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Oak, Fire, and Global Change in the Eastern USA: What Might the Future Hold?

Abstract

The pace of environmental and socioeconomic change over the past 100 years has been rapid. Changes in fire regimes, climate, and land use have shaped the structure and function of most forest ecosystems, including oak (Quercus spp. L.) forests in the eastern United States. New stressors such as air pollution and invasive species have contributed to and interacted with climate and fire to alter current forest conditions. While changing fire regimes have altered species composition of the current forest, oak regeneration is constrained by many factors that may affect future forests. Over the remainder of the twenty-first century, an accelerating pace of climate and socioeconomic changes will influence the future range of variation in Eastern oak forests. Some of these impacts will be direct, such as changes in tree growth rates, while other impacts will be indirect, such as new disturbance regimes. While it is likely that fire will be important in shaping oak forests in the twenty-first century, it is less clear exactly what that role will be. For example, it is uncertain whether our current scientific knowledge on the use of prescribed fire in oak forests will be applicable under novel climate and changing socioeconomic conditions. We propose that the combination of climate change, wildfire, and other disturbances will create stand conditions that favor oaks with or without management. However, management intervention (e.g., prescribed fire, thinning, or a combination) could reduce wildfire hazard, particularly in the wildland-urban interface, and create more desirable stand conditions that are resilient to future stressors such as changing precipitation patterns and warmer temperatures.

Resumen

El ritmo de los cambios ambientales y socioeconómicos en los últimos 100 años ha sido rápido. Cambios en los regímenes de fuego, en el clima y en el uso de la tierra han modelado la estructura y función de la mayoría de los ecosistemas boscosos incluyendo los bosques de roble (Quercus spp. L.) en el este de los EEUU. Nuevos agentes de estrés como la contaminación del aire y las especies invasoras han contribuido e interactuado con el clima y el fuego para alterar las condiciones actuales reinantes en el bosque. Mientras que el cambio en los regímenes de fuego han alterado la composición de especies en el bosque actual, la regeneración del roble está condicionada por varios factores que podrían afectar los bosques futuros. En lo que queda del siglo XXI, un ritmo acelerado de cambios climáticos y socioeconómicos influirán en el futuro rango de variación en los bosques orientales de roble. Algunos de estos impactos van a ser directos, como cambios en las tasas de crecimiento, mientras que otros impactos van a ser indirectos como nuevos regímenes de disturbios. Si bien es muy probable que el fuego sea un importante modelador de los bosques de roble en el siglo XXI, no está tan claro cuál será su rol. Por ejemplo, es incierto si nuestro conocimiento científico actual sobre el uso de quemas prescriptas será aplicable bajo las nuevas condiciones climáticas y los cambios socioeconómicos. Nosotros proponemos que la combinación del cambio climático, los incendios y otros disturbios crearán condiciones en el rodal que van a favorecer los robles con o sin manejo. Sin embargo, las intervenciones en el manejo (por ej. quemas prescriptas, raleos o una combinación), podrían reducir el peligro de incendios, particularmente en la interfaz urbano-rural y crear condiciones deseables en el rodal que sean resilientes a futuros agentes de estrés como cambios en los patrones de precipitación y las altas temperaturas.

Introduction

Contemporary oak (Quercus spp. L.) forests in the eastern United States are undergoing changes that include a greater abundance of mesophytic, fire-sensitive, and shade-tolerant tree species (Nowacki and Abrams 2008, Elliott and Vose 2011). The historic role of fire in oak forests of the eastern US has been examined by numerous investigators who generally conclude that a regime of frequent, low-intensity fires has occurred over the much of the region (e.g., McEwan et al. 2011, Brose et al. 2013, Flatley et al. 2013, Abrams and Nowacki 2015, Stambaugh et al. 2015). Fire was likely more frequent in communities adapted to (or tolerant of) fire, such as oak, mixed oak-pine (-Pinus spp. L.), and xeric pine-oak (Guyette et al. 2006, Brose and Waldrop 2014).

While fire was likely a major causal factor in the establishment and maintenance of oak forests, the mechanisms underlying these changes are complex. McEwan et al. (2011) suggested that fire, climate, and disturbance regimes in the nineteenth and early twentieth centuries enhanced and perpetuated oak species, whereas wetter conditions and altered fire and disturbance regimes in the twentieth century no longer favored oaks. Nowacki and Abrams (2015) concluded that post-European settlement vegetation dynamics (i.e., an increase in mesophytic species) has been driven primarily by lack of fire, with climate playing a minor role. Hence, contemporary forests are changing because successional processes are no longer arrested by fire and other disturbances, and wetter conditions favor more mesophytic species. Most notably, the expansion of more shade-tolerant Acer rubrum L. has been observed across most of the historical range of oak-dominated forests in the eastern US (Abrams 2005, Fei and Steiner 2007, Elliott and Vose 2011). Other non-oak species are expanding as well (Rentch et al. 2003, Ozier et al. 2006, McEwan et al. 2011). For example, in the southern Appalachians, Elliott and Vose (2011) documented an increase in the importance of Liriodendron tulipifera L. and Betula spp. L., and a decline in importance of several oak species (Figure 1). In the Missouri Ozarks, Hanberry et al. (2012) examined changes in forest composition by comparing General Land Office (GLO) records and current USDA Forest Service Forest Inventory and Analysis (FIA) data and found that the contemporary forest condition has changed from open oak-pine savannas and woodlands to more homogeneous mixed hardwood forests over the past 50 years. They concluded that these forests would likely proceed to even denser forests of shade-tolerant species, assuming climate and disturbance regimes (such as fire) remained constant (Hanberry et al. 2012).

Figure 1
figure1

Changes in forest species composition in southern Appalachian forests (updated and adapted from Elliott and Vose 2011). Long-term changes for unmanaged forests; measured in 1934 to 1935, 1969 to 1973, 1988 to 1993, and 2009 to 2013 within Coweeta Basin, western North Carolina (latitude 35° 03′ N, longitude 83° 25′ W). Importance value = (relative density + relative basal area) ÷ 2.

Although data are limited, the shift in composition to a greater proportion of mesophytic, fire-sensitive species in upland mixed-oak forest ecosystems across the eastern US has consequences for ecosystem function. Alexander and Arthur (2010) found that Acer rubrum altered hydrology and nutrient availability by changing the amount, spatial distribution, and chemical composition of stemflow and throughfall. Species also vary in litterfall decomposition rates and nutrient release, with higher decomposition rates and nutrient cycling rates generally associated with A. rubrum and Liriodendron tulipifera (Knoepp et al. 2005, Ball et al. 2009, Keiser et al. 2013) versus oak species.

Changes in species composition can also influence productivity and growth responses to climate variability. For example, Hart et al. (2012) analyzed climate-growth relationships in the Cumberland Plateau and suggested that Acer rubrum is more sensitive to warmer and dry conditions than oaks. Elliott et al. (2015) used a combination of dendrochronology and long-term, on-site climate records to evaluate climate-growth relationships of six dominant hardwood species in the southern Appalachians of North Carolina. They found differences in climate sensitivities that corresponded with xylem anatomy, in which mesophytic species with diffuse-porous xylem (Acer rubrum, Liriodendron tulipifera, and Betula lenta L.) were generally more sensitive to precipitation distribution (such as small storms and dry spell length) than xeric or semi-mesophytic species (Quercus alba L., Q. montana Willd., and Q. rubra L.) with ring-porous xylem (Elliott et al. 2015). In southern Indiana, Roman et al. (2015) found that carbon accumulation in oak species was less impacted by a severe drought than were Acer saccharum Marshall, Liriodendron tulipifera, and Sassafras albidum (Nutt.) Nees. Fewer studies are available that assess the impacts of drought on mortality in eastern US forests and the relationships are complex and multifactored. For example, Dietz and Moorcroft (2011) analyzed long-term forest mortality patterns and found that factors such as stand characteristics and air pollution were stronger drivers of mortality patterns than climate variation. However, in a study examining species-specific mortality patterns across the southeastern US, Klos et al. (2009) found a much higher mortality rate in mesophytic species (Acer spp., Betula spp., Fagus grandifolia Ehrh., Liriodendron tulipifera, Magnolia spp. L., Nyssa spp. L.) versus oak species under severe drought conditions. Taken together, these observational data suggest that mesophytic species are more vulnerable to drought both in terms of reduced growth and higher mortality, and hence may be disproportionately impacted by rising air temperatures and changing drought regimes expected with climate change. A key question is how these new drought regimes will interact with fire (wildfire and prescribed fire) to shape forest structure and function.

