Red Oak (red + oak)

Distribution by Scientific Domains


Selected Abstracts


Vegetation and disturbance history of a rare dwarf pitch pine community in western New England, USA

JOURNAL OF BIOGEOGRAPHY, Issue 10-11 2002
Glenn Motzkin
Abstract Aim, This study documents the vegetation history and age-structure of a rare, ridgetop dwarf pine,oak community and compares the dynamics of this unusual vegetation with similar dwarf pine communities found elsewhere in the north-eastern United States (US). Location, The study area is located on the summit of Mt Everett in the Taconic Mountains of south-western Berkshire County, Massachusetts, USA (42°06,N 73°26,W). Methods, Vegetation composition, tree age-structure, physical site characteristics, and evidence of fire and other disturbances were determined for twelve 15 × 15 m plots in dwarf pine,oak vegetation and two plots in oak forests on the summit. Age-structure analyses, tree-ring patterns, and historical records of human and natural disturbance were used to investigate the long-term history and dynamics of the summit vegetation. Results, The summit of Mt Everett has been dominated by dwarf pines (1,3 m tall) and ericaceous shrubs similar to the modern vegetation throughout the historical period; there is no evidence that tall-stature forests occurred on the site at any point in the past few centuries. The summit supports uneven-aged stands; pitch pine (Pinus rigida) recruitment began in the 1830s and occurred in every decade since the 1860s. Average pitch pine age is seventy-eight with a range of 12,170 years. Red oak (Quercus rubra) and red maple (Acer rubrum) increased in importance in the twentieth century, with most stems establishing from 1940 to 1980. Pitch pine radial growth rates averaged <0.5 mm year,1 while red oak and red maple averaged 1.0 and 0.8 mm year,1, respectively. In some areas, hardwoods have overtopped pitch pines, apparently resulting in pitch pine mortality. Whereas most dwarf pitch pine communities occur on sites that burn frequently and have a high degree of cone serotiny, we found no evidence of recent fires or cone serotiny. Small amounts of macroscopic charcoal that we documented may have resulted from fires in the pre-European or early historical periods. Conclusions, Harsh edaphic conditions and chronic low-level disturbances on the summit, including frequent winter storms, have apparently contributed to the establishment, long-term persistence, and slow radial growth of dwarf pitch pines on Mt Everett. The ability of dwarf pines to persist on a site in the absence of frequent fire is highly unusual among North-eastern barrens and has not been well-incorporated into previous conceptual ecological models of these communities. Our results suggest that even among North-eastern barrens, the summit of Mt Everett is characterized by highly unusual vegetation and dynamics. The site has long been recognized as regionally significant and should be afforded the strictest conservation protection. With no evident history of human disturbance or recent fire, there is no apparent need for immediate active management of the site. [source]


Potential Effects of Passenger Pigeon Flocks on the Structure and Composition of Presettlement Forests of Eastern North America

CONSERVATION BIOLOGY, Issue 6 2003
JOSHUA W. ELLSWORTH
We suggest that the activities of roosting and nesting Passenger Pigeons caused widespread, frequent disturbances in presettlement eastern forests through tree limb and stem breakage and nutrient deposition from pigeon excrement. We suspect that the deposition of fine fuels resulting from such disturbances may have influenced fire intensity and frequency in presettlement forests. Further, we propose that consumption of vast quantities of acorns by pigeons during the spring breeding season may partially explain the dominance of white oak (Quercus alba) throughout much of the presettlement north-central hardwoods region. Consequently, the pigeon's extinction may have facilitated the increase and expansion of northern red oak (Quercus rubra) during the twentieth century. Although it is difficult to accurately quantify how physical and chemical disturbances and mast consumption by Passenger Pigeon flocks affected forest ecology, we suspect they shaped landscape structure and species composition in eastern forests prior to the twentieth century. We believe their impact should be accounted for in estimates of the range of natural variability of conditions in eastern hardwood forests. Resumen:,Consideramos los posibles efectos que pudieron haber tenido parvadas de Palomas Migratorias (Ectopistes migratorius) sobre el régimen de perturbación y la composición de especies de bosques en Norte América oriental antes de la colonización. Sugerimos que las actividades de perchado y anidación de las palomas causaron perturbaciones frecuentes y extensas en los bosques orientales antes de la colonización por medio de la ruptura de ramas y tallos de árboles y la deposición de nutrientes del excremento de las palomas. Sospechamos que la deposición de combustibles resultantes de tales perturbaciones pudo haber influido en la intensidad y frecuencia de incendios forestales. Más aún, proponemos que el consumo de grandes cantidades de bellotas por las palomas en la primavera puede parcialmente explicar la dominancia de roble blanco (Quercus alba) en muchos de los bosques nor-orientales. En consecuencia, la extinción de la paloma pudo haber facilitado el incremento y expansión del roble rojo (Quercus rubra) durante el siglo veinte. Aunque es difícil cuantificar con precisión como las perturbaciones físicas y químicas y el consumo masivo por parvadas de palomas migratorias afectaron a la ecología forestal, sospechamos que modelaron la estructura del paisaje y la composición de especies en los bosques orientales antes del siglo veinte. Creemos que su impacto debería ser considerado cuando se hacen estimaciones del rango de variabilidad natural de las condiciones en bosques orientales de maderas duras. [source]


