$$

• ${\varphi }_{RSA}$ reference trait value [m² g⁻¹]

• ${\beta }_{W,RSA}$ slope of response function [-]

• ${\alpha }_{W,RSA,05}$ response at $W_{p,t}=0.5$ for species with the reference trait value[-]

• ${\delta }_{W,RSA}$ scales the difference in the growth reducer between species [g m⁻²]

Visualization

• scaling of the soil water content in the rooting zone by permanent wilting point and water holding capacity

permanent wilting point (PWP)
water holding capacity (WHC)

• growth reducer

response at Wₚ = 0.5 for species with the reference trait value (α_WRSA05) (strong to weak growth reduction)
difference between species (δ_WAT_rsa) (no to strong difference)	10
slope of response (β_WAT_rsa)
reference trait value (ϕ_TRSA)

API

GrasslandTraitSim.water_reduction! Function

water_reduction!(; container, W, PWP, WHC)

Reduction of growth based on the plant available water and the root surface area per belowground biomass.

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