Of Mice and Men in Gabon: Changes in Rodent Communities Associated with Logging and Hunting

Abstract

Worldwide tropical rainforests are under increasing pressure from timber extraction and bushmeat hunting. Hunting and logging have been linked to long-term reductions in carbon storage potential, loss of floristic diversity, and diminished regeneration of valued timber species. Many studies have focused on the consequences of hunting on medium and large bodied mammals and how shifts in their population affect forest dynamics. Far less work has been carried out on how small mammal communities may be indirectly affected by hunting and logging despite indications that their communities are likely altered by anthropogenic disturbance. Because of their important role as seed predators, changes in rodent populations could substantially alter long-term trajectories of vegetation communities. In this study, I investigate whether rodent communities and seed predation in the forests of Northeastern Gabon are altered by hunting and logging as well as changes in forest structure potentially caused by these disturbances. I hypothesized that I would find elevated abundance, biomass, and diversity of rodents as well as higher rates of rodent seed predation in hunted and logged sites compared to protected sites. Moreover, I hypothesized that changes in forest structure associated with disturbance, such as dense understories and high densities of lianas, would accompany these shifts in the small mammal community. Employing rodent trapping and seed predation trials at sites in and around the Ivindo National Park and surrounding villages, I found no change in the number, total biomass, or level of seed predation of rodents associated with human impact. However, I detected a significant shift in rodent species composition from small-bodied species dominating protected sites to large-bodied species dominating disturbed sites with hunting and logging. This change in the rodent community was associated with decreased understory openness, increased downed wood basal area, and increased numbers of lianas. This first documentation of changes in Central African rodent communities associated with hunting and logging lays an important foundation to future work determining the role of small mammals in long-term alterations in forest structure with implications for both conservation and timber management.