The tree census, paleopollen, fossil charcoal, human population, and climate data presented here provide unique support for important anthropogenic influences on fire over the last 2000 years in the eastern USA. This includes multiple instances of climate fire anomalies that may be best explained by the role of human-caused burning.
The coupling of paleoecological and tree census data to address larger global change questions is a novel research approach to describe and ascribe recent vegetation dynamics vis-à-vis the climate versus disturbance debate.
The aims of the study are to (1) compile and compare pre-European settlement versus modern upland arboreal pollen and tree survey data from a large number of studies in various forest regions in the eastern USA, (2) analyze fossil charcoal dating back 2000 years for the northern versus central/southern tiers of the eastern USA, and (3) compare and contrast compositional and ecophysiological attributes for both datasets and temporal changes to known climate or disturbance phenomena to elucidate global change impacts and the drivers of forest change.
We analyzed paleoecological (pollen and charcoal) and tree census studies to compare protohistoric and modern vegetation assemblage for eastern North America, including the drivers of forest change. A total of seven forest types in the north and central regions of the eastern USA were used to co-analyze fossil pollen, fossil charcoal, and tree survey data.
Disparities and consistencies existed when independently assessing witness tree and pollen records. Although forests north of the tension zone line (TZL) contained mostly Fagus, Pinus, Tsuga, and Acer witness trees, pollen records were dominated, as expected, by high-pollen-producing Pinus, Quercus, Tsuga, and Betula. Here, present-day pollen and tree survey data revealed significant declines in Fagus, Pinus, Tsuga, and Larix and increases in Acer, Populus, Fraxinus, Quercus, and Abies. South of the TZL, both witness tree and pollen records pointed to Quercus and Pinus domination, with declines in Quercus and Castanea and increases in Acer and Betula based on present-day data. Modern assemblages comprise tree genera that are increasingly cool-adapted, shade-tolerant, drought-intolerant pyrophobes. Paleocharcoal data from 1 to 1750 AD indicate a slight increase in burning in southern forests and stable levels in the north, despite the increasing cold associated with the Little Ice Age. The most significant increase in burning followed the dramatic increase in human population associated with European settlement prior to the early twentieth century.
Post-1940, fire suppression was an ecologically transformative event in all datasets. Our analysis identifies multiple instances in which fire and vegetation changes were likely driven by shifts in human population and land use beyond those expected from climate alone.
During the last five centuries, vegetation in eastern North America has been impacted by a suite of global change phenomena (Abrams and Nowacki 2008, 2015; Munoz and Gajewski 2010; McEwan et al. 2011; Woodall et al. 2013). This includes the initiation and rapid expansion of Euro-American settlement, Native American depopulation, and dramatic changes in the magnitude, extent, and type of land use practices, abrupt shifts and/or reversals in fire regimes, outbreaks of insect and disease, and significant climate change (Crosby 1976; McAndrews 1988; Denevan 1992; Whitney 1994; Parshall and Foster 2002; Foster 2004; Munoz et al. 2010). At the beginning of this five-century period, the northern hemisphere was in the midst of the Little Ice Age (LIA; ca. 1400 to 1850; Fig. 1; Mann et al. 2009) and the initial stages of European settlement took place within this climatic regime. The LIA was followed by abrupt warming associated primarily with the end of a natural cooling period coupled with increased anthropogenic modifications to atmospheric chemistry (Ruddiman 2005; Mann et al. 2009; IPCC 2013). Human populations and their impacts on vegetation through land use have also changed appreciably during the late Holocene (Denevan 1992; Abrams and Nowacki 2008; Munoz and Gajewski 2010; Nowacki et al. 2012; Munoz et al. 2014). Nevertheless, we still have only a marginal understanding of the role of climate and disturbance and their interactions with vegetation dynamics, past and present, for most regions (Rhemtulla et al. 2009). The importance of climate versus human impacts on protohistoric ecosystems in eastern North America is a highly debated issue (Munoz et al. 2010; Pinter et al. 2011; Marlon et al. 2013). One argument emphasizes the role of climate driving fire and vegetation dynamics (Parshall and Foster 2002; Shuman et al. 2004; Pederson et al. 2015); another argues that human-caused disturbance, including intentional burning, has been the primary driver, particularly during the second half of the Holocene (Guyette et al. 2006; Steyaert and Knox 2008; Nowacki and Abrams 2008, 2015). A more complete understanding of past human-fire-climate-vegetation dynamics and their anomalies requires additional research (Munoz et al. 2014; Abrams and Nowacki 2015).
The study of fossil charcoal as an indicator of fire has helped elucidate disturbance regimes and their impacts in pollen interpretation (Patterson and Sassaman 1988; Parshall and Foster 2002). Charcoal data from sediment records can be used to provide information about past fire activity from local to global scales (Marlon et al. 2008). Nevertheless, the role of fire, including its origin, drivers, and extent in various forest types and regions, remains a contentious idea among historical ecologists (Pinter et al. 2011; Marlon et al. 2013; Abrams and Nowacki 2008, 2015). Opinions differ about the roles and relative strength of climate versus human (anthropogenic) drivers of fire, including the Early Anthropocene Burning Hypothesis. It deals with the possibility that the early human use of fire was profound, frequent, and prevalent, resulting in it becoming an early ecological driver (Ruddiman 2005; Marlon et al. 2013; Abrams and Nowacki 2015). This presumes that small populations of humans were able to burn expansive areas. Other issues that need to be resolved are the extent of lightning as an ignition source and whether burning was localized or ubiquitous in various vegetation types in the eastern USA (Ruffner and Abrams 1998; Nowacki et al. 2012).
The impact of present and future climate change and other global change phenomena on world ecosystems is one of the premier research topics for ecologists and environmental scientists of this era (IPCC 2013). Research techniques in the field of historical ecology have particular relevance for assessing the impacts of climate and humans on ecosystems because what has happened in the past may provide important clues of what will happen in the future (Foster 1998; Egan and Howell 2001). For example, it is possible to study how various ecosystems responded to abrupt climate change (cooling and warming) and shifts in disturbance regimes in the past (Jackson 2006; Booth et al. 2012; Nowacki and Abrams 2015). Studies of this type have often involved the use of early land survey (witness trees and associated line notes) or paleoecology data (sediment pollen and charcoal in lakes, bogs, and caves). Comparative tree censuses using witness and modern tree data can provide fairly reliable information about forest change spanning several centuries, whereas paleoecology chronologies often span many millennia (Whitney 1994; Schulte and Mladenoff 2001; Foster 2004; Munoz et al. 2010).
Paleoecology and tree census studies have vastly contributed to our understanding of vegetation dynamics and the impacts of climate and disturbance as vegetation drivers. These include broad-scale and long-term climate change over centuries or millennia, as well as changes and interactions from both anthropogenic and natural changes in climate and perturbations. The reaction of ecosystems to global change factors can be assessed by examining the impacts of changing environmental conditions in the past, including the rise and fall of various vegetation. Indeed, recent paleoecological modeling studies have simulated responses to future environmental change (Jackson et al. 2009; Hannah et al. 2014). This type of information is critical to ecologists, land managers, and policy makers trying to make informed decisions about conservation, environmental change, and ecosystem resilience.
Many comparative tree studies have been amassed to assess post-European settlement changes to investigate the impacts of recent climate change on vegetation dynamics (see Appendix S1 of Nowacki and Abrams 2015). The same can be said for paleoecology studies (Davis 1963; Webb III et al. 1981; Schwartz 1989; Paciorek and McLachlan 2009). The coupling paleoecological and tree census data to address larger global change questions seems to us an important, but underutilized, research approach. The potential exists for studies to more accurately describe and ascribe recent vegetation dynamics to its causal factors, particularly in relation to the climate versus disturbance debate. A recent paper by Nowacki and Abrams (2015) presented a unique approach to untangle the role of climate versus disturbance as forest change drivers over multiple centuries. This was accomplished by categorizing major tree species/genera into temperature, shade tolerance (succession), and pyrogenicity classes based on ecophysiological characteristics, and then applying those classes to comparative studies of past and present tree censuses. In contrast, paleoecological studies have typically concentrated on documenting vegetation dynamics and their relationship to environmental changes over the Late Quaternary (Davis 1969; Webb 1983; Russell et al. 1993; Shuman et al. 2004; Williams et al. 2004). Relatively few paleoecological studies investigated the impacts of late Holocene climatic variability on vegetation dynamics.
For understanding the relative roles of climatic variability and disturbance regimes on vegetation communities, we use an approach that integrates historical and modern tree surveys with fossil pollen and charcoal data (cf. Dawson et al. 2016). Witness trees (trees used to demarcate property corners in early historical land surveys; also referred to as corner trees and bearing trees) provide a “snapshot” of forest composition during the time of land survey, spanning from the 1600s (eastern colonies) to the early 1900s (Minnesota) (Whitney 1994; Schulte and Mladenoff 2001). Although there are some shortcomings (Schulte and Mladenoff 2001; Whitney and DeCant 2001), witness tree data probably provide the best depictions of arboreal vegetation during the onset of European settlement, especially when compiled at the landscape scale (Delcourt and Delcourt 1996). Witness tree data are extensively used in historical ecology studies throughout the eastern USA (Whitney 1994). When paired with current vegetation surveys (e.g., Forest Inventory and Analysis data), changes in arboreal composition and structure can be deciphered and associated ecological drivers assigned (Nowacki and Abrams 2008, 2015).
