Arthropods Associated with Leaf Litter of Fraser Fir in the Great Smoky Mountains National Park

Fraser Fir, Abies fraseri (Pursh) Poiret, is a southern endemic conifer species restricted to the higher elevations of the southern Applachian mountains. This forest type is currently threatened by the balsam woolly adelgid, Adelges piceae (Ratzeburg), an exotic pest species native to Europe. This insect has destroyed more than 95% of the mature Fraser fir within the boundaries of the Great Smoky Mountains National Park (GRSM). The adelgid damages Fraser fir by disrupting the flow of nutrients in the vascular tissues of the bark. This disruption is due to abnormal growth of the vascular tissues resulting from a reaction to the saliva of the adelgid which is injected during feeding.

This study was conducted to determine the arthropod fauna present in Fraser fir leaf litter and the seasonal abundance of those arthropods. Arthropods were collected from leaf litter beneath Fraser fir trees at three locations within the GRSM (Mt. Buckley, Mt. LeConte and Mt. Sterling) from June 1991 to May 1992. A total of 62 species representing 5 classes, 15 orders and 45 families of arthropods was collected. The greatest number of arthropods was collected in the summer months, with the highest total monthly collection occurring in August.

About 97.5% of the ca. 75,000 specimens collected were members of the taxa Acari and Collembola. The 20 members of the order Acari comprised 71.5% and 18 members of the order Collembola comprised 25.9% of the total collection. Arthropods collected included predators, scavengers, herbivores, fungivores and detritivores. Overall species diversity (H') was 2.21 and species evenness (J') was 0.54. Although the species composition varied somewhat at each site, the species diversity and evenness were similar.