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The ectomycorrhizal fungi associated with American chestnut ( Castanea dentata) were characterized using DNA extracted from the root-tips of naturally occurring saplings from a forest in northeastern Tennessee. A total of 18 taxa were recorded, although one of these ( Oidiodendron maius) was surprising because it has been reported previously to form what appear to be mycorrhizal associations only with members of the Ericaceae. One-third of the recorded taxa were representatives of the genera Russula or Lactarius (both members of the family Russulaceae), and three other genera ( Cortinarius, Tomentella, and Tricholoma, each represented by two species). The data presented herein at least suggest that members of the Russulaceae are among the most common and widespread ectomycorrhizal fungi associated with naturally occurring individuals of American chestnut in the forests of eastern North America in which it was once dominant. However, it should be pointed out that our data are limited and thus are best considered as preliminary. [ABSTRACT FROM AUTHOR]

North American Castanea consists of three morphologically variable species: Castanea dentata, Castanea pumila, and Castanea ozarkensis. Taxonomy of these species has been complicated by intermediate morphology, similarity in growth habit due, in part, to the chestnut blight, and putative naturally occurring hybridization in the southern Appalachians. The primary goal of this study was to determine if chloroplast DNA (cpDNA) distribution reflects the morphological variation observed in North American Castanea. To that end, we sequenced a single cpDNA gene region for 233 accessions collected from much of the range of the genus in North America. Once samples were grouped into haplotypes, we sequenced additional cpDNA regions to ensure that the observed haplotypic relationships were robust. We identified four main lineages and observed that for three of these, leaf and twig morphology are reliable predictors of haplotype identity (especially outside of the southern Appalachians). Haplotypes of the fourth lineage are shared among accessions of C. dentata and C. pumila, and trees with intermediate morphology. Geographic mapping of the haplotypes showed that they are largely found in separate geographic ranges but overlap in the southern Appalachians. While three clades closely correspond to the morphology of North American Castanea, it appears that the fourth lineage may have been recognized in the past as the hybrid taxon Castanea x neglecta because of its morphology that is intermediate between C. dentata and C. pumila. [ABSTRACT FROM AUTHOR]

The factors affecting tree mortality have a significant impact on forest dynamics. Trees experience numerous biotic and abiotic stresses, and allocation of available resources can determine tree survival in different conditions. Recent studies support an intraspecific relationship between radial growth rate and longevity. This study investigates the existence of such a relationship in the American chestnut [Castanea dentata (Marsh.) Borkh.] across a landscape in southwestern Virginia. Growth rate and age at death were measured on basal cross sections of recently dead American chestnuts. The relationships between growth rate and age at death and between growth rate and chestnut blight presence were analyzed. Average growth rate during the first 10 years of growth and age at death were correlated; chestnuts with fast early growth died younger than chestnuts with slow early growth. Additionally, we found that the average growth rate during the last 10 years of growth was a significant predictor of blight infection at death. Our results provide further support for a link between radial growth rates and longevity within species. Our results also support previous findings that relate radial growth rates to blight susceptibility, possibly due to tradeoffs in resource allocation to growth versus defense. This study emphasizes the impact of life history on mortality in a tree hosting a pathogen and could inform forest management practices for chestnut conservation in the face of potential mortality from blight infection. [ABSTRACT FROM AUTHOR]

The vascular flora of the North Chickamauga Creek Gorge State Natural Area (NCCG) was studied during three growing seasons from 2006 to 2008. NCCG is located in Hamilton and Sequatchie Counties, Tennessee, on the eastern edge of the Cumberland Plateau. Within the study area are 2,862 ha of eastern deciduous forest that contains 12 distinct habitat types. A survey of these habitat types yielded 110 families, 329 genera, and 604 species or lesser taxa, including 238 county records. Seventy-six introduced species were found, comprising 13% of the total flora. Eleven species with either a state or federal listing were documented: Castanea dentata, Diervilla lonicera, Diervilla rivularis, Glyceria acutifolia, Nestronia umbellula, Spiraea virginiana, Scatellaria montana, Sahatia capitata, Woodwardia virginica, Panax quinquefolium, and Viola tripartita. A species-area curve for the Cumberland Plateau of Tennessee was constructed from the current study and seven other similar studies of the plateau. Three family level species-area linear regression lines were also constructed, demonstrating that the natural area reaches or exceeds expectations for Asteraceae, Poaceae, and Cyperaceae. [ABSTRACT FROM AUTHOR]