The Experts below are selected from a list of 216 Experts worldwide ranked by ideXlab platform
Ronald J. Newton - One of the best experts on this subject based on the ideXlab platform.
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Expression of a transcription factor from Capsicum annuum in pine calli counteracts the inhibitory effects of salt stress on adventitious shoot formation
Molecular Genetics and Genomics, 2006Co-Authors: Wei Tang, Ronald J. Newton, Thomas M. CharlesAbstract:Transcription factors regulating the stress-responsive gene expression play an important role in plant stress adaptation. In this study, we examined the salt stress tolerance of transgenic Vir- ginia pine (Pinus virginiana Mill.) overexpressing a Capsicum annuum ERF/AP2-type transcription fac- tor (CaPF1), which may enhance the ability of trans- genic plants to tolerate various kinds of stresses during vegetative growth. CaPF1 transgene increased the salt and oxidative stress tolerances of pine tissues and counteracted the inhibitory eVects of salt stress on the growth of transgenic Virginia pine calli, shoots, and plants. To our surprise, the ability of shoot formation was enhanced in three CaPF1 transgenic Virginia pine cell lines under stress of diVerent NaCl concentrations. NaCl at 200 mM signiWcantly increased the frequency of adventitious shoot formation and the number of shoots per gram calli. Measurement of plant hor- mone demonstrated that the levels of cytokinin was altered in CaPF1-overexpressed Virginia pine calli, compared to the control. Based on our results, we speculate that the altered level of cytokinin may result in enhancing adventitious shoot formation of transgenic calli exposed to salt for 1 week via an unknown mechanism.
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Differential gene silencing induced by short interfering RNA in cultured pine cells associates with the cell cycle phase
Planta, 2006Co-Authors: Wei Tang, Ronald J. Newton, Douglas A. WeidnerAbstract:The double-stranded short interfering RNA (siRNA) molecules can silence targeted genes through sequence-specific cleavage of the cognate RNA transcript. The rapid adoption of technologies based on this siRNA interference mechanism has been a widely used method to analyze gene function in plants, invertebrates, and mammalian systems. In order to understand the dynamics of siRNA-mediated gene inactivation during cell division, we have investigated the relationship between the cell cycle phase and the post-transcriptional gene silencing mediated by siRNA in gfp transgenic Virginia pine ( Pinus virginiana Mill.) cells. Among the different phases of the cell cycle, transgenic cells at the M phase gave 2–3 times lower gfp silencing than those at the G1, S, and G2 phases. The similar results of the siRNA-mediated gfp silencing were obtained in three transgenic cell lines. Differential gfp silencing induced by siRNA has been confirmed by northern blot, laser scanning microscopy, and siRNA analysis. These data suggested that siRNA-mediated gene inactivation is associated with the cell cycle phase in Virginia pine.
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Polyamines promote root elongation and growth by increasing root cell division in regenerated Virginia pine (Pinus virginiana Mill.) plantlets
Plant Cell Reports, 2005Co-Authors: Wei Tang, Ronald J. NewtonAbstract:Polyamines have been demonstrated to play an important role in adventitious root formation and development in plants. Here, we present a detailed analysis of influence of exogenously added polyamines on adventitious root development and its relationship to cold tolerance in Virginia pine ( Pinus virginia Mill.). Our results demonstrated that polyamines putrescine (Put), spermidine (Spd), and spermine (Spm) at 0.001 mM improve rooting frequency and promote root elongation. Put, Spd, and Spm at 0.01–1 mM decrease rooting frequency and reduce root elongation root elongation. Measurements of diamine oxidase (DAO, EC 1.4.3.6) and polyamine oxidase (PAO, EC 1.4.3.4) activities showed that higher DAO and PAO enzyme activities were obtained when high concentrations of polyamines were applied and when plantlets were treated for 5–7 week at 4°C and 16°C. Survival rate of plantlets increased with the treatment of polyamines at low temperature. Polyamines increased mitotic index of cells in root tips of regenerated plantlet cultured on medium containing 0.001 μM Put, Spd, or Spm, but did not increase mitotic index in tissues of needle tips of the same plantlets. These results demonstrated that polyamines promote root elongation and growth by increasing root cell division in regenerated Virginia pine plantlets.
