Effects of Prescribed Burning on Advanced Regeneration in Upland Oak Forests of Missouri
ABSTRACT Seventy years of fire-suppression and inappropriate management practices have resulted i... more ABSTRACT Seventy years of fire-suppression and inappropriate management practices have resulted in numerous forest health problems in the current oak-hickory forests of Missouri, and have often resulted in the failure to adequately attain oak regeneration. The Chilton Creek Prescribed Burning Project, initiated by The Nature Conservancy in 1996, was designed to study the effects of prescribed fire on oak regeneration. Three different approaches to the use of prescribed fire were tested: annual burning (sites burned each year), random burning (sites burned randomly with a mean return interval of 3.6 yrs), and high-intensity random burning (same as random burn, but with higher fire intensities due to south-facing steep slopes and higher fuel loads) were implemented to monitor the dynamics of advanced regeneration. The presence and condition of regeneration, in terms of tree density and aggregate height, was recorded in 26 permanent plots in 1997 (pre-fire) and again in 2007 (post-fire). Post-treatment red oak densities were reduced by 53, 49, and 26% with the annual burn, the random burn and the high-intensity random burn, respectively. The random burn treatment significantly reduced the aggregate height of hickory compared with the other two treatments – the random burn reduced aggregate height by 83% while the annual burn and high-intensity random burn reduced the height by 40% and 65%, respectively. Preliminary results from this study suggest that increasing fire intensity favors red oak regeneration, although it also favors the growth of hickory. The time since the last burns under each of these treatments likely influenced these results.
Effects of Timber Harvesting on the Understory Oak Regeneration in Upland Oak Forests in the Missouri Ozarks
In the Missouri Ozarks, widespread oak decline in the overstory, along with failure to attain ade... more In the Missouri Ozarks, widespread oak decline in the overstory, along with failure to attain adequate regeneration have plagued oak-hickory forests. The reason for this has largely been attributed to long-term fire suppression and low-intensity timber management that has little impact on the main canopy. The Missouri Ozark Forest Ecosystem Project (MOFEP) was initiated in 1989 by Missouri Department of Conservation as a long-term, landscape-level study designed to evaluate the effects of timber harvest activities, both even-aged and uneven-aged, on oak forest ecosystem attributes. We used sixteen-year (1990-2006) MOFEP data to evaluate oak regeneration under various stand treatments. Pre-harvest data (1990-1995) indicated that oak regeneration in both the white oak and red oak groups had an inverse relationship with overstory density. Changes in understory density of the two groups were examined following treatments that included clearcutting, intermediate harvest (e.g., thinning), single-tree selection, group selection, and a no harvest control. The post-harvest data (1997-2006) indicated that in 2001, seedling (\u3c1.5 inches dbh) density of white oak and red oak group species were 17 times and 13 times greater respectively than in 1995 on the clearcut sites. All of the other treatments had slight, but non-significant increases in oak seedling density. In 2006, sapling (1.5 inc
Coppice regeneration is favored in North America for oak (Quercus spp.) regeneration. Altho~gh mo... more Coppice regeneration is favored in North America for oak (Quercus spp.) regeneration. Altho~gh models of oak stump sprouting do not consider Armillaria root disease, many oak stumps in upland Ozark forest stands carry active Armillaria root crown infections. The spatial pattern of sprouting on oak stumps is related to the circumferential distribution of Annillaria-infected roots. We draw attention to the proper interpretation of sprout "tree" age, re: root system age and the ages of Armillaria infections present. The pattern of channels left by decay of stump root systems seems well-suited to attrxting roots into contact with Amillaria inocula.
There are various definitions for savanna and woodland in the ecological literature. Characterist... more There are various definitions for savanna and woodland in the ecological literature. Characteristic elements of each community are broadly defined and often overlap according to the authorities (Curtis 1959; Nuzzo 1986; Nelson 2010). Some confusion is inevitable when categorizing what is in reality a continuum of states from prairie to forest in which there can be much variation. Additional variation arises within each of these community types producing unique associations where composition and structure are further modified by site factors such as soil texture, depth, drainage, and parent materials, which control water and nutrient availability. Nonetheless, given sufficient distance between two points along the continuum, distinct communities are recognizable. Ground flora composition and species dominance, overstory tree density, and number of canopy layers are used to distinguish between savannas and woodlands. Community structure and composition are interrelated because overhead tree canopies and shrub layers modify the microenvironment, in particular available light, at the ground, which influences floral diversity and species dominance. Historically, fire is considered to have been CONTENTS
Variability in historic fire regimes in eastern North America resulted in an array of oak savanna... more Variability in historic fire regimes in eastern North America resulted in an array of oak savannas, woodlands and forests that were dominant vegetation types throughout the region. In the past century, once abundant woodlands have become scarce due to conversion to agriculture, or development of forest structure in the absence of fire. Restoration of oak woodlands is a primary goal for land management agencies and conservation organizations. Although oak woodlands can be restored with a long-term regimen of prescribed burning, a combination of prescribed burning, timber harvesting and forest thinning produces the desired structure and composition more efficiently. Sustaining oak woodlands requires an occasional longer fire-free period to allow for replacement of the overstory by recruitment of trees from the reserve of oak sprouts that have accumulated in the understory. Prescribed fire is useful for sustaining oak woodlands, but it must be used judiciously to minimize timber damage...
