Christopher Roos
Southern Methodist University, Anthropology, Faculty Member
- University of Arizona, Laboratory of Tree-Ring Research, Department Memberadd
- Archaeology, Paleoecology, Geoarchaeology, Southwestern Archaeology, Pacific Archaeology, Climate Change, and 18 moreDendrochronology, Fire History, Paleoclimatology, Complex Adaptive Systems, Resilience, Historical Ecology, Environmental Archaeology, Evolutionary Anthropology, Charcoal analysis (Archaeology), Archaeological Soil Micromorphology, Fire Ecology, Landscape Ecology, Archaeology of Fire, Use of fire, Climate Change Adaptation, Archaeological Science, Human Behavioral Ecology, and Microstratigraphyedit
The historical and modern importance of crown fires in ponderosa pine and dry mixed-conifer forests of the southwest USA has been much debated. The microscopic reflectance of charcoal in polished blocks under oil shows promise as a... more
The historical and modern importance of crown fires in ponderosa pine and dry mixed-conifer forests of the southwest USA has been much debated. The microscopic reflectance of charcoal in polished blocks under oil shows promise as a semiquantitative proxy for fire severity using charcoal from post-fire landscapes. We measured the reflectance of 33 modern charcoal samples to evaluate (1) whether charcoal reflectance can distinguish between crown fires and surface fires in these forests; and (2) whether surface fires with masticated fuels burn with severities similar to surface fires in grass, litter and duff fuels. The charcoal analysed was primarily collected after wildland fires under two different conditions: (l) wildfires with moderate to high severity and crown fire behaviour (n ¼ 17), and (2) prescribed fires with low to moderate severity but no crown fire behaviour (n ¼ 16). Statistical analysis indicates that charcoal reflectance produced in crown fires significantly differs from surface fire charcoal, particularly surface fire charcoal formed in grass, duff and litter fuels. However, charcoal produced from surface fires in masticated fuels is indistinguishable from crown fire charcoal, suggesting that fires in areas that have experienced in situ mastication may have soil impacts similar to crown fires.
Research Interests:
Fire use has played an important role in human evolution and subsequent dispersals across the globe, yet the relative importance of human activity and climate on fire regimes is controversial. This is particularly true for historical fire... more
Fire use has played an important role in human evolution and subsequent dispersals across the globe, yet the relative importance of human activity and climate on fire regimes is controversial. This is particularly true for historical fire regimes of the Americas, where indigenous groups used fire for myriad reasons but paleofire records indicate strong climate–fire relationships. In North American grasslands, decadal-scale wet periods facilitated widespread fire activity because of the abundance of fuel promoted by pluvial episodes. In these settings, human impacts on fire regimes are assumed to be independent of climate, thereby diminishing the strength of climate–fire relationships. We used an offsite geoarchaeological approach to link terrestrial records of prairie fire activity with spatially related archaeological features (driveline complexes) used for intensive, communal bison hunting in north-central Montana. Radiocarbon-dated charcoal layers from alluvial and colluvial deposits associated with driveline complexes indicate that peak fire activity over the past millennium occurred coincident with the use of these features (ca. 1100–1650 CE). However , comparison of dated fire deposits with Palmer Drought Severity Index reconstructions reveal strong climate–fire linkages. More than half of all charcoal layers coincide with modest pluvial episodes, suggesting that fire use by indigenous hunters enhanced the effects of climate variability on prairie fire regimes. These results indicate that relatively small, mobile human populations can impact natural fire regimes, even in pyrogeographic settings in which climate exerts strong, top-down controls on fuels. anthropogenic burning | bison hunting | pyric herbivory | climate–fire relationships | hunter-gatherers
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Research Interests:
Interannual climate variations have been important drivers of wildfire occurrence in ponderosa pine forests across western North America for at least 400 years, but at finer scales of mountain ranges and landscapes human land uses... more
Interannual climate variations have been important drivers of wildfire occurrence in ponderosa pine forests across western North America for at least 400 years, but at finer scales of mountain ranges and landscapes human land uses sometimes overrode climate influences. We reconstruct and analyse effects of high human population densities in forests of the Jemez Mountains, New Mexico from ca 1300 CE to Present. Prior to the 1680 Pueblo Revolt, human land uses reduced the occurrence of widespread fires while simultaneously adding more ignitions resulting in many small-extent fires. During the 18th and 19th centuries, wet/dry oscillations and their effects on fuels dynamics controlled widespread fire occurrence. In the late 19th century, intensive livestock grazing disrupted fuels continuity and fire spread and then active fire suppression maintained the absence of widespread surface fires during most of the 20th century. The abundance and continuity of fuels is the most important controlling variable in fire regimes of these semi-arid forests. Reduction of widespread fires owing to reduction of fuel continuity emerges as a hallmark of extensive human impacts on past forests and fire regimes. This article is part of the themed issue 'The interaction of fire and mankind'.