Because of the historic role of fire in eastern US oak forests, many researchers have assessed the potential for re-introducing fire to alter species composition, with an overall objective of increasing oak dominance and regeneration, while decreasing more mesophytic species. The thick bark of many oak species imparts resistance to fire for larger trees, while a well-developed root system imparts fire resilience in smaller-stemmed advanced regeneration by promoting aggressive re-sprouting (Nowacki and Abrams 2008, Brose and Waldrop 2014). Overall, most studies indicate that frequent fires are required to kill non-oak species (Hutchinson et al. 2012, Arthur et al. 2015) and that oak regeneration is enhanced if fire is used in combination with other treatments such as thinning (Brose et al. 2013, Brose and Waldrop 2014). While fire appears to be a viable tool for oak management in contemporary forests, prescribed fire is currently used over a small fraction of the range of mixed-oak forests (Melvin 2012). As a result, if current climate and other disturbance regimes are upheld, it is likely that the pattern of increasing mesophytic and fire-intolerant species maintaining or gaining dominance in mixed-oak forests will continue in the eastern US (McEwan et al. 2011).

Approach

Several recent papers have raised questions about how climate change and other factors (e.g., invasive species) will impact oak forests and interact with prescribed fire and other restoration efforts (Arthur et al. 2012, Hart and Buchanan 2012, Dey 2014); however, to our knowledge, there are no definitive experiments or studies that can be drawn upon for direct inferences. When responses are understood at a mechanistic level, the ability to extrapolate beyond historical observations and to model ecosystem dynamics is improved, but not without uncertainty. An alternative is to synthesize our current understanding of species responses to observed climate variability and altered disturbance regimes and project how these responses might shape the structure and function of future forests under new climate and disturbance regimes. Hence, this hypothesis-based approach provides a starting point for decisions about potential management and restoration approaches, while recognizing that uncertainty requires monitoring and adaptations as additional observations and experiments accumulate. For example, a reasonable hypothesis is that the rapid pace and magnitude of climate change will influence competitive dynamics and regeneration patterns among species (Clark et al. 2014 a) and increase wildfire frequency and area burned (Flannigan et al. 2009, Slocum et al. 2010 a, Liu et al. 2012, Flannigan et al. 2013), all of which will favor oaks. Alternatively, more severe drought and an expanding wildland-urban interface may reduce the ability to utilize prescribed fire in the future (Mitchell et al. 2014), limiting the ability of managers to use fire as a management tool to help shape the structure and function of future oak forests.

An important question facing land managers is how to manage oak forests in anticipation of the direct and indirect effects of future climate change that include changes in wildfire regimes and potential limits to the use of prescribed fire. To address this question, we synthesized existing literature to examine two propositions for the eastern US: 1) climate change will facilitate the re-establishment of oak dominance in hardwood forests; and 2) management intervention can be used to accelerate re-establishment of oak forests, but an increase in oak dominance will occur with or without management. Through these propositions, we advance the concepts that management interventions will be more effective under changing climate regimes and management will be necessary to sustain ecosystem services in future oak forests.

Propositions

Proposition 1: Climate Change Will Facilitate an Increase in Oak Dominance in Hardwood Forests of the Eastern US

As discussed by McEwan et al. (2011), causal factors underlying changes in eastern US oak forests over the past century are complex, but changes in precipitation regimes (i.e., reduced drought severity and frequency; Pederson et al. 2015) and disturbance regimes (Nowacki and Abrams 2015) were likely major driving variables in the twentieth century. With a reduction in widespread fire and other disturbances, more mesophytic, shade-tolerant, and fire-sensitive species have taken advantage of these wetter conditions over the past century, with some suggestion that changes in the structure of the canopy and litter promotes a self-perpetuating mesic environment that provides a competitive advantage (Abrams 2005, Nowacki and Abrams 2008, Alexander and Arthur 2010, Kreye et al. 2013). Whether these changes will be sufficient to offset the impacts of drier and warmer conditions projected for the future is unknown. Global Climate Models (GCMs) indicate that the climate of the eastern US will experience increasing temperatures and associated evapotranspiration throughout the twenty-first century (IPCC 2014, Melillo et al. 2014). Predicting changes in precipitation is challenging and highly uncertain; however, in general, models predict an increased number of consecutive dry days for many areas within the range of Eastern oak forests (Walsh et al. 2014). Bedel et al. (2013) concluded that conditions in southern and mid-south regions of the US will likely become drier overall, given a warmer environment during future spring and summer seasons (Figure 2; http://nca2014.globalchange.gov/report/regions/southeast). Higher temperatures and altered precipitation patterns will likely result in changes in tree growth rates, mortality rates, competition, and species interactions, all of which can modify the distribution of tree species in favor those more adapted to xerophytic conditions (Klos et al. 2009, Clark et al. 2012, Clark et al. 2014b, Elliott et al. 2015, Zolkos et al. 2015).

Figure 2
figure2

Projected future temperature across the southeastern US reflects the increase in number of days above 35°C (from: http://nca2014.globalchange.gov/report/regions/southeast).

Historically, drought has been a major driver of large-scale tree mortality in the eastern US (Pederson et al. 2014) and recent studies have reported an increase in drought- and heat-related mortality across the globe and in the US (Allen et al. 2010, van Mantgem et al. 2013, Williams et al. 2013); however, drought tolerance varies considerably among species (Meinzer et al. 2013). The physiological basis regulating differential species responses to drought is largely driven by variation in the ability of tree species to survive long periods with substantial soil water deficits or high vapor pressure deficits (VPD), or both (Domec et al. 2015, McDowell and Allen 2015). This survival depends (in part) on stomatal control (the ability of leaf stomata to close when VPD is high) and on the hydraulic systems of trees (the ability to move soil water from roots to the leaves). Trees that have a high degree of stomatal sensitivity to VPD and maintain leaf or xylem water potentials well above critical water potentials are classified as more isohydric, whereas trees that allow actual leaf or xylem water potentials to fall throughout the day and approach critical water potentials are classified as anisohydric (Klein 2014). High VPD can stress the water-conducting system and elicit stomatal closure. Excessively high transpiration in response to greater VPD can result in cavitation (or air bubbles), which restricts water transport (Sperry 2011). Hence, severe drought can cause irreparable cavitation in the xylem, resulting in hydraulic failure and subsequent desiccation of foliage (Tyree and Sperry 1989, McDowell et al. 2011). Alternatively, trees can close their stomata to reduce the risk of hydraulic failure, but stomatal closure results in diminished photosynthesis that can reduce tree growth and lead to carbon starvation and eventual tree death (McDowell et al. 2011).