Paleoecological data (biological and geochemical remains preserved in sedimentary archives) record environmental changes over centuries to millennia through the use of proxies. In this study, we use fossil pollen as a proxy of past vegetation composition and change (Davis 1969; Russell et al. 1993; Shuman et al. 2004; Williams et al. 2004) and fossil charcoal as a proxy of past biomass burning (Power et al. 2010; Marlon et al. 2013). The combination of these different data types should give a broader perspective of how past and projected climatic change will impact vegetation communities. More specifically, the objectives of this study are to (1) compile and compare pre-European settlement versus modern upland arboreal pollen and tree survey data from large number of studies in various forest regions in the eastern USA, (2) analyze fossil charcoal dating back 2000 years for the northern versus central/southern tiers of the eastern USA, and (3) compare and contrast compositional and ecophysiological attributes for both datasets and temporal changes to known climate or disturbance phenomena to elucidate global change impacts and the drivers of forest change.
A total of seven forest types in the north and central regions of the eastern USA were used to co-analyze fossil pollen, fossil charcoal, and tree survey data (Tables 1 and 2; Fig. 2). These forest types were assembled, and the tension zone line (TZL) struck using ecological subsections as base units (Cleland et al. 2007). Four of the forest types are located north of the TZL, and three forests types are located to its south (Fig. 2). The TZL is a boundary between two distinct floristic zones, in this case conifer-northern hardwood and sub-boreal to the north and oak-pine to the south (Curtis 1959). Most of the pollen chronologies used for study were extracted from Neotoma V1.0, a relational multiproxy paleoenvironmental database (Grimm 2008), with additional data extracted from published literature (Table 1). Using a criteria similar to Munoz et al. (2010), we excluded a pollen record if it (a) did not contain dated radiocarbon years within the study periods (pre-European and Little Ice Age versus modern), (b) contained a hiatus of > 500 years of accurately dated samples within the study period, (c) had no chronological control (other than the top of the core) within the study period, (d) had samples from large bodies of water (> 115 ha) or very small ponds (< 1 ha) (leaving only larger ponds and small lakes for our analysis), and (e) had samples located in present-day urban areas that might have impacted modern vegetation assemblages. By applying these criteria, we filtered our initial population of 129 pollen chronologies to 76 for this study.
We used the Neotoma age-depth information for our chronologies, which typically use the European settlement horizon as a chronological control. Whenever possible, we used age-depth models based on calibrated 14C dates, but for this time period, there is not a major difference between radiocarbon and calibrated ages. Arboreal pollen percentages for selected taxa (Table 3) were calculated using the terrestrial pollen sum (Table 1). First, we eliminated all herb and shrub pollen; then, the remaining tree pollen were relativized for each species with the total tree pollen count equal to 100%. Taxonomic resolution of pollen data were reduced to the genus level in arboreal taxa where species-level identification were made (e.g., Acer saccharum and Acer rubrum were aggregated to Acer) because most records are not identified beyond the genus level. The protohistoric period encompasses Native American occupation during the Little Ice Age (ca. 1400 to 1850 AD), while the contemporary period reflects post-Euro-American land use and climate change after ca. 1850.
Charcoal data are from the Global Charcoal Database (GCD, v. 2) (Daniau et al. 2012), including 13 records from north of 42° N latitude (2430 samples) and 11 records south of 42° N latitude (428 samples), and were used to reconstruct trends in biomass burning for the eastern USA during the past 2000 years (Table 2). Data from the GCD are typically standardized to produce anomalies from a shared base period for multiple records. Standardizing the charcoal values makes comparisons possible across many records, despite differences in specific particle size classes measured, lab, and analytical methodologies. For standardization, each record was “presampled” to a common temporal window (10 years in this case). A weighted mean was calculated if multiple values existed within a given 10-year period for each record. The presampled records were subsequently rescaled, transformed, and converted to z scores following the protocol detailed in Power et al. (2010) and implemented via the PfTransform (paleofire) function in the paleofire R package (Blarquez et al. 2014). A base period of 2000–200 cal year BP was used to calculate the z scores. The standardized and normalized charcoal records were then smoothed using a 200-year window width with the pfCompositeLF (paleofire) function to create a composite for the northern and southern zones, divided at 42° N latitude, and for the entire eastern USA, along with 5% and 95% bootstrap confidence intervals.
Climatic data was compiled and synthesized for the eastern USA, including temperature anomaly for the northeastern USA and Palmer drought severity index (PDSI) from three sites north and three sites south of the tension line. The east–west gradient of PDSI data are from three northern locations that were in Vermont, Michigan, and Wisconsin while the three southern sites were in Virginia, south central Pennsylvania, and Kentucky. The annual PDSI values were smoothed using a 20-year running average. The mean annual temperature and PDSI data were obtained from Mann et al. (2009) and the North American Drought Atlas (http://iridl.ldeo.columbia.edu/SOURCES?.LDEO/.TRL/.NADA2004/.pdsi-atlas.html), respectively. Temperature data were obtained by extracting data from the paleoclimate dataset reconstructed by Mann et al. (2009) covering grid cells in the eastern USA.
For tree census data, we identified 52 studies in the eastern USA that produced a total of 192 datasets available for analysis (Nowacki and Abrams 2015). Early tree surveys chronicle the westward progression of European land acquisition, with some dating back to the seventeenth century along the Atlantic Coast (Whitney and Davis 1986; Foster et al. 1998; Thompson et al. 2013). These are divided into two time periods, the early historic (1620 to 1850 AD) and contemporary (1940 to 2000 AD), making these as similar as possible with the paleopollen data.
Population estimates for the eastern USA were obtained from the HYDE 3.1 global population dataset (Klein Goldewijk et al. 2011) by aerially averaging data from grid cells between 25° N and 49° N latitude and 95° E and 65° E longitude. Temperature data were obtained by extracting data from the paleoclimate dataset reconstructed by Mann et al. (2009) covering grid cells in the eastern USA.
2.1 Data analysis
Major tree genera in eastern North American (16 genera distributed across the seven forest types in our study region) were classified by temperature, shade tolerance, and pyrogenicity (including drought tolerance) based on available data, published literature, and authors’ knowledge (Table 3). Temperature classes were established using actual temperature data from the Climate Change Tree Atlas (Prasad et al. 2007–ongoing). Each tree genus was classified into one of four temperature classes (cold, cool, warm, and hot) based on the average annual temperature within its ecological range (US distribution; Nowacki and Abrams 2015). Genera were also categorized by shade tolerance (intolerant, intermediate, and tolerant) and pyrogenicity (pyrophilic and pyrophobic) based on their known life history and physiological characteristics (Table 3). Individual tree percentages from pollen and survey data were tallied by temperature (cold, cool, warm), shade tolerance (intolerant, intermediate, tolerant), and pyrogenicity (pyrophilic, pyrophobic) classes based on the lowest taxonomic level reported for each dataset. All of the genera classified as pyrophilic were also classified as drought tolerant (Burns and Honkala 1990); thus, changes in pyrogenicity are indicative of changes in climate conditions and drought tolerance. Absolute percentage changes were then calculated for each class by subtracting protohistoric from contemporary abundances, and two-tailed t tests were performed between the two time periods to test for statistical differences in both the pollen and tree survey data.
PDSI was consistently higher (less droughty) in northern forests than southern, where it was typically above and below zero, respectively (Fig. 1a, b). However, PDSI generally increased after about 1900 in southern regions, but within the historic range of variability. Temperatures across the eastern USA declined from 500 to ~ 1700 AD and abruptly increased thereafter (Fig. 1c).
Pollen assemblages from the Great Lakes beech-maple (Fagus-Acer) forest are dominated by oak (Quercus) and pine (Pinus) in the protohistoric and contemporary periods because these genera are high-pollen producers (Tables 3 and 4). Inconsistent with the principal components by which this forest type was named (sensu Braun 1950), beech and maple, with intermediate and low pollen production, were vastly underrepresented in the pollen record. However, protohistoric tree surveys supported the forest type designation, with elevated occurrences of beech and maple followed by oak, although this is based on only two sites. Arboreal pollen assemblages exhibited little change over the study period, but tree survey data document a large decline in beech (− 29%). Pollen assemblages in the protohistoric Great Lakes conifer-northern hardwood biome were dominated by high-pollen producers of pine and birch (Betula) and intermediate pollen producer hemlock (Tsuga), whereas the tree survey data indicate that these forests were dominated by pine, hemlock, and maple (Table 4). In this region, tree survey data document significant changes in 11 species with the largest increases for maple, aspen (Populus), and oak and largest decreases for pine and hemlock. Although no statistically significant changes in the relative abundances were found in any of the pollen taxa, the direction of change for the important genera (maple, pine, and hemlock) correspond to that found in the tree survey data.
