Effect of Seedling Size and First-order Lateral Roots on Early Development of Northern Red Oak on a Mesic Site: Eleventh-year Results

The effect of initial first-order lateral root (FOLR) groupings of northern red oak (Quercus rubra) seedlings on a high quality mesic site was followed for eleven years on a shelterwood and a clearcut area. The initial FOLR number groups were empirically determined as low (0 to 6) medium (7 to 12) and high ( 12). The shelterwood overstory was removed before the beginning of the eighth growing season and a circle (0.9 meter radius) was released around individual oaks in the clearcut. Individuals in the clearcut responded favorably to release, with some obtaining 6 to 8 meter in height by age 11. After the same period mean height from the shelterwood plantings was about 60 centimeter more than their initial height in 1990. It appears that large thrifty northern red oak seedlings can be established in properly controlled clearcut areas provided post harvest control of stumps is completed in a timely fashion. The shelterwood system with artificial regeneration does not appear to be a viable regeneration alternative as tested here. INTRODUCTION The basic tenets for northern red oak (NRO) (Quercus rubra) regenerat ion have been descr ibed by Sanders (1971, 1972). Working on lower quality sites in the central s ta tes , he c lea r l y es tab l i shed tha t success fu l regenera t ion depended a lmos t exc lus ive ly on the p resence o f advanced oak reproduc t ion when the mature s tand was harves ted . On s i tes where the research was comp le ted , fas te r g rowing compet ing spec ies were a minor p rob lem a t bes t . However , ob ta in ing the necessary advanced oak reproduction proved to be time consuming and difficult. Research after Sanders’ was directed at various methods of obtaining adequate advanced reproduc t ion by a t tempt ing to combine bo th na tu ra l and var ious combina t ions o f a r t i f i c ia l regeneration (Johnson 1993, Loftis 1983). This later research was applied to high quality mesic sites as well as s i tes comparab le to those on wh ich Sanders ’ research was completed. The use of the shelterwood system to encourage the deve lopment o f advanced natura l regeneration became the norm on these higher quality sites as clearcutting in any form became vilified by many uninfo rmed ind iv idua ls . In add i t ion , var ious combina t ions o f root/top pruning of nursery stock were extensively tested to improve their growth performance and, to increase the number o f NRO a f te r she l te rwood was removed. Eventually, it became apparent that competition from faster growing species made it very difficult to maintain a viable presence of NRO on the desirable mesic sites and NRO’s fu tu re on these s i tes became ques t ionab le (McGee and Loftis 1986). Kellison (1993) most recently suggested that if new technology was not soon developed then NRO may become the “Ca l i fo rn ia Condor ” o f the eas tern dec iduous f o r e s t s . The initial objective of this research was directed at de te rmin ing whether the nursery fe r t i l i t y p ro toco l deve loped at our research center cou ld produce “advanced oak regeneration“ in the nursery in a single growing season. A secondary objective was to determine if a first-order lateral roo t (FOLR) g rad ing sys tems p rev ious ly used fo r sweetgum could be modified to select the best oak seedlings for outplanting in both a clearcut and shelterwood operation on a high quality mesic site. METHOD Two adjacent areas on the USDA Forest Service’s Grandfather Ranger District on the Pisgah National Forest, 12 miles northwest of Marion, NC, were used in this study. The site index for yellow poplar (Lirodendron tulipfera) was approx imate ly 100 (base age 50) . The main c rown canopy was a mixture of northern red oak, white oak (Q. alba), red maple (Acer rubrum), and yellow poplar. The clearcut area to be used for NRO enrichment planting was a small segment of a larger harvested area. The shelterwood area ‘Principle Silviculturist and Research Plant Physiologist, Institute of Tree-Root Biology, USDA Forest Service, 320 Green Street, Athens, GA.; Project Forester, Technical Development Unit, N.C. Division of Forest Resources, Morganton, NC 28655; Station Mathematical Statistician, USDA Forest Service, 200 Weaver Boulevard, Asheville, NC 28802, respectively. Citation for proceedings: Outcalt, Kenneth W., ed. 2002. Proceedings of the eleventh biennial southern silvicultural research conference Gen. Tech. Rep. SRS-48. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 622 p.