2014. Proceedings of the Indiana Academy of Science 123(1):7–13 TREE-RING ANALYSIS IN INDIANA WITH SPECIAL ATTENTION TO DENDROARCHAEOLOGY Darrin L. Rubino: Biology Department, Hanover College, Hanover, IN 47243, USA ABSTRACT. Although tree-ring studies have been performed in Indiana since the 1930s, their study in the state has been sporadic, and many gaps in our current understanding of tree growth and forest dynamics exist. Most notably, very little information regarding tree growth prior to the nineteenth century has been made available in the state. The tree rings in timbers of historically erected buildings can be used to build centuries- long chronologies for Indiana and the Mid-Ohio River Valley. Through tree-ring analysis, especially of nineteenth century buildings found throughout the region, study of past growth patterns and dynamics of the old-growth forest that once covered the state is possible. Keywords: Tree rings, dendrochronology, dendroarchaeology INTRODUCTION study long-term growth rates and tease out Tree rings, the annual increments of wood that the influence of different variables on tree are deposited around the circumference of woody growth (e.g., how droughts of varying degrees plants each year, offer a unique opportunity to of severity affect growth in given years). study growth patterns in trees and forests over Additionally, variation in tree-ring widths extended time periods. Dendrochronology is the allows for samples to be crossdated. Cross- science of assigning accurate calendar dates to dating is the process of matching the pattern of individual tree rings and using these accurately small and large tree rings among numerous dated rings to interpret past influences on tree trees throughout a particular forested stand or growth. Dendrochronological techniques have geographic region (e.g., Stokes & Smiley 1968; been used to examine the influence of various Fritts 1976). Consistent crossdating among factors on growth rates. For instance, dendro- tree rings is essential for ensuring that the chronological methods have been used to study exact calendar date is assigned to individual a wide range of topics including forest fire tree rings. In Indiana, drought events result in history, insect outbreaks, ecological phenomena decreases in radial growth rates with the size of (e.g., disturbance events such as wind storms), individual rings decreasing as stress during and climatic influences on tree growth (Fritts & a particular year increases. Reliably dated Swetnam 1989; Schweingruber 1989). chronologies (i.e., compilation of accurately The width of individual tree rings varies from dated and measured tree rings from a number year to year. Tree-ring width in a given year is of trees) can, therefore, be created in a given governed by a suite of biotic and abiotic factors region. For example, common crossdating with larger rings being formed during years of signals in southeastern Indiana oak (Quercus favorable growing season conditions and smal- L.) trees includes very small tree rings (in ler rings in less favorable years. Factors relation to neighboring tree rings) in 1930, affecting individual tree-ring widths include, 1936, 1944, and 1984 and smaller than normal but are not limited to, age-related growth rings in 1954, 1970, 1988, 1994, and 2000 trends, climate, and disturbances which origi- (Fig. 1). If the pattern of rings in a putatively nate from within or outside a forested stand. dated tree-ring sample crossdates or matches The size of a tree ring is, therefore, an aggregate this pattern, the sample is considered to be response to the conditions experienced by a tree dated accurately and that the exact year of in a given year (Cook 1987). The variation in formation of each tree ring is known. ring width permits dendrochronologists to Since droughts affect fairly large areas simul- taneously, relatively homogeneous signals Corresponding author: Darrin L. Rubino, 812-866-7247 throughout an area are created, and cross- (phone), 812-866-6752 (fax), [email protected]. dating is possible. 7 8 PROCEEDINGS OF THE INDIANA ACADEMY OF SCIENCE Figure 1.—Mean tree-ring chronology for white oaks (Quercus subgenus Lepidobalanus) growing in Happy Valley, a forested ravine of Hanover College (Jefferson County, Indiana). Sample depth refers to the number of tree rings dated and measured for a particular year. Dendrochronology in Indiana.