The Physiological Diversity and Similarity of Ten Quercus Species

Baaed on anatomlcal. photosynthetic, and biochemical data, the range of physiological differences and almllarlllea waa defined for ten Quercus species. There were no correlations between apaclea’ ilte adaptablllty, leaf anatomy and photoayhlhetlo rate (A). For exampla, cherrybark oak, a meak-hydrtc type, and post oak, a xerlc type. have the largeat alomatal aperture among species examlti but the former has 66 percent higher maxlmum A than the laker. Northern red oak has lwice as many rtomata as Shumard oak and both species have similar atomalal aperture. Maximum A and pholoaynlhetk l cllve ndialfon at 50 percent maxlmum A (PAR,) of these apeclea ranged between 6.3 end 19.6 ~mol/mz.a and behveen 160 and 360 ~moUm*.a, reapectfvefy. Generally, seedling taproots have hlghar lavela of soluble sugar and starch than stems. The highest lavela of soluble sugar and atarch in alema and roola occurred In Juty and November, respectively. Sucrose aynlhaae was lhe dominant l ucroae meleboltzlng enzyme aolMly end exhlbied unique, chancteriallo aeaaonal pallema for roots and stems of northern red oak and cherrybark oak. It la concluded from theae,dala that each’oak species must be treated Individually when Incorporated inlo the management and restoration of ecosystems. INTRODUCTION To meet the demand for hardwood seedlings for the artificial regeneration and restoration of diverse ecosystems, we postulate that each tree species has unique traits and must be dealt with individually. For example, many Quercus species grow wel onty over a narrow range of sites with different soit mOi8tUre contents. Furthermore, relative terms such as shade intolerant and tolerant are often used to describe light requirement8 of these species (Burns and Honkala 1990). However, onfy a few Studies reported the quantitative light requirements for photosynthesis for a limited number of oak species (Hanson and other8 1988; Ktelner and other8 1992; Kubiske and Abram8 1992; Weber and Gates 1990). The seasonal relationships between sucrose sources, such as photosynthet ic and sucrose expor t ing leaves, and sinks, 8UCh as sucrose importing, growing, and reserve storing stdms and roots, need to be established to fur ther understand the b io logy of Ind iv idua l spec ies . Performance of each species In the ecosystems can then be evaluated quantitatively. The objective8 of this study were to grow ten oak spec ies ind iv idua l ly adapted to a range of soil water conditions from hydric lo xccY under the same field conditions and to study roma parameter8 that determine the dynamic source-rink relationships of these plants. MATERIALS AND METHODS Seedling Culture Seedlings of 10 oak species, black (Quercus wow Lam.), bur (Q. mecrocerpa Michx.), cherrybark (0 pegode Raf.), chestnut (Q. prinus L.), northern fad (0 rubra L.), nuttall (Q. nuffallii Palmer), overcup (0. @#a Walt.), post (Q. sfellefa Wangenh.), Shumard (0 shumerdii Buckt.), and white oak (Q. alba L.), war. grown according to a single nursery cultural protocd & Kormanik and o thers (1994) a t the Georg ia Fora@y Commission’8 Flint River Nursery located near Montezuma, GA. The seedl ings were l i f ted a t tha ti of the first growing season and transplanted Into Ow Institute of Tree Root Biology experimental nursery beds a t Whi teha l l Nursery , Athens, GA in midJrnvur 1992. ‘Paper presentad at the Eighth Biennial Southern Silvlcultural Research Conference, Auburn, AL, Nov. l-3,1994. ‘Research Plant Phyalologlat, lnat Tree Blol, USDA-Forest Setvke, Athena, GA; Research Associate, Dept Bicchem 1 Md W. L** GeWgla, Athena, GA; Research Aaaodale, Depl Blochem 8 Mot Blot, Untv Georgia, Athena, GA; Research Forester, USDA-Fwrrl *u Charleston, SC; Research Forester, USDA-Forest Service, Athens, GA; and Research Professor Biochem, Depl Biochem 6 Md 6d. w Georgla, Athsna, GA (respectlvety).