For land management, the principle challenge relates to prediction. Managers need to know how today's management decisions will impact tomorrow's ecosystem processes.Ra! Ra! Sis Boom Bah! Yes! And guess what, that means using models. All the fancy remote sensing in the world is no good unless you can use that data to meet the principle challenge. The trouble is, managers are often reluctant to recognize that models can be helpful. In my recent experience, if models are "known" to have flaws (see quote by George Box), or produce a range of predictions because of statistical error in parameter estimates or inherent variation (demographic stochasticity), then they are labeled useless. Better to use gut instinct to make decisions.
I do believe models are useful even when they are not (and they never will be) perfect.
Jeffery T Morisette et al. (2009) Tracking the rhythm of the seasons in the face of global change:
phenological research in the 21st century. Frontiers in Ecology and the Environment 7:253-260