Protohistoric pollen assemblages in the Northeast conifer-northern hardwoods exhibited high abundances of birch, pine, hemlock, oak, and beech (Table 4), whereas tree survey data indicated that these forests were disproportionally beech dominated, followed hemlock and maple. Over the period of study, the pollen data document statistically significant declines in the abundances of hemlock and beech and increases in birch and maple, all of which correspond to trends observed in the tree survey record. Protohistoric pollen assemblages in sub-boreal conifer forests were again dominated by high-pollen producers pine and birch, while tree survey data document a diverse forest community dominated by pine, larch (Larix), spruce (Picea), and birch (Table 4). Over the period of record, sub-boreal forest pollen assemblages document statistically significant increases in oak, aspen, and ash (Fraxinus), whereas tree survey data statistically document a more robust array of compositional shifts, with significant increases in aspen, ash, maple, and fir (Abies) and decreases in pine, larch, and birch.
Pollen assemblages in the oak-pine forests south of the TZL (including the Central, Great Lakes, and Northeast regions) are dominated by oak and pine over the period of study, with few significant shifts in the abundances of any genera documented (Table 5). Correspondingly, tree survey data recorded the same dominants over the period of record. However, tree survey data did record significant declines in oak and chestnut and significant increases in maple. In most cases, the direction of change recorded in tree surveys paralleled those in the pollen record.
Compositional differences between pollen and tree survey data were generally consistent with differences in pollen productivity (Table 3), with high-pollen-producers pine, birch, and oak overrepresented and low-pollen-producers maple and aspen underrepresented relative to tree survey data. Overall, forests north of the TZL were dominated by genera typical of conifer-northern hardwoods, including pine, birch, beech, hemlock, and maple. Forests south of the TZL were dominated by oak followed by pine in both data types. Here, high-pollen-producing pine and birch were overrepresented and low-pollen-producing maple and aspen were underrepresented in the pollen record relative to tree surveys.
Tree genera were partitioned into temperature, shade tolerance, pyrogenicity (including drought classes) and applied to pre-European fossil pollen and witness tree data (Fig. 3). The Great Lakes beech-maple pollen data were dominated by warm-adapted trees that were evenly split between two shade-tolerant classes (intolerant and intermediate) and both fire/drought classes. Witness trees from the same forest type had few cold-adapted, intolerant pyrophiles. The Great Lakes conifer-northern hardwood pollen data were dominated by cold-adapted, shade-intolerant (early successional) trees that were nearly evenly split between pyrophiles and pyrophobes. Witness trees differed from this by having had a higher proportion of cool-adapted, shade-tolerant, drought-intolerant/pyrophobic trees. In protohistoric Northeast conifer-northern hardwoods, pollen data was dominated by cold-adapted, drought-intolerant pyrophobes that were evenly split between shade intolerant and tolerant trees. Witness trees had a higher proportion of cool- and warm-adapted, shade-tolerant pyrophobes. The sub-boreal forest was greatly dominated by cold-adapted, shade-intolerant trees with more drought-tolerant pyrophiles in the pollen data and more drought-intolerant pyrophobes in the witness tree data.
South of the TZL, pre-European Central oak-pine forests were composed mostly of warm-adapted, shade-intermediate, drought-tolerant pyrophiles, with a slightly higher proportion of cold and shade-intolerant trees in the pollen versus witness tree data (Fig. 4). The Great Lakes oak-pine forest too was dominated by warm-adapted, shade-intermediate, drought-tolerant pyrophiles in both datasets. The Northeast oak-pine forest had a fairly even distribution of tree species across all ecophysiological classes, but tended to be dominated by warm-adapted, shade-intermediate pyrophiles, more so in the witness tree record (Fig. 4). Pollen data had somewhat more cold-adapted, intolerant and drought-intolerant pyrophobic trees. Overall, forests south of the TZL contained a higher proportion of warm-adapted, shade-intermediate, drought-tolerant and pyrophilic trees prior to European settlement, whereas northern forests were dominated by cold-adapted, shade-intolerant species that were fairly evenly split between pyrophobes and pyrophiles. However, in the north, witness tree data consistently had higher values for shade-tolerant, drought-intolerant, and pyrophobic genera, which can be attributed to differential pollen production among genera.
Comparing mean pre- and post-European settlement changes in the transformed ecophysiology data, the Great Lakes beech-maple forests exhibited a decrease in warm-adapted, shade-tolerant, drought-intolerant pyrophobes in both data types (Table 6). Temporal changes in the Great Lakes conifer-northern hardwood forest included an increase in warm-adapted, shade- and drought-tolerant pyrophilic survey trees, whereas pollen data showed a decline in drought-tolerant pyrophilic trees and neutral shade tolerance changes. Northeast conifer-northern hardwoods had a decrease in warm-adapted, shade-tolerant trees and an increase in drought-tolerant pyrophiles in both datasets. The sub-boreal conifers exhibited an increase in cool and warm-adapted and shade-tolerant trees and a decline in drought-tolerant pyrophiles, the latter only in pollen data. South of the TZL, Central oak-pine forest type had a decline in warm, intolerant, drought-tolerant/pyrophilic trees in both datasets (Table 6). In the Great Lakes oak-pine forest type, tree composition exhibited an overall decline in temperature and drought/fire adaptation and an increase in shade tolerance in the tree survey data. Ecophysiological changes in Northeast oak-pine forests varied between pollen and witness tree data, while both data types showed a general cooling of temperature adaptation they differed in the direction or lack of changes in shade and drought tolerance and pyrogenicity. Across all three ecophysiological classes, the magnitude of temporal change (as an absolute value) was significantly greater (P < 0.001) for tree surveys than for pollen data. The overall temporal change was also somewhat higher in southern versus northern forests (Table 6). In most cases, the direction of change was similar between pollen and witness tree data. Northern forests were highly variable in terms of temperature, tolerance, and pyrogenicity/drought changes, going up in two and down in two forest types. In contrast, southern forests exhibited an overall decline in temperature adaptation and drought/ pyrogenicity but were inconsistent in shade-tolerant changes. In five of seven forest types, aggregated tree genera registered temperature declines from past to present and moved in the opposite direction of the prevailing post-1820 warming (Table 6; Fig. 1).
Trends in standardized charcoal accumulation rates (the charcoal index) show different trajectories in biomass burning in the northern and southern zones of the eastern USA (Fig. 5). In the north, variations in standardized charcoal accumulation rates show relatively minor variations from 1 to 1750 AD, with the maximum occurring between 1 and 200 AD and the minimum occurring around 1200 AD. After European settlement, around 1750 AD, charcoal levels increased rapidly towards present. Confidence intervals in the most recent decades expand substantially from their previous range, indicating increased variability in the time series. In the southern zone, the charcoal records are much lower resolution (i.e., each sediment core was sampled less frequently than what is typical in the north), and as a result, there are less than one fifth of the samples than what is available in the north. Nevertheless, the combined data from the southern zone show a gradual upward trend from 1 to 1750 AD, with the minimum around 1 AD and the pre-European maximum around 700 AD. After 1750 AD, charcoal levels in the southern zone form a parabola, increasing rapidly, cresting around 1900, then declining thereafter. Taken as a whole (24 records; 2858 samples), the eastern US standardized charcoal index shows a flat trend, until the large increase in burning during the European settlement era. A decline in recent centuries is also evident in the south and the eastern USA as a whole. Population from the HYDE 3.1 database shows a gradual increase from 1 to 1500 AD. Population declines from 1500 to 1600 AD (consistent with the Native American pandemic), increases slightly from 1600 to 1700 AD, and shows a rapid increase subsequently towards present after European colonization. The initial increase in charcoal predated abrupt warming that started about 1820 (Figs. 1 and 5).
The disparities of using pollen-based versus tree census data, and their inherent differences, in vegetation reconstruction have been previously recognized by paleoecologists (Dawson et al. 2016). Pollen data are parsed from accumulations of particulate matter cast from large catchments that collect incrementally over long-time periods. When considering species differences in pollen production, dissemination and preservation, differential rates of deposition and mixing of sediments over time, radiocarbon-dating uncertainties, and the segment sizes required to gain adequate pollen counts, it is not surprising that the resulting data are rather low spatiotemporal resolution (within-core samples often spanning multiple years representing hundreds of hectares of depositional input). Exceptions occur where varves exist in sediment samples. In contrast, survey or census data are obtained from the direct measure of living trees surrounding a specific point at a specific time, thus resulting in high spatiotemporal resolution. However, this method has its limitations as well. For instance, witness trees have their own set of species selection biases contingent on tree size, wood durability and commercial value, surveyor instructions and partialities, and ease of reach and scribing survey trees (Bourdo 1956; Whitney 1994; Black and Abrams 2001; Schulte and Mladenoff 2001). Despite their respective weaknesses, both data types are invaluable to the understanding of historical ecology, particularly when used in the proper context. This compilation adds to this discussion by quantifying the disparities among these two data types in forest reconstruction and tracking compositional change over time, with cautions and remedies.
