American chestnut was formerly a major component of forests throughout the Appalachian coalfields and beyond. Chestnut's strong, lightweight wood was naturally rot-resistant, making it a preferred timber tree for many purposes. Unlike many nut-producing trees that flower early in the year, American chestnuts flower in June and July, so they were less susceptible to a late freeze or frost that could damage the flowers. Due in part to its late flowering, American chestnuts produced a reliable and abundant nut crop that was an important source of nutrition for wildlife, livestock, and humans.
Old-growth forests provide an invaluable ecological benchmark in an otherwise widely managed forest landscape. These forests permit insight into important processes that might not otherwise be observable in the landscape; i.e., processes that only manifest themselves at the latest stages of forest succession or in the absence of anthropogenic disturbance. Dysart Woods is one of a small number of remnant old-growth stands in Ohio and is believed to be the only example of mixed mesophytic forest vegetation in the state.
Five inland halophytes, Atriplex prostrata, Hordeum jubatum, Salicornia europaea, Spergularia marina, and Suaeda calceoliformis, were grown in controlled laboratory conditions under three salinity treatments (0.5, 1.5, and 2.5% NaCl) and three density treatments (5, 15, and 30 plants∙100 cm −2 ) to determine the effects of salinity and density on survival, growth, and ion accumulation. The more salt sensitive species, A. prostrata and H. jubatum, had significant (P < 0.05) density-dependent mortality. Density significantly reduced biomass production for all species, except for H. jubatum in the high-salinity treatment. Succulence in Suaeda calceoliformis shoots increased in the high-salinity treatment, but H. jubatum plants were desiccated at the time of harvest. The ash, sodium, and chloride contents of shoots increased with salinity for all species. Sodium and Cl − ion contents for all species –treatment combinations were an order of magnitude higher than that of Mg 2 + , Ca 2+ , and K. Although A. prostrata, Salicornia europaea, and Suaeda calceoliformis accumulated similar levels of Na + in their shoots, Suaeda calceoliformis plants from the two higher densities in the low-salinity treatment accumulated twice as much total Na + per pot than A. prostrata, and seven times more Na + than Salicornia europaea. Based on these laboratory studies, Suaeda calceoliformis planted in densities ranging from 15 to 30 plants∙100 cm −2 would accumulate more Na + from saline-contaminated soils than the other species. Key words: bioremediation, Atriplex, Hordeum, Salicornia, Spergularia, Suaeda..
In order to determine how salinity and exposure time affect seed viability and germination, seeds of five halophytes, Atriplex prostrata, Hordeum jubatum, Salicornia europaea, Spergularia marina, and Suaeda calceoliformis were exposed to 3.0, 5.0, and 10.0% NaCl solutions for 30, 60, 90, 365, and 730 d. Recovery experiments in distilled water indicated significantly different species responses to salinity over time. Percentage germination and rate of germination in H. jubatum were dramatically reduced following extended exposure and all seeds exposed to 10% NaCl for > 1 yr failed to germinate. Spergularia marina seeds were stimulated following short-term exposure to 3% NaCl; however, germination was delayed and overall germination was significantly reduced with exposure time in the two higher salinity levels. Percentage germination in A. prostrata decreased over time, but salinity level was not related to this reduction. Germination of S. europaea and S. calceoliformis, the most salt-tolerant species being tested, was stimulated by exposure to high salinity. Both species had a significant increase in percentage germination and in the germination rate when compared to seeds germinated in distilled water. Baseline germination data from seeds placed in 0, 1, 2, and 3% NaCl solutions indicated that S. europaea and S. calceoliformis were the only species to germinate in the 3% NaCl solution. Spergularia marina failed to germinate in the 2% NaCl treatment, and germination of A. prostrata and H. jubatum was significantly reduced at this salinity level. It is concluded that prolonged exposure to saline solutions can inhibit or stimulate germination in certain species, and the resulting germination and recovery responses are related to the duration and intensity of their exposure to salt in their natural habitats.
Hybrid chestnut (Castanea dentata × C. mollissima) has the potential to provide a valuable agroforestry crop on formerly coal mined landscapes. However, the soil interactions of mycorrhizal fungi and buried metals associated with mining are not known. This study examined soil, plant tissue, and ectomycorrhizal (ECM) root colonization on eight-year-old hybrid (BC 1 F 3 and BC 2 F 3 ) and American chestnuts on a reclaimed coal mine in Ohio, USA. Chestnut trees were measured and ECM colonization on roots was quantified. Leaves, flowers, and soil were analyzed for heavy metals. Differences were not detected among tree types regarding metal accumulation in plant tissue or ECM colonization. BC 2 F 3 hybrids had greater survival and less cankers than American chestnuts (P= 0.006 and <0.0001). Taller trees were associated with greater ECM root colonization and correlated with an increase in Al uptake (P= 0.02 and 0.01). When comparing tissue, manganese and aluminum were in higher concentrations in leaves than flowers, where copper and selenium were significantly higher in floral tissue (P< 0.05). All trees were flowering at this time meriting further examination in nut tissue. Block effects for selenium and zinc indicate the variability in reclaimed soils requiring further monitoring for possible elemental transfer to nut and wood tissue.
The objective of this study was to evaluate the influence of five different species of ectomycorrhizal (ECM) fungi on root colonization of native fungi on putatively blight resistant chestnut hybrids (Castanea dentata x C. mollissima) in a reclaimed mine site in central Ohio. The five species were Hebeloma crustuliniforme, Laccaria bicolor, Scleroderma polyrhizum, Amanita rubescens, and Suillus luteus. We used a combination of DNA sequencing of the ITS region and phylogenetic analyses to indentify fungi found on roots after 12 and 18 months in the field. Non-metric multidimensional scaling (NMDS) ordinations were used to determine if ECM community composition was influenced by the fungal inoculum used. The results of this study demonstrated that the selected ECM species do not persist on chestnut after one year in the field. In addition, these selected ECM species did not impede natural root colonization of native fungi or influence ECM community composition after two growing seasons. Although these species did not persist in the field, the presence of ECM inoculum (with the exception of Amanita) greatly contributed to the survival of hybrid chestnut seedlings. Therefore, introduced inoculum that was present in the very early stages of outplanting had persisting effects with regard to seedling establishment in the field, even if the original inoculum did not persist. ECM fungi native to the area colonized chestnuts resulting in increased growth rates. These native assemblages may contain species better able to form functional mycorrhizas under these environmental extremes. Therefore, the conservation of these species may be necessary to facilitate long-term survival of deciduous tree species historically native to these lands. Additional Keywords: root colonization of fungi, chestnut restoration.
