The Central Hardwood Region (CHR) is experiencing a lack of desirable hardwood regeneration on productive sites across the landscape. To better understand what facilitates desirable hardwood regeneration, additional studies that test the interaction of multiple disturbances are needed. For this reason, a demonstration area on the north end of Trail of Tears State Forest (Union County, Illinois) was established to compare hardwood regeneration response following four treatments: (1) burn only, (2) thin/burn, (3) harvest/thin/burn, and (4) control. Treatments were implemented beginning in 2014 to determine what combination of silvicultural practices best promotes desirable hardwood regeneration among large saplings (>3.3’ in height and 1” DBH to 3” DBH), small saplings (>3.3’ in height and up to 1” DBH), and seedlings (1”- 3.3’ in height) and increases midstory Quercus alba radial growth (stems >3” DBH). Eighty plots were surveyed in the summer of 2021, and overstory, regeneration, and canopy openness data were collected. Midstory Q. alba individuals were cored to elucidate the relationship of radial growth and silvicultural treatments. There was no significant difference of Quercus spp. density among treatments for any regeneration size class. No silvicultural releases were detected in midstory Q. alba individuals since treatment application in 2014. These results indicate that either there had not been enough time since treatment application, or the management practices did not alter canopy openness enough to cause a radial growth increase. Given the absence of Quercus spp. regeneration and growth using the four treatments, I suggest managers should also consider other factors such as deer population densities, non-Quercus competition vigor, and forest floor light availability when attempting to regenerate productive forests in the CHR.

<p> An open Quercus-dominated vegetation association, known locally as the oak plains, was found at a number of locations in southern Ontario until disturbance by European settlers in the late 18th and early 19th centuries. Two contrasting theories have been suggested in the literature regarding the origin of the oak plains. One suggests they developed as the result of burning by pre-European natives, while the other considers them to be relics of a warmer, drier mid-Holocene climate. In this paper, the factors which led to the development of the oak plains are examined. The hypothesis that the oak plains resulted from native burning of the natural vegetation was tested by pollen analysis of a 5 m sediment core from Decoy Lake, a small kettle basin near Paris, Ontario located in an area mapped by early surveyors as oak plains. The Decoy Lake record was then compared to those of two nearby lakes supporting mesic forests. This palaeoecological analysis was supported by an investigation of physical factors controlling the historical distribution of the oak plains in a study area between Cambridge and Long Point on Lake Erie. </p> <p> The distribution of the oak plains and other vegetation associations in pre-settlement times, reconstructed from early survey records, correlated fairly well with the texture of soils and underlying Quaternary parent materials. Within the defined study area, the oak plains were restricted almost exclusively to well-drained soils overlying coarse-textured till and sandy outwash and deltaic deposits. Climatic factors and topography varied within the study area, but showed little correlation with the distribution of vegetation associations. <p> <p> The fossil pollen record at Decoy Lake indicates that a QuercusPinus- herb pollen assemblage, unique to southern Ontario, was found from 4000 yr BP until pre-settlement times. This suggests that the oak plains have existed in the area for at least 4000 years. The oak plains replaced an assemblage dominated by Pinus strobus. The warm, dry Hypsithermal appears to have allowed Pinus strobus to remain dominant on the well drained soils around Decoy Lake until after 5000 yr BP, 2000 to 3000 years longer than at other southern Ontario sites. The Picea zone (11,800 yr BP to 10,100 yr B P), Pin us banksiana/resinosa zone ( 10,100 yr BP to c. 9000 yr BP), and the replacement of Pinus banksiana/resinosa by Pinus strobus (c. 9000 yr BP) occurred contemporaneously with other records from southern Ontario. </p> <p> The hypothesis that anthropogenic factors resulted in the development of the oak plains was rejected since this association developed 2500 years before the onset of agricultural activity by natives in southern Ontario. Instead, it appears post-Hypsithermal increases in moisture, perhaps coupled with an amelioration of winter temperatures, led to the replacement of Pinus strobus by the oak plains in some areas of well-drained soils between 6300 yr BP and 4000 yr BP. The pollen record from Decoy Lake provides the first evidence from southern Ontario for substantial vegetation response to mid to late Holocene climatic change. </p> / Thesis / Master of Science (MSc)

