In a special issue of Biological Conservation this month ('Defaunation's impact in tropical terrestrial ecosystems'), ANPN afflilates John Poulsen and Connie Clark published a study looking at the relative effects of logging and hunting on forest structure.
Comparing different sites in Northern Congo, they measured the effects of logging and hunting on seed disperal, seed predation and herbivory. All sites still contained a full complement of large mammals, but differed in relative densities. They found that even partial defaunation reduced herbivory rates and seed dispersal distances. In addition, they found that logged and hunted sites had lower above-ground biomass than logged-only forests, despite similar timber extraction practices having been employed. They suggest that the removal of herbivores could favour the survival of fast-growing, low wood density species, with consequences for long-term carbon storage potential.
Poulsen JR, Clark CJ, Palmer TM, 2013. Ecological erosion of an Afrotropical forest and potential consequences for tree recruitment and forest biomass. Biological Conservation 163:122-130.