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Native American populations declined between 1492 and 1900 CE, instigated by the European colonization of the Americas. However, the magnitude, tempo, and ecological effects of this depopulation remain the source of enduring debates.... more
Native American populations declined between 1492 and 1900 CE,
instigated by the European colonization of the Americas. However,
the magnitude, tempo, and ecological effects of this depopulation
remain the source of enduring debates. Recently,
scholars have linked indigenous demographic decline, Neotropical
reforestation, and shifting fire regimes to global changes in
climate, atmosphere, and the Early Anthropocene hypothesis. In
light of these studies, we assess these processes in coniferdominated
forests of the Southwest United States. We compare
light detection and ranging data, archaeology, dendrochronology,
and historical records from the Jemez Province of New Mexico to
quantify population losses, establish dates of depopulation events,
and determine the extent and timing of forest regrowth and fire
regimes between 1492 and 1900. We present a new formula for the
estimation of Pueblo population based on architectural remains and
apply this formula to 18 archaeological sites in the Jemez Province.
A dendrochronological study of remnant wood establishes dates of
terminal occupation at these sites. By combining our results with
historical records, we report a model of pre- and post-Columbian
population dynamics in the Jemez Province. Our results indicate that
the indigenous population of the Jemez Province declined by 87%
following European colonization but that this reduction occurred
nearly a century after initial contact. Depopulation also triggered
an increase in the frequency of extensive surface fires between 1640
and 1900. Ultimately, this study illustrates the quality of integrated
archaeological and paleoecological data needed to assess the links
between Native American population decline and ecological change
after European contact.
instigated by the European colonization of the Americas. However,
the magnitude, tempo, and ecological effects of this depopulation
remain the source of enduring debates. Recently,
scholars have linked indigenous demographic decline, Neotropical
reforestation, and shifting fire regimes to global changes in
climate, atmosphere, and the Early Anthropocene hypothesis. In
light of these studies, we assess these processes in coniferdominated
forests of the Southwest United States. We compare
light detection and ranging data, archaeology, dendrochronology,
and historical records from the Jemez Province of New Mexico to
quantify population losses, establish dates of depopulation events,
and determine the extent and timing of forest regrowth and fire
regimes between 1492 and 1900. We present a new formula for the
estimation of Pueblo population based on architectural remains and
apply this formula to 18 archaeological sites in the Jemez Province.
A dendrochronological study of remnant wood establishes dates of
terminal occupation at these sites. By combining our results with
historical records, we report a model of pre- and post-Columbian
population dynamics in the Jemez Province. Our results indicate that
the indigenous population of the Jemez Province declined by 87%
following European colonization but that this reduction occurred
nearly a century after initial contact. Depopulation also triggered
an increase in the frequency of extensive surface fires between 1640
and 1900. Ultimately, this study illustrates the quality of integrated
archaeological and paleoecological data needed to assess the links
between Native American population decline and ecological change
after European contact.
