Ecosystem health is about much more than primary productivity.
Primary productivity is certainly important, but it is one of many ecosystem functions.
The debate described by Wardle et al. Adding belowground biomass helps, but all harvest-method estimates still fall short of actual carbon fixed by plants. If so, we might be looking at the most critical function but an inappropriate evaluation of it. Few conservationists would conclude that the former are unhealthy and the latter healthy. One natural system, the southern California salt marsh plain, lends itself very well to experimentation with species richness and identity, because it typically includes just 8 halophytes.