Our reconstruction of forest composition from fossil pollen versus tree surveys revealed important similarities and differences between the two data types. The disparities can be largely explained by genera variations in pollen production and dispersal (Table 3). Almost universally, high-pollen producers (birch, pine, and oak) were over represented, intermediate pollen producers (beech, hemlock, and elm) were adequately represented, and low-pollen producers (fir, maple, and aspen) were underrepresented in pollen records relative to tree surveys. Discrepancies were most stark and numerous north of the TZL where low-pollen-producing genera (fir, maple, cedar, ash, larch, and aspen) were more abundant, and thus largely underrepresented in pollen records relative to other genera (Table 4). Indeed, the biggest disparity between the two data types existed in the Great Lakes beech-maple protohistoric forest, which was dominated by oak and pine as pollen versus beech and maple as witness trees (the later consistent with the forest type’s namesake). Discrepancies were less apparent in oak-pine forests south of the TZL, having reasonably similar pollen and tree survey composition and dominance except for the high-pollen-producing birch. Paleoecologists have long recognized the incongruence between tree pollen counts and tree census data (Fagerlind 1952; Potzger et al. 1956; Davis and Goodlett 1960), and have made corresponding adjustments in their interpretation of forest composition and dominance, including pollen correction factors (Davis 1963; Andersen 1970; Prentice and Webb III 1986; Jackson and Williams 2004). We used correction factors to categorize pollen-to-tree census relationships (Table 7). Although correction factors seem like an attractive method to recalibrate pollen to better equate/correspond to tree census data, problems exist with that approach as (1) the relationship between vegetation and pollen percentage is not linear, (2) a linear correction factor assumes an intercept of zero (e.g., zero pollen percent = tree absence), and (3) the relationship between vegetation and pollen percentage is not constant across space or time (pers. comm, Dr. Samuel Munoz, November 26, 2014). However, correction factors are valuable in that they capture the magnitude of difference (thus the scope of the problem) between pollen records and tree census data at the species/genera level. Palynologists are developing more robust and elaborate methods to close the gap between pollen and actual tree census data (Paciorek and McLachlan 2009; Sugita et al. 2006, 2010).
When evaluating temporal variation in forest composition and dominance, we found that the finer resolution of tree census data captured many important changes in genera abundance not seen in the pollen data. This included the well-documented declines in oak and chestnut and increases in maple census trees south of the TZL (Nowacki and Abrams 2008). North of the TZL, census trees routinely showed significant declines in beech and pine and increases in maple and aspen, changes that were only marginally evident in pollen data. While these compositional shifts make sense ecologically (see below), it is important to point out that witness tree surveys are very different in methodology and point location from current tree surveys. The greatest methodological departures occur in the far eastern portions of the USA (original 13 colonies) where metes-and-bounds surveys were conducted, and property corners were oftentimes marked by widely and irregularly spaced, single trees (Thomas-Van Gundy and Nowacki 2013). The General Land Office Survey (GLO), conducted from Ohio westward, generally recorded two to four witness trees at section and quarter-section corners and at river crossings (“meander posts”) (Bourdo 1956; Whitney 1994; Black and Abrams 2001). The point-based tree data recorded by GLO surveys differ substantially from modern-day surveys (e.g., Forest Inventory and Analysis) which often use replicated fixed-area plots within forest stands. In contrast, tree variation in fossil pollen is recorded using a uniform analytical technique often from a single sediment core from a lake or bog, which minimizes spatial-temporal errors. Witness trees often only make up a small portion of any one forest or location, whereas paleoecological data are derived from a larger geographic catchment representing both local and regional vegetation (Jackson 1994; Fuller et al. 1998). However, individual witness tree warrants were often combined into connect drafts to increase number of survey trees and geographic area relative to a single tract of land. Nevertheless, when interpreting these types of data, one should be aware of the inherent differences among pollen, witness tree, and modern forest surveys.
Many palynological studies have reported substantial changes in forest composition from the pre-European settlement to present day. After European settlement, forests in the northeast had considerably less beech, chestnut, hickory, and hemlock and more birch, spruce, and fir (Russell and Davis 2001; Munoz et al. 2010). In this study, we also found that hemlock and beech pollen declined and that of birch increased in the Northeast conifer-northern hardwood forest. Former chestnut-hemlock forests in north-central Massachusetts are now dominated by oak as a result of human activity, including the introduction of chestnut blight (Fuller et al. 1998; Foster et al. 2002b). Following European settlement in New England, conifer-hardwood forests had declines in hemlock and beech and increases in white pine or pitch pine that invaded the open and abandoned forests (Parshall and Foster 2002). In our study, pine pollen dominated most forest types, but did not change significantly, likely reflecting its status as a high-pollen-producing species (Davis and Goodlett 1960). In southeastern New York, forests exhibited a decline in pine (mostly Pinus strobus) and an increase in birch and oak (Pederson et al. 2005). A substantial increase in yellow birch (Betula alleghaniensis) pollen during the late Holocene in the western Great Lakes region is attributed to a wetter climate (increased lake levels; Jackson and Booth 2002). In this study, birch pollen did not increase significantly following European settlement in the Great Lakes forests. A broad-scale study by Gajewski (1987) reported that hemlock and beech declined in northern New England while expanding in the Midwest over the past 500 years. This is consistent with the significant pollen declines in our Northeast conifer northern hardwoods, but we found no such increase of these genera in the Great Lakes beech-maple and conifer-northern hardwoods (spanning the Midwest). Davis et al. (1998) reported that former pine forests in northern Wisconsin and Michigan became dominated by hemlock and northern hardwoods in more recent years. Our Great Lakes-conifer-northern hardwood forests were dominated by these species (including birch), both pre- and post-European settlement, with pine and hemlock exhibiting non-significant declines.
Pollen records indicate that strong climate-vegetation relations existed prior to European arrival in certain segments of North America (Watts 1979; Shuman et al. 2004; Gill et al. 2009; Munoz et al. 2010). However, climatic controls of vegetation seemingly dissipated during the onset of European settlement, with humans (disturbance) becoming the primary driver of compositional change and leading to regional vegetation homogenization (Fuller et al. 1998; Foster et al. 1998). This post-European disruption of climate-vegetation relationships was recently corroborated in comparative tree survey data, whereby compositional changes have been attributed to changes in land use history rather than climate (Nowacki and Abrams 2015). The synchrony of European population expansion and Native American depopulation differed on the North American continent. Native American populations started declining from the very instant of European arrival driven largely by introduced diseases (Crosby 1976; Dobyns 1993). Starting along travel route of DeSoto’s 1539–1542 expedition and from early settlements along the East Coast, an ensuing pandemic was unleashed, quickly sweeping across America along major travel corridors and decimating Native American populations throughout the sixteenth and seventeenth centuries (Richter 2001; Mann 2005). Coupled with intertribal conflicts and social upheavals, population reductions of 80–90% likely happened among Native Americans. In many locations, this “wave of death” preceded European settlement by a hundred years or more, especially west of the Appalachians.
Extensive settlement of the eastern USA was not complete until about 1850, effectively expanding westward from the East Coast (Hart and Buchanan 2012). Concurrent with European settlement, the exploitation of forests occurred at an ever-increasing pace until the early twentieth century (Whitney 1994; Abrams 2003; Nowacki and Abrams 2008; Rhemtulla et al. 2009). Most of the eastern seaboard and the Ohio Valley were already logged at least once by the mid-nineteenth century. By 1920, approximately 99% of the original forest was gone. Not only were the original forests cut, but there was a large loss of forest area to land clearing for agriculture during the nation-building period. The “Great Cutover” logged billions of board feet of timber in the eastern and western USA and produced vast areas covered in “slash” (logging debris; Whitney 1994; Abrams 2003; Nowacki and Abrams 2008). As the slash dried, huge wildfires followed, which burned with an intensity not experienced in the original forest (Pyne 1982; Fig. 2). These fires ushered in the fire suppression (Smokey Bear) era in the USA starting in the 1930s. The most noticeable feature of the 2000-year fire history here is a large increase in burning during the past ~ 300 years associated with European land clearance for agriculture. Biomass burning peaked between 1800 and 1900 AD based on historical records, followed by substantial declines after ca. 1940.