The southern Appalachian Mountains have long been an area of interest for the analysis of forest species growth and composition. Past forest vegetation studies focus on species composition and structure for relatively local scale research areas. Species distribution within this geographic area was compiled from studies published from 1956 to 2006. The distribution of hardwood species within the southern Appalachians decreased as the elevation of the sites increased, but this relationship could not be solely attributed to elevation gradient. In order to better understand the relationship between elevation on the radial growth of tree species within the region, an elevation microsite was selected to explore the relationship between elevation and the radial growth of upland oak. Eight study sites across an elevation gradient were selected, and 20 oak tree cores were collected, cross-dated, measured, and a master chronology was created for each site. The correlation between ring width index and Palmer drought severity index (PDSI), precipitation and temperature was calculated with each site's master chronology. There was a significant positive correlation between PDSI and ring width index during the growing season for a majority of the year, and a significant positive correlation between precipitation and ring width index during the growing season. Even though the master chronologies originated from eight separate sites, there were common dendroclimatic responses across seven of the sites. Canonical correspondence analysis of site characteristics and ring width index indicate that the master chronologies can be grouped into three separate chronologies based upon similar environmental and site characteristic responses. / Master of Science

Survival, growth and dieback, endogenous auxin and total non-structural carbohydrate (TNC) relations of underplanted northern red oak (Quercus rubra L.) seedlings were investigated. Greenhouse-grown red oak seedlings were subjected to 0, 63, or 92% shade and soil water potential was permitted to reach -0.3 or -2.0 MPa before rewatering. In a field study, underplanted northern red oaks were exposed to three levels of canopy removal (0, 70, or 90% residual canopy). White oak (Q. alba L.) and eastern white pine (Pinus strobus L.) were included in the field experiment for comparative purposes. In the greenhouse, dieback was observed under full sunlight and 92% shade but not in intermediate shading. In the field, dieback was greatest following complete canopy removal; but dieback was usually followed by rapid sprout growth and, as a result, average seasonal height increases generally were unaffected by light availability. Seasonal height increases were small (1-4 cm) and survival usually exceeded 90% in both the field and greenhouse. Field-grown white oaks displayed similar growth and dieback as red oaks. White pines grew 3 cm and 10 cm under 0 and 90% residual canopy, respectively. Final TNC leves from red oaks grown in drier soils and full sunlight were greater than seedlings grown under full shade and higher soil moistures (27 and 17% of total dry weight, respectively). Under full sunlight, as occur with complete canopy removal, dieback was probably related to internal moisture/temperature stress. Dieback under 92% shade was likely induced by carbohydrate depletion and weak, succulent growth resulting from the chronically low light levels. Thus, oak dieback appears to be a survival mechanism in which an advantageous root/shoot ratio is maintained and nutrients can be conserved. High or low TNC was not strongly related to dieback or sprout growth in this study. However, decreased TNC concentrations associated with increased shade indicated that long-term low light intensities may adversely affect growth and survival of red oak. Quantification of endogenous auxin in oak stems with gas chromatography was impossible due to low IAA levels (less than 0.8 uM) and small amounts of available tissue. Large amounts of IAA were found to be lost to sublimation when IAA was subjected to vacuum. / Ph. D.

Over the course of the last century mycorrhizal symbiosis has come to be recognized as highly beneficial for the host plant. Increased growth, water relations, nutrient acquisition, amelioration of the effects of metal toxicity, and increased resistance to pathogens are all benefits attributed to plants colonized by mycorrhizal fungi. A large body of literature exists that indicates that mycorrhizal inoculation programs are useful for improving the performance of forest tree seedlings. Commercial mycorrhizal products, many containing the ectomycorrhizal fungus Pisolithus tinctorius (Pers.) Coker and Couch (Pt), have emerged from this research and are now being marketed for landscape tree growers. In this study, two experiments were conducted to determine the best protocol for inoculation of landscape trees, and to determine if mycorrhizal inoculation is beneficial to trees growing in modern landscape tree container production systems. The first experiment evaluated mycorrhizal inoculation programs utilizing two inocula types employing various substrates for landscape tree production in containers. Quercus palustris Muenchh. (pin oak) and Q. coccinea Muenchh. (scarlet oak) grown in pine bark, sterilized pine bark, sterilized mineral soil, and sterilized vermiculite-based substrates were inoculated with Pt commercial spore inoculum or Pt vegetative inoculum. The vegetative inoculum was unsuccessful at forming mycorrhizae even though the Pt continued to live in the planting substrates. A higher proportion of pin oak was colonized than scarlet oak in all substrates, and vermiculite was a superior environment for mycorrhizal formation than the other three substrates. The second experiment examined the effectiveness of an indigenous mycorrhizal fungus, Scleroderma bovista Fr., to increase growth and resistance to drought stress of scarlet oak grown in containers in the pot-in-pot growing system. Scleroderma bovista did not affect tree growth, and mycorrhizal trees in containers proved to be more susceptible to drought stress than nonmycorrhizal trees. Leaf water potential was more negative for mycorrhizal trees, and conductance was lower for mycorrhizal trees after a 10 day dry down period. A commercial Pt product was also used as an inoculum in this study and again proved completely ineffective at colonizing scarlet oak in pine bark substrate. / Master of Science