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High efficiency inducible gene expression system based on activation of a chimeric transcription factor in transgenic pine
Plant Cell Reports, 2005Co-Authors: Wei Tang, Ronald J. Newton, Thomas M. CharlesAbstract:Inducible gene expression systems are needed in functional genomics of tree species. A glucocorticoid-inducible gene expression system was established in a gymnosperm species Virginia pine (Pinus virginiana Mill.) through Agrobacterium tumefaciens-mediated genetic transformation. The results demonstrate that expression of the m-gfp5-ER reporter gene was tightly controlled and 0.1 μM of the glucocorticoid hormone triamcinolone was able to induce m-gfp5-ER expression in transgenic cells. Differential expression of gfp in transgenic cells induced by different concentrations of triamcinolone was observed and confirmed by Northern Blot analysis and by quantitative green fluorescence analyses with Laser Scanning Microscopy. In transgenic plantlets, triamcinolone was taken up efficiently by roots. Triamcinolone was able to induce m-gfp5-ER activity throughout the whole plant. The phenotype of transgenic plantlets was not affected 6 weeks after treatment with 0.1–10 μM triamcinolone. However, 6-week inductions with 100 μM triamcinolone caused growth retardation and developmental defects, as well as inhibition of root formation and elongation. With careful selection of transgenic lines, the inducible gene expression presented in this study could be a very valuable alternative for functional identification of novel genes in plants, especially in pine.
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Overexpression of the Pepper Transcription Factor CaPF1 in Transgenic Virginia Pine (Pinus virginiana Mill.) Confers Multiple Stress Tolerance and Enhances Organ Growth
Plant Molecular Biology, 2005Co-Authors: Wei Tang, Thomas M. Charles, Ronald J. NewtonAbstract:Transcription factors play an important role in regulating gene expression in response to stress and pathogen tolerance. We describe here that overexpression of an ERF/AP2 pepper transcription factor ( CaPF1 ) in transgenic Virginia pine ( Pinus virginiana Mill.) confers tolerance to heavy metals Cadmium, Copper, and Zinc, to heat, and to pathogens Bacillus thuringiensis and Staphylococcus epidermidis , as by the survival rate of transgenic plants and the number of decreasing pathogen cells in transgenic tissues. Measurement of antioxidant enzymes ascorbate peroxidase (APOX), glutathione reductase (GR), and superoxide dismutase (SOD) activities demonstrated that the level of the enzyme activities was higher in transgenic Virginia pine plants overexpressing the CaPF1 gene, which may protect cells from the oxidative damage caused by stresses, compared to the controls. Constitutive overexpression of CaPF1 gene enhanced organ growth by increasing organ size and cell numbers in transgenic Virginia pine plants over those in control plants.
Wei Tang - One of the best experts on this subject based on the ideXlab platform.
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Expression of a transcription factor from Capsicum annuum in pine calli counteracts the inhibitory effects of salt stress on adventitious shoot formation
Molecular Genetics and Genomics, 2006Co-Authors: Wei Tang, Ronald J. Newton, Thomas M. CharlesAbstract:Transcription factors regulating the stress-responsive gene expression play an important role in plant stress adaptation. In this study, we examined the salt stress tolerance of transgenic Vir- ginia pine (Pinus virginiana Mill.) overexpressing a Capsicum annuum ERF/AP2-type transcription fac- tor (CaPF1), which may enhance the ability of trans- genic plants to tolerate various kinds of stresses during vegetative growth. CaPF1 transgene increased the salt and oxidative stress tolerances of pine tissues and counteracted the inhibitory eVects of salt stress on the growth of transgenic Virginia pine calli, shoots, and plants. To our surprise, the ability of shoot formation was enhanced in three CaPF1 transgenic Virginia pine cell lines under stress of diVerent NaCl concentrations. NaCl at 200 mM signiWcantly increased the frequency of adventitious shoot formation and the number of shoots per gram calli. Measurement of plant hor- mone demonstrated that the levels of cytokinin was altered in CaPF1-overexpressed Virginia pine calli, compared to the control. Based on our results, we speculate that the altered level of cytokinin may result in enhancing adventitious shoot formation of transgenic calli exposed to salt for 1 week via an unknown mechanism.