The charcoal index between 1 and 1750 AD in this study suggests stable levels of burning in the north and a slight increase in the south. It is interesting to note that southern forests exhibited a slight increase in burning associated with the Medieval Warm Period (ca. 950 to 1250 AD) but did not decline with the LIA (ca. 1350–1850; Mann et al. 2009). In northern forests, the charcoal index dipped between 1000 and 1200 AD and then increased at the start of the LIA, the opposite of what would be expected from climate control. However, the greater abundance of samples in the north makes north/south comparisons difficult. Munoz et al. (2010) reported a steep rise in burning after 1000 AD that continued through the LIA in the northeastern USA. A synthesis of pre-European fire return intervals for the eastern USA report a north to south trend, with generally longer fire frequency in the cool north (> 16 years) and shorter in the hot south (< 2 years; Guyette et al. 2012). A slight increase in fires in the southern zone prior to 1750 AD corresponds with a gradual increase in Native American populations estimated during that time, so the increased burning may have been due to a growing number of human-set fires.
Based on fire-scar data for the eastern USA, the major factors controlling late Holocene differences in fire regimes are human population density, culture, and annual drought (Guyette et al. 2006, 2012). For the period between 1650 and 1930, these authors report stable levels of burning in the Northeast and Midwest and increased burning in the Upper Lake States and Central Plains, with no decline as a result of the Little Ice Age. The fossil charcoal trend here also indicates that there was no significant decline in burning in either the northern or southern zone, which would be expected if changing Native American populations controlled charcoal levels. The absence of a decline is also somewhat surprising given that the general ubiquity of reduced biomass burning observed elsewhere in the Americas has a result of simultaneous depopulation and cooling climate (Power et al. 2012; Stambaugh et al. 2013). In southeast New York, for example, transitioning to the LIA resulted in pine forests converting to spruce and hemlock and a corresponding decline in paleocharcoal relative to during the Medieval Warm Period (Pederson et al. 2005). Variations in temperature or drought, however, are not a good explanation for the pre-European settlement increase in biomass burning in the southern zone because the paleoclimate data suggest that conditions became progressively cooler after 1100 AD (Fig. 1), which would not explain increased fires. This suggests a disconnect whereby human burning often trumped climate, even in the face of depopulation (Abrams and Nowacki 2015). Moreover, it has been argued that few people can be responsible for burning large areas (Kay 2007; Bond and Keeley 2005; Pinter et al. 2011). Climate warmed after 1600 before an abrupt decline in the early 1800s without much noticeable impact on charcoal abundance. This was followed by another period of accelerated warming after ca. 1840 that persists to the present day. The abrupt and sustained increase in charcoal starting in the early 1700s predates the latest warming phase but is highly consistent with the increase in human population and associated activities (cf. Parshall and Foster 2002; Munoz et al. 2010; Marlon et al. 2013). The large decrease in fire after 1940, mainly attributed to active fire suppression via the Smokey Bear campaign (Abrams 2010), occurred during a significant warming period and may represent another important fire-climate disconnect. However, the decline of burning may have been facilitated by lessening frequency and intensity of drought after 1930 (Fig. 1; McEwan et al. 2011). The impact of severe drought and drought lessening is apparently quite important in the ecological history of the eastern USA. In the Big Woods of Minnesota, a transition from savanna woodlands to closed deciduous forest has been attributed to early (ca. AD 1300) drought reducing fuels and the impact of fire (Shuman et al. 2009). Pulse of tree recruitment at the subcontinental scale during droughts of the late 1600s was severe enough to open large canopy gaps in the eastern broadleaf forests and impact forest composition (Pederson et al. 2014).
The resilience of eastern forests that followed the clearcut and catastrophic fire era, as indicated by the results of this study, reinforces the disturbance attributes for most of its species (Nowacki and Abrams 2008). Nevertheless, there was the near eradication of chestnut, which was once an associate of oak along the Appalachian Mountains from the chestnut blight (Cryphonectria parasitica; Whitney 1994). However, generally low levels of chestnut were recorded in the pollen and witness tree records in this study, and its relative pollen production is unknown (Table 2; Steve Jackson personal communication October 2014). It has been suggested that the abundance of chestnut might have been overemphasized in the past, especially at regional scales (Hanberry and Nowacki 2016).
We recorded a large decline in pine, hemlock, and larch (in the sub-boreal forest), called “deconiferization,” which is attributed to intensive logging and their inability to reproduce sprout vegetatively (Abrams 2001; Nowacki and Abrams 2008). The Great Lakes region experienced a large increase in aspen, an aggressive pioneer tree species, as a direct result of clearcutting and burning the original conifer-northern hardwood forests (Nowacki and Abrams 2008). Large increases also occurred in maples, with cool-based sugar maple being the principal maple species regenerating within mesic conifer-northern hardwoods and warm-based red maple within more xeric pine-northern hardwoods (Nowacki and Abrams 2015). While evident in our witness tree data, the apparent lack of this response in pollen data is likely due to maple having low-pollen presence in sediment records (Prentice and Webb III 1986). Moreover, the paleochronologies used here had an average ending date of 1966 and thus often do not capture the last half-century of forest change.
The more aggressive of the maple species, particularly over the last 50 years, is red maple which is now a dominant tree over much of the eastern USA (Abrams 1998). The dramatic rise of red maple has been attributed to a suite of factors, including the extensive and repeated logging during the late nineteenth and early twentieth centuries, the loss of chestnut, the suppression of understory burning, and increased precipitation (Abrams 1992; Abrams 1998; Fei and Steiner 2007; McEwan et al. 2011). We can add increase in temperature as a driver for this warm-adapted maple as compared with sugar maple. The increase in red maple is believed to be one of several important factors responsible for oak decline in the eastern USA, which is mostly evident south of the TZL in this study. The coincidence of active fire suppression, a warming climate, and lessening of drought during the twentieth century make moisture attributions difficult. For example, there is little evidence in the paleoecology literature that maple (including red maple) significantly increased to become a forest dominant during past wet periods prior to twentieth century (Gajewski 1987; Russell et al. 1993; Foster et al. 2002; Pederson et al. 2005). In contrast, tree survey studies indicate that red maple responded quite quickly to fire suppression after 1940 (Larsen 1959; Lorimer 1984; Abrams 1992; Shumway et al. 2001). Following European settlement, the pollen and tree survey data used here revealed changes in the ecophysiological environment indicative of an overall cooling and loss of pyrogenicity and drought and increase in shade tolerance. This is consistent with a mesophication of forests in the eastern USA, which has been primarily attributed to the decline of burning after 1940 (Nowacki and Abrams 2008, 2015). The overall cooling is particularly noteworthy because forests are becoming more mesic despite general warming over the period of study.
In conclusion, paleoecological (pollen and charcoal), tree census, land use history, and climate data used in concert in this study provided a more robust interpretation of historical ecology than possible with only one data type by compensating for inherent weaknesses in each data type. The charcoal, human population, and climate data provided important support for the anthropogenic fire hypothesis over the last 2000 years in the eastern USA, including multiple instances of climate-fire disconnects that may be best explained by the role of human-caused burning.
Raw data were generated in the lab of MDA. Derived data supporting the findings of this study are available from the corresponding author [MDA] on request.