Contains 14 full-length papers and 40 abstracts of posters that were presented at the 4th Fire in... more Contains 14 full-length papers and 40 abstracts of posters that were presented at the 4th Fire in Eastern Oak Forests conference, held in Springfield, MO, May 17-19, 2011. The conference was attended by over 250 people from 65 different organizations and entities, representing 22 states and 1 Canadian province.
Silviculture of forests in the Eastern United States
The forests of the Eastern United States are diverse and provide many products and amenities for ... more The forests of the Eastern United States are diverse and provide many products and amenities for people living in the area and beyond. Eastern temperate forests play an important role in determining water yield and quality. They have the potential to sequester large quantities of carbon and influence air quality, and thus climate. Our standard of living is very much linked to the health and productivity of forests. Forests cover approximately 41 percent of the Eastern United States, on average, but vary considerably at the State level, ranging from 6 percent in Iowa to 89 percent in Maine (Smith and others 2004).
Oak (Quercus L.) is an abundant and widely distributed genus in eastern North America. A history ... more Oak (Quercus L.) is an abundant and widely distributed genus in eastern North America. A history of periodic fire, grazing, canopy disturbance and timber harvesting has favored oak's dominance. But, changes in this regime toward much less fire or complete fire suppression, and selective cutting are causing the successional replacement of oak. High populations of forest herbivores such as whitetailed deer (Odocoileus virginianus), invasive species such as gypsy moth (Lymantria dispar), or dominance of native flora such as mountain laurel (Kalmia latifolia) can also inhibit oak regeneration and add to its loss within a region. Successful oak regeneration is dependent on having an adequate number of large oak advance reproduction before stand regeneration. However, this prerequisite is often lacking in eastern oak forests. Many oak stands have either few or no oak advance reproduction, and when present, it is small and noncompetitive. These common situations can be addressed through silviculture.
Variability in historic fire regimes in eastern North America resulted in an array of oak natural... more Variability in historic fire regimes in eastern North America resulted in an array of oak natural communities that were dominant across the region. In the past century, savannas and woodlands have become scarce because of conversion to agriculture or development of forest structure in the absence of fire. Their restoration is a primary goal for public agencies and conservation organizations. Although they can be restored with a long-term regimen of prescribed burning, a combination of fire, timber harvesting, and forest thinning produces the desired structure and composition more efficiently. Prescribed fire is useful for sustaining oak savannas and woodlands, but it must be used judiciously to minimize timber damage and decreases in value. Integrating fire within a modified shelterwood approach promotes competitive oak reproduction and is flexible enough to produce savannas or woodlands. Sustaining these communities requires the replacement of the overstory during periods of no fire.
The long history of fire in North America spans millennia and is recognized as an important drive... more The long history of fire in North America spans millennia and is recognized as an important driver in the widespread and long-term dominance of oak species. Early European settlers intensified the occurrence of fire from about 1850 to 1950, with dates varying by region. This resulted in much forest damage and gained fire a negative reputation. The lack of fire for the past 50 years due to suppression programs is now indicted as a major cause of widespread oak regeneration failures. Alarms are sounding for the continued loss of oak forests. The use of prescribed fire is increasing in forest management and ecosystem restoration. An understanding of fire effects on trees can provide the basis for the silviculture of restoring and sustaining oak ecosystems. We present an overview of fire-tree wounding interactions, highlight important determinants of fire injury and damage, and discuss several practical situations where fire can be used to favor oak while minimizing damage and devaluation of the forest. We also identify stages in stand development, regeneration methods, and management objectives for which fire has the potential of causing substantial damage and alternative practices should be preferred.
EFFECTS OF AN INTERMEDIATE-SCALE WIND EVENT ON FOREST COMPOSITION, STRUCTURE, AND STRUCTURAL COMPLEXITY by LAUREN ELIZABETH COX JUSTIN L. HART, COMMITTEE CHAIR
Regime Shifts and Weakened Environmental Gradients in Open
Fire suppression allows tree species that are intolerant of fire stress to increase their distrib... more Fire suppression allows tree species that are intolerant of fire stress to increase their distribution, potentially resulting in disruption of historical species-environmental relationships. To measure changes between historical General Land Office surveys (1815 to 1850) and current USDA Forest Inventory and Assessment surveys (2004 to 2008), we compared composition, distribution, and site factors of 21 tree species or species groups in the Missouri Ozarks. We used 24 environmental variables and random forests as a classification method to model distributions. Eastern redcedar, elms, maples, and other fire-sensitive species have increased in dominance in oak forests, with concurrent reductions by oak species; specific changes varied by ecological subsection. Ordinations displayed loss of separation between formerly distinctive oak and fire-sensitive tree species groups. Distribution maps showed decreased presence of disturbance-dependent oak and pine species and increased presence o...
