Photosynthetic Characteristics of Five Hardwood Species in a Mixed Stand
In 1998, photosythesis (Pn) was measured in cherrybark oak, green ash, swamp chestnut oak, sweetgum, and water hickory in a mixed stand established in February 1994. Based on the apparent quantum yield obtained from light response curves, cherrybark oak had the lowest Pn in August whereas sweetgum, green ash, and water hickory were equally active in Pn. Daily August Pn of sweetgum and green ash peaked before 10 am and decreased sharply thereafter. Between 3 and 5pm, sweetgum and green ash Pn were about 40 of their peak Pn. Daily September Pn did not show such sharp decreases in the afternoon for any species. Sweetgum had the highest chlorophyll level and the largest specific leaf weight in August. The ability of cherrybark oak and swamp chastnut oak to maintain laaves with adequate chlorophyll contents contributed to their active Pn in mid-December.