## 2 Materials and Methods
### LAI Parameterization and Calculation  
Models differ in the way they calculate LAI, but all of them reported 1-sided LAI and use self-calculated LAI, independent from the satellite measurements. Their main difference is the choice of imposed or dynamic vegetation. The former uses a land-cover map to generate PFT categories, while the latter generates PFT categories based on climatic and competition dynamics.  
* CLM4 CN. The model has 16 PFTs. In this version the carbon-nitrogen cycling model simulates leaf carbon and specific leaf area to calculate the LAI for each PFT.
* LPJ. The leaf area index is updated daily and depends on temperature, soil water, and plant productivity for each PFT. The models have 3 different phenology types (evergreen, summergreen, raingreen) and 11 PFTs.
* LPJ-GUESS. The leaf area index is updated daily and depends on temperature, soil water, and plant productivity for each PFT. The models have 3 different phenology types (evergreen, summergreen, raingreen) and 11 PFTs.
* ORCHIDEE. LAI is estimated based on temperature. It also uses a maximum LAI threshold after which no more carbon is allocated to the leaves.
* OCN employs an approach based on the pipe-model for allocation, which results in much more rapid leaf development, and does not prescribe a maximum leaf area-rather, the maximal annual LAI is an emergent outcome of the NPP of the vegetation and the costs (roots, shoot) for maintaining the leaf area, which varies as a function of water and nitrogen stress.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Model Name** & **Abbreviation** & **Spatial Resolution** & **Number of PFTs** & **Vegetation** & **Fire dynamics** & **Full Nitrogen Cycle** & **References** \\ \hline
**Community** & & & & & & & \\
**Land Model 4 CN** & & & & & & & \\
**Land-Potsam-Jena** & LPJ & & & & & & \\
**LPJ-GUESS** & GUESS & & & & & & \\
**ORCHIDEE-CN** & OCN & & & & & \\
**ORCHIDEE** & ORC & & & & & & \\
**Sheffield-DGVM** & SDGVM & & & & & & \\
**TRIFFID** & TRI & & & & & & \\
**VEGAS** & VEG & & & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Characteristics of the eight dynamic global vegetation models (re-drawn from [PERSON] _et al._[8]).  
* SDGVM. LAI is calculated to optimize stem & root NPP. This is achieved through consideration of the net carbon balance of the bottom layer of the canopy. The fraction of NPP available for leaf production is adjusted each year based on this carbon balance. The rate at which this fraction is adjusted is PFT-dependent.
* TRIFFID. LAI is calculated for each of the 5 PFTs, based on parameters describing the minimum, maximum and balanced LAI if full cover is reached. The actual LAI is then calculated as a function of the balanced LAI and the phonological status of the vegetation, which depends on temperature.
* VEGAS. The model has five PFTs: broadleaf tree, needleleaf tree, C3 grass, C4 grass, and crop. Whether a tree PFT is deciduous or evergreen is dynamically determined, so it has essentially 7 functional types. Phenology is calculated for each PFT as the balance between growth and respiration. The actual leaf mass is calculated based on photosynthesis allocation, and then converted to leaf area index.