Our Swedish forests have always been under the exposure of fire, more or less. The historical influence of fires, have made some species bound to these habitats or temporarily using them. Among these species, beetles (Coleoptera) are numerous. One of the tree species with the most historic influence of fire as well as inhabiting a great beetle-fauna is the oak (Quercus sp.). An area with an especially rich beetle-fauna tied to the oak and a extensive history of fire is the Hornsö-area in Smaland.  The purpose of this study is to investigate how the beetle-fauna and number of individuals differs between newly dead oaks in burnt areas and outside them, in the Hornsö area. The two studied families was long-horn beetles (Cerambycidae) and bark beetles (Scolytinae). The beetles were reared from hatching boxes. The study aims to fil in knowledge gaps about which species that are pyrophilous respectively fire-favoured. In the future this could contribute to a better knowledge about how to manage the oakforests and it`s associated species. The results shows that bark beetles are more numerous on burned oaks, that have died recently where the fire have been limited to the ground. It also seems like bark beetles are more numerous on smaller diameter trees. Future studies should focus on studying wood a wider range of diameters as well as more trees and samples. A longer time for rearing the insects would also be desirable.

We describe methods and progress in developing the American Long Oak Chronology (ALOC), an effort to construct an oak tree-ring chronology from the Central US that spans the Holocene. Since 2000, we have collected and measured ring widths on over 550 pieces of subfossil oak (Quercus) wood. Over 330 oak samples have been radiocarbon dated, with ages ranging up to 14,000 cal yr B.P. A 1,093- year-long tree-ring record has been constructed from live and subfossil bur oaks (Q. macrocarpa Michx.) and swamp white oaks (Q. bicolor Willd.) growing along and buried in sediments of streams that flow through northern Missouri and southern Iowa, USA. Here we describe the ALOC for the period A.D. 912–2004 to demonstrate its dendrochronological value, display the material quality, and emphasize the importance of chronology construction. We also report on progress in developing older floating chronologies. The development of more long, multi-millennium chronologies will be an important contribution to dendroclimatology. These chronologies will be particularly useful to the Central US, a region with a continental climate and limited temporal depth of annually resolved paleorecords. Perhaps more critical is its location in the middle of one of the most important agricultural regions in the world.

Oaks function as habitat for a myriad of species including 300 species of lichens. Many of the associated species, which are included on the Swedish red-list, depend on old oaks with hollows and deep bark fissures and hence their future is threatened due to a lack of middle-aged oaks. Ongoing studies examine whether veteranisation can speed up the aging process and reduce the delivery time of “new” old oaks; thus reducing the gap between young and old oaks. Decay processes can be facilitated in oaks by inflicting different types of wounds (i.e., veteranisation), such as broken off branches or sawed out nestboxes. In this study bark fissure depth and species richness of lichens were analyzed for oaks subjected to veteranisation, which were compared to controls, ten years after treating them. Bark fissure depth and species richness were analyzed for 49 oaks based on data from from 2014 and 2022. No significant differences were detected between veteranised oaks compared to the control oaks. The time from treatment to the undertaking of this study was only ten years and continued monitoring of the effects on the lichen flora is recommended. / Ekar utgör livsmiljö för en lång rad arter, där lavar utgör cirka 300 arter. Många av ekarnas arter är rödlistade och beroende av gamla ekar med håligheter och djupa barksprickor, men deras framtid hotas på grund av bristen på medelålders ekar som kan efterträda dagens gamla individer. Pågående studier undersöker om veteraniseringsåtgärder kan påskynda åldrandet hos unga ekar, och därmed minska generationsglappet mellan gamla och unga ekar. Utvecklingen av svampangrepp och rötskador kan underlättas hos ekar genom de tillfogas olika skador (så kallad veteranisering), som avbrutna grenar eller utsågade holkar. I denna undersökning analyserades barksprickdjup och artrikedom av lavar hos veteraniserade respektive icke-veteraniserade ekar tio år efter åtgärd. Barksprickdjup och artrikedom analyserades för 49 ekar baserat på data från år 2014 och 2022. Inga signifikanta skillnader kunde ses mellan de veteraniserade ekarna jämfört med kontrollerna. Tiden från veteraniseringsåtgärderna till denna undersöknings utförande har varit kort, och det kan vara av värde att göra ytterligare utvärderingar av effekterna på lavfloran i framtiden.