  Modelling complex systems such as agroecosystems often requires the
quantification of a large number of input factors. Sensitivity analyses are
useful to determine the appropriate spatial and temporal resolution of models
and to reduce the number of factors to be measured or estimated accurately.
Comprehensive spatial and temporal sensitivity analyses were applied to the
NitroScape model, a deterministic spatially distributed model describing
nitrogen transfers and transformations in rural landscapes. Simulations were
led on a theoretical landscape that represented five years of intensive farm
management and covering an area of $3\, km^2$. Cluster analyses were applied to
summarize the results of the sensitivity analysis on the ensemble of model
outputs. The methodology we applied is useful to synthesize sensitivity
analyses of models with multiple space-time input and output variables and
could be ported to other models than NitroScape.
