# Improving a Process-Based Model to Simulate Forest Carbon Allocation under Varied Stand Density
## 2 Materials and Methods
### Simulations  
#### 2.3.1 Parameterization and Initialization  
The TRIPLEX-Management model was parameterized and verified for jack pine (_Pinus banksiana_ Lamb.) and trembling aspen (_Populus tremuloides_ Michx.) using the growth and yield data in Canada from several previous studies [18,19]. It was also parameterized for subtropical forest regions in southeastern China [36] and temperate forest ecosystems in northeastern China [24]. In this study, we maintained the most general and non-species  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline
**Site** & **Location** & \begin{tabular}{c} **Planting** \\ **Year** \\ \end{tabular} & **MAT** & **MAP** & **Soil Type** & **Soil Texture** & **Age** & **SD** & **DBH** & **H** & **Reference** \\ \hline Dongtai1 & 120\({}^{\circ}\)49\({}^{\prime}\) E, 33°05\({}^{\prime}\) N & 2006 & 14.6 & 1069 & \begin{tabular}{c} Desalted \\ meadow \\ \end{tabular} & Sandy loam & 9 & 333 & 23.23 & 21.28 & [28] \\ Dongtai2 & 120\({}^{\circ}\)49\({}^{\prime}\) E, 33°05\({}^{\prime}\) N & 2006 & 14.6 & 1069 & \begin{tabular}{c} Desalted \\ meadow \\ \end{tabular} & Sandy loam & 7 & 667 & 16.21 & 18.08 & [29] \\ Dongtai3 & 120\({}^{\circ}\)49\({}^{\prime}\) E, 33°05\({}^{\prime}\) N & 1996 & 14.6 & 1069 & \begin{tabular}{c} Desalted \\ meadow \\ \end{tabular} & Sandy loam & 15 & 333 & 33.2 & 27.3 & [30] \\ Dongtai4 & 120\({}^{\circ}\)49\({}^{\prime}\) E, 33°05\({}^{\prime}\) N & 2006 & 14.6 & 1069 & \begin{tabular}{c} Desalted \\ meadow \\ \end{tabular} & Sandy loam & 10 & 607 & 20.85 & 18.91 & [31] \\ Dongtai5 & 120\({}^{\circ}\)49\({}^{\prime}\) E, 33°05\({}^{\prime}\) N & 2006 & 14.6 & 1069 & \
\begin{tabular}{c} Desalted \\ meadow \\ \end{tabular} & Sandy loam & 10 & 312 & 27.82 & 20.63 & [31] \\ Suining1 & 118\({}^{\circ}\)04\({}^{\prime}\) E, 33°53\({}^{\prime}\) N & 1998 & 16 & 1300 & Aluvial sandy & Sandy loam & 9 & 204 & 31.2 & 25.9 & [32] \\ Suining2 & 118\({}^{\circ}\)04\({}^{\prime}\) E, 33°53\({}^{\prime}\) N & 1998 & 16 & 1300 & Aluvial sandy & Sandy loam & 9 & 278 & 30.5 & 26.4 & [32] \\ Suining3 & 118\({}^{\circ}\)04\({}^{\prime}\) E, 33°53\({}^{\prime}\) N & 1998 & 16 & 1300 & Aluvial sandy & Sandy loam & 9 & 400 & 24.8 & 26.2 & [32] \\ Suining4 & 118\({}^{\circ}\)04\({}^{\prime}\) E, 33°53\({}^{\prime}\) N & 1998 & 16 & 1300 & Aluvial sandy & Sandy loam & 9 & 625 & 20.4 & 25 & [32] \\ Zhoushan & 119\({}^{\circ}\)40\({}^{\prime}\) E, 32°20\({}^{\prime}\) N & 2002 & 14.5 & 1000 &
\begin{tabular}{c} Lacustrine \\ sediments \\ \end{tabular} & Clay texture & 10 & 1111 & 19.8 & 18.2 & [33] \\ Sihong1 & 118\({}^{\circ}\)36\({}^{\prime}\) E, 33°28\({}^{\prime}\) N & 2007 & 14.4 & 972.5 & Deposited soil & Sandy black & 13 & 400 & 21.75 & 24.48 & [34] \\ Sibong2 & 118\({}^{\circ}\)36\({}^{\prime}\) E, 33°28\({}^{\prime}\) N & 2007 & 14.4 & 972.5 & Deposited soil & Sandy black & 13 & 278 & 24.79 & 25.62 & [34] \\ Ganyu & 119\({}^{\circ}\)07\({}^{\prime}\) E, 34°50\({}^{\prime}\) N & 2002 & 13.2 & 976.4 & Tibba sandy & Sandy loam & 8 & 1111 & 11.96 & 12.6 & [35] \\ \hline \hline \end{tabular}
\end{table}
Table 1: Stand, climate, and soil characteristics of the sampling sites in northern Jiangsu Province.  
or site-specific parameters, including the radiation extinction coefficient, soil water depth, and lignin-nitrogen ratio. We updated some species-specific parameters retrieved from the literature (Table 2). Site-specific parameters were estimated using the site and stand characteristics of the sampling plots (e.g., environmental or site conditions, stand stock, and growth characteristics of tree species). The site-specific parameters included species, renewal year, latitude, site type, soil organic carbon, and stocking level. We modified the initial stocking level using the planting density.