Another factor determining vulnerability to cavitation among species is xylem anatomy, with ring-porous xylem being more vulnerable to cavitation than diffuse-porous or tracheid xylem anatomies. In eastern US oak forests, mesophytic species (e.g., Acer spp., Liriodendron tulipifera, and Nyssa spp.) are typically isohydric, diffuse-porous, whereas oaks are anisohydric, ring-porous (Table 1). These differences in stomatal conductance and xylem anatomy also influence whole-tree transpiration rates, with significantly greater water use by diffuse-porous species than ring-porous species under the same climatic and environmental factors (Ford et al. 2011 a, von Allmen et al. 2015, Vose et al. 2016). Some of these factors may translate into different growth sensitivities to climate variability (von Allmen et al. 2015). For example, recent studies examining growth responses to climate variability suggest that stem wood growth is generally more sensitive to dry periods in diffuse-porous species versus ring-porous species (Pederson et al. 2012, Brzostek et al. 2014, Elliott et al. 2015). Despite being anisohydric, drought tolerance of oak trees is facilitated by deep rooting depths (Abrams 1990, Meinzer et al. 2013) and other physiological adaptations that facilitate stable water use and xylem pressure (McCulloh et al. 2010, Meinzer et al. 2013, von Allmen et al. 2015).

Table 1 Common tree species across the eastern United States classified by hydrotype (mesophytic, semi-mesophytic, or xerophytic)a, xylem anatomy (diffuse-porous, ring-porous, semi-ring-porous, or tracheid)b, and stomatal control (isohydric or anisohydric)c. Classifications were extracted from the literature;a hydrotype (Flatley et al. 2015),b xylem anatomy (Ewers et al. 2007) andc stomatal control (Roman et al. 2015).

Taken together, these physiological and morphological differences help provide a mechanistic understanding for field observations of reduced growth and higher mortality in mesophytic species (Acer rubrum, Liriodendron tulipifera, and Betula lenta) versus oak species (Quercus alba, Q. montana, and Q. rubra) under severe drought conditions. Hence, if drought frequency and severity increase as projected in GCMs (IPCC 2014, Melillo et al. 2014), these observed differences in drought tolerance between diffuse-porous and ring-porous species are likely to influence forest dynamics over large areas of the eastern US. These dynamics will be driven by a combination of direct effects (e.g., changes in competitive ability due to climate variation; Pederson et al. 2015) and indirect effects resulting from altered disturbance regimes (Nowacki and Abrams 2015). Predicting future species composition in oak forests is challenging; however, modeling approaches suggest that temperate forest stands will see an increase in oaks over the next 50 to 100 years due to altered climate conditions (Bachelet et al. 2003, Clark et al. 2014 b). An increased oak component could result from reduced growth and higher mortality of mesophytic, diffuse-porous species relative to oak species; however, longer-term and sustained changes will also require successful oak regeneration (Abrams 2005, Fei et al. 2011) and the ability of oaks to outcompete other xerophytic species that will also be favored under drier conditions (Table 1). The challenges of oak regeneration under current climate conditions and disturbance regimes are well documented (Brose et al. 2013, Brose and Waldrop 2014). Although it is difficult to predict how increased drought frequency and severity will impact oak recruitment in the future, some studies suggest that oak regeneration will be favored. For example, Ibáñez et al. (2007) suggested that Quercus rubra recruitment would benefit under climate change conditions that result in warmer and drier conditions. In addition, more frequent and severe fires (as defined by Keeley 2009) resulting from drier fuels and greater fuel loads could also favor oak regeneration (Blankenship and Arthur 2006, Brose et al. 2013).

Fires in the eastern US could increase in frequency and area burned during periods of low precipitation and high temperatures (Lafon and Quiring 2012). Compared to the earlier period of 1979 to 1996, fire season length has increased across the globe during the period 1996 to 2013, in which temperatures, length of rain-free intervals, and wind speeds were more pronounced and significantly related to fire season length (Jolly et al. 2015). For example, fire season length has shown a significant increase in the eastern US Coastal Plains (Jolly et al. 2015). Over the last decade, this region has witnessed a substantial increase in wildfires and a group of large fires in Okefenokee National Wildlife Refuge, the Osceola National Forest, and adjacent lands burned 243 000 ha in 2007 (Georgia Forestry Commission 2007). Several models using GCMs coupled with indices of fire danger have predicted significant increases in wildfire area burned and fire severity, particularly in the Northern Hemisphere, including the southeastern US (Lafon and Quiring 2012, Liu et al. 2012, Bedel et al. 2013, Flannigan et al. 2013, Mitchell et al. 2014). These models converge on the projection that mixed-oak forests in the eastern US will likely experience greater prolonged dry periods, increased wildfire risk, and larger areas burned.

In addition to climate change and fire risk predictions, future projections indicate rapid land use and land cover changes, with 12 to 17 million hectares of new development by 2060 (Wear and Greis 2013). These changes are driven in large part by increase in human population (Figure 3a), and urbanization is greatest at the periphery of urban centers, expanding the wildland-urban interface (WUI) (Figure 3b, Wear 2011) through many areas of the Eastern oak forest range. This increasingly fragmented landscape may decrease opportunities for prescribed burning due to a larger WUI (Mitchell et al. 2014), while at the same time predicted hotter, drier conditions seem likely to increase wildfire risk (Krawchuk et al. 2009, Marlon et al. 2009, Liu et al. 2012), causing concerns for the safety and health of an expanding population in the WUI.

Figure 3
figure3

(A) Projected changes in human population density (by county) from the time period 1997 to 2060 (Wear 2011). Data are the change in people per square kilometer (values are approximate after unit conversions and rounding) under the International Panel on Climate Change (IPCC) A1B emissions scenario. Areas in green denote areas where population density is projected to decrease. (B) Forecasted change in the proportion of the county in urban land use, A1B scenario, 1997 to 2060 (Wear 2011).

Proposition 2: Management Intervention May Accelerate Re-Establishment of Oak Forests, but Oak Dominance Will Increase with or without Management

If projections of future climate and fire interactions are correct for the eastern US (Flannigan et al. 2009; Slocum et al. 2010 a, b; Liu et al. 2012; Mitchell et al. 2014), we propose that changes in the frequency and severity of droughts and wildfire will favor oaks over the long term with or without management. A key question for land managers is whether they should anticipate and help guide these dynamics using management tools such as prescribed fire (Ryan et al. 2013) and thinning over shorter time scales or allow them to unfold without intervention over longer time scales (Figure 4). More frequent and severe wildfires may reduce tree vigor (Clark et al. 2012, Arthur et al. 2015), accelerate decomposition and nutrient losses (Trammell et al. 2004, Knoepp et al. 2009, Alexander and Arthur 2010, Nave et al. 2011, Elliott et al. 2012), and decrease net primary productivity and carbon accumulation and storage (Brzostek et al. 2014). If these dynamics occur, the resulting condition of these highly disturbed forest ecosystems may be inconsistent with management goals. As an alternative, management actions could be used to facilitate a more rapid transition to greater oak dominance, which would, in turn, create stands more resistant and resilient to these future climate stressors (Millar et al. 2007), while providing a greater level of ecosystems services. We recognize that our propositions are simplifications of highly complex relationships that depend on the interaction of factors such as local site conditions (e.g., xeric vs. mesic upland oak stands), initial species composition, and historical and contemporary disturbance regimes that could yield a variety of potential outcomes in time and space (sensu alternative stable states; Nowacki and Abrams 2008). For example, under low and moderate precipitation deficits, mesic upland stands may have sufficient soil water availability to buffer low and moderate deficits, but they would reach a threshold at high precipitation deficits in which ecosystem condition would decline due to accelerated mortality of mesophytic species (Figure 5a). In contrast, under high precipitation deficits, xeric upland sites may be less prone to threshold responses than mesic upland sites because they have a greater proportion of drought-adapted xerophytic species. Active management (prescribed fire, thinning, or a combination) could be used to modify species composition in favor of more drought tolerant species and reduce water demand, both of which would decrease drought vulnerability and impacts on ecosystem condition (Figure 5b).

Figure 4
figure4

Conceptual diagram of future pathways to more oak-dominated forests with passive management or active management intervention (see Agee 2002). With passive management, stand structure and function will be driven by drought and wildfire that will favor oaks; however, the stands will be less vigorous and poorer quality. As an alternative, active management would facilitate and sustain desirable stand conditions that are more resistant and resilient to current and future droughts and wildfire. Active management could include selective removal of mesophytic species with thinning and prescribed fire.