Abrams MD (1992) Fire and the development of oak forests. BioScience 42:346–353
Abrams MD (1998) The red maple paradox. BioScience 48:355–364
Abrams MD (2001) Eastern white pine versatility in the presettlment forest. BioScience 51:967–979
Abrams MD (2003) Where has all the white oak gone? BioScience 53:927–939
Abrams MD (2010) Native Americans, Smoky Bear and the rise and fall of eastern oak forests. Penn St Envtl Law Rev 18:141–154
Abrams MD, Nowacki GJ (2008) Native Americans as active and passive promoters of mast and fruit trees in the eastern USA. The Holocene 18:1123–1137
Abrams MD, Nowacki GJ (2015) Exploring the early Anthropocene burning hypothesis and climate-fire anomalies for the eastern US. J Sustain Forest 34:30–48
Ahearn PJ (1976) Late-glacial and postglacial pollen record from Demont lake, Isabella County, Michigan. Senior thesis, Alma College
Almendinger JC (1985) The late-Holocene development of jack pine forests on outwash plains, north-central Minnesota. University of Minnesota, Dissertation
Almquist-Jacobson H, Sanger D (1995) Holocene climate and vegetation in the Milford drainage basin, Maine, U.S.A., and their implications for human history. Veg Hist Archaeobot 4:211–222
Alwin BC (1982) Vegetation history of the Sugar Hills area, Itasca CO, Minnesota. University of Minnesota, Thesis
Andersen ST (1970) The relative pollen productivity and pollen representation of north European trees, and correction factors for tree pollen spectra. Dan Geol Undersog 2
Anderson RS (1979) A Holocene record of vegetation and fire at upper south branch pond in northern Maine. University of Maine, Thesis
Blarquez O, Bartlein PJ, Vannière B, Marlon JR, Daniau A-L, Power MJ, Brewer S (2014) Paleofire: an R package to analyse sedimentary charcoal records from the global charcoal database to reconstruct past biomass burning. Comput Geosci 72:255–261
Bennett KD (1987) Holocene history of forest trees in southern Ontario. Can J Bot 65:1792–1801
Black BA, Abrams MD (2001) Influences of physiography, surveyor bias, and native American catchments on witness tree distribution in southeastern Pennsylvania. Ecology 82:2574–2586
Bond WJ, Keeley JE (2005) Fire as a global ‘herbivore’: the ecology and evolution of flammable ecosystems. Trends Ecol Evol 20:387–394
Booth RK, Jackson ST, Sousa VA, Sullivan ME, Minckley TA, Clifford MJ (2012) Multidecadal drought and amplified moisture variability drove rapid forest community change in a humid region. Ecology 93:219–226
Bourdo EA (1956) A review of the general land office survey and of its use in qualitative studies of former forests. Ecology 37:754–768
Braun EL (1950) Deciduous forests of eastern North America. The Free Press, New York
Burns RM, Honkala BH (tech cords) (1990) silvics of North America: 1. conifers; 2. hardwoods. Agriculture handbook 654, vol 2. U.S. Department of Agriculture, Forest Service, Washington, DC
Brugam RB (1978) Pollen indicators of land-use change in southern Connecticut. Quat Res 9:349–362
Calcote R (2003) Mid-Holocene climate and the hemlock decline: the range limit of Tsuga canadensis in the western Great Lakes region, USA. The Holocene 13:215–224
Clark JS, Hussey TC (1996) Estimating the mass flux of charcoal from sedimentary records: effects of particle size, morphology, and orientation. The Holocene 6:129–144
Clark JS, Royall PD (1996) Local and regional sediment charcoal evidence for fire regimes in presettlement northeastern North America. J Ecol 84:365–382
Cleland DT, Freeouf JA, Keys Jr. JE, Nowacki GJ, Carpenter C, McNab WH (2007) Ecological subregions: sections and subsections of the conterminous United States (1:3,500,000) (CD-ROM) (Sloan AM, cartog). USDA Forest Service general technical report WO-76, Washington, DC
Cole KL, Taylor RS (1995) Past and current trends of change in a dune prairie/oak savanna reconstructed through a multiple-scale history. J Veg Sci 6:399–410
Craig AJ (1969) Vegetational history of the Shenandoah Valley, Virginia. Geol Soc Am Spec Pap 123:283–296
Cridlebaugh PA (1984) American Indian and euro-American impact upon Holocene vegetation in the lower little Tennessee River valley, East Tennessee. University of Tennessee, Dissertation
Crosby AW (1976) Virgin soil epidemics as a factor in the aboriginal depopulation in America. William Mary Q 33:289–299
Curtis JT (1959) The vegetation of Wisconsin: an ordination of plant communities. The University of Wisconsin press. Madison, WI
Daniau A-L, Bartlein PJ, Harrison SP, Prentice IC, Brewer S, Friedlingstein P, Harrison-Prentice TI, Inoue J, Izumi K, Marlon JR, Mooney S, Power MJ, Stevenson J, Tinner W, Andrič M, Atanassova J, Behling H, Black M, Blarquez O, Brown KJ, Carcaillet C, Colhoun EA, Colombaroli D, Davis BAS, D'Costa D, Dodson J, Dupont L, Eshetu Z, Gavin DG, Genries A, Haberle S, Hallett DJ, Hope G, Horn SP, Kassa TG, Katamura F, Kennedy LM, Kershaw P, Krivonogov S, Long C, Magri D, Marinova E, McKenzie GM, Moreno PI, Moss P, Neumann FH, Norström E, Paitre C, Rius D, Roberts N, Robinson GS, Sasaki N, Scott L, Takahara H, Terwilliger V, Thevenon F, Turner R, Valsecchi VG, Vannière B, Walsh M, Williams N, Zhang Y (2012) Predictability of biomass burning in response to climate changes. Glob Biogeochem Cycles 26. https://doi.org/10.1029/2011GB004249
Davis MB (1963) On the theory of pollen analysis. Am J Sci 261:897–912
Davis MB (1969) Climatic changes in southern Connecticut recorded by pollen deposition at Rogers Lake. Ecology 50:409–422
Davis MB, Goodlett JC (1960) Comparison of the present vegetation with pollen-spectra in surface samples from Brownington pond, Vermont. Ecology 41:346–357
Davis MB, Calcote RR, Sugita S, Takahara H (1998) Patchy invasion and the origin of a hemlock-hardwoods forest mosaic. Ecology 79:2641–2659
Davis MB, Deevey ES Jr (1964) Pollen accumulation rates: estimates from late-glacial sediment of Rogers Lake. Science 145:1293–1295
Dawson A, Paciorek CJ, McLachlan JS, Goring S, Williams JW, Jackson ST (2016) Quantifying pollen-vegetation relationships to reconstruct ancient forests using 19th-century forest composition and pollen data. Quat Sci Rev 137:156–175
Delcourt HR (1979) Late Quaternary vegetation history of the eastern Highland rim and adjacent Cumberland plateau of Tennessee. Ecol Monogr 49:255–280
Delcourt HR, Delcourt PA (1996) Presettlement landscape heterogeneity: evaluating grain of resolution using general land office survey data. Landsc Ecol 11:363–381
Denevan WM (1992) The pristine myth: the landscape of the Americas in 1492. Ann Assoc American Geogr 82:369–385
Dobyns HF (1993) Disease transfer at contact. Annu Rev Anthr 22:273–291
Egan D, Howell EA (eds) (2001) The historical ecology handbook: a restorationist’s guide to reference ecosystems. Island Press, Washington, DC
Ewing HA (2000) Ecosystem development and response to climatic change: a comparative study of forest-lake ecosystems on different substrates. University of Minnesota, Dissertation
Fagerlind F (1952) The real signification of pollen diagrams. Bot Not 105:185–224
Fei S, Steiner KC (2007) Evidence for increasing red maple abundance in the eastern United States. For Sci 53:473–477
Foster CHW (ed) (1998) Stepping back to look forward: a history of the Massachusetts Forest. Harvard University Press, Cambridge, MA
Foster DR, Motzkin G, Slater B (1998) Land-use history as long-term broad-scale disturbance: regional forest dynamics in Central New England. Ecosystems 1:96–119
Foster DR, Hall B, Barry BS, Clayden S, Parshall T (2002a) Cultural, environmental and historical controls of vegetation patterns and the modern conservation setting on the island of Martha's Vineyard, USA. J Biogeogr 29:1381–1400
Foster DR, Clayden S, Orwig DA, Hall B, Barry S (2002b) Oak, chestnut and fire: climatic and cultural controls of long-term forest dynamics in New England, USA. J Biogeogr 29:1359–1379
Foster DR (2004) The physical and biological setting for ecological studies. In: Foster DR, Aber JD (eds) Forests in time. Yale University Press, New Haven, pp 19–31
Francis DR, Foster DR (2001) Response of small New England ponds to historic land use. The Holocene 11:301–312
Fuller JL (1995) Holocene forest dynamics in southern Ontario, Canada. University of Cambridge, Dissertation
Fuller JL, Foster DR, McLachlan JS, Drake N (1998) Impact of human activity on regional forest composition and dynamics in Central New England. Ecosystems 1:76–95
Gajewski K (ed) (1985) Late-Holocene pollen data from lakes with varved sediments in northeastern and northcentral United States, IES Report, vol 124. University of Wisconsin, Madison, WI, Center for Climatic Research
Gajewski KJ (1983) On the interpretation of climatic change from the fossil record: climatic change in central and eastern United States over the past 2000 years estimated from pollen data. University of Wisconsin, Dissertation
Gajewski K (1987) Climatic impacts on the vegetation of eastern North America during the past 2000 years. Vegetatio 68:179–190
