Stump Sprouting 2 Years after Thinning in a Cherrybark Oak Plantation

Stump sprouts are considered an important regeneration source in hardwood management, especially in upland oak-dominated forests. Less is known about stump sprouting in bottomland oak forests. Therefore, the objective of this study was to determine the success and growth of stump sprouts following 2 thinning levels, 70-75 percent of initial stocking (light thinning) and 45-50 percent of initial stocking (heavy thinning) in a 35year-old cherrybark oak (Quercus pagoda Raf.) plantation in Concordia Parish, LA. Two growing seasons after thinning, cherrybark oak sprout success was 37 percent across the study site, a 200 percent decrease from the previous year. A severe drought occurred during this time and may have contributed to the low sprouting success. Stumps averaged 8.5 sprouts over the 2-year study period, and dominant sprouts were 82 inches tall. Results from this study indicate that greater weights should be placed on stump sprout potential in bottomland hardwood regeneration evaluation models. INTRODUCTION Sprouts are generally defined as shoots arising from the base of woody plants or as suckers from roots (Helms 1998). Though called various names, tree sprouts can usually be divided into 3 types for management purposes: seed l ing sp rou ts , roo t sp rou ts , and s tump sp rou ts . Seedling sprouts are stems that arise from existing or severed seed l ings or sap l ings ( 53 inches dbh) where the root system may be several to many years older than the stem (McQuilkin 1975). Root sprouts, or suckers, arise f rom adven t i t i ous suppressed buds on roo t sys tems o f ex is t ing or severed t rees (Korman ik and Brown 1967) . Stump sprouts arise from the base of severed stems and can appear anywhere from the top to the base of the stump. Stump and root sprouts are considered one of three broad classes of oak reproduction (Aust and others 1985), the others be ing new seed l ings tha t deve lop f rom acorns which germinated just before or soon after harvest and advance regenerat ion o lder regenerat ion l iv ing underneath a forest canopy (Smith and others 1997). Advance regenerat ion and sprouts have long been cons idered the most impor tan t source o f hardwood regenera t ion , especially for the various oak species (Hodges 1987, Johnson 1994) . Sprout surv iva l and deve lopment have been wellstudied for a variety of upland oak species including northern red oak (Quercus rubra L.) (Johnson 1975, Johnson and Rogers 1980), black oak (Q. velutina Lam.) (Johnson and Sander 1988), white oak (Q. a/& L.) (McQuilkin 1975, Lynch and Bassett 1987), and others (Cobb and o thers 1985, Lowel l and o thers 1987) . Th is in format ion has been incorpora ted in to severa l hardwood regenera t ion eva luat ion mode ls des igned to de termine i f sufficient density and stocking of oak regeneration exists prior to a harvest for regeneration success (Sander and others 1976, Johnson 1977, Sander and o thers 1984, Dey 1993, Dey and others 1996). Less is known about the role of sprouting in the regenerat ion o f bo t tomland oak spec ies (Gard iner and He lmig 1997, Golden 1999). The stump sprouting component of bottomland hardwood regenerat ion eva luat ion models re ly on the best information currently available, i.e., personal observat ions , resu l ts f rom up land oak sprou t ing research , and l im i ted bo t tomland oak sprout ing research (Johnson 1980, Johnson and Deen 1993, Hart and others 1995, Belli and others 1999). Therefore, the objective of this study was to add to the sprou t ing knowledge o f bo t tomland oak spec ies . Specifically, we examined success and growth of cherrybark oak (Q. pagoda Raf.) stump sprouts following two intensities of thinning in a 35year-old plantation. Twoyear results are reported. MATERIALS AND METHODS Study Site Description The study site is located on the Red River Wildlife Management Area in Concordia Parish, east-central LA. Physiographically, the site is located in the Natural Levee Subreg ion , M iss iss ipp i R iver F loodp la in Reg ion o f the Al luv ia l F loodp la in Prov ince (Evans and o thers 1983) and is protected from flooding by the mainline levee system. Soils a re composed o f Commerce s i l t l oam (Aeric F luvaquen ts ) and Bru in s i l t l oam (F luvaquent ic Eu t rudepts ) . The fo rmer soil is deep and somewhat poorly drained while the latter so i l i s deep and moderate ly we l l d ra ined. Ra in fa l l averages 59 inches per year and is generally evenly distributed throughout the year a l though per iod ic summer droughts occur (Evans and others 1983). Average temperature is 67 degrees Fahrenhe i t w i th a h igh o f 81 degrees Fahrenhe i t in July and August (Evans and others 1983). Cherrybark oak site index, base age 50 years, was estimated at 110 feet (Baker and Broadfoot 1979) . ‘Associate Professor, Professor, and Graduate Research Assistant, School of Forestry, Wildlife, and Fisheries, Louisiana Agricultural Center, Louisiana State University, Baton Rouge, LA 70803, respectively. Citafion 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.