It is difficult to predict changes in the vulnerability to invasive species; however, known (and unknown) invasive species could interact with drought and create new fire regimes that dramatically alter structure and function. For example, the expansion of the highly flammable cogongrass (Imperata cylindrical [L.] P. Beauv.) in the US coastal plain forests could have substantial impacts on fire regimes and fire behavior (Lippincott 2000) in that region. Invasion by Microstegium vimineum (Trin.) A. Camus, a non-native annual grass, resulted in a positive invasion-fire feedback in which biomass and recruitment of the invasive species were greater in burned than unburned deciduous forests (Wagner and Fraterrigo 2015). Similarly, more severe fires that expose mineral soil could facilitate establishment of a wide variety of light-seeded species. The conditions created by changing climate, along with other global changes such as elevated CO2, more fragmented landscapes, and invasive plant and animal species, will likely create novel structural and functional characteristics (Hiers et al. 2012) that are not analogous to most of the oak forests that existed prior to mesophication (sensu Nowacki and Abrams 2008). Exactly how these external drivers will shape the structure and functions of eastern US oak forests is unknown. This uncertainty emphasizes the need to closely monitor forest change and responses to management actions in order to adapt to unanticipated outcomes.

What types of management actions could be implemented in current forests to help facilitate the transition to more resistant and resilient oak forests in the future? Prescribed fire will continue to be a critical management tool in oak forests (Ryan et al. 2013); however, there will be challenges to using prescribed fire in an increasingly human-dominated landscape (Figure 3b; Mitchell et al. 2014). More variable climate conditions may also result in greater and more flammable fuels, especially if drought increases mortality (Klos et al. 2009). These changing conditions emphasize the need for collaborative partnerships between land managers and researchers to conduct large-scale experiments, monitor change and effectiveness, and implement adaptive management as needed. As a starting point, some guidance is provided by the large number of prescribed fire studies in eastern US oak forests. For example, Brose and Waldrop (2014) reviewed the literature over the past 50 years and concluded that oak regeneration is most successful after multiple growing-season fires and after a substantial reduction in overstory density. The success of using fire to alter species composition is variable; however, a common theme is that single, low-intensity fires often increase the importance of mesophytic species (Elliott et al. 1999, Blankenship and Arthur 2006). Like oak regeneration, multiple fires are more likely to promote mature oak forests (Hutchinson et al. 2012), although frequent or mixed-severity fires can reduce the vigor of surviving oaks. In addition to favoring oak dominance, reducing density of mesophytic species will likely create stands that are more drought tolerant and resistant to large-scale mortality from changing climatic conditions. Oaks also have the added benefit of requiring less water for evapotranspiration, and hence greater water yield would be expected in stands that have perennial or ephemeral streams (Ford et al. 2011 b, von Allmen et al. 2015, Vose et al. 2016). This could have important implications for creating stand conditions that sustain ecosystem services, such as water supply, under drier conditions. In areas where prescribed fire is not feasible (e.g., WUI areas), stand structure could be altered by mechanical or herbicide removal of mesophytic species.

Conclusions

Restoration ecology has been guided by the notion of historical reference conditions (e.g., Falk et al. 2006, Stanturf et al. 2014). Similarly, the concept of desired future conditions has often been referenced by historical observations and experiences of land managers (e.g., Druckenbrod et al. 2006, Dey and Schweitzer 2014). Recently, both of these concepts have been challenged because the rapid pace of environmental changes will create novel conditions in which historical reference conditions are not appropriate and desired future conditions are not achievable (Hobbs et al. 2014, Golladay et al. 2015, Hanberry et al. 2015). In the case of oak restoration, using prescribed fire could be viewed as an example of congruence among historical reference conditions, desired future conditions, and achievable future conditions. This congruence is possible because the reference condition (i.e., oak-dominated forests) was created under climatic conditions and disturbance regimes that are likely to be represented in the coming decades as a result of climate warming in the eastern US.

If an increase in oak dominance is the primary desired future condition, then only passive management may be required as we hypothesize that an increase in drought, wildfire frequency and severity, and other disturbances will favor oaks over mesophytic species in the long term (Figure 5). However, these new disturbance regimes may result in undesirable changes (e.g., reduced biomass and productivity, invasive species) in forest structure and function and decrease ecosystem services provided by oak forests. Instead of passive management, we advocate for active management (Agee 2002) to facilitate a more rapid transition to oak dominance that could alleviate some of the negative impacts of severe droughts and wildfire on forest health and productivity, while at the same time protecting or enhancing ecosystem services such as streamwater quantity and quality. The primary constraint will be a growing WUI that will ultimately limit the widespread application of prescribed fire and increase pressure to prevent and extinguish wildfires.

Figure 5
figure5

Ecosystem condition with (A) passive management and (B) active management (e.g., thinning, prescribed fire, or a combination of the two; see Agee 2002). Relationships between drought and forest condition are complex and driven by differences in site conditions, current stand structure and composition, and historical and current disturbance regimes. For example, within the continuum of site conditions that support oak forests, we hypothesize that ecosystem condition (based on metrics such growth rate, mortality) on mesic upland sites will be more resilient to low and moderate levels of precipitation deficit relative to xeric upland sites; however, at high precipitation deficits, ecosystem condition on mesic uplands will degrade in a “threshold response” due to high rates of tree mortality. Xeric upland oak sites will be inherently more resistant and resilient to drought at all levels due to a greater proportion of dry site oaks (e.g., white oak [Q. alba], scarlet oak [Q. coccinea]). Active management could be used to maintain a higher level of ecosystem condition and reduce the magnitude of response to drought.

While our propositions are based on synthesis and interpretation of the scientific literature, several unknowns could further shape these future oak-dominated forests, such that novel structural and functional characteristics may emerge that will require adaptive management and restoration strategies (Hiers et al. 2012). For example, invasive species (insects, plants, diseases) and other global changes such as elevated CO2 could play a role in forest dynamics and disturbance regimes. In addition, if future wildfires are more frequent and severe, then reduced tree vigor and nutrient loss could decrease stand productivity. We propose that the combination of climate change, wildfire, and other disturbances will create stand conditions that favor oaks with or without management. However, management intervention (e.g., prescribed fire, thinning, or a combination) could reduce wildfire hazard, particularly in the WUI, and create more desirable stand conditions that are resilient to future stressors such as changing precipitation patterns and warmer temperatures. Like most projections of the future, we acknowledge that there is uncertainty in our propositions and surprises are likely. While some of this uncertainty may be reduced through additional field observations, results from new experiments, and better models, monitoring, and adaptive management will be critical components of any management activity.

Literature Cited

  1. Abrams, M.D. 1990. Adaptations and responses to drought in Quercus species of North America. Tree Physiology 7: 229–238. doi: 10.1093/treephys/7.1-2-3-4.227

    Article  Google Scholar 

  2. Abrams, M.D. 2005. Prescribing fire in Eastern oak forests: is time running out? Northern Journal of Applied Forestry 22: 190–196.

    Google Scholar 

  3. Abrams, M.D., and G.J. Nowacki. 2015. Exploring the early Anthropocene burning hypothesis and climate-fire anomalies for the eastern US. Journal of Sustainable Forestry 34: 30–48.