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Differential gene silencing induced by short interfering RNA in cultured pine cells associates with the cell cycle phase
Planta, 2006Co-Authors: Wei Tang, Ronald J. Newton, Douglas A. WeidnerAbstract:The double-stranded short interfering RNA (siRNA) molecules can silence targeted genes through sequence-specific cleavage of the cognate RNA transcript. The rapid adoption of technologies based on this siRNA interference mechanism has been a widely used method to analyze gene function in plants, invertebrates, and mammalian systems. In order to understand the dynamics of siRNA-mediated gene inactivation during cell division, we have investigated the relationship between the cell cycle phase and the post-transcriptional gene silencing mediated by siRNA in gfp transgenic Virginia pine ( Pinus virginiana Mill.) cells. Among the different phases of the cell cycle, transgenic cells at the M phase gave 2–3 times lower gfp silencing than those at the G1, S, and G2 phases. The similar results of the siRNA-mediated gfp silencing were obtained in three transgenic cell lines. Differential gfp silencing induced by siRNA has been confirmed by northern blot, laser scanning microscopy, and siRNA analysis. These data suggested that siRNA-mediated gene inactivation is associated with the cell cycle phase in Virginia pine.
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Polyamines promote root elongation and growth by increasing root cell division in regenerated Virginia pine (Pinus virginiana Mill.) plantlets
Plant Cell Reports, 2005Co-Authors: Wei Tang, Ronald J. NewtonAbstract:Polyamines have been demonstrated to play an important role in adventitious root formation and development in plants. Here, we present a detailed analysis of influence of exogenously added polyamines on adventitious root development and its relationship to cold tolerance in Virginia pine ( Pinus virginia Mill.). Our results demonstrated that polyamines putrescine (Put), spermidine (Spd), and spermine (Spm) at 0.001 mM improve rooting frequency and promote root elongation. Put, Spd, and Spm at 0.01–1 mM decrease rooting frequency and reduce root elongation root elongation. Measurements of diamine oxidase (DAO, EC 1.4.3.6) and polyamine oxidase (PAO, EC 1.4.3.4) activities showed that higher DAO and PAO enzyme activities were obtained when high concentrations of polyamines were applied and when plantlets were treated for 5–7 week at 4°C and 16°C. Survival rate of plantlets increased with the treatment of polyamines at low temperature. Polyamines increased mitotic index of cells in root tips of regenerated plantlet cultured on medium containing 0.001 μM Put, Spd, or Spm, but did not increase mitotic index in tissues of needle tips of the same plantlets. These results demonstrated that polyamines promote root elongation and growth by increasing root cell division in regenerated Virginia pine plantlets.
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High efficiency inducible gene expression system based on activation of a chimeric transcription factor in transgenic pine
Plant Cell Reports, 2005Co-Authors: Wei Tang, Ronald J. Newton, Thomas M. CharlesAbstract:Inducible gene expression systems are needed in functional genomics of tree species. A glucocorticoid-inducible gene expression system was established in a gymnosperm species Virginia pine (Pinus virginiana Mill.) through Agrobacterium tumefaciens-mediated genetic transformation. The results demonstrate that expression of the m-gfp5-ER reporter gene was tightly controlled and 0.1 μM of the glucocorticoid hormone triamcinolone was able to induce m-gfp5-ER expression in transgenic cells. Differential expression of gfp in transgenic cells induced by different concentrations of triamcinolone was observed and confirmed by Northern Blot analysis and by quantitative green fluorescence analyses with Laser Scanning Microscopy. In transgenic plantlets, triamcinolone was taken up efficiently by roots. Triamcinolone was able to induce m-gfp5-ER activity throughout the whole plant. The phenotype of transgenic plantlets was not affected 6 weeks after treatment with 0.1–10 μM triamcinolone. However, 6-week inductions with 100 μM triamcinolone caused growth retardation and developmental defects, as well as inhibition of root formation and elongation. With careful selection of transgenic lines, the inducible gene expression presented in this study could be a very valuable alternative for functional identification of novel genes in plants, especially in pine.