Research Interests: Native American Studies, Archaeology, Anthropology, Historical Archaeology, Historical Demography, and 24 moreSouthwestern United States (Archaeology in North America), Fire Ecology, Dendroecology, LiDAR, Dendrochronology, North American Southwest, Native American, Remote sensing and GIS applications in Landscape Research, Southwestern Archaeology, LiDAR for Forestry, Ancestral Pueblo (Archaeology), Native American Anthropology, Native American (History), Anthropocene studies, Archaeology of the U.S. Southwest, Tree Ring, Dendrochronology, Climate Change, LiDAR for Landscape Archaeology, Anthropocene, Dendroarchaeology, LiDAR for Archaeology, The Anthropocene, Native American Demography and Epidemiology, Jemez Mountains, and Jemez Pueblo
Research Interests:
Humans use combustion for heating and cooking, managing lands, and, more recently, for fuelling the industrial economy. As a shift to fossil-fuel-based energy occurs, we expect that anthropogenic biomass burning in open landscapes will... more
Humans use combustion for heating and cooking, managing lands, and, more recently, for fuelling the industrial economy. As a shift to fossil-fuel-based energy occurs, we expect that anthropogenic biomass burning in open landscapes will decline as it becomes less fundamental to energy acquisition and livelihoods. Using global data on both fossil fuel and biomass burning emissions, we tested this relationship over a 14 year period (1997–2010). The global average annual carbon emissions from biomass burning during this time were 2.2 Pg C per year (+0.3 s.d.), approximately one-third of fossil fuel emissions over the same period (7.3 Pg C, +0.8 s.d.). There was a significant inverse relationship between average annual fossil fuel and bio-mass burning emissions. Fossil fuel emissions explained 8% of the variation in biomass burning emissions at a global scale, but this varied substantially by land cover. For example, fossil fuel burning explained 31% of the variation in biomass burning in woody savannas, but was a non-significant predictor for evergreen needleleaf forests. In the land covers most dominated by human use, croplands and urban areas, fossil fuel emissions were more than 30-and 500-fold greater than biomass burning emissions. This relationship suggests that combustion practices may be shifting from open landscape burning to contained combustion for industrial purposes, and highlights the need to take into account how humans appropriate combustion in global modelling of contemporary fire. Industrialized combustion is not only an important driver of atmospheric change, but also an important driver of landscape change through companion declines in human-started fires. This article is part of the themed issue 'The interaction of fire and mankind'.
Research Interests:
Living with fire is a challenge for human communities because they are influenced by socioeconomic , political, ecological and climatic processes at various spatial and temporal scales. Over the course of 2 days, the authors discussed how... more
Living with fire is a challenge for human communities because they are influenced by socioeconomic , political, ecological and climatic processes at various spatial and temporal scales. Over the course of 2 days, the authors discussed how communities could live with fire challenges at local, national and trans-national scales. Exploiting our diverse, international and interdisciplinary expertise, we outline generalizable properties of fire-adaptive communities in varied settings where cultural knowledge of fire is rich and diverse. At the national scale, we discussed policy and management challenges for countries that have diminishing fire knowledge, but for whom global climate change will bring new fire problems. Finally, we assessed major fire challenges that transcend national political boundaries, including the health burden of smoke plumes and the climate consequences of wildfires. It is clear that to best address the broad range of fire problems, a holistic wildfire scholarship must develop common agreement in working terms and build across disciplines. We must also communicate our understanding of fire and its importance to the media, politicians and the general public. This article is part of the themed issue 'The interaction of fire and mankind'.
Research Interests:
Fire has been an important part of the Earth system for over 350 Myr. Humans evolved in this fiery world and are the only animals to have used and controlled fire. The interaction of mankind with fire is a complex one, with both positive... more
Fire has been an important part of the Earth system for over 350 Myr. Humans evolved in this fiery world and are the only animals to have used and controlled fire. The interaction of mankind with fire is a complex one, with both positive and negative aspects. Humans have long used fire for heating, cooking, landscape management and agriculture, as well as for pyrotechnologies and in industrial processes over more recent centuries. Many landscapes need fire but population expansion into wildland areas creates a tension between different interest groups. Extinguishing wildfires may not always be the correct solution. A combination of factors, including the problem of invasive plants, landscape change, climate change, population growth, human health, economic, social and cultural attitudes that may be transnational make a re-evaluation of fire and mankind necessary. The Royal Society meeting on Fire and mankind was held to address these issues and the results of these deliberations are published in this volume. This article is part of the themed issue 'The interaction of fire and mankind'. We are uniquely fire creatures on a uniquely fire planet. —S. J. Pyne
Research Interests:
Research Interests:
In our 2011 synthesis (Bowman et al., Journal of Biogeography, 2011, 38, 2223–2236), we argued for a holistic approach to human issues in fire science that we term ‘pyrogeography’. Coughlan & Petty (Journal of Biogeography, 2013, 40,... more
In our 2011 synthesis (Bowman et al., Journal of Biogeography, 2011, 38, 2223–2236), we argued for a holistic approach to
human issues in fire science that we term ‘pyrogeography’. Coughlan & Petty (Journal of Biogeography, 2013, 40, 1010–1012) critiqued our paper on the grounds that our ‘pyric phase’ model was built on outdated views of cultural development, claiming we developed it to be the unifying explanatory framework for all human–fire sciences. Rather, they suggest that ‘historical ecology’ could provide such a framework. We used the ‘pyric transition’ for multiple purposes but did not offer it as an exclusive explanatory framework for pyrogeography. Although ‘historical ecology’ is one of many useful approaches to studying human–fire relationships, scholars should also look to political and evolutionary ecology, ecosystems and complexity theories, as well as empirical generalizations to build an interdisciplinary fire science that incorporates human, ecological and biophysical
dimensions of fire regimes.