    Article  Google Scholar 

  4. Agee, J.K. 2002. The fallacy of passive management: managing for firesafe forest reserves. Conservation in Practice 3: 18–26. doi: 10.1111/j.1526-4629.2002.tb00023.x

    Article  Google Scholar 

  5. Alexander, H.D., and M.A. Arthur. 2010. Implications of a predicted shift from upland oaks to red maple on forest hydrology and nutrient availability. Canadian Journal of Forest Research 40: 716–726. doi: 10.1139/X10-029

    Article  CAS  Google Scholar 

  6. Allen, C.D., A.K. Macalady, H. Chenchouni, D. Bachelet, N. McDowell, M. Vennetier, T. Kitzberger, A. Rigling, D.D. Breshears, E.H. Hogg, P. Gonzalez, R. Fensham, Z. Zhang, J. Castro, N. Demidova, J.-H. Lim, G. Allard, S.W. Running, A. Semerci, and N. Cobb. 2010. A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests. Forest Ecology and Management 259: 660–684. doi: 10.1016/j.foreco.2009.09.001

    Article  Google Scholar 

  7. Arthur, M.A., H.D. Alexander, D.C. Dey, C.J. Schweitzer, and D.L. Loftis. 2012. Refining the oak-fire hypothesis for management of oak-dominated forest of the eastern United States. Journal of Forestry 110: 257–266. doi: 10.5849/jof.11-080

    Article  Google Scholar 

  8. Arthur, M.A., B.A. Blankenship, A. Schörgendorfer, D.L. Loftis, and H.D. Alexander. 2015. Changes in stand structure and tree vigor with repeated prescribed fire in an Appalachian hardwood forest. Forest Ecology and Management 340: 46–61. doi: 10.1016/j.foreco.2014.12.025

    Article  Google Scholar 

  9. Bachelet, D., R.P. Neilson, T. Hickler, R.J. Drapek, J.M. Lenihan, M.T. Sykes, B. Smith, S. Sitch, and K. Thonicke. 2003. Simulating past and future dynamics of natural ecosystems in the United States. Global Biogeochemical Cycles 17(2): 1045. doi: 10.1029/2001GB001508

    Article  CAS  Google Scholar 

  10. Ball, B.A., M.A. Bradford, and M.D. Hunter. 2009. Nitrogen and phosphorus release from mixed litter layers is lower than predicted from single species decay. Ecosystems 12: 87–100. doi: 10.1007/s10021-008-9208-2

    Article  CAS  Google Scholar 

  11. Bedel, A.P., T.L. Mote, and S.L. Goodrick. 2013. Climate change and associated fire potential for the south-eastern United States in the 21st century. International Journal of Wildland Fire 22: 1034–1043. doi: 10.1071/WF13018

    Article  Google Scholar 

  12. Blankenship, B.A., and M.A. Arthur. 2006. Stand structure over 9 years in burned and fire-excluded oak stands on the Cumberland Plateau, Kentucky. Forest Ecology and Management 225: 134–145. doi: 10.1016/j.foreco.2005.12.032

    Article  Google Scholar 

  13. Brose, P.H., D.C. Dey, R.J. Phillips, and T.A. Waldrop. 2013. A meta-analysis of the fire-oak hypothesis: does prescribed burning promote oak reproduction in eastern North America? Forest Science 59: 322–334. doi: 10.5849/forsci.12-039

    Article  Google Scholar 

  14. Brose, P.H., and T.A. Waldrop. 2014. Making sense out of confusion: a review of fire-oak papers published in the past 50 years. Pages 12–24 in: T.A. Waldrop, editor. Proceedings of a conference on wildland fire in the Appalachians: discussions among managers and scientists. USDA Forest Service General Technical Report SRS-199, Southern Research Station, Asheville, North Carolina, USA.

    Google Scholar 

  15. Brzostek, E.R., D. Dragoni, H.P. Schmid, A.F. Rahman, D. Sims, C.A. Wayson, D.J. Johnson, and R.P. Phillips. 2014. Chronic water stress reduces tree growth and the carbon sink of deciduous hardwood forests. Global Change Biology 20: 2531–2539. doi: 10.1111/gcb.12528

    Article  Google Scholar 

  16. Clark, J.S., D.M. Bell, M. Kwit, A. Stine, B. Vierra, and K. Zhu. 2012. Individual-scale inference to anticipate climate-change vulnerability of biodiversity. Philosophical Transactions of the Royal Society B 367: 236–246. doi: 10.1098/rstb.2011.0183

    Article  Google Scholar 

  17. Clark, J.S., D.M. Bell, M.C. Kwit, and K. Zhu. 2014a. Competition-interaction landscapes for the joint response of forests to climate change. Global Change Biology 20: 1979–1991. doi: 10.1111/gcb.12425

    Article  Google Scholar 

  18. Clark, J.S., A.L.E. Gelfand, C.W. Woodall, and K. Zhu. 2014b. More than the sum of the parts: forest climate response from joint species distribution models. Ecological Applications 24: 990–999. doi: 10.1890/13-1015.1

    Article  Google Scholar 

  19. Clark, K.L., N. Skowronski, M. Gallagher, H. Renninger, and K. Schäferb. 2012. Effects of invasive insects and fire on forest energy exchange and evapotranspiration in the New Jersey pinelands. Agricultural and Forest Meteorology 166–167: 50–61. doi: 10.1016/j.agrformet.2012.07.007

    Article  Google Scholar 

  20. Dey, D.C. 2014. Sustaining oak forests in eastern North America: regeneration and recruitment, the pillars of sustainability. Forest Science 60: 926–942. doi: 10.5849/forsci.13-114

    Article  Google Scholar 

  21. Dey, D.C., and C. J. Schweitzer. 2014. Restoration for the future: endpoints, targets, and indicators of progress and success. Journal of Sustainable Forestry 33: S43–S65. doi: 10.1080/10549811.2014.883999

    Article  Google Scholar 

  22. Dietze, M.C., and P.R. Moorcroft. 2011. Tree mortality in the eastern and central United States: patterns and drivers. Global Change Biology 17: 3312–3326. doi: 10.1111/j.1365-2486.2011.02477.x

    Article  Google Scholar 

  23. Domec, J.-C., J.S. King, E. Ward, A.C. Oishi, S. Palmroth, A. Radecki, D.M. Bell, G. Miao, M. Gavazzi, D.M. Johnson, S.G. McNulty, G. Sun, and A. Noormets. 2015. Conversion of natural forests to managed forest plantations decreases tree resistance to prolonged droughts. Forest Ecology and Management 355: 58–71. doi: 10.1016/j.foreco.2015.04.012

    Article  Google Scholar 

  24. Druckenbrod, D.L., V.H. Dale, and L.M. Olsen. 2006. Comparing current and desired ecological conditions at a landscape scale in the Cumberland Plateau and Mountains, USA. Journal of Land Use Science 1: 169–189. doi: 10.1080/17474230601079480

    Article  Google Scholar 

  25. Elliott, K.J., R.L. Hendrick, A.E. Major, J.M. Vose, and W.T. Swank. 1999. Vegetation dynamics after a prescribed fire in the southern Appalachians. Forest Ecology and Management 114: 1–15. doi: 10.1016/S0378-1127(98)00351-X

    Article  Google Scholar 

  26. Elliott, K.J., and J.M. Vose. 2011. The contribution of the Coweeta Hydrologic Laboratory to developing an understanding of long-term (1934–2008) changes in managed and unmanaged forests. Forest Ecology and Management 261: 900–910. doi: 10.1016/j.foreco.2010.03.010

    Article  Google Scholar 

  27. Elliott, K.J., J.M. Vose, J.D. Knoepp, and B.D. Clinton. 2012. Restoration of shortleaf pine (Pinus echinata)-hardwood ecosystems severely impacted by the southern pine beetle (Dendroctonus frontalis). Forest Ecology and Management 274: 181–200. doi: 10.1016/j.foreco.2012.02.034

    Article  Google Scholar 

  28. Elliott, K.J., C.F. Miniat, N. Pederson, and S.H. Laseter. 2015. Forest tree growth response to hydroclimate variability in the southern Appalachians. Global Change Biology 21: 4627–4641. doi: 10.1111/gcb.13045

    Article  Google Scholar 

  29. Ewers, B.E., D.S. MacKay, and S. Samata. 2007. Interannual consistency in canopy stomatal conductance control of leaf water potential across seven tree species. Tree Physiology 27: 11–24. doi: 10.1093/treephys/27.1.11

    Article  CAS  Google Scholar 

  30. Falk, D.A., M.A. Palmer, and J.B. Zedler, editors. 2006. Foundations of restoration ecology. Island Press, Washington, D.C., USA.