Geiss CE, Umbanhowar CE, Camill P, Banerjee SK (2003) Sediment magnetic properties reveal Holocene climate change along the Minnesota prairie-forest ecotone. J Paleolimnol 30:151–166
Gill JL, Williams JW, Jackson ST, Lininger KB, Robinson GS (2009) Pleistocene megafaunal collapse, novel plant communities, and enhanced fire regimes in North America. Science 326:1100–1103
Grimm EC (2008) Neotoma, an ecosystem database for the Pliocene, Pleistocene, and Holocene. Springfield, MA: Illinois state museum scientific papers E series 1
Guyette RP, Stambaugh MC, Muzika RM, Dey DC (2006) Fire scars reveal variability and dynamics of eastern fire regimes. In: Dickinson MB (ed) fire in eastern oak forests: delivering science to land managers, proceedings of a conference; 2005 November 15-17; Columbus, OH. Gen. Tech. Rep. NRS-P-1. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, northern Research Station, pp 20-39
Guyette RP, Stambaugh MC, Dey DC, Muzika R (2012) Predicting fire frequency with chemistry and climate. Ecosystems 15:322–335
Hanberry BB, Nowacki GJ (2016) Oaks were the historical foundation genus of the east-Central United States. Quat Sci Rev 145:94–103
Hannah L, Flint L, Syphard AD, Moritz MA, Buckley LB, McCullough IM (2014) Fine-grain modeling of species’ response to climate change: holdouts, stepping-stones, and microrefugia. Trends Ecol Evol 29:390–397
Hart JL, Buchanan ML (2012) History of fire in eastern oak forests and implications for restoration. In: Dey DC (ed) proceedings of the 4th fire in eastern oak forests conference, GTR-NRS-P-102, USDA Forest Service, pp 34-51
Heide KM (1981) Late Quaternary vegetational history of north-Central Wisconsin, U.S.a.: estimating forest composition from pollen data. Dissertation, Brown University
IPCC (2013) Summary for policymakers. In: Stocker TF, Qin D, Plattner G-K, Tignor M, Allen SK, Boschung J, Nauels A, Xia Y, Bex V, Midgley PM (eds) Climate change 2013: the physical science basis. Cambridge University Press, Cambridge and New York, Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change
Jackson ST (1994) Pollen and spores in quaternary lake sediments as sensors of vegetation composition: theoretical models and empirical evidence. In: Traverse A (ed) Sedimentation of organic particles. Cambridge University Press, Cambridge, pp 253–286
Jackson ST (2006) Vegetation, environment, and time: the origination and termination of ecosystems. J Veg Sci 17:549–557
Jackson ST, Booth RK (2002) The role of Late Holocene climate variability in the expansion of yellow birch in the western Great Lakes region. Divers Distrib 8:275–284
Jackson ST, Betancourt JL, Booth RK, Gray ST (2009) Ecology and the ratchet of events: climate variability, niche dimensions, and species distributions. Proc Natl Acad Sci 106:19685–19692
Jackson ST, Williams JW (2004) Modern analogs in quaternary paleoecology: Here today, gone yesterday, gone tomorrow? Annu Rev Earth Planet Sci 32:495–537
Jacobson Jr GL, Webb III T, Grimm EC (1987) Patterns and rates of vegetation change during the deglaciation of eastern North America. In: Ruddiman WF, Wright Jr HE (eds) North America and adjacent oceans during the last deglaciation. The Geology of North America K-3, Geological Society of America, Boulder, Colorado, pp 277–288
Jensen K, Lynch EA, Calcote R (2007) Interpretation of charcoal morphotypes in sediments from ferry Lake, Wisconsin, USA: do different plant fuel sources produce distinctive charcoal morphotypes? The Holocene 17:907–915
Kay CE (2007) Are lightning fires unnatural? A comparison of aboriginal and lightning ignition rates in the United States. In: Proceedings of the 23rd tall timbers fire ecology conference: fire in grassland and Shrubland ecosystems. Tall Timbers Research Station, Tallahassee, pp 16–28
Kellogg DC (1991) Prehistoric landscapes, paleoenvironments, and archaeology of Western Muscongus Bay, Maine. University of Maine, Dissertation
Kerfoot WC (1974) Net accumulation rates and the history of cladoceran communities. Ecology 55:51–61
Klein Goldewijk K, Beusen A, de Vos M, Drecht G (2011) The HYDE 3.1 spatially explicit database of human induced land use change over the past 12,000 years. Glob Ecol and Biogeogr 20:73–86
Kneller M, Peteet DM (1993) Late-Quaternary climate in the ridge and valley of Virginia, U.S.a.: changes in vegetation and depositional environment. Quat Sci Rev 12:613–628
Larsen JA (1959) A study of an invasion by red maple of an oak woods in southern Wisconsin. Am Midl Nat 49:908–914
Lorimer CG (1984) Development of the red maple understory in northeastern oak forests. For Sci 30:3–22
Mann CC (2005) 1491: new revelations of the Americas before Columbus. Alfred A, Knopf, New York
Mann ME, Zhang Z, Rutherford S, Bradley RS, Hughes MK, Shindell D, Ni F (2009) Global signatures and dynamical origins of the little ice age and medieval climate anomaly. Science 326:1256–1260
Manny BA, Wetzel RG, Bailey RE (1978) Paleolimnological sedimentation of organic carbon, nitrogen, phosphorous, fossil pigments, pollen, and diatoms in a hypereutrophic, hardwater lake: a case history of eutrophication. Polskie Arch Hydrobiol 25:243–267
Marlon, J.R., Bartlein, P.J., Carcaillet, C., Gavin, D.G., Harrison, S.P., Higuera, P.E., Joos, F., Power, M.J., Prentice, I.C. (2008) Climate and human influences on global biomass burning over the past two millennia. Nature Geoscience DOI :https://doi.org/10.1038/ngeo313
Marlon JR, Bartlein PJ, Daniau A-L, Harrison SP, Power MJ, Tinner W, Tracy S (2013) Global biomass burning: a synthesis and review of Holocene paleofire records and their controls. Quat Sci Rev 65:5–25
McAndrews JH (1968) Pollen evidence for the protohistoric development of the “Big Woods” in Minnesota (U.S.A.). Rev Palaeobot Palynol 7:201–211
McAndrews JH (1973) Pollen analysis of the sediments of the Great Lakes of North America. In: Palynology: Holocene and Marine Palynology. Proceeding of the III International Palynological Conference. Nauka, Moscow, Russia, pp 76–80
McAndrews JH (1981) Late Quaternary climate of Ontario: temperature trends from the fossil pollen record. In: Mahaney WC (ed) Quaternary Paleoclimate. Geo Abstracts, Ltd., England, pp 319–333
McAndrews JH (1984) Late Quaternary vegetation history of Rice Lake, Ontario, and the McIntyre archaeological site. Archaeol Surv Can Pap 126:161–189
McAndrews JH (1988) Human disturbance of north American forests and grasslands: the fossil pollen record. In: Huntley B, Webb T III (eds) Vegetation history. Kluwer, Handbook of Vegetation Science Series, pp 673–697
McCarthy FMG (1986) Late Holocene water levels in Lake Ontario: evidence from grenadier pond. University of Toronto, M.S. Thesis
McEwan RW, Dyer JM, Pederson N (2011) Multiple interacting ecosystem drivers: toward an encompassing hypothesis of oak forest dynamics across eastern North America. Ecography 34:244–256
Mott RJ (1975) Palynological studies of lake sediment profiles from southwestern New Brunswick. Can J Earth Sci 12:273–288
Munoz SE, Gajewski K (2010) Distinguishing prehistoric human influence on late-Holocene forests in southern Ontario, Canada. The Holocene 20:967–981
Munoz SE, Gajewski K, Peros MC (2010) Synchronous environmental and cultural change in the prehistory of the northeastern United States. Proc Natl Acad Sci 107:22008–22013
Munoz SE, Mladenoff DJ, Schroeder S, Williams JW (2014) Defining the spatial patterns of historical land use associated with the indigenous societies of eastern North America. J Biogeogr 41:2195–2210. https://doi.org/10.1111/jbi.12386
Nelson DM, Hu FS, Tian J, Stefanova I, Brown TA (2004) Response of C3 and C4 plants to middle-Holocene climatic variation near the prairie-forest ecotone of Minnesota. Proc Natl Acad Sci 101:562–567
Nowacki GJ, Abrams MD (2008) Demise of fire and mesophication of eastern U.S. forests. BioScience 58:123–138
Nowacki GJ, Abrams MD (2015) Is climate an important driver of post-European vegetation change in the eastern United States? Glob Change Biol 21:314–334
Nowacki GJ, MacCleery DW, Lake FK (2012) Native Americans, ecosystem development, and historical range of variation. In: Weins JA, Hayward GD, Safford HD, Giffen CM (eds) Historical environmental variation in conservation and natural resource management. Wiley-Blackwell, West Sussex, pp 76–91
Ogden JG III (1966) Forest history of Ohio. I. Radiocarbon dates and pollen stratigraphy of silver Lake, Logan County, Ohio. Ohio J Sci 66:387–400
Ogden JG III (1969) Correlation of contemporary and Late Pleistocene pollen records in the reconstruction of postglacial environments in northeastern North America. Mitt Int Ver Theor Angew Limnol 17:64–77
Paciorek CJ, McLachlan JS (2009) Mapping ancient forests: Bayesian inference for spatio-temporal trends in forest composition. J Am Stat Assoc 104:608–622. https://doi.org/10.1198/jasa.2009.0026
Parshall T, Foster DR (2002) Fire on the New England landscape: regional and temporal variation, cultural and environmental controls. J Biogeogr 29:1305–1317
Patterson WA, Sassaman KE (1988) Indian fires in the prehistory of New England. In: Nicholas GP (ed) Holocene human ecology in northeastern North America. Plenum Press, New York, pp 107–135