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Overexpression of the Pepper Transcription Factor CaPF1 in Transgenic Virginia Pine (Pinus virginiana Mill.) Confers Multiple Stress Tolerance and Enhances Organ Growth
Plant Molecular Biology, 2005Co-Authors: Wei Tang, Thomas M. Charles, Ronald J. NewtonAbstract:Transcription factors play an important role in regulating gene expression in response to stress and pathogen tolerance. We describe here that overexpression of an ERF/AP2 pepper transcription factor ( CaPF1 ) in transgenic Virginia pine ( Pinus virginiana Mill.) confers tolerance to heavy metals Cadmium, Copper, and Zinc, to heat, and to pathogens Bacillus thuringiensis and Staphylococcus epidermidis , as by the survival rate of transgenic plants and the number of decreasing pathogen cells in transgenic tissues. Measurement of antioxidant enzymes ascorbate peroxidase (APOX), glutathione reductase (GR), and superoxide dismutase (SOD) activities demonstrated that the level of the enzyme activities was higher in transgenic Virginia pine plants overexpressing the CaPF1 gene, which may protect cells from the oxidative damage caused by stresses, compared to the controls. Constitutive overexpression of CaPF1 gene enhanced organ growth by increasing organ size and cell numbers in transgenic Virginia pine plants over those in control plants.
Thomas M. Charles - One of the best experts on this subject based on the ideXlab platform.
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Expression of a transcription factor from Capsicum annuum in pine calli counteracts the inhibitory effects of salt stress on adventitious shoot formation
Molecular Genetics and Genomics, 2006Co-Authors: Wei Tang, Ronald J. Newton, Thomas M. CharlesAbstract:Transcription factors regulating the stress-responsive gene expression play an important role in plant stress adaptation. In this study, we examined the salt stress tolerance of transgenic Vir- ginia pine (Pinus virginiana Mill.) overexpressing a Capsicum annuum ERF/AP2-type transcription fac- tor (CaPF1), which may enhance the ability of trans- genic plants to tolerate various kinds of stresses during vegetative growth. CaPF1 transgene increased the salt and oxidative stress tolerances of pine tissues and counteracted the inhibitory eVects of salt stress on the growth of transgenic Virginia pine calli, shoots, and plants. To our surprise, the ability of shoot formation was enhanced in three CaPF1 transgenic Virginia pine cell lines under stress of diVerent NaCl concentrations. NaCl at 200 mM signiWcantly increased the frequency of adventitious shoot formation and the number of shoots per gram calli. Measurement of plant hor- mone demonstrated that the levels of cytokinin was altered in CaPF1-overexpressed Virginia pine calli, compared to the control. Based on our results, we speculate that the altered level of cytokinin may result in enhancing adventitious shoot formation of transgenic calli exposed to salt for 1 week via an unknown mechanism.
-
High efficiency inducible gene expression system based on activation of a chimeric transcription factor in transgenic pine
Plant Cell Reports, 2005Co-Authors: Wei Tang, Ronald J. Newton, Thomas M. CharlesAbstract:Inducible gene expression systems are needed in functional genomics of tree species. A glucocorticoid-inducible gene expression system was established in a gymnosperm species Virginia pine (Pinus virginiana Mill.) through Agrobacterium tumefaciens-mediated genetic transformation. The results demonstrate that expression of the m-gfp5-ER reporter gene was tightly controlled and 0.1 μM of the glucocorticoid hormone triamcinolone was able to induce m-gfp5-ER expression in transgenic cells. Differential expression of gfp in transgenic cells induced by different concentrations of triamcinolone was observed and confirmed by Northern Blot analysis and by quantitative green fluorescence analyses with Laser Scanning Microscopy. In transgenic plantlets, triamcinolone was taken up efficiently by roots. Triamcinolone was able to induce m-gfp5-ER activity throughout the whole plant. The phenotype of transgenic plantlets was not affected 6 weeks after treatment with 0.1–10 μM triamcinolone. However, 6-week inductions with 100 μM triamcinolone caused growth retardation and developmental defects, as well as inhibition of root formation and elongation. With careful selection of transgenic lines, the inducible gene expression presented in this study could be a very valuable alternative for functional identification of novel genes in plants, especially in pine.
