Distribution, historical development and ecophysiological attributes of oak species in the eastern United States

Abstract

Summary &mdash; Approximately 30 Quercus (oak) species occur in the eastern United States, of which Q alba, Q rubra, Q velutina, Q coccinea, Q stellata and Q prinus are among the most dominant. Quercus distribution greatly increased at the beginning of the Holocene epoch (10 000 years BP), but has exhibited major changes since European settlement in the 18th and 19th centuries. For example, large-scale increases in Quercus species have occurred as a result of fire exclusion in the central tallgrass prairie and savanna regions. In the northern conifer and hardwood forests of New England and the Lake States region, Q rubra exhibited a dramatic increase following early logging and fire. Quercus species have also increased in the mid-Atlantic region from land-clearing, the charcoal iron industry and the eradication of Castanea dentata following European settlement. Studies of the dendroecology and successional dynamics of several old-growth forests indicate that prior to European settlement Quercus grew and regenerated in uneven-aged conditions. At times oak growth was very slow (< 1.0 mm/year) for long periods, which is usually characteristic of highly shade-tolerant species. Quercus

Growth dynamics of oak seedlings ( Quercus macrocarpa Michx. and Quercus muhlenbergii Engelm.) from gallery forests: implications for forest expansion into grasslands

“…The relative harshness of the grassland climate likely precludes most eastern deciduous forest tree species from this region, and it may restrict those tree species that can persist to riparian sites. Even in riparian sites, however, evaporative demand is high (Hayden 1998), and the climate likely selects for morphological and physiological traits that enable trees to avoid or tolerate water stress in a region that is much more xeric compared to eastern deciduous forests (Abrams 1990(Abrams , 1996Hayden 1998). Indeed, previous research has shown that the root system of Q. macrocarpa is capable of extending 4.5 m into deep soils as adults (Weaver and Kramer 1932), and perhaps as much as 1.5 m in seedlings (Holch 1931).…”

Adaptive Variation and Introgression of a CONSTANS-Like Gene in North American Red Oaks

“…velutina populations and the sympatric population (PV-DC), introgression of the 141 bp allele was higher into Q. velutina than into Q. ellipsoidalis. Quercus velutina is less water efficient than Q. ellipsoidalis and generally found in savannas [16,46,47], while Q. ellipsoidalis is generally found on very dry sandy sites, possibly creating differences in introgression patterns between the three species in their sympatric range.…”

Resprouting ability of Quercus crispula seedlings depends on the vegetation cover of their microhabitats

“…Like other Quercus species, Q. crispula can resprout vigorously following shoot destruction. The vigorous resprouting characteristics of Quercus species are thought to be of adaptive value following large-scale disturbances such as wildfire (e.g., Abrams 1996), and their seedlings also resprout after small-scale disturbances (Crow 1992;Herrera 1995). In the Japanese deciduous forests, where humid conditions and wildfires occur relatively infrequently, the shoots of Q .…”