BLACK CARPENTER ANTS IN THE OZARK MOUNTAINS OF ARKANSAS: RELATIONSHIPS WITH PRESCRIBED FIRE, SITE AND STAND VARIABLES, AND RED OAK BORER BLACK CARPENTER ANTS IN THE OZARK MOUNTAINS OF ARKANSAS: RELATIONSHIPS WITH PRESCRIBED FIRE, SITE AND STAND VARIABLES, AND RED OAK BORER A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Entomology By ROBIN MICHELLE VERBLE University of Southern Indiana Bachelor of Science in Biophysics, 2006 August 2008 University of Arkansas ABSTRACT Black carpenter ants, Camponotus pennsylvanicus DeGeer, are nearly ubiquitous in eastern North American forests. These ants are documented as predators of red oak borer, Enaphalodes rufulus Haldeman, a native longhorn beetle that underwent an unprecedented population increase and decline in the oak hickory forests of the Ozark Mountains of Arkansas from the late 1990’s to 2005. My objective was to examine red oak borer emergence holes and site aspects and correlate these forest and tree attributes with presence or absence of black carpenter ants. Historic red oak borer population data, tree REP class and site aspects for 13 separate plots were used. At each site, all red oaks >10 cm DBH were baited for black carpenters ants using a mixture of tuna in oil and honey. Black carpenter ants are more likely to be found on trees with low levels of previous red oak borer infestation versus those trees with previously high levels of infestation. These results may suggest black carpenter ants play a role in controlling red oak borer populations. Distribution of black carpenter ants in red oaks prior to and during the outbreak is unknown. Future investigations should be directed at efforts to understand whether black carpenter ants simply prefer different apparently healthy trees or if, via predation, these ants are acting as agents of red oak borer control. I also examined how tree species and size, site and stand variables, and management practices influence black carpenter ant abundance. Fire treatment, tree species, and tree size were described for 18 plots. All trees were baited as described above, and black carpenter ant presence/absence was recorded for each tree. Black carpenter ants were more commonly present on oaks than on hickories and appear to prefer large trees over small trees. Time elapsed since a prescribed burn appears to be important in determining black carpenter ant presence, potentially via fire- induced habitat modifications, although further investigation is necessary to either confirm or refute this hypothesis. This thesis is approved for recommendation to the Graduate Council Thesis Director: _____________________________________ Dr. Frederick M. Stephen Thesis Committee: _____________________________________ Dr. Timothy J. Kring _____________________________________ Dr. Lynne C. Thompson THESIS DUPLICATION RELEASE I hereby authorize the University of Arkansas Libraries to duplicate this thesis when needed for research and/or scholarship. Agreed_____________________________________ Robin Verble Refused_____________________________________ Robin Verble ACKNOWLEDGEMENTS First and foremost I would like to thank Dr. Fred Stephen. His personal and professional advice, seemingly endless patience, support and guidance as I found my way through the processes of graduate school have been invaluable. I would also like to thank Dr. Tim Kring for his enthusiasm, suggestions and honest advice. Dr. Lynne Thompson has provided a great deal of insight into my project and I owe him great thanks for his advice and helpful suggestions. Dr. Rob Wiedenman, thank you for your spirited support of my outreach endeavors, professional advice and the many opportunities to expand my horizons. Most notably, I would like to thank my field assistants, Tyler CarlLee and Matthew McCall for their willingness to work bizarre hours, remarkable patience and unwavering enthusiasm. Forest entomology laboratory members, John Riggins, Laurel Haavik and Larry Galligan are owed great thanks for listening, discussing ideas and not complaining (too loudly) about the stinky tuna and honey baits. Mike Melnechuk, thank you, not only for your continued friendship, but for helping me understand fire effects, locate plots and solidifying my love of prescribed fire. I would like to thank my father, Mark Verble, for inspiring me to a career in science and believing in my dreams, and my mother, Karen Verble, for her unconditional love and many long hours of telephone conversations. I suppose I should thank my little brother, Todd Verble, for being pretty cool. Megan and Kent Swedlund, thank you for all the phone calls, visits, and cards. Finally, Seth Pearson, thank you for your unwavering confidence in me, the lengthy discussions about the merits of prescribed fire and for always believing there is a way to get the cat out of the box. vivi TABLE OF CONTENTS Page Thesis Abstract………………………………………………… ii Acknowledgements…………………………………………… vi Table of Contents……………………………………………… vii Chapter 1—Introduction & Literature Review………………. 