human issues in fire science that we term ‘pyrogeography’. Coughlan & Petty (Journal of Biogeography, 2013, 40, 1010–1012) critiqued our paper on the grounds that our ‘pyric phase’ model was built on outdated views of cultural development, claiming we developed it to be the unifying explanatory framework for all human–fire sciences. Rather, they suggest that ‘historical ecology’ could provide such a framework. We used the ‘pyric transition’ for multiple purposes but did not offer it as an exclusive explanatory framework for pyrogeography. Although ‘historical ecology’ is one of many useful approaches to studying human–fire relationships, scholars should also look to political and evolutionary ecology, ecosystems and complexity theories, as well as empirical generalizations to build an interdisciplinary fire science that incorporates human, ecological and biophysical
dimensions of fire regimes.
Research Interests:
Research Interests:
Geoarchaeological analyses, including soil micromorphology and chemistry, were used to characterize the deposition history of a fourteenth-century Pueblo ceremonial structure (or kiva) at Fourmile Ruin, east-central Arizona. These... more
Geoarchaeological analyses, including soil micromorphology and chemistry, were used to characterize the deposition history of a fourteenth-century Pueblo ceremonial structure (or kiva) at Fourmile Ruin, east-central Arizona. These subterranean structures were often ritually “closed” by Pueblo societies
through the burning of roofs and the deposition of special objects. These conspicuous markers are absent in the Fourmile Ruin kiva, but the composition of constituent materials and sedimentation processes nonetheless signal complex, highly-orchestrated closure activities. The study demonstrates the efficacy
of geoarchaeological analyses of stratified deposits for modeling the subtle behaviors associated with the ritual closure and abandonment of sacred places.
through the burning of roofs and the deposition of special objects. These conspicuous markers are absent in the Fourmile Ruin kiva, but the composition of constituent materials and sedimentation processes nonetheless signal complex, highly-orchestrated closure activities. The study demonstrates the efficacy
of geoarchaeological analyses of stratified deposits for modeling the subtle behaviors associated with the ritual closure and abandonment of sacred places.
Research Interests:
Research Interests:
Settlement structure plays an important role in explanations of social and political change in Late Prehistoric eastern North America but ethical and logistical challenges posed by extensive horizontal excavations mean that archaeologists... more
Settlement structure plays an important role in explanations of social and political change in Late Prehistoric eastern North America but ethical and logistical challenges posed by extensive horizontal excavations mean that archaeologists must develop low cost, minimally-invasive methods for inferring key properties of village structure. There are two important components of most villages in the region: 1) the peripheral distribution of middens; and 2) the size and location of formal communal spaces or plazas, each of which leaves traces in soil chemistry. In shallowly buried, plowed village sites where artifacts have been physically displaced, the chemical signature of middens may be more resistant to disturbance and provide an enduring signature of ancient settlement structure. We conducted a systematic soil phosphorus survey at the Late Prehistoric Period (AD 1000-1600) Reinhardt Site (33PI880) in central Ohio to test for the presence and approximate size of a central plaza and the shape and distribution of peripheral midden deposits. Soil samples from the modern plowzone (N=131) were analyzed for Mehlich-2 extractable phosphorus using molybdate colorimetry. The interpolated phosphorus distributions indicate a clear ring midden approximately 160m across with an internal plaza that is roughly 30m x 40m. Artifact distributions from a shovel-test pit survey and interpolations of plowzone magnetic susceptibility measurements identify the location of the village but are ambiguous with regards to village size and do not clearly distinguish the central plaza. Our results suggest that systematic surveys of soil phosphorus are a rapid, minimally-invasive, and inexpensive method for generating data on the size and shape of villages and their plazas.
