Great Smoky Mountains

Patterns of past fire disturbance may be an important contributor to contemporary vegetation composition and structure in old-growth forests of the southern Appalachian Mountains. However, due to a lack of information on pre-suppression fire regimes, vegetation pattern in the region has been primarily attributed to variability in soils and climate. To assess the pre-suppression fire regime's role in shaping vegetation pattern, we characterized temporal patterns of tree establishment in an old-growth forest that experienced two centuries of frequent fire, followed by a century of fire exclusion. Forest plots were inventoried and cored to characterize age structure and composition in yellow pine, chestnut oak, white pine-oak, and cove forest communities on the south-facing slope of an old-growth watershed in Great Smoky Mountains National Park, Tennessee USA. We compared the timing and composition of tree establishment from the following disturbance periods: (1) frequent fire 1700–1909; (2) post fire 1910–1949; and (3) mesophication 1950–2000. Non-metric multidimensional scaling characterized successional change between the three age classes. Multivariate dispersion, species richness, and beta diversity were calculated for establishment in each disturbance period. We found distinct peaks in tree establishment in the yellow pine, chestnut oak, and white pine-oak stand types that occurred soon (<40 years) after fire cessation at the site. Xerophytic fire-tolerant species dominated establishment during the period of frequent fire; a mixture of xerophytic and mesophytic species established during the period immediately following the last major fire; and mesophytic, fire-intolerant species dominated establishment during the recent period of mesophication. Cohort recruitment was less clearly linked to fire suppression in the mesic cove stands; however ''fire protected'' cove stands exhibited different age structure and composition compared to cove stands adjacent to the frequently burned south-facing slope. Mean plot level species richness was greatest in the tree cohort that established soon after the last major fire; while beta diversity and multivariate dispersion were highest in the trees that had established during the frequent fire period. Tree establishment has generally shifted from shade-intolerant, drought-tolerant species to shade-tolerant, drought-intolerant species along the entire south-facing slope. Successional trajectory indicates a loss of yellow pine and chestnut oak communities as the xeric and sub-xeric sites convert to white pine and cove forest communities, which were formerly restricted to sub-mesic and mesic positions. Declines in beta diversity and multivariate dispersion within younger age classes indicate that in the absence of fire disturbance, community differentiation is declining along the topographic moisture gradient.

Abrams Creek drainage was surveyed for adult mayflies (Ephemeroptera), stoneflies (Plecoptera), and caddisflies (Trichoptera) during summer 2001 as part of the All Taxa Biodiversity Inventory in the Great Smoky Mountains National Park (GRSM). Nine reaches were collected, up to five times, using primarily ultraviolet light trapping. Of the 35,710 specimens examined, 164 species resulted. These consisted of 35 species of mayflies, 36 stoneflies, and 93 caddisflies. Eight species are new to Tennessee, while 39 are new GRSM records. Three rarely collected mayflies, Epeorus vitreus (Walker), Leucrocuta thetis (Traver), and Nixe spinosa (Traver), were taken. Rare caddisflies included Ceratopsyche macleodi (Flint), Cheumatopsyche helma Ross, Hydroptila chattanooga Frazer and Harris, H. talladega Harris, and Chimarra augusta Morse. No rare stoneflies were collected. Additional specimens of two undescribed (but known to specialists) species were taken in Goera (Trichoptera) and Isoperla (Plecoptera). Specimens of Hydroptila nr. amoena Ross (Trichoptera) and a Caenis nr. mccafferti Provonsha (Ephemeroptera) are possibly new to science, but require more specimens and study. More effort concentrated in southwestern GRSM and in Ephemeroptera and Trichoptera should yield additional significant records.

• Premise of the study: Angiosperms frequently have mixed sexual and asexual reproductive strategies, which can have significant consequences for population and community structure. Many tree species respond to disturbance by vegetative sprouting over sexual reproduction, but the ability to do so varies within and among species and is poorly studied. We tested the hypothesis that root sprouting in Fagus grandifolia is more important in high-elevation beech forests (extreme environmental conditions), relative to lower-elevation cove hardwood forests (optimal environmental conditions), in Great Smoky Mountains National Park.
• Methods: Four cove hardwood and two high-elevation beech gap forests were sampled. Fagus grandifolia trees were tagged, mapped, and genotyped at each site using six nuclear microsatellite loci. A subset of trees was cored to determine minimum ages of identifi ed clonal lineages. Relationships between measures of clonal richness, diameter, forest type, and elevation were compared by nonparametric analyses.
• Key results: Five of six sites were highly dependent on sprouting; one site was entirely dependent on reproduction by seed. Clonal richness did not differ signifi cantly by forest type or elevation, but differed signifi cantly from previously published work. Tree diameter was signifi cant by elevation and signifi cant between the present study and previously published work.
• Conclusions: The results of this study in the context of previously published work suggest that relatively recent recruits may be more likely to refl ect both sexual and asexual strategies, whereas mature F. grandifolia may be more likely to be the result
of persistent clonal lineages.