Red spruce is a shade-tolerant conifer whose distribution and abundance reflect Quaternary climate history as well as natural and anthropogenic disturbances. This species once extended further south than its present localities, because of natural and anthropogenic disturbances such as logging, windthrow, and fire. Little is known about the disturbance regime of this species, because long term stand dynamics are difficult to obtain. This-long lived species is hypothesized to be suffering a decline in radial growth, density and abundance at the present time. Recent research suggests pollution, biotic stresses, climate change and natural stand dynamics are the driving forces behind these decreases. The purpose of this study is to investigate the influence of fire in a mesic ecosystem, specifically a high-elevation red spruce (Picea rubens Sarg.) forest on Whitetop Mountain in the southern Appalachian Mountains. Six plots were established in a high elevation red spruce stand to characterize the stand composition. Tree ring data were collected to investigate radial growth relations to inter-annual climatic variability and cross-sections were used to investigate fire history. Red spruce continued to establish throughout the 19th century until a severe fire occurred in 1919 and caused a new cohort of yellow birch (Betula alleghaniensis Britt.) to establish within the stand. Logging and fire caused high mortality in the stand, yet many spruce remain that outdate the past disturbances. Red spruce saplings continue to persist in the stand, showing regeneration despite the abundant hardwoods. Moisture was the main contributing factor to red spruce growth in the dendroclimatic analysis. Red spruce radial growth was significantly correlated to high precipitation and low temperatures of the previous growing season, which is similar to recent research results. This study collaborates the current literature on red spruce growth along with the results found here in creating a model to represent the growth characteristics of red spruce when inter-mixed with hardwoods after a severe disturbance.

Red spruce is a shade-tolerant conifer whose distribution and abundance reflect Quaternary climate history as well as natural and anthropogenic disturbances. This species once extended further south than its present localities, because of natural and anthropogenic disturbances such as logging, windthrow, and fire. Little is known about the disturbance regime of this species, because long term stand dynamics are difficult to obtain. This-long lived species is hypothesized to be suffering a decline in radial growth, density and abundance at the present time. Recent research suggests pollution, biotic stresses, climate change and natural stand dynamics are the driving forces behind these decreases. The purpose of this study is to investigate the influence of fire in a mesic ecosystem, specifically a high-elevation red spruce (Picea rubens Sarg.) forest on Whitetop Mountain in the southern Appalachian Mountains. Six plots were established in a high elevation red spruce stand to characterize the stand composition. Tree ring data were collected to investigate radial growth relations to inter-annual climatic variability and cross-sections were used to investigate fire history. Red spruce continued to establish throughout the 19th century until a severe fire occurred in 1919 and caused a new cohort of yellow birch (Betula alleghaniensis Britt.) to establish within the stand. Logging and fire caused high mortality in the stand, yet many spruce remain that outdate the past disturbances. Red spruce saplings continue to persist in the stand, showing regeneration despite the abundant hardwoods. Moisture was the main contributing factor to red spruce growth in the dendroclimatic analysis. Red spruce radial growth was significantly correlated to high precipitation and low temperatures of the previous growing season, which is similar to recent research results. This study collaborates the current literature on red spruce growth along with the results found here in creating a model to represent the growth characteristics of red spruce when inter-mixed with hardwoods after a severe disturbance.

Thesis (Ph. D.) in Forest Resources--University of Maine, 2000. / Includes vita. Includes bibliographical references (leaves 134-143).

Thesis (M.S.) in Forestry--University of Maine, 2006. / Includes vita. Includes bibliographical references (leaves 87-96).

No description available.

Isozymes of glutathione reductase (GR) have been purified from red spruce. A major isozyme is present throughout the year, while one isozyme is present only during summer in non-hardened needles. A third isozyme is present only during winter in hardened needles. The isozymes present in non-hardened and hardened needles have been designated GR-INH and GR-IH, respectively. The major GR isoform has been designated GR-2NH or GR-H, depending on whether it was purified from nonhardened or hardened needles. GR-2NH and GR-2H have been purified to homogeneity, as judged by SDS polyacrylamide gel electrophoresis. GR-lNH and GR-IH showed several contaminating proteins in the final preparations. GR-2NH and GR-2H could each be further separated into five charge isomers by isoelectric focussing, and the relative abundance of these charge isomers differs between preparations from non-hardened and hardened needles. GR-1NH and GR-1H differ from GR-2NH and GR-2H with respect to their kinetic, immunological, and physical characteristics. GR-1NH appears different from GR-1H based on chromatographic and electrophoretic behaviour. However, no differences in the temperature dependence of kinetic parameters between either isozyme have been found. The amino-terminal sequences of GR-1H and GR-2H show a high degree of homology with GR's from other organisms. Oligonucleotides derived from the amino-terminal sequences of GR-1H and GR-2H, or from conserved regions within other GR's have been derived and used to amplify cDNA by the polymerase chain reaction. A 500 base pair cDNA, produced with oligonucleotides expected to be specific for GR-1H has been used to transform E.coli. The differences between the isozymes are discussed with respect to temperature adaptation of enzyme function in a species that experiences extreme temperature differences during its life cycle. / Ph. D.

Thesis (Ph. D.) in Forest Resources--University of Maine, 2002. / Includes vita. Includes bibliographical references (leaves 216-241).

No description available.

No description available.

Three studies were performed to investigate the impact of air pollution on high-elevation red spruce-Fraser fir forests in the Southern Appalachians. In the first study, red spruce (Picea rubens Sarg.) and Fraser fir (Abies fraseri (Pursh.) Poir.) seedlings were submitted to long-term (2.5 yrs), multiple growing cycle (4 and 5, respectively), intermittent ozone fumigations (0.025, 0.070, and 0.150 ppm). No effect of ozone exposure on growth and gas exchange of the seedlings was found. Net photosynthesis at saturating light intensity was reduced in both species and the light compensation point was shifted upwards in spruce when exposed to ozone. Fraser fir seedlings showed inconsistent responses of CO₂ curve parameters to ozone exposure. There were indications that ozone exposure modified cell wall modulus of elasticity in both species. In the second study, the impact of summer exposure to ambient pollutants on winter hardiness in red spruce seedlings was examined. The seedlings were subjected to the following summertime treatments while kept in exclusion chambers on the top of Whitetop Mountain (Virginia): ambient air and clouds, ambient air with clouds excluded, charcoal filtered air, and chamberless control treatment. During the following winter the seedlings were placed in Blacksburg (Virginia), in two locations: in the open and in a shadehouse. A number of conducted tests indicated that there were significant differences in winter damage between the chamber treatments and chamberless control, as well as between the winter exposure locations. Among the summer chamber exposure regimes, the treatment excluding clouds seemed to perform the best (although not all the evidence supports the latter statement). In the third study, the physiology of red spruce trees of various sizes (seedlings, saplings, and overstory trees), growing on two sites on the top of Whitetop Mtn., was compared and related to ambient ozone concentration. Some seedlings were treated with an antioxidant EDU, to help evaluate the impact of ozone on their physiology. The trees of various sizes showed clear differences in gas exchange, with overstory trees photosynthesizing at the lowest rates, and seedlings - at the highest. Overstory trees also showed more negative shoot water potential and higher night respiration than smaller tree sizes. No deleterious effects of ambient ozone on red spruce physiology were detected. / Ph. D.