Species-specific differences in oak foliage affect preference and performance of gypsy moth caterpillars

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2003
L. K. Foss
Abstract The gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae), is an introduced defoliator that preferentially feeds on oaks, Quercus spp. (Fagaceae) in the north-eastern USA. As the gypsy moth expands its geographic range, the extensive oak component in forests and urban environments of the USA assure its successful establishment. Given their economic and ecological importance, and the gypsy moth's potential to cause mortality, we evaluated caterpillar preference and performance on various oaks prevalent in the central hardwoods region. Most of the physical and chemical characteristics we measured, from budbreak phenology to foliar chemistry, varied significantly among the oak species tested. Similarly, insect preference and performance varied significantly, though not always in predictable ways. Caterpillar preference was compared for black, Q. velutina Lamarck, burr, Q. macrocarpa Michaux, cherrybark, Q. pagoda Rafinesque, northern red, Q. rubra L., pin, Q. palustris Muenchhausen, swamp white, Q. bicolor Willdenow, white, Q. alba L., and willow, Q. phellos L., oaks. Gypsy moth preference was greatest for black and burr, and least for northern red, pin, and willow oaks. We assessed foliar characteristics and caterpillar performance on foliage from burr, cherrybark, northern red, pin, and willow oaks. Caterpillar preference did not always correlate with performance. Gypsy moth consumption and growth were highest, and development most rapid, on pin oak, which had high nitrogen and tannin levels, and was among the least preferred. Northern red and willow oaks were also among the least preferred and were the least suitable tested, producing caterpillars with moderate to low consumption and growth rates, as well as the longest development. Northern red oak contained the lowest foliar tannins; willow oak foliage was lowest in carbohydrates and nitrogen. Our results suggest that a combination of foliar characteristics may be responsible for gypsy moth preference and performance, and that an optimal combination of foliar components serves to maximize host suitability. These data will provide information useful for planning and managing urban forests in the presence of expanding gypsy moth populations. [source]


The effect of organic acids on base cation leaching from the forest floor under six North American tree species

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2001
F. A. Dijkstra
Summary Organic acidity and its degree of neutralization in the forest floor can have large consequences for base cation leaching under different tree species. We investigated the effect of organic acids on base cation leaching from the forest floor under six common North American tree species. Forest floor samples were analysed for exchangeable cations and forest floor solutions for cations, anions, simple organic acids and acidic properties. Citric and lactic acid were the most common of the acids under all species. Malonic acid was found mainly under Tsuga canadensis (hemlock) and Fagus grandifolia (beech). The organic acids were positively correlated with dissolved organic carbon and contributed significantly to the organic acidity of the solution (up to 26%). Forest floor solutions under Tsuga canadensis contained the most dissolved C and the most weak acidity among the six tree species. Under Tsuga canadensis we also found significant amounts of strong acidity caused by deposition of sulphuric acid from the atmosphere and by strong organic acids. Base cation exchange was the most important mechanism by which acidity was neutralized. Organic acids in solution from Tsuga canadensis, Fagus grandifolia, Acer rubrum (red maple) and Quercus rubra (red oak) were hardly neutralized while much more organic acidity was neutralized for Acer saccharum (sugar maple) and Fraxinus americana (white ash). We conclude that quantity, nature and degree of neutralization of organic acids differ among the different tree species. While the potential for base cation leaching with organic acids from the forest floor is greatest under Tsuga canadensis, actual leaching with organic anions is greatest under Acer saccharum and Fraxinus americana under which the forest floor contains more exchangeable cations than does the strongly acidified forest floor under Tsuga canadensis. [source]