    Google Scholar 

  31. Fei, S., and K.C. Steiner. 2007. Evidence for increasing red maple abundance in the eastern United States. Forest Science 53: 473–477.

    Google Scholar 

  32. Fei, S., N. Kong, K.M. Steiner, W.K. Moser, and E.B. Steiner. 2011. Change in oak abundance in the eastern United States from 1980 to 2008. Forest Ecology and Management 262: 1370–1377. doi: 10.1016/j.foreco.2011.06.030

    Article  Google Scholar 

  33. Flannigan, M.D., M.A. Krawchuk, W.J. de Groot, B.M. Wotton, and L.M. Gowman. 2009. Implications of changing climate for global wildland fire. International Journal of Wildland Fire 18: 483–507. doi: 10.1071/WF08187

    Article  Google Scholar 

  34. Flannigan, M., A.S. Cantin, W.J. de Groot, M. Wotton, A. Newbery, and L.M. Gowman. 2013. Global wildland fire season severity in the 21st century. Forest Ecology and Management 294: 54–61. doi: 10.1016/j.foreco.2012.10.022

    Article  Google Scholar 

  35. Flatley, W.T., C.W. Lafon, H.D. Grissino-Mayer, and L.B. LaForest. 2013. Fire history, related to climate and land use in three southern Appalachian landscapes in the eastern United States. Ecological Applications 23: 1250–1266. doi: 10.1890/12-1752.1

    Article  Google Scholar 

  36. Ford, C.R., R.M. Hubbard, and J.M. Vose. 2011a. Quantifying structural and physiological controls on variation in canopy transpiration among planted pine and hardwood species in the southern Appalachians. Ecohydrology 4: 183–195. doi: 10.1002/eco.136

    Article  Google Scholar 

  37. Ford, C.R., S.J. Laseter, W.T. Swank, and J.M. Vose. 2011b. Can forest management be used to sustain water-based ecosystem services in the face of climate change? Ecological Applications 21: 2049–2067. doi: 10.1890/10-2246.1

    Article  Google Scholar 

  38. Georgia Forestry Commission. 2007. Georgia wildfires of 2007: summary of facts and costs for recovery. Georgia Forestry Commission, Dry Branch, Georgia, USA.

    Google Scholar 

  39. Golladay, S.W., K.L. Martin, J.M. Vose, D.N Wear, A.P. Covich, R.J. Hobbs, K.D. Klepzig, G.E. Likens, R.J Naiman, and A.W. Shearer. 2015. Achievable future conditions as a framework for guiding forest conservation and management. Forest Ecology and Management 360: 80–96. doi: 10.1016/j.foreco.2015.10.009

    Article  Google Scholar 

  40. Guyette, R.P., D.C. Dey, M.C. Stambaugh, and R.-M. Musika. 2006. Fire scars reveal variability and dynamics of Eastern fire regimes. Pages 20–39 in: M.B. Dickinson, editor. Proceedings of a conference on fire in Eastern oak forests: delivering science to land managers. USDA Forest Service General Technical Report NRS-P-1, Northern Research Station, Newtown Square, Pennsylvania, USA.

    Google Scholar 

  41. Hanberry, B.B., D.C. Dey, and H.S. He. 2012. Regime shifts and weakened environmental gradients in open oak and pine ecosystems. PLoS ONE 7: e41337. doi: 10.1371/journal.pone.0041337

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  42. Hanberry, B.B., R.F. Noss, H.D. Safford, S.K. Allison, and D.C. Dey. 2015. Restoration is preparation for the future. Journal of Forestry 113: 425–429. doi: 10.5849/jof.15-014

    Article  Google Scholar 

  43. Hart, J.L., and M.G. Buchanan. 2012. History of fire in Eastern oak forests and implications for restoration. Pages 34–51 in: D.C. Dey, M.C. Stambaugh, S.L. Clark, and C.J. Schweitzer, editors. Proceedings of the 4th Fire in Eastern Oak Forests Conference. USDA Forest Service General Technical Report NRS-P-102, Northern Research Station, Newtown Square, Pennsylvania, USA.

    Google Scholar 

  44. Hart, J.L., M.G. Buchanan, S.L. Clark, and S.J. Toreano. 2012. Canopy accession strategies and climate-growth relationships in Acer rubrum. Forest Ecology and Management 282: 124–132. doi: 10.1016/j.foreco.2012.06.033

    Article  Google Scholar 

  45. Heirs, J.K., R.J. Mitchell, A. Barnett, J.R. Waters, M. Mack, B. Williams, and R. Sutter. 2012. The dynamic reference concept: measuring restoration success in a rapidly changing no-analog future. Ecological Restoration 30: 27–36. doi: 10.3368/er.30.1.27

    Article  Google Scholar 

  46. Hobbs, R.J., E. Higgs, C.M. Hall, P. Bridgewater, F.S. Chapin III, E.C. Ellis, J.J. Ewel, L.M. Hallett, J. Harris, K.B. Hulvey, S.T. Jackson, P.L. Kennedy, C. Kueffer, L. Lach, T.C. Lantz, A.E. Lugo, J. Mascaro, S.D. Murphy, C.R. Nelson, M.P. Perring, D.M. Richardson, T.R. Seastedt, R.J. Standish, B.M. Starzomski, K.N. Suding, P.M. Tognetti, L. Yakob, and L. Yung. 2014. Managing the whole landscape: historical, hybrid, and novel ecosystems. Frontiers in Ecology and the Environment 12: 557–564. doi: 10.1890/130300

    Article  Google Scholar 

  47. Hutchinson, T.F., R.P. Long, J. Rebbeck, E.K. Sutherland, and D.A. Yaussy. 2012. Repeated prescribed fires alter gap-phase regeneration in mixed-oak forests. Canadian Journal of Forest Research 42: 303–314. doi: 10.1139/x11-184

    Article  Google Scholar 

  48. Ibáñez, I., J.S. Clark, S. LaDeau, and J. Hille Ris Lambers. 2007. Exploiting temporal variability to understand tree recruitment response to climate change. Ecological Monographs 77: 163–177. doi: 10.1890/06-1097

    Article  Google Scholar 

  49. IPCC [Intergovernmental Panel on Climate Change]. 2014. Climate Change 2014: Synthesis Report, Contribution of Working Groups I, II and III to the Fifth Assessment Report of the IPCC (Core Writing Team, R.K. Pachauri and L.A. Meyer, [editors]). Intergovernmental Panel on Climate Change, Geneva, Switzerland.

    Book  Google Scholar 

  50. Jolly, W.M., M.A. Cochrane, P.H. Freeborn, Z.A. Holden, T.J. Brown, G.J. Williamson, and D.M.J.S. Bowman. 2015. Climate-induced variations in global wildfire danger from 1979 to 2013. Nature Communications 6: 7537. doi: 10.1038/ncomms8537

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  51. Keiser, A.D., J.D. Knoepp, and M.A. Bradford. 2013. Microbial communities may modify how litter quality affects potential decomposition rates as tree species migrate. Plant and Soil 372: 167–176. doi: 10.1007/s11104-013-1730-0

    Article  CAS  Google Scholar 

  52. Keeley, J.E. 2009. Fire intensity, fire severity and burn severity: a brief review and suggested usage. International Journal of Wildland Fire 15: 116–126. doi: 10.1071/WF07049

    Article  Google Scholar 

  53. Klein, T. 2014. The variability of stomatal sensitivity to leaf water potential across tree species indicates a continuum between isohydric and anisohydric behaviours. Functional Ecology 28: 1313–1320. doi: 10.1111/1365-2435.12289

