tailieunhanh - Báo cáo lâm nghiệp: "Distribution, historical development and ecophysiological attributes of oak species in the eastern United States "

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế, đề tài:"Distribution, historical development and ecophysiological attributes of oak species in the eastern United States. | 487 Ann Sci For 1996 53 487-512 Elsevier INRA Review article Distribution historical development and ecophysiological attributes of oak species in the eastern United States MD Abrams The Pennsylvania state University School of Forest Resources 4 Ferguson Building University Park PA 16802 USA Received 6 September 1994 accepted 19 June 1995 Summary Approximately 30 Quercus oak species occur in the eastern United States of which Q alba Q rubra Q velutina Q coccinea Q stellata and o 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 tailgrass 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. Quer-cus 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 Quer-cus grew and regenerated in uneven-aged conditions. At times oak growth was very slow mm year for long periods which is usually characteristic of highly shade-tolerant species. Quercus species exhibited continuous recruitment into the canopy during the 17th 18th and 19th centuries but stopped recruiting in the early 20th century. Since that time later successional mixed-mesophytic species have dominated understory and canopy recruitment which coincides with the period of fire exclusion throughout much of the eastern biome. Major oak replacement species include Acer rubrum A sac-charum Prunus serotina and others. Logging of oak forests that have understories .