We evaluated whether changes in fine root non-structural carbohydrate reserves of Fagus sylvatica... more We evaluated whether changes in fine root non-structural carbohydrate reserves of Fagus sylvatica and Pinus sylvestris trees influence potential enzymatic activities of their ectomycorrhizal symbionts from winter towards spring reactivation, and whether these changes influence potential soil enzymatic activities. We analyzed sugar and starch concentrations in the fine roots of Fagus sylvatica and Pinus sylvestris and potential activities of ß-glucosidase, ß-xylosidase, and cellobiohydrolase (as proxies for carbon-degrading enzymes) as well as leucine aminopeptidase and chitinase (as proxies for nitrogen-degrading enzymes) of their dominant ectomycorrhizal symbionts as well as in the soil. Sugar concentrations in the fine roots were significantly positively correlated with enzymatic activities of the ectomycorrhizal symbionts. In Pinus sylvestris, both carbon- and nitrogen-degrading enzyme activities showed significant positive correlations with fine root sugar concentrations. In Fag...
Carbohydrate reserves provide advantages for mature trees experiencing frequent disturbances; how... more Carbohydrate reserves provide advantages for mature trees experiencing frequent disturbances; however, it is unclear if selective pressures operate on this characteristic at the seedling or mature life history stage. We hypothesized that natural selection has favored carbohydrate reserves in species that have an evolutionary history of frequent disturbance and tested this using three southern pine species that have evolved across a continuum of fire frequencies. Longleaf pine (Pinus palustris) roots exhibited higher maximum starch concentrations than slash (P. elliottii) and loblolly (P. taeda), which were similar. Longleaf also relied on starch reserves in roots more than slash or loblolly, depleting 64, 41, and 23 mg g−1 of starch, respectively, between seasonal maximum and minimum, which represented 52%, 45%, and 26% of reserves, respectively. Starch reserves in stems did not differ among species or exhibit temporal dynamics. Our results suggest that an evolutionary history of di...
ABSTRACT Background/Question/Methods The allocation of assimilated carbon to storage pools provid... more ABSTRACT Background/Question/Methods The allocation of assimilated carbon to storage pools provides a critical carbohydrate buffer when metabolic demands exceed current photosynthetic supply. Despite the importance of carbon storage to the forest carbon cycle, our process-level understanding of the controls on carbon storage pools and fluxes at tree and ecosystem scales remains relatively poor. Recent evidence suggests that stored carbon pools increased even after growth had ceased in trees experiencing drought and that tapping of rubber trees resulted in increased—not decreased—stored carbon pools. These observations suggest a paradigm shift away from the concept that stored carbon pools are a sink of low priority that accumulate passively when photosynthetic inputs exceed demand and toward the concept that these pools are active sinks of high priority. It follows that allocation toward storage—at the expense of growth—is a trait that would be under selective pressure since species that allocate toward storage are more resilient to disturbance. Using the fire-dependent longleaf pine ecosystem in a series of manipulative and observational studies, we explore how stored carbon dynamics are controlled by a combination of evolutionary, physiological, and ecological pressures. Results/Conclusions Multiple lines of evidence support the concept that stored carbon dynamics are controlled by a combination of evolutionary, physiological, and ecological pressures. Our manipulative studies revealed that roots of longleaf pine contained large stored carbon pools that maintained belowground metabolism for a year after the photosynthetic carbohydrate supply was restricted. Likewise, the concentration of stored carbon in the smallest, most metabolically active roots was not influenced until nearly one year later. Our observational studies indicate that stored carbon pools differ among closely related pine species with overlapping natural distributions, but evolutionary histories of different disturbance frequencies and thus, different selective pressures on carbon storage. Our comparisons of stored carbon pools between longleaf trees growing under xeric or mesic soil moisture regimes, in combination with other drought studies, indicate that allocation toward storage exhibits plasticity through space and time in response to both short- and long-term variations in resource availability. We expect a continuum of responses to disturbances related to ecological niche and evolutionary adaptation that influence the availability of carbohydrates for metabolic demands, as well as a continuum in stored carbon pools and metabolic buffering capacity among species as well as spatially, temporally, and developmentally within a given species.
Quasi one-dimensional iron chains are formed in thermally evaporated iron phthalocyanine thin fil... more Quasi one-dimensional iron chains are formed in thermally evaporated iron phthalocyanine thin films on silicon substrates. The chain length is modified by the substrate growth temperature and can be controlled within one order of magnitude. The surface morphology of organic thin films (80nm) is studied with atomic force microscopy. The grains are randomly oriented, have odd shapes, and are strongly
Handbook of Research on Innate Leadership Characteristics and Examinations of Successful First-Time Leaders, 2021
In this case study, a faculty member at a Historically Black College/University (HBCU) shares the... more In this case study, a faculty member at a Historically Black College/University (HBCU) shares their story of working as a white male in an all-Black college from first hire, to leaving, to returning in order to lead their former academic program. During their first year of leadership the author faced personal tragedy, professional promotion, strained relationships with colleagues, and finally, a global pandemic that changed the world. For those interested in the experiences of a first-time leader, this is a unique case study.