    Article  Google Scholar 

  54. Klos, R.J., G.G. Wang, W.L. Bauerle, and J.R. Rieck. 2009. Drought impact on forest growth and mortality in the southeast USA: an analysis using forest health and monitoring data. Ecological Applications 19: 699–708. doi: 10.1890/08-0330.1

    Article  Google Scholar 

  55. Knoepp, J.D., B.C. Reynolds, D.A. Crossley, and W.T. Swank. 2005. Long-term changes in forest floor processes in southern Appalachian forests. Forest Ecology and Management 220: 300–312. doi: 10.1016/j.foreco.2005.08.019

    Article  Google Scholar 

  56. Knoepp, J.D., K.J. Elliott, J.M. Vose, and B.D. Clinton. 2009. Effects of prescribed fire in mixed-oak forests of the southern Appalachians: forest floor, soil, and soil solution nitrogen responses. Journal of the Torrey Botanical Society 136: 380–391. doi: 10.3159/08-RA-052.1

    Article  Google Scholar 

  57. Krawchuk, M.A., M.A. Moritz, M.-A. Parisien, J. Van Dorn, and K. Hayhoe. 2009. Global pyrogeography: the current and future distribution of wildfire. PLoS ONE 4: e5102. doi: 10.1371/journal.pone.0005102

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  58. Kreye, J.K., J.M. Varner, J.K. Heirs, and J. Mola. 2013. Toward a mechanism for eastern North America forest mesophication: differential litter drying across 17 species. Ecological Applications 23: 1976–1986. doi: 10.1890/13-0503.1

    Article  Google Scholar 

  59. Lafon, C.W., and S.M. Quiring. 2012. Relationships of fire and precipitation regimes in temperate forests of the eastern United States. Earth Interactions 16: 1–15. doi: 10.1175/2012EI000442.1

    Article  Google Scholar 

  60. Lippincott, C.L. 2000. Effects of Imperata cylindrica (L.) Beauv. (cogongrass) invasion on fire regime in Florida Sandhills (USA). Natural Areas Journal 20: 140–149.

    Google Scholar 

  61. Liu, Y.-Q., S.L. Goodrick, and J.A. Stanturf. 2012. Future US wildfire potential trends projected using a dynamically downscaled climate change scenario. Forest Ecology and Management 294: 120–135. doi: 10.1016/j.foreco.2012.06.049

    Article  Google Scholar 

  62. Marlon, J.R., P.J. Bartlein, M.K. Walsh, S.P. Harrison, K.J. Brown, M.E. Edwards, P.E. Higuera, M.J. Power, R.S. Anderson, C. Briles, A. Brunelle, C. Carcaillet, M. Daniels, F.S. Hu, M. Lavoie, C. Long, T. Minckley, P.J.H. Richard, A.C. Scott, D.S. Shafer, W. Tinner, C.E. Umbanhowar, Jr., and C. Whitlock. 2009. Wildfire responses to abrupt climate change in North America. Proceedings of the National Academy of Sciences 106: 2519–2524. doi: 10.1073/pnas.0808212106

    Article  Google Scholar 

  63. McCulloh, K., J.S. Sperry, B. Lachenbruch, F.C. Meinzer, P.B. Reich, and S. Voelker. 2010. Moving water well: comparing hydraulic efficiency in twigs and trunks of coniferous, ring-porous, and diffuse-porous saplings from temperate and tropical forests. New Phytologist 186: 439–450. doi: 10.1111/j.1469-8137.2010.03181.x

    Article  Google Scholar 

  64. McDowell, N.G., D.J. Beerling, D.D. Breshears, R.A. Fisher, K.F. Raffa, and M. Stitt. 2011. The interdependence of mechanisms underlying climate-driven vegetation mortality. Trends in Ecology & Evolution 26: 523–532. doi: 10.1016/j.tree.2011.06.003

    Article  Google Scholar 

  65. McDowell, N.G., and C.D. Allen. 2015. Darcy’s law predicts widespread forest mortality under climate warming. Nature Climate Change 5: 669–672. doi: 10.1038/nclimate2641

    Article  Google Scholar 

  66. McEwan, R.W., J.M. Dyer, and N. Pederson. 2011. Multiple interacting ecosystem drivers: toward an encompassing hypothesis of oak forest dynamics across eastern North America. Ecography 34: 244–256. doi: 10.1111/j.1600-0587.2010.06390.x

    Article  Google Scholar 

  67. Meinzer, F.C., D.R. Woodruff, D.M. Eissenstat, H.S. Lin, T.S. Adams, and K.A. McCulloh. 2013. Above- and belowground controls on water use by trees of different wood types in an eastern US deciduous forest. Tree Physiology 33: 345–356. doi: 10.1093/treephys/tpt012

    Article  Google Scholar 

  68. Melillo, J.M., T.C. Richmond, and G.W. Yohe, editors. 2014. Climate change impacts in the United States: the third national climate assessment. US Global Change Research Program, Washington, D.C., USA.

    Google Scholar 

  69. Melvin, M. 2012. 2012 national prescribed fire use survey report. Technical Report 01-12. Coalition of Prescribed Fire Councils, Inc., Newton, Georgia, USA.

    Google Scholar 

  70. Millar, C.I., N.L. Stephenson, and S.L. Stephens. 2007. Climate change and forests of the future: managing in the face of uncertainty. Ecological Applications 17: 2145–2151. doi: 10.1890/06-1715.1

    Article  Google Scholar 

  71. Mitchell, R.J., Y. Liu, J.J. O’Brien, K.J. Elliott, G. Starr, C. Ford Miniat, and J.K. Hiers. 2014. Future climate and fire interactions in the southeastern region of the United States. Forest Ecology and Management 327: 316–326. doi: 10.1016/j.foreco.2013.12.003

    Article  Google Scholar 

  72. Nave, L.E., E.D. Vance, C.W. Swanston, and P.S. Curtis. 2011. Fire effects on temperate forest soil C and N storage. Ecological Applications 21: 1189–1201. doi: 10.1890/10-0660.1

    Article  Google Scholar 

  73. Nowacki, G.J., and M.D. Abrams. 2008. The demise of fire and “mesophication” of forests in the eastern United States. BioScience 58: 123–138. doi: 10.1641/B580207

    Article  Google Scholar 

  74. Nowacki, G.J., and M.D. Abrams. 2015. Is climate an important driver of post-European vegetation change in the eastern United States? Global Change Biology 21: 314–334. doi: 10.1111/gcb.12663

    Article  Google Scholar 

  75. Ozier, T.B., J.W. Groninger, and C.M. Ruffner. 2006. Community composition and structural changes in a managed Illinois Ozark Hills forest. American Midland Naturalist 155: 253–269. doi: 10.1674/0003-0031(2006)155[253:CCASCI]2.0.CO;2

    Article  Google Scholar 

  76. Pederson, N., J.M. Dyer, R.W. McEwan, A.E. Hessi, C. Mock, D. Orwig, H.E. Rieder, and B.I. Cook. 2014. The legacy of episodic events in shaping broadleaf dominated forests. Ecological Monographs 84: 599–620. doi: 10.1890/13-1025.1

    Article  Google Scholar 

  77. Pederson, N., A.W. D’Amato, J.M. Dyer, D.R. Foster, D. Goldblum, J.L. Hart, A.E. Hessl, L.R. Iverson, S.T. Jackson, D. Martin-Benito, B.C. McCarthy, R.W. McEwan, D.J. Mladenoff, A.J. Parker, B. Shuman, and J.W. Williams. 2015. Climate remains an important driver of post-European vegetation change in the eastern United States. Global Change Biology 21: 2105–2110. doi: 10.1111/gcb.12779

    Article  Google Scholar 

  78. Pederson, N., K. Tackett, R.W. McEwan, S. Clark, A. Cooper, G. Brosi, R. Eaton, and R.D. Stockwell. 2012. Long-term drought sensitivity of trees in second-growth forests in a humid region. Canadian Journal of Forest Research 42: 1837–1850. doi: 10.1139/x2012-130