Research Interests: Archaeology, Prehistoric Archaeology, Anthropology, Geoarchaeology, Settlement Patterns, and 8 moreArchaeological Method & Theory, Archaeological GIS, North American archaeology, Upper Mississippian Societies (Archaeology), Phosphate Analysis, Archaeological Geophysics, Midwest Archaeology, and Geographic Information Systems (GIS)
Research Interests:
Inferences about settlement structure play an important role in explanations of social and political change in Late Prehistoric eastern North America, but ethical and logistical challenges posed by extensive horizontal excavations mean... more
Inferences about settlement structure play an important role in explanations of social and political change in Late Prehistoric eastern North America, but ethical and logistical challenges posed by extensive horizontal excavations mean that archaeologists must develop low cost, minimally invasive methods for investigating key properties of village structure.
Lithic raw material differences are widely assumed to be a major determining factor of differences in stone tool morphology seen across archaeological sites, but the security of this assumption remains largely untested. Two different sets... more
Lithic raw material differences are widely assumed to be a major determining factor of differences in
stone tool morphology seen across archaeological sites, but the security of this assumption remains
largely untested. Two different sets of raw material properties are thought to influence artifact form. The
first set is internal, and related to mechanical flaking properties. The second set is external, namely the
form (size, shape, presence of cortex) of the initial nodule or blank from which flakes are struck. We
conducted a replication experiment designed to determine whether handaxe morphology was influenced
by raw materials of demonstrably different internal and external properties: flint, basalt, and
obsidian. The knapper was instructed to copy a “target” model handaxe, produced by a different knapper,
35 times in each toolstone type (n ¼ 105 handaxes). On each experimental handaxe, 29 size-adjusted
(scale-free) morphometric variables were recorded to capture the overall shape of each handaxe in order
to compare them statistically to the model. Both Principal Components Analysis (PCA) and a
Multivariate Analysis of Variance (MANOVA) were used to determine if raw material properties were a
primary determinate of patterns of overall shape differences across the toolstone groups. The PCA results
demonstrated that variation in all three toolstones was distributed evenly around the model target form.
The MANOVA of all 29 size-adjusted variables, using two different tests, showed no statistically significant
differences in overall shape patterns between the three groups of raw material. In sum, our results
show that assuming the primacy of raw material differences as the predominant explanatory factor in
stone tool morphology, or variation between assemblages, is unwarranted.
stone tool morphology seen across archaeological sites, but the security of this assumption remains
largely untested. Two different sets of raw material properties are thought to influence artifact form. The
first set is internal, and related to mechanical flaking properties. The second set is external, namely the
form (size, shape, presence of cortex) of the initial nodule or blank from which flakes are struck. We
conducted a replication experiment designed to determine whether handaxe morphology was influenced
by raw materials of demonstrably different internal and external properties: flint, basalt, and
obsidian. The knapper was instructed to copy a “target” model handaxe, produced by a different knapper,
35 times in each toolstone type (n ¼ 105 handaxes). On each experimental handaxe, 29 size-adjusted
(scale-free) morphometric variables were recorded to capture the overall shape of each handaxe in order
to compare them statistically to the model. Both Principal Components Analysis (PCA) and a
Multivariate Analysis of Variance (MANOVA) were used to determine if raw material properties were a
primary determinate of patterns of overall shape differences across the toolstone groups. The PCA results
demonstrated that variation in all three toolstones was distributed evenly around the model target form.
The MANOVA of all 29 size-adjusted variables, using two different tests, showed no statistically significant
differences in overall shape patterns between the three groups of raw material. In sum, our results
show that assuming the primacy of raw material differences as the predominant explanatory factor in
stone tool morphology, or variation between assemblages, is unwarranted.