The aim of this study is to understand how forest management and topographic variation influence litter invertebrate community structure and functional diversity. We studied soil and leaf-litter invertebrates since they are widely used as indicators of ecosystem disturbance and recovery due to their rapid reproductive rates, sensitivity to soil characteristics and microclimate, and roles in food webs. This study was conducted in oak-hickory forests as part of the Hardwood Ecosystem Experiment located in southern Indiana. The Hardwood Ecosystem Experiment is a long-term study aimed at understanding the ecological consequences of forest management practices, using experimental clearcut and patch-cut treatments, which occurred in 2008, in replicated management units within Indiana State Forests. Within five management units, we selected several sample sites according to a nested hierarchical design: SW and NE facing slopes, upper and lower topographic positions, and pairs of 50-m transects that were in clearcut or patch-cut areas and adjacent unmanaged forest stands. We collected leaf litter in 0.25-m2 quadrats for invertebrate extraction at three locations along each transect. Invertebrates were identified to order, beetles to family, and ants were identified to species, in order to understand the taxonomic richness and functional diversity present.
Results/Conclusions
We found greater taxonomic richness in the unmanaged areas compared to managed areas, notably, 22 orders were found within managed areas while 26 were found within unmanaged areas. Similarly, there was nearly a 50% reduction in abundance in the harvested areas compared to unmanaged areas. We found that the effects of slope aspect and topographic position were variable among taxa and in some cases interacted with the effects of forest management. For instance, forest management affects invertebrate richness in mesic lowlands to a lesser extent than management practices in the xeric upslope, as shown by a 17% loss in richness between control and managed xeric upslopes, compared to a 5% loss in the mesic lowlands. Our results suggest that invertebrate diversity and potentially their ecosystem functions will be more resilient to clearcut and patch-cut disturbances in mesic than in xeric forest stands.