Vegetation and disturbance history of a rare dwarf pitch pine community in western New England, USA

JOURNAL OF BIOGEOGRAPHY, Issue 10-11 2002
Glenn Motzkin
Abstract Aim, This study documents the vegetation history and age-structure of a rare, ridgetop dwarf pine,oak community and compares the dynamics of this unusual vegetation with similar dwarf pine communities found elsewhere in the north-eastern United States (US). Location, The study area is located on the summit of Mt Everett in the Taconic Mountains of south-western Berkshire County, Massachusetts, USA (42°06,N 73°26,W). Methods, Vegetation composition, tree age-structure, physical site characteristics, and evidence of fire and other disturbances were determined for twelve 15 × 15 m plots in dwarf pine,oak vegetation and two plots in oak forests on the summit. Age-structure analyses, tree-ring patterns, and historical records of human and natural disturbance were used to investigate the long-term history and dynamics of the summit vegetation. Results, The summit of Mt Everett has been dominated by dwarf pines (1,3 m tall) and ericaceous shrubs similar to the modern vegetation throughout the historical period; there is no evidence that tall-stature forests occurred on the site at any point in the past few centuries. The summit supports uneven-aged stands; pitch pine (Pinus rigida) recruitment began in the 1830s and occurred in every decade since the 1860s. Average pitch pine age is seventy-eight with a range of 12,170 years. Red oak (Quercus rubra) and red maple (Acer rubrum) increased in importance in the twentieth century, with most stems establishing from 1940 to 1980. Pitch pine radial growth rates averaged <0.5 mm year,1 while red oak and red maple averaged 1.0 and 0.8 mm year,1, respectively. In some areas, hardwoods have overtopped pitch pines, apparently resulting in pitch pine mortality. Whereas most dwarf pitch pine communities occur on sites that burn frequently and have a high degree of cone serotiny, we found no evidence of recent fires or cone serotiny. Small amounts of macroscopic charcoal that we documented may have resulted from fires in the pre-European or early historical periods. Conclusions, Harsh edaphic conditions and chronic low-level disturbances on the summit, including frequent winter storms, have apparently contributed to the establishment, long-term persistence, and slow radial growth of dwarf pitch pines on Mt Everett. The ability of dwarf pines to persist on a site in the absence of frequent fire is highly unusual among North-eastern barrens and has not been well-incorporated into previous conceptual ecological models of these communities. Our results suggest that even among North-eastern barrens, the summit of Mt Everett is characterized by highly unusual vegetation and dynamics. The site has long been recognized as regionally significant and should be afforded the strictest conservation protection. With no evident history of human disturbance or recent fire, there is no apparent need for immediate active management of the site. [source]


The effects of high temperature on isoprene synthesis in oak leaves

PLANT CELL & ENVIRONMENT, Issue 7 2000
E. L. Singsaas
ABSTRACT Isoprene emission from plants is highly temperature sensitive and is common in forest canopy species that experience rapid leaf temperature fluctuations. Isoprene emission declines with temperature above 35 °C but the temperature at which the decline begins varies between 35 and 44 °C. This variability is caused by the rate at which leaf temperature is increased during measurement with lower temperatures associated with longer measurement cycles. To investigate this we exposed leaves of red oak (Quercus rubra L.) to temperature regimes of 35,45 °C for periods of 20,60 min. Isoprene emission increased during the first 10 min of high temperature exposure and then decreased over the next 10 min until it reached steady state. This phenomenon was common at temperatures above 35 °C but was not noticeable at temperatures below that. The response was reversible within 30 min by lowering leaf temperature to 30 °C. Because there is no storage of isoprene inside the leaf, this behaviour indicates regulation of isoprene synthesis in the leaf. We demonstrated that the variability in isoprene decline results from regulation and explains the variability in the temperature response. This is consistent with our theory that isoprene protects leaves from damage caused by rapid temperature fluctuations. [source]