1 Chapter 2— Occurrence of black carpenter ants in trees previously infested with red oak borer Introduction……………………………………………… 33 Methods…………………………………………………….. 35 Results…………………………………………………........ 38 Discussion………………………………………………….. 38 Tables & Figures…………………………………………… 41 References………………………………………………… 44 Chapter 3— Occurrence of black carpenter ants in oak-hickory forests in relation to prescribed fire and site-stand variables Introduction……………………………………………….. 48 Methods…………………………………………………… 51 Results……………………………………………………... 53 Discussion…………………………………………………. 55 Tables & Figures…………………………………………... 59 References…………………………………………………. 62 Chapter 4—Summary and future directions……………. 66 viii CHAPTER 1 LITERATURE REVIEW 1 1 OZARK MOUNTAINS OF ARKANSAS The Ozark Highlands are a physiographic province extending from south central Missouri south and west into Arkansas and Oklahoma at elevations of 75-750 meters above sea level (Read 1952). The Ozarks are characterized by limestone, sandstone and shale rocks, sometimes exposed, and shallow, undeveloped poor soils (Beilmann and Brenner 1951). Rocks of the Ozark Highlands are sedimentary and form a broad dome that has been highly eroded since the Paleozoic era (Read 1952). Other than alluvial stream bottoms, soils of the region are formed by weathering rock (Read 1952). Drainage-limiting fragipan soils are present on broad ridgetops (Jenkins and Pallardy 1995). The Ozark Plateau of Arkansas receives an average of 77-110 centimeters of precipitation per year. Of this, 40% of the precipitation is received in the spring, 33% in the summer and fall, and 27% in the winter (Read 1952, NOAA 2007). On average 199 days per year are frost free. The mean temperature in January is 2.2 C, and the mean July temperature is 23.9 C (Read 1952, NOAA 2007). The forests of the Ozarks are oak- hickory dominated with significant components of oak-pine and pine. The average age range for trees in Ozark forests is 35-75 years (Loewenstein et al. 2000). Within the Ozark Highlands, the Ozark National Forest is located in north central and northwestern Arkansas and comprises 4900 square kilometers (Anonymous 2008). The modern Ozarks are heavily forested with few natural prairie openings. Using General Land Office notes, Foti (2004) estimated that the Boston Mountain region of the Ozark Plateau historically had 129 trees over 13.2 cm DBH per hectare. Today, there are 378. trees >13.2 cm DBH per hectare in this region. This near tripling in tree 2 density is attributed to fire suppression in the region throughout much of the twentieth century (Foti 2004). Historic accounts of the region describe a much more open landscape with a greater percentage of unforested land (Palmer 1921). Early explorers report a scarce quantity of timber on the hills and many “balds” and “barrens” (Palmer 1921). The Ozark Plateau was heavily logged in the late nineteenth century and early twentieth century. Regeneration that occurred after the widespread deforestation resulting from timber harvesting created even-aged stands (Jenkins and Pallardy 1995). After many areas were logged, severe fires were allowed to burn through the areas with the intention of promoting oak regeneration (VanLear 2004). These fires were halted in the late 1920’s with the enactment of the fire protection and suppression laws (Fralish 2004). Total suppression of fire in the region has dramatically altered the landscape, allowing mesophytic species such as maple and ash to become more prevalent in an area that was once dominated by oak and hickory. Oak and hickory seedlings rarely reach sapling size in modern forests, due to competition for light (Fralish 2004). In 1999 the Ozark Highlands experienced a red oak decline event that severely affected (>75% mortality and dieback) 300,000 hectares of the Ozark-St. Francis National Forest (Heitzman 2003). OAK DECLINE Oak decline is a “progressive and general dieback from the tips of branches” caused by a complex interaction of environmental stresses, pests and site factors” 3 (Wargo et al. 1983). Historically, oak decline events have been observed throughout much of the eastern United States, including the Ozark Plateau of Arkansas and Missouri. In 1996, it was estimated that 1.6 million hectares of oak forests in the southeastern United States were affected by decline (Oak et al.1996). Manion (1992) developed a forest decline model that includes predisposing factors, inciting factors and contributing factors. Predisposing