Pederson N, D'amato AW, Dyer JM, Foster DR, Goldblum D, Hart JL, Hessl AE, Iverson LR, Jackson ST, Martin-Benito D, McCarthy BC (2015) Climate remains an important driver of post-European vegetation change in the eastern United States. Glob Chang Biol 21:2105–2110
Pederson DC, Peteet DM, Kurdyla D, Guilderson T (2005) Medieval warming, little ice age, and European impact on the environment during the last millennium in the lower Hudson Valley, New York, USA. Quat Res 63:238–249
Pederson N, Dyer JM, McEwan RW, Hessl AE, Mock C, Orwig D, Rieder HE, Cook BI (2014) The legacy of episodic climatic events in shaping broadleaf-dominated forests. Ecol Monogr 84:599–620
Pyne SJ (1982) Fire in America: a cultural history of wildland and rural fire. Princeton University Press
Pinter N, Fiedel S, Keeley JE (2011) Fire and vegetation shifts in the Americas at the vanguard of Paleoindian migration. Quat Sci Rev 30:269–272
Potzger JE, Courtemanche A, Sylvio BM, Hueber FM (1956) Pollen from moss polsters on the mat of lac Shaw bog, Quebec, correlated with a forest survey. Butl Univ Bot Stud 13:24–35
Power MJ, Marlon JR, Bartlein PJ, Harrison SP (2010) Fire history and the global charcoal database: a new tool for hypothesis testing and data exploration. Paleogeogr, Paleoclim, Paleoecol 291:52–59
Power MJ, Mayle FE, Bartlein PJ, Marlon JR, Anderson RS, Behling H, Brown KJ, Carcaillet C, Colombaroli D, Gavin DG, Hallett DJ, Horn SP, Kennedy LM, Lane CS, Long CJ, Moreno PI, Paitre C, Robinson CG, Taylor Z, Walsh MK (2012) Climatic control of the biomass-burning decline in the Americas after AD 1500. The Holocene 23:3–13
Prasad AM, Iverson LR, Matthews S, Peters M (2007-Ongoing) a climate change atlas for 134 forest tree species of the eastern United States [database]. Northern Research Station, USDA Forest Service, Delaware, Ohio. http://www.nrs.fs.fed.us/atlas/tree (accessed 3 January 2014)
Prentice IC, Webb T III (1986) Pollen percentages, tree abundances and the Fagerlind effect. J Quat Sci 1:35–43
Rhemtulla JM, Mladenoff DJ, Clayton MK (2009) Legacies of historical land use on regional forest composition and structure in Wisconsin, USA (mid-1800s to 1930s to 2000s). Ecol Appl 19:1061–1078
Richter DK (2001) Facing east from Indian country: a native history of early America. Harvard University Press, Cambridge
Robinson GS, Pigott BL, Burney DA (2005) Landscape paleoecology and megafaunal extinction in southeastern New York state. Ecol Monogr 75:295–315
Ruddiman WF (2005) Plows, plagues, and petroleum: how humans took control of climate. Princeton University Press, Princeton
Ruffner CM, Abrams MD (1998) Lightning strikes and resultant fires from archival (1912-1917) and current (1960-1997) information in Pennsylvania. J Torrey Bot Soc 125:249–252
Russell EWB, Davis RB (2001) Five centuries of changing forest vegetation in the northeastern United States. Plant Ecol 155:1–13
Russell EWB, Davis RB, Anderson RS, Rhodes TE, Anderson DS (1993) Recent centuries of vegetational change in the glaciated North-Eastern United States. J Ecol 81:647–664
Schulte LA, Mladenoff DJ (2001) The original U.S. public land survey records: their use and limitations in reconstructing pre-European settlement vegetation. J For 99:5–10
Schwartz MW (1989) Predicting tree frequencies from pollen frequency: an attempt to validate the R value method. New Phytol 112:129–143
Shane LCK (1991) Vegetation history of western Ohio. Final Report on 1990 Grant from the Ohio Department of Natural Resources, Limnological Research Center, University of Minnesota
Shuman B, Newby P, Huang Y, Webb T III (2004) Evidence for the close climatic control of New England vegetation history. Ecology 85:1297–1310
Shuman B, Henderson AK, Plank C, Stefanova I, Ziegler SS (2009) Woodland-to-forest transition during prolonged drought in Minnesota after ca. AD 1300. Ecology 90:2792–2807
Shumway DL, Abrams MD, Ruffner CM (2001) A 400-year history of fire in an old-growth oak forest in western Maryland, USA. Can J For Res 31:1437–1443
Spear RW (1981) The history of high-elevation vegetation in the White Mountains of New Hampshire. University of Minnesota, Dissertation
Stambaugh MC, Guyette RP, Marschall JM (2013) Fire history in the Cherokee nation of Oklahoma. Hum Ecol 41:749–758
Steyaert LT, Knox RG (2008) Reconstructed historical land cover and biophysical parameters for studies of land-atmosphere interactions within the eastern United States. J Geophys Res 113:1–27. https://doi.org/10.1029/2006JD008277
Stuiver M (1969) Yale natural radiocarbon measurements IX. Radiocarbon 11:545–658
Sugita S, Parshall T, Calcote R (2006) Detecting differences in vegetation among paired sites using pollen records. The Holocene 16:1123–1135
Sugita S, Parshall T, Calcote R, Walker K (2010) Testing the landscape reconstruction algorithm for spatially explicit reconstruction of vegetation in northern Michigan and Wisconsin. Quat Res 74:289–300
Swain AM (1974) A history of fire and vegetation in northeastern Minnesota as recorded in lake sediments. University of Minnesota, Dissertation
Thomas-Van Gundy MA, Nowacki GJ (2013) The use of witness trees as pyro-indicators for mapping past fire conditions. For Ecol Manag 304:333–344
Thompson JR, Carpenter DN, Cogbill CV, Foster DR (2013) Four centuries of change in northeastern United States forests. PLoS One 8:e72540
Waddington JCB (1969) A stratigraphic record of the pollen influx to a lake in the Big Woods of Minnesota. Geol Soc Am Spec Pap 123:263–282
Watts WA (1979) Late Quaternary vegetation of central Appalachia and the New Jersey coastal plain. Ecol Monogr 49:427–469
Watts WA, Hansen BCS (1988) Environment of Florida in the late Wisconsin and Holocene. In: Purdy B (ed) Wet Site Archaeology. Telford Press, Caldwell, NJ
Webb SL (1983) The Holocene extension of the range of American beech (Fagus grandifolia) into Wisconsin: paleoecological evidence for long-distance seed dispersal. University of Minnesota, Dissertation
Webb T III, Howe SE, Bradshaw RHW, Heide KM (1981) Estimating plant abundances from pollen percentages: the use of regression analysis. Rev Palaeobot Palynol 34:269–300
Weninger JM, McAndrews JH (1989) Late Holocene aggradation in the lower Humber River valley, Toronto, Ontario. Can J Earth Sci 26:1842–1849
Whitehead DR, Crisman TL (1978) Paleolimnological studies of small New England (U.S.A.) ponds. Part I. late-glacial and postglacial trophic oscillations. Polskie Arch Hydrobiol 25:471–481
Whitehead DR, Jackson ST (1990) The regional vegetational history of the high peaks (Adirondack Mountains), New York. Bulletin no. 478, New York state museum, Albany, NY
Whitney GG (1994) From coastal wilderness to fruited plain: a history of environmental change in temperate North America 1500 to the present. Cambridge University Press, New York
Whitney GG, Davis WC (1986) From primitive woods to cultivated woodlots: Thoreau and the forest history of Concord, Massachusetts. J For Hist 30:70–81
Whitney GG, DeCant JP (2001) Government land office surveys and other early land surveys. In: Egan D, Howell EA (eds) The historical ecology handbook: a restorationist’s guide to reference ecosystems. Island Press, Washington, DC, pp 147–172
Wilkins GR (1985) Late-quaternary vegetational history at Jackson pond, Larue County, Kentucky. The University of Tennessee, Thesis
Williams JW, Schuman BN, Webb T III, Bartlein PJ, Leduc PL (2004) Late-Quaternary vegetation dynamics in North America: scaling from taxa to biomes. Ecol Monogr 74:309–303
Winkler MG (1985) A 12,000-year history of vegetation and climate for Cape Cod, Massachusetts. Quat Res 23:301–312
Woodall CW, Zhu K, Westfall JA, Oswalt CM, D’Amato AW, Walters BF, Lintz HE (2013) Assessing the stability of tree ranges and influence of disturbance in eastern U.S. forests. For Ecol Manag 291:172–180
Woods KD, Davis MB (1989) Paleoecology of range limits: beech in the Upper Peninsula of Michigan. Ecology 70:681–696
We wish to thank Drs. Sam Munoz, David Foster, and Steve Jackson for advice concerning methodology and interpretation of data in this study. We thank Jennifer Marlon for providing the paleocharcoal and human population data and analysis. We thank Chris Bouma and Janet Ellsworth for data synthesis and analysis.
The Agric. Experiment Station of Penn State University. Project 4240.
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Contribution of the co-authors
MDA: literature review, data compilation, data analysis, and wrote first draft of paper
GJN: literature review, data compilation, data analysis, wrote sections of the paper, and edited entire paper.
This article is part of the topical collection on Wood formation and tree adaptation to climate.
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Abrams, M.D., Nowacki, G.J. Global change impacts on forest and fire dynamics using paleoecology and tree census data for eastern North America. Annals of Forest Science 76, 8 (2019). https://doi.org/10.1007/s13595-018-0790-y