## 3 Results
### Thinning  
Following 30% thinning, annual GPP simulations showed an initial decline in both modules, and then a recovery over several years (Figure 9a). Using the PSIM module, the largest difference from unthinned simulations was in 2009 with a 17% reduction in GPP, which recovered fully to that of the unthinned by 2013. For PnET, the largest difference from unthinned simulations was in 2008 with a 20% reduction and, although this difference reduced by 2010, it maintained a similar difference (4-11% lower) for the duration of the simulations. The initial small change in GPP after thinning in the PSIM module more closely fit the measured changes than did the PnET module equivalent, which had a larger initial decline. Annual TER simulation (Figure 9b) also showed a decline in PSIM following the thin (maximum difference 15% in 2009), which recovered gradually but not completely by the end of the study (6% difference in 2014). For PnET, simulated TER increased slightly (by 5%) in 2007 and 2008 after thinning, before declining, and the difference in simulated  
Figure 8: Sensitivity tests showing % change in simulated annual CO\({}_{2}\) and N\({}_{2}\)O fluxes with chosen PSIM module parameter values (**a**) increased by 10% and (**b**) decreased by 10% (except DLEAFSHED; changed by 10 days and 20 days). Figure 7: Sensitivity tests showing % change in simulated annual CO\({}_{2}\) and N\({}_{2}\)O fluxes with chosen PnET module parameter values (**a**) increased by 10% and (**b**) decreased by 10% (except SENESCTART: changed by 30 days). values continued to increase thereafter to 12% by 2014. For PSIM, the maximum change in NEP was small (28%) compared to PnET, which showed a maximum reduction in NEP of 131%, resulting in negative NEP (i.e., a net loss of CO\({}_{2}\)) in 2008 (Figure 9c). PnET simulations produced a 47% increase in soil CO\({}_{2}\) efflux in 2008, whereas PSIM simulated a 12% decrease, increasing to 15% in 2009 and 2010 (Figure 9d). Both modules also showed an increase in simulated N\({}_{2}\)O emissions after the thin, and although relatively small in absolute values, the proportional increase was larger in PnET (39%) than for PSIM (17%) (Figure 9e). It should be noted that although soil CO\({}_{2}\) and N\({}_{2}\)O flux measurements are shown in Figure 9d,e, these were from the Tower Site and will not have been directly affected by the thinning. For the 15% simulated thinning, the differences in simulated fluxes followed the same trends as those produced by the 30% thin. For PSIM simulations, the 15% thin closely matches whole-stand EC measurements immediately after the thin in 2007-2009 (Figure 10a-c). The significant decrease in both measured GPP and TER in 2010 has been attributed to a defoliating caterpillar infestation [29], which may explain a poor model fit for 2010 and possibly subsequent years. However, both PSIM and PnET simulations showed a decrease in GPP and TER in the same year, suggesting an environmental effect may also have contributed to the low measured values in 2010. Figure 9: Annual eddy covariance CO\({}_{2}\) and soil gas flux measurements at the Straits Inclosure Tower Site for: (**a**) GPP, (**b**) TER, (**c**) NEP, (**d**) soil CO\({}_{2}\) and (**e**) soil N\({}_{2}\)O compared with simulated values from PnET, and PSIM with a 0%, 15% and 30% thinning event in September 2007 (marked with black arrow). [PERSON] et al. [45] reported changes in measured stand CO\({}_{2}\) fluxes after the thinning event in 2007; while fluxes in 2008 were little changed, there were markedly increased respiration rates in 2009 from the eastern thinned area, likely to be caused by the decomposition of brash and stumps. Monthly measured TER data partitioned into eastern (thinned) and western (unthinned) sectors from [45] in 2009 and 2012 were compared with 0% and 30% thinning simulated using PnET and PSIM (Figure 10). To account for the small differences in weather conditions when the wind is from east or west, simulated daily data were separated into east and west sectors.