Riparian Forest Restoration: Increasing Success by Reducing Plant Competition and Herbivory

RESTORATION ECOLOGY, Issue 2 2002
Bernard W. Sweeney
Abstract The reestablishment of riparian forest is often viewed as "best management practice" for restoring stream ecosystems to a quasi-natural state and preventing non-point source contaminants from entering them. We experimentally assessed seedling survivorship and growth of Quercus palustris (pin oak), Q. rubra (red oak), Q. alba (white oak), Betula nigra (river birch), and Acer rubrum (red maple) in response to root-stock type (bare root vs. containerized), herbivore protection (tree shelters), and weed control (herbicide, mowing, tree mats) over a 4-year period at two riparian sites near the Chester River in Maryland, U.S.A. We started with tree-stocking densities of 988/ha (400/ac) in the experimental plots and considered 50% survivorship (i.e., a density of 494/ha [200/ac] at crown closure) to be an "acceptable or minimum" target for riparian restoration. Results after four growing seasons show no significant difference in survivorship and growth between bare-root and containerized seedlings when averaged across all species and treatments. Overall survivorship and growth was significantly higher for sheltered versus unsheltered seedlings (49% and 77.6 cm vs. 12.1% and 3.6 cm, respectively) when averaged across all species and weed control treatments. Each of the five test species exhibited significantly higher 4-year growth with shelter protection when averaged across all other treatments, and all species but river birch had significantly higher survivorship in shelters during the period. Seedlings protected from weeds by herbicide exhibited significantly higher survivorship and growth than seedlings in all other weed-control treatments when averaged across all species and shelter treatments. The highest 4-year levels of survivorship/growth, when averaged across all species, was associated with seedlings protected by shelters and herbicide (88.8%/125.7cm) and by shelters and weed mats (57.5%/73.5 cm). Thus, only plots where seedlings were assisted by a combination of tree shelters and either herbicide or tree mats exhibited an "acceptable or minimum" rate of survivorship (i.e.,>50%) for riparian forest restoration in the region. Moreover, the combined growth and survivorship data suggest that crown closure over most small streams in need of restoration in the region can be achieved most rapidly (i.e., 15 years or less) by protecting seedlings with tree shelters and controlling competing vegetation with herbicides. [source]


Hydraulic properties and freezing-induced cavitation in sympatric evergreen and deciduous oaks with contrasting habitats

PLANT CELL & ENVIRONMENT, Issue 12 2001
J. Cavender-Bares
Abstract We investigated the hydraulic properties in relation to soil moisture, leaf habit, and phylogenetic lineage of 17 species of oaks (Quercus) that occur sympatrically in northern central Florida (USA). Leaf area per shoot increased and Huber values (ratio of sapwood area to leaf area) decreased with increasing soil moisture of species' habitats. As a result, maximum hydraulic conductance and maximum transpiration were positively correlated with mean soil moisture when calculated on a sapwood area basis, but not when calculated on a leaf area basis. This reveals the important role that changes in allometry among closely related species can play in co-ordinating water transport capacity with soil water availability. There were significant differences in specific conductivity between species, but these differences were not explained by leaf habit or by evolutionary lineage. However, white oaks had significantly smaller average vessel diameters than red oaks or live oaks. Due to their lower Huber values, maximum leaf specific conductivity (KL) was higher in evergreen species than in deciduous species and higher in live oaks than in red oaks or white oaks. There were large differences between species and between evolutionary lineages in freeze,thaw-induced embolism. Deciduous species, on average, showed greater vulnerability to freezing than evergreen species. This result is strongly influenced by evolutionary lineage. Specifically, white oaks, which are all deciduous, had significantly higher vulnerability to freezing than live oaks (all evergreen) and red oaks, which include both evergreen and deciduous species. These results highlight the importance of taking evolutionary lineage into account in comparative physiological studies. [source]