Technical Report NPS/NER/NRTR--2004/001
Carolyn G. Mahan
Penn State Institutes of
To assess invertebrate biodiversity associated with eastern hemlock (Tsuga canadensis) forests at Shenandoah National Park (SHEN), 12,978 invertebrate specimens were collected at a hemlock forest (Limberlost) and, for comparison, a hardwood forest (Matthews Arm) during August 1997. The specimens we collected comprised 19 insect orders representing 161 families. In addition, 14 other related invertebrate orders representing 33 families were collected. As of June 2004, of the 12,978 total specimens collected, 286 species (both genus and species known) were identified. However, another 3,286 specimens (25%) were identified to the morphospecies level. For the purpose of this report, morphospecies are specimens that have been sorted and classified as distinct, although unidentified, taxa according to their shape and morphological characteristics. All Coleoptera (beetles), Lepidoptera (moths and butterflies), Opiliones (daddy longlegs or harvestmen), Araneae (spiders), Hemiptera (true bugs), Homoptera (aphids, planthoppers, scale insects), Hymenoptera (bees, wasps and ants), Plecoptera (stoneflies), Psocopotera (psocids), Trichoptera (caddisflies), Thysanoptera (thrips), Chilopoda (centipedes), Diplopoda (millipedes), and Blattaria (cockroaches) were identified either to the named species level or sorted to morphospecies. Most of the Diptera (flies), except for the families Cecidomyiidae, Sciaridae, and Sphaeroceridae have been identified to species or morphospecies. Of the remaining invertebrate orders, most were identified to the family level except Acari (mites, ticks), Pseudoscorpiones (pseudoscorpians), Ephemeroptera (mayflies), Protura (proturans), Isopoda (sowbugs), Siphonaptera (fleas), and Stylomatophora (snails and slugs). Our collection potentially contains many more species because 1,209 specimens of Acari (mites), 2,478 specimens of Collembola (springtails), and 3,138 specimens of Cecidomyiidae (gall midges) were not sorted to morphospecies.
All specimens were prepared and curated at the Frost Entomological Museum, The Pennsylvania State University. Furthermore, all specimens identified were entered into the SHEN Biodiversity Database and will be provided to park personnel for inclusion in the NPSpecies online database.
The invertebrate biodiversity of the hemlock (Limberlost) and hardwood (Matthews Arm) forest stands at SHEN were compared by examining species richness and abundance as well as conducting guild analyses. The species were assigned to guilds based on immature feeding behavior as reported in the literature. These guilds were used to describe differences between the two forest types. The hemlock stand contained higher numbers of individuals in 14 out of 33 orders collected at SHEN. In particular, Ephemeroptera (mayflies), Plecoptera (stoneflies), and Psocoptera (booklice) were only found, or were more abundant, at Limberlost. In addition, members of the moss grazer guild were only found at Limberlost. These taxa may be dependent on the dense canopy and moist microclimate that occur within hemlock stands.
Our study documented one new state record (Arctogeophilus fulvus) and a new Madison County record (Stimamia bidens) for centipedes collected at Limberlost. In addition, a new species in the order Homoptera (Cyrtolobus n. sp. nr. invermis) and ten new species in the order Diptera in the families Mycetophilidae (9) and Psychodidae (1) were documented.
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