Regenerating oak stands the “natural” way
Managing Oak Forests in the Eastern United States, 2016
Fire suppression allows tree species that are intolerant of fire stress to increase their distrib... more Fire suppression allows tree species that are intolerant of fire stress to increase their distribution, potentially resulting in disruption of historical species-environmental relationships. To measure changes between historical General Land Office surveys (1815 to 1850) and current USDA Forest Inventory and Assessment surveys (2004 to 2008), we compared composition, distribution, and site factors of 21 tree species or species groups in the Missouri Ozarks. We used 24 environmental variables and random forests as a classification method to model distributions. Eastern redcedar, elms, maples, and other fire-sensitive species have increased in dominance in oak forests, with concurrent reductions by oak species; specific changes varied by ecological subsection. Ordinations displayed loss of separation between formerly distinctive oak and fire-sensitive tree species groups. Distribution maps showed decreased presence of disturbancedependent oak and pine species and increased presence of fire-sensitive species that generally expanded from subsections protected from fire along rivers to upland areas, except for eastern redcedar, which expanded into these subsections. Large scale differences in spatial gradients between past and present communities paralleled reduced influence of local topographic gradients in the varied relief of the Missouri Ozarks, as fire-sensitive species have moved to higher, drier, and sunnier sites away from riverine corridors. Due to changes in land use, landscapes in the Missouri Ozarks, eastern United States, and worldwide are changing from open oak and pine-dominated ecosystems to novel oak-mixed species forests, although at fine scales, forests are becoming more diverse in tree species today. Fire suppression weakened the influence by environmental gradients over species dominance, allowing succession from disturbance-dependent oaks to an alternative state of fire-sensitive species. Current and future research and conservation that rely on historical relationships and ecological principles based on disturbance across the landscape will need to incorporate modern interactions among species for resources into management plans and projections.
Spatial pattern corrections and sample sizes for forest density estimates of historical tree surveys
Landscape Ecology, 2011
The U.S. General Land Office land surveys document trees present during European settlement. Howe... more The U.S. General Land Office land surveys document trees present during European settlement. However, use of these surveys for calculating historical forest density and other derived metrics is limited by uncertainty about the performance of plotless density estimators under a range of conditions. Therefore, we tested two plotless density estimators, developed by Morisita and Pollard, for two, three, and four
Description: Growth and yield projections aid foresters in assessing timber management opportunit... more Description: Growth and yield projections aid foresters in assessing timber management opportunities and in making management decisions. With these uses, questions arise about the reliability and limits of growth and yield simulators. Using long-term studies of hardwood stands in ...
Description: The individual-tree, distance-independent stand growth simulator NE-TWIGS has been t... more Description: The individual-tree, distance-independent stand growth simulator NE-TWIGS has been tested for Ontario's tolerant hardwood stands using data from long-term permanent sample plots. NE-TWIGS provides reliable short-term (5-year) predictions of stand basal area ( ...
—Variability in historic fire regimes in eastern North America resulted in an array of oak savann... more —Variability in historic fire regimes in eastern North America resulted in an array of oak savannas, woodlands and forests that were dominant vegetation types throughout the region. In the past century, once abundant woodlands have become scarce due to conversion to agriculture, or development of forest structure in the absence of fire. Restoration of oak woodlands is a primary goal for land management agencies and conservation organizations. Although oak woodlands can be restored with a long-term regimen of prescribed burning, a combination of prescribed burning, timber harvesting and forest thinning produces the desired structure and composition more efficiently. Sustaining oak woodlands requires an occasional longer fire-free period to allow for replacement of the overstory by recruitment of trees from the reserve of oak sprouts that have accumulated in the understory. Prescribed fire is useful for sustaining oak woodlands, but it must be used judiciously to minimize timber damage and decreases in value. Integrating fire in a silvicultural prescription that uses the shelterwood regeneration method to promote competitive oak reproduction has been successfully applied in the eastern US to sustain oak forests. Restoration of oak ecosystems is possible but requires innovative combinations of traditional practices, including prescribed burning.
Variability in historic fire regimes in eastern North America resulted in an array of oak natural... more Variability in historic fire regimes in eastern North America resulted in an array of oak natural communities that were dominant across the region. In the past century, savannas and woodlands have become scarce because of conversion to agriculture or development of forest structure in the absence of fire. Their restoration is a primary goal for public agencies and conservation organizations. Although they can be restored with a long-term regimen of prescribed burning, a combination of fire, timber harvesting, and forest thinning produces the desired structure and composition more efficiently. Prescribed fire is useful for sustaining oak savannas and woodlands, but it must be used judiciously to minimize timber damage and decreases in value. Integrating fire within a modified shelterwood approach promotes competitive oak reproduction and is flexible enough to produce savannas or woodlands. Sustaining these communities requires the replacement of the overstory during periods of no fire.
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