## 3 Results and Discussion
### Control Capacity  
We interpret the N control capacity ratio as the degree of control that each system components exerts on the release dynamics of nitrogen cycling within the model domain (Figure 11). There is, of course, a degree of subjectivity in the definitions, nonetheless evaluating the results in this fashion provides a unique mechanism to evaluate the relative importance of components, and how this degree of control varies with time. These kinds of analyses are available only through the use of the continuously varying results, which are not typically measured over long periods, providing significant further utility in the application and development of conceptual numerical simulation.  
Figure 11: The nitrogen control capacity. (**a**) The plot outlines the summed rate terms which are used to estimate the control capacity of the watershed components as indicated in the legend. These four time series correspond directly to Equations (1)–(4); (**b**) The plot represents the control capacity, where the time series from the upper plot have been normalized by the total rate of nitrogen movement. (**c**) The plot represents the monthly averages of the control capacity, again including comparisons of the four different watershed components.  
As expected given the well-established capacity of these types of watersheds to retain N, vegetation and soils exert a primary control on N dynamics. Hydrologic flushing of nitrogen is well-represented during the winter period, though even during periods of elevated N export and flushing, vegetation and soils still represent important controls (Figure 11). The explanation behind the result is clear--the Mediterranean climate in the Pacific Northwest results in significant winter moisture, which produces increased soil moisture, higher soil water flux, and larger stream discharge than seen during the dry summer period. In addition, the lower temperatures that dominate during the winter period suppress primary production and SOM dynamics. During the growing season, however, hydrologic flushing moves into the background, while control capacity of other components increases. This change in control is most evident in June-August, when mobilization rates tend to increase and flushing rates decrease. SOM contributes a larger portion of available nitrogen than the vegetation during this period of time, and this is primarily because uptake increases and the vegetation acts as a stronger sink of N that SOM during the summer period. This difference is in part a reflection of our lumping of litter and live biomass in our definition of control capacity. Particulate flushing of nitrogen mimics hydrologic flushing because of increased mobilization of aquatic biomass during the wet season, but the signal is muted when compared to hydrologic flushing. The lower seasonal variability develops at least in part because particulate inputs are derived directly from the litterfall/mortality model which did not include seasonal effects.  
These results lend credence to the idea that understanding the dynamics of nitrogen, carbon, and water in ecosystems requires a multidisciplinary approach [39]. This approach certainly includes attention to flushing behavior, but the level of attention given to flushing must be on par with that given to production of available nitrogen, which may be dissolved or in particulate forms. Furthermore, the seasonality of the system imposes a series of constraints that result in predictable temporal variation in the activity of different system components. This variation is difficult to approach through standard field-based budget techniques; however numerical modeling can be used to extend budget results to provide a clearer picture of the seasonality.