—Tree-ring and Parke Counties (Hawley 1941). She was studies, designed to answer very different working to determine if dendrochronological questions, have been performed sporadically analysis would be possible in the Midwest in Indiana since the 1930s. For example, Edwin United States. If so, chronologies would be Lincoln Moseley identified the pattern of wide created in the hopes of dating Native American and narrow tree rings in oaks throughout ruins in the region. As an example of the several Midwestern states, including Indiana, different groups interested in tree-ring sciences, in the 1930s. Moseley was interested in historic the work performed by Hawley and the lab in climate cycles/patterns and hoped to create Chicago was funded by the Indiana Historical a method of predicting future droughts, Ohio Society (Hawley 1941). River floods, and lake levels (Moseley 1939; More recent studies have focused on stress Stuckey 1998). Diller (1935) and Friesner & leading to oak mortality (Pederson 1998); Friesner (1941) studied the impact of climatic interactive effects of acidic deposition, drought, variables including temperature and precipita- and insect attack on various oak species tion on tree growth in the state in the northern (LeBlanc 1998); impact of early season water half of Indiana and Marshall County, respec- balance on white oak (Quercus alba L.) growth tively. In 1934, Florence Hawley Senter who (LeBlanc & Terrell 2001); impact of soil texture was serving as the Director of the Laboratory on tree growth (Charton & Harman 1973); and of Dendrochronology at the University of the effects of insect outbreaks (Speer et al. Chicago (Nash 1999) studied trees from Clin- 2010) on tree growth. Cook produced an oak ton, Crawford, Knox, Marion, Noble, Owen, chronology for Pulaski Woods in north central RUBINO—DENDROCHRONOLOGY IN INDIANA 9 Indiana (International Tree-Ring Data Bank walnut (Juglans nigra L.), and various hickory 2013) while creating a continental-wide tree- species (Carya Nutt. spp.). A better under- ring database. standing of forest growth and dynamics will Most tree-ring studies in the state have surely require new or additional studies of these focused on oaks (Quercus L. spp.) especially and other common species found throughout those in the ‘‘white oak’’ subgenus [Quercus the state. subgenus Lepidobalanus including white oak Dendroarchaeology in Indiana.—Using stan- (Q. alba), chestnut oak (Q. prinus L.), or post dard dendrochronological techniques, the dat- oak (Q. stellata Wangenh.)]. Species in the ing of tree rings in living trees is relatively white oak group are often chosen for dendro- straightforward. Since the year of sampling is chronological analysis in eastern North Amer- known, calendar dates can be given to in- ica due to their reliable crossdating and dividual tree rings starting with assignment of consistent response to climatic variables such the current year to the outermost ring (if the as temperature, precipitation, and drought growing season for that year has begun) and indices (e.g., Wedel & Hawley 1941; Sheppard assigning the corresponding previous year to et al. 1988; Rubino & McCarthy 2000). In each ring until the pith or center of the sample Indiana, studies on other species have been is reached. If the sample crossdates with other performed to a lesser degree (Diller 1935; samples, confident dates can be given to the Friesner & Friesner 1941; LeBlanc 1998; individual tree rings in the sample, and it can be Pederson 1998; Sparks & Bishop 2009; Speer included in a regional chronology. et al. 2010). These species include American However, date assignment is not always this beech (Fagus grandifolia Ehrh.), bitternut hick- straightforward. For example, if a sample is ory (Carya cordiformis (Wangenh.) K. Koch), obtained from a timber of a structure with an sassafras (Sassafras albidum (Nutt.) Nees.), unknown construction date (which is almost sugar maple (Acer saccharum Marshall), tulip always the case), assignment of the dates in poplar (Liriodendron tulipifera L.), white ash which the rings were formed is more compli- (Fraxinus americana L.), and various oaks in cated. Dating of such a sample could be the red/black group (Quercus subgenus Ery- performed using dendroarchaeological tech- throbalanus) including black (Q. velutina Lam.), niques. Dendroarchaeology is a sub-field of northern red (Q. rubra L.), and pin oak (Q. dendrochronology that deals specifically with palustris Muenchh.). Taxonomy and nomen- the sampling of historically erected buildings clature follow Gleason & Cronquist (1991). The and other wooden objects to tap the tree-ring above is not intended to be a thorough information found within their timbers. In historical review of all dendrochronological dendroarchaeological studies, the formation studies performed in the state but rather date of an individual tree ring is unknown. a representation of the various types of work The date, however, can be determined by that have been done. crossdating the pattern of small and large rings Despite the long use of dendrochronology to in a sample of unknown age with accurately explore tree growth in the state, many gaps in dated chronologies that have been prepared our knowledge persist. For example, tulip from the same geographic region (Fig. 2). poplar, an important species in many forest Crossdating is a highly reliable method for types of Indiana, has had only very limited dating wood of unknown age, and dendroarch- study; from 1930 to 1939 Friesner & Friesner aeological techniques have proven to be power- (1941) studied tulip poplar growth in Marshall ful and effective research tools, especially in dry County in relation to climate. Limited analysis climates such as the American Southwest (Nash of other widely distributed species such as ash, 1999).