    Article  Google Scholar 

  79. Rentch, J.S., M.A. Fajvan, and R.R. Hicks Jr. 2003. Oak establishment and canopy accession strategies in five old-growth stands in the central hardwood forest region. Forest Ecology and Management 184: 285–297. doi: 10.1016/S0378-1127(03)00155-5

    Article  Google Scholar 

  80. Roman, D.T., K.A. Novick, E.R. Brzostek, D. Dragoni, F. Rahman, and R.P. Phillips. 2015. The role of isohydric and anisohydric species in determining ecosystem-scale response to severe drought. Oecologia 179: 641–654. doi: 10.1007/s00442-015-3380-9

    Article  CAS  Google Scholar 

  81. Ryan, K.C., E.E. Knapp, and J.M. Varner. 2013. Prescribed fire in North American forests and woodlands: history, current practice, and challenges. Frontiers in Ecology and the Environment 11: e15–e24. doi: 10.1890/120329

    Article  Google Scholar 

  82. Ryan, M.G., J.M. Vose, P.J. Hanson, L.R. Iverson, C.F. Miniat, C.H. Luce, L.E. Band, S.L. Klein, D. McKenzie, and D.N. Wear. 2014. Forest processes. Pages 25–54 in: D.L. Peterson, J.M. Vose, and T. Patel-Weynand, editors. Climate change and the United States forest. Springer, Dordrecht, The Netherlands. doi: 10.1007/978-94-007-7515-2_3

    Chapter  Google Scholar 

  83. Slocum, M.G., B. Beckage, W.J. Platt, S.L. Orzell, and W. Taylor. 2010a. Effect of climate on wildfire size: a cross-scale analysis. Ecosystems 13: 828–840. doi: 10.1007/s10021-010-9357-y

    Article  Google Scholar 

  84. Slocum, M.G., W.J. Platt, B. Beckage, S.L. Orzell, and W. Taylor. 2010b. Accurate quantification of seasonal rainfall and associated climate-wildfire relationships. Journal of Applied Meteorology and Climatology 49: 2559–2573. doi: 10.1175/2010JAMC2532.1

    Article  Google Scholar 

  85. Sperry, J.S. 2011. Hydraulics of vascular water transport. Pages 303–327 in: P. Wojtaszek, editor. Mechanical integration of plant cells and plants, signaling and communication in plants. Volume 9. Springer-Verlag, Berlin, Germany. doi: 10.1007/978-3-642-19091-9_12

    Chapter  Google Scholar 

  86. Stambaugh, M.C., J.M. Varner, R.F. Noss, D.C. Dey, N.L. Christensen, R.F. Baldwin, R.P. Guyette, B.B. Hanberry, C.A. Harper, S.G. Lindblom, and T.A. Waldrop. 2015. Clarifying the role of fire in the deciduous forests of eastern North America: reply to Matlack. Conservation Biology 29: 942–946. doi: 10.1111/cobi.12473

    Article  Google Scholar 

  87. Stanturf, J.A., B.J. Palik, M.I. Williams, R.K. Dumroese, and P. Madsen. 2014. Forest restoration paradigms. Journal of Sustainable Forestry 33: S161–S194. doi: 10.1080/10549811.2014.884004

    Article  Google Scholar 

  88. Trammell, T.L.E., C.C. Rhoades, and P.A. Bukaveckas. 2004. Effects of prescribed fire on nutrient pools and losses from glades occurring within oak-hickory forests of central Kentucky. Restoration Ecology 12: 597–604. doi: 10.1111/j.1061-2971.2004.00275.x

    Article  Google Scholar 

  89. Tyree, M.T., and J.S. Sperry. 1989. Vulnerability of xylem to cavitation and embolism. Annual Review of Plant Physiology and Molecular Biology 40: 19–38. doi: 10.1146/annurev.pp.40.060189.000315

    Article  Google Scholar 

  90. van Mantgem, P.J., J.C.B. Nesmith, M.B. Keifer, E.E. Knapp, A. Flint, and L. Flint. 2013. Climatic stress increases forest fire severity across the western United States. Ecology Letters 16: 1151–1156. doi: 10.1111/ele.12151

    Article  Google Scholar 

  91. von Allmen, E.I., J.S. Sperry, and S.E. Bush. 2015. Contrasting whole-tree water use, hydraulics, and growth in a co-dominant diffuse-porous vs. ring-porous species pair. Trees 29: 717–728. doi: 10.1007/s00468-014-1149-0

    Article  Google Scholar 

  92. Vose, J.M., C.F. Miniat, C.H. Luce, H. Asbjornsen, P.V. Caldwell, J.L. Campbell, G.E. Grant, D.J. Isaak, S.P. Loheide, and G. Sun. 2016. Ecohydrological implications of drought. Pages 231–251 in: J.M. Vose, J.S. Clark, C.H. Luce, and T. Patel-Weynand, editors and lead authors. Drought impacts on US forests and rangelands: a comprehensive science synthesis. USDA Forest Service General Technical Report WO-GTR-93b, Washington, D.C., USA.

  93. Wagner, S.A., and J.M. Fraterrigo. 2015. Positive feedbacks between fire and non-native grass invasion in temperate deciduous forests. Forest Ecology and Management 354: 170–176. doi: 10.1016/j.foreco.2015.06.024

    Article  Google Scholar 

  94. Walsh, J., D. Wuebbles, K. Hayhoe, J. Kossin, K. Kunkel, G. Stephens, P. Thorne, R. Vose, M. Wehner, J. Willis, D. Anderson. S. Doney, R. Feely, P. Hennon, V. Kharin, T. Knutson, F. Landerer, T. Lenton, J. Kennedy, and R. Somerville. 2014. Chapter 2: Our changing climate. Pages 19–67 in: J.M. Mellillo, T.C. Richmond, and G.W. Yohe, editors. Climate change impacts in the United States: the third national climate assessment. US Global Change Research Program, Washington, D.C., USA.

    Chapter  Google Scholar 

  95. Wear, D.N. 2011. Forecasts of county-level land uses under three future scenarios: a technical document supporting the Forest Service 2010 RPA assessment. USDA Forest Service General Technical Report SRS-GTR-141, Southern Research Station, Asheville, North Carolina, USA.

    Google Scholar 

  96. Wear, D.N., and J.G. Greis, editors. 2013. The Southern Forest Futures Project: technical report. USDA Forest Service General Technical Report SRS-GTR-178, Southern Research Station, Asheville, North Carolina, USA.

    Google Scholar 

  97. Williams, A.P., C.D. Allen, A.K. Macalady, D. Griffin, C.A. Woodhouse, D.M. Meko, T.W. Swetnam, S.A. Rauscher, R. Seager, H.D. Grissino-Mayer, J.S. Dean, E.R. Cook, C. Gangodagamage, M. Cai, and N.G. McDowell. 2013. Temperature as a potent driver of regional forest drought stress and tree mortality. Nature Climate Change 3: 292–297. doi: 10.1038/nclimate1693

    Article  Google Scholar 

  98. Zolkos, S.G., P. Jantz, T. Corimier, L.R. Iverson, D.W. McKenney, and S.J. Goetz. 2015. Projected tree species redistribution under climate change: implications for ecosystem vulnerability across protected areas in the eastern United States. Ecosystems 18: 202–220. doi: 10.1007/s10021-014-9822-0

    Article  CAS  Google Scholar 

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Acknowledgements

We thank K. Martin and D. Peterson for helpful comments on an early draft of the manuscript. This project was supported by the USDA Forest Service, Southern Research Station.

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Correspondence to James M. Vose.

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Vose, J.M., Elliott, K.J. Oak, Fire, and Global Change in the Eastern USA: What Might the Future Hold?. fire ecol 12, 160–179 (2016). https://doi.org/10.4996/fireecology.1202160

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Keywords

  • Acer
  • climate change
  • drought
  • prescribed fire
  • Quercus