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Overexpression of the Pepper Transcription Factor CaPF1 in Transgenic Virginia Pine (Pinus virginiana Mill.) Confers Multiple Stress Tolerance and Enhances Organ Growth
Plant Molecular Biology, 2005Co-Authors: Wei Tang, Thomas M. Charles, Ronald J. NewtonAbstract:Transcription factors play an important role in regulating gene expression in response to stress and pathogen tolerance. We describe here that overexpression of an ERF/AP2 pepper transcription factor ( CaPF1 ) in transgenic Virginia pine ( Pinus virginiana Mill.) confers tolerance to heavy metals Cadmium, Copper, and Zinc, to heat, and to pathogens Bacillus thuringiensis and Staphylococcus epidermidis , as by the survival rate of transgenic plants and the number of decreasing pathogen cells in transgenic tissues. Measurement of antioxidant enzymes ascorbate peroxidase (APOX), glutathione reductase (GR), and superoxide dismutase (SOD) activities demonstrated that the level of the enzyme activities was higher in transgenic Virginia pine plants overexpressing the CaPF1 gene, which may protect cells from the oxidative damage caused by stresses, compared to the controls. Constitutive overexpression of CaPF1 gene enhanced organ growth by increasing organ size and cell numbers in transgenic Virginia pine plants over those in control plants.
John E Linhoss - One of the best experts on this subject based on the ideXlab platform.
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regeneration of virginia pine Pinus virginiana following southern pine beetle dendroctonus frontalis outbreak in the sipsey wilderness alabama
Forest Ecology and Management, 2005Co-Authors: Scot R Duncan, John E LinhossAbstract:We examined regeneration patterns of Virginia pine (Pinus virginiana) following a severe southern pine beetle (Dendroctonus frontalis) epidemic in the Sipsey Wilderness of the Bankhead National Forest, Alabama. Our findings illustrate how a passive approach to forest management, as mandated for such wilderness areas, can lead to considerable changes in the structure and species composition of protected ecosystems. P. virginiana is an early-successional species and large mature stands are found within the wilderness. P. virginiana reportedly needs direct sunlight and exposed soil to establish. Succession in surviving stands is leading to the establishment of hardwood forest. Because management to slow the beetle epidemic is prohibited in the wilderness, many stands of P. virginiana were killed. The resulting gaps may provide habitat for new P. virginiana recruitment, thus prolonging the existence of these stands in the forest. To determine how the epidemic has affected recruitment patterns of P. virginiana, we surveyed existing or recently beetle-killed stands, designating four habitat types corresponding to the presence and absence of direct sunlight and exposed soil. Densities of small saplings were low within gaps, where sunlight is plentiful but exposed soil is uncommon. Small saplings were most dense where hiking trails crossed through gaps; such areas are small, but provide direct sunlight and exposed soil. No small saplings were found in the shade of surviving P. virginiana stands, even near trails. In another survey, we found that small sapling densities were positively correlated with gap size. Recruitment density in some of the gaps was sufficient to replace beetle-killed stands. Greenhouse experiments conducted to examine the importance of sunlight and exposed soil for germination and seedling survival unexpectedly revealed that P. virginiana can germinate and survive in shade, below leaf litter, or in the presence of both. Inadvertently, the experiment suggested moderate amounts of shade and litter can facilitate germination when water availability is low. Altogether, our results suggest that P. virginiana is recruiting in gaps created by the epidemic, but this is confined to larger gaps. Over time, the distribution of P. virginiana in the wilderness will likely be no different than had the epidemic not occurred, as succession in the gaps and in mature unaffected P. virginiana stands should lead to the same type of mature forest.
Ryan E Casey - One of the best experts on this subject based on the ideXlab platform.