We evaluated whether changes in fine root non-structural carbohydrate reserves of Fagus sylvatica... more We evaluated whether changes in fine root non-structural carbohydrate reserves of Fagus sylvatica and Pinus sylvestris trees influence potential enzymatic activities of their ectomycorrhizal symbionts from winter towards spring reactivation, and whether these changes influence potential soil enzymatic activities. We analyzed sugar and starch concentrations in the fine roots of Fagus sylvatica and Pinus sylvestris and potential activities of ß-glucosidase, ß-xylosidase, and cellobiohydrolase (as proxies for carbon-degrading enzymes) as well as leucine aminopeptidase and chitinase (as proxies for nitrogen-degrading enzymes) of their dominant ectomycorrhizal symbionts as well as in the soil. Sugar concentrations in the fine roots were significantly positively correlated with enzymatic activities of the ectomycorrhizal symbionts. In Pinus sylvestris, both carbon- and nitrogen-degrading enzyme activities showed significant positive correlations with fine root sugar concentrations. In Fag...
Carbohydrate reserves provide advantages for mature trees experiencing frequent disturbances; how... more Carbohydrate reserves provide advantages for mature trees experiencing frequent disturbances; however, it is unclear if selective pressures operate on this characteristic at the seedling or mature life history stage. We hypothesized that natural selection has favored carbohydrate reserves in species that have an evolutionary history of frequent disturbance and tested this using three southern pine species that have evolved across a continuum of fire frequencies. Longleaf pine (Pinus palustris) roots exhibited higher maximum starch concentrations than slash (P. elliottii) and loblolly (P. taeda), which were similar. Longleaf also relied on starch reserves in roots more than slash or loblolly, depleting 64, 41, and 23 mg g−1 of starch, respectively, between seasonal maximum and minimum, which represented 52%, 45%, and 26% of reserves, respectively. Starch reserves in stems did not differ among species or exhibit temporal dynamics. Our results suggest that an evolutionary history of di...
ABSTRACT Background/Question/Methods The allocation of assimilated carbon to storage pools provid... more ABSTRACT Background/Question/Methods The allocation of assimilated carbon to storage pools provides a critical carbohydrate buffer when metabolic demands exceed current photosynthetic supply. Despite the importance of carbon storage to the forest carbon cycle, our process-level understanding of the controls on carbon storage pools and fluxes at tree and ecosystem scales remains relatively poor. Recent evidence suggests that stored carbon pools increased even after growth had ceased in trees experiencing drought and that tapping of rubber trees resulted in increased—not decreased—stored carbon pools. These observations suggest a paradigm shift away from the concept that stored carbon pools are a sink of low priority that accumulate passively when photosynthetic inputs exceed demand and toward the concept that these pools are active sinks of high priority. It follows that allocation toward storage—at the expense of growth—is a trait that would be under selective pressure since species that allocate toward storage are more resilient to disturbance. Using the fire-dependent longleaf pine ecosystem in a series of manipulative and observational studies, we explore how stored carbon dynamics are controlled by a combination of evolutionary, physiological, and ecological pressures. Results/Conclusions Multiple lines of evidence support the concept that stored carbon dynamics are controlled by a combination of evolutionary, physiological, and ecological pressures. Our manipulative studies revealed that roots of longleaf pine contained large stored carbon pools that maintained belowground metabolism for a year after the photosynthetic carbohydrate supply was restricted. Likewise, the concentration of stored carbon in the smallest, most metabolically active roots was not influenced until nearly one year later. Our observational studies indicate that stored carbon pools differ among closely related pine species with overlapping natural distributions, but evolutionary histories of different disturbance frequencies and thus, different selective pressures on carbon storage. Our comparisons of stored carbon pools between longleaf trees growing under xeric or mesic soil moisture regimes, in combination with other drought studies, indicate that allocation toward storage exhibits plasticity through space and time in response to both short- and long-term variations in resource availability. We expect a continuum of responses to disturbances related to ecological niche and evolutionary adaptation that influence the availability of carbohydrates for metabolic demands, as well as a continuum in stored carbon pools and metabolic buffering capacity among species as well as spatially, temporally, and developmentally within a given species.
Quasi one-dimensional iron chains are formed in thermally evaporated iron phthalocyanine thin fil... more Quasi one-dimensional iron chains are formed in thermally evaporated iron phthalocyanine thin films on silicon substrates. The chain length is modified by the substrate growth temperature and can be controlled within one order of magnitude. The surface morphology of organic thin films (80nm) is studied with atomic force microscopy. The grains are randomly oriented, have odd shapes, and are strongly
Handbook of Research on Innate Leadership Characteristics and Examinations of Successful First-Time Leaders, 2021
In this case study, a faculty member at a Historically Black College/University (HBCU) shares the... more In this case study, a faculty member at a Historically Black College/University (HBCU) shares their story of working as a white male in an all-Black college from first hire, to leaving, to returning in order to lead their former academic program. During their first year of leadership the author faced personal tragedy, professional promotion, strained relationships with colleagues, and finally, a global pandemic that changed the world. For those interested in the experiences of a first-time leader, this is a unique case study.
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