Stomatal resistance of New Guinea Impatiens pot plants. Part 1: Model development for well watered plants based on design of experiments

Estimating Dynamic Non‐Water‐Limited Canopy Resistance Over the Globe: Changes, Contributors, and Implications

“…These mean that the optimized θ s is higher than RZSW at all the gird cells and in all the months. Together with the comparison results in Figure 2, these results suggest that our method for estimating r cs is reasonable and robust, because it meet all the physical assumptions and the observed relationships in previous studies (Bouhoun Ali et al., 2016; Irmak & Mutiibwa, 2010; Jarvis, 1976; Uddin et al., 2016).…”

“…Though the generalized‐linear model (Irmak & Mutiibwa, 2010) is limited in saturated regions (e.g., well‐watered fields), we adopt the its structure to develop a model suitable for both saturated and unsaturated fields, by considering the impacts of root zone soil water content (RZSW) on canopy resistance. After reviewing the reported relationships between canopy resistance and its potential drivers (Bouhoun Ali et al., 2016; Irmak & Mutiibwa, 2010; Jarvis, 1976; Uddin et al., 2016), here we choose LAI (dimensionless), R n (W m −2 ), T a (°C), [CO 2 ] (ppm), VPD (kPa), W s (wind speed, m s −1 ), and root zone soil water content (denoted as RZSW, kg m −2 ) as the drivers, and finally construct a canopy resistance ( r c ) model by comparing the performances of different model structures (more information in Supporting Information ): $$${r}_{c}=\mathrm{exp}\left[\alpha +\beta \text{LAI}+\delta {R}_{n}+\lambda {\left({T}_{a}-{T}_{opt}\right)}^{2}+\eta \left[{\text{CO}}_{2}\right]+\mu \text{VPD}+\xi {W}_{s}+\tau \left({\theta }_{s}-\text{RZSW}\right)\right]$$$ where the meanings and units of the parameters in Equation are summarized in Table 1. As pointed out in previous studies, increasing LAI, R n , and RZSW mainly result in decreasing r c (Irmak & Mutiibwa, 2010; Jarvis, 1976; Mankin et al., 2019); while increasing [CO 2 ] (Jarvis et al., 1999; Kergoat et al., 2002; Purcell et al., 2018), VPD (McAdam & Brodribb, 2015) and W s (Irmak & Mutiibwa, 2010) generally induces increasing r c , and increasing T a mainly causes decreasing (increasing) r c when T a is lower (higher) than an threshold value ( T opt ) (Jarvis, 1976).…”

“…Though the generalized-linear model (Irmak & Mutiibwa, 2010) is limited in saturated regions (e.g., well-watered fields), we adopt the its structure to develop a model suitable for both saturated and unsaturated fields, by considering the impacts of root zone soil water content (RZSW) on canopy resistance. After reviewing the reported relationships between canopy resistance and its potential drivers (Bouhoun Ali et al, 2016;Irmak & Mutiibwa, 2010;Jarvis, 1976;Uddin et al, 2016), here we choose LAI (dimensionless), R n (W m −2 ), T a (°C), [CO 2 ] (ppm), VPD (kPa), W s (wind speed, m s −1 ), and root zone soil water content (denoted as RZSW, kg m −2 ) as the drivers, and finally construct a canopy resistance (r c ) model by comparing the performances of different model structures (more information in Supporting Information S1):…”