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A 200-year paleoecological record of Pinus vivginiana, trace metals, sedimentation, and mining disturbance in a Maryland serpentine barren1
2020Co-Authors: William B Hilgartner, Mark Nejako, Ryan E CaseyAbstract:Hilgartner, W. B. (Engineering Programs for Professionals, The Johns Hopkins University Baltimore, MD 21218 and Science Department, Friends School, Baltimore, MD 21210), M. Nejako (Department of Biological Sciences, Towson University, Towson, MD 21252), and R. Casey (Department of Chemistry, Towson University, Towson, MD 21252). A 200-year paleoecological record of Pinus virginiana, trace metals, sedimentation, and mining disturbance in a Maryland serpentine barren. J. Torrey Bot. Soc. 136: 257-271. 2009.?The objective of this study was to provide stratigraphic data that could augment historic and recent ecological information concerning the cause of the 20th century vegetation shift from grassland to pine forest in a central Maryland serpentine barren, and potentially elucidate the role of fire, chromium mining, grazing, and other disturbances on serpentine vegetation. A 46-cm core was extracted from a shallow pond draining the watershed of Chimney Branch, underlain by serpentinite. Core chronostratigraphy was established by identifying two sharp spikes in Cr concentrations correlated with historic Cr mining activity peaks and an abrupt increase in pine needle abundance, when pine populations expanded around the coring site. Pine needle analysis reveals that Pinus virginiana (Virginia pine) has been present within a few meters of the coring site since ca. 1810, 120 years earlier than previously documented. A dearth of charcoal over the 200-yr period indicates there were no major fires at the coring site after 1820, although small ground fires within a few 10 s of meters cannot be precluded. Mean sedimentation rates between dated horizons reveal that sediment efflux was highest during the early to mid-19th century (0.51-0.35 cm yr_1), synchronous with active Cr mining activity, and lowest in the past 50 years (0.19 cm yr"1) when the area fell under state management and pine forest expanded. Metal concentrations were highest for Cr and Ni, followed in decreasing order by V, Zn, Cu, and Pb. Results from this study suggest that 1) while Pinus virginiana was present in the early 1800s in sheltered lowland sites chromite-mining and its erosive effects on soil development may have been a factor in suppressing pine expansion in the Chimney Branch watershed between 1820 and 1920. Hence, pine expansion may be a natural stage in the succession of serpentine vegetation related directly to increasing soil depth, with the pace of expansion influenced by fire or mining disturbance; and 2) variation in Cr concentrations combined with mining history and macrofossils, in conjunction with aerial photos and recent studies, can provide useful stratigraphic dates to establish ecosystem development within the past 200 years in a serpentine environment.
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a 200 year paleoecological record of Pinus virginiana trace metals sedimentation and mining disturbance in a maryland serpentine barren1
Journal of The Torrey Botanical Society, 2009Co-Authors: William B Hilgartner, Mark Nejako, Ryan E CaseyAbstract:Abstract The objective of this study was to provide stratigraphic data that could augment historic and recent ecological information concerning the cause of the 20th century vegetation shift from grassland to pine forest in a central Maryland serpentine barren, and potentially elucidate the role of fire, chromium mining, grazing, and other disturbances on serpentine vegetation. A 46-cm core was extracted from a shallow pond draining the watershed of Chimney Branch, underlain by serpentinite. Core chronostratigraphy was established by identifying two sharp spikes in Cr concentrations correlated with historic Cr mining activity peaks and an abrupt increase in pine needle abundance, when pine populations expanded around the coring site. Pine needle analysis reveals that Pinus virginiana (Virginia pine) has been present within a few meters of the coring site since ca. 1810, 120 years earlier than previously documented. A dearth of charcoal over the 200-yr period indicates there were no major fires at the cori...
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a 200 year paleoecological record of Pinus virginiana t race metals sedimentation and mining disturbance in a maryland
2009Co-Authors: William B Hilgartner, Mark Nejako, Ryan E CaseyAbstract:) when the area fell under state management and pine forest expanded. Metal concentrations were highest for Cr and Ni, followed in decreasing order by V, Zn, Cu, and Pb. Results from this study suggest that 1) while Pinus virginiana was present in the early 1800s in sheltered lowland sites chromite-mining and its erosive effects on soil development may have been a factor in suppressing pine expansion in the Chimney Branch watershed between 1820 and 1920. Hence, pine expansion may be a natural stage in the succession of serpentine vegetation related directly to increasing soil depth, with the pace of expansion influenced by fire or mining disturbance; and 2) variation in Cr concentrations combined with mining history and macrofossils, in conjunction with aerial photos and recent studies, can provide useful stratigraphic dates to establish ecosystem development within the past 200 years in a serpentine environment.