USDA on the Effects of Fire on Cultural Resources and Archaeology
On May 2012 the United States the Department of Agricolture (USDA) has published the Technical Report: Wildland Fire in Ecosystems – Effects of Fire on Cultural Resources and Archaeology.
The document aims to provide a synthesis of knowledge on the effects of fire on cultural resources, useful for fire managers, cultural resource specialists, and archaeologists. The primary goal is twofold: to educate cultural resource professionals about fire processes and, at the same time, to inform fire management professionals about the importance of protecting cultural resources.
The Report
The document is structured into nine chapters that address different aspects, such as:
- Introduction and Conceptual Framework: It defines what is meant by cultural resources, both tangible and intangible, and introduces a framework for assessing and managing the effects of fire. It emphasizes the importance of a multidisciplinary approach that takes into account legal aspects and collaboration with local communities.
- Fire Processes and Modeling: The text provides a scientific basis for understanding how fire spreads and what factors influence its intensity and severity, including concepts such as fire intensity, burning depth, and fire regimes. Models are presented to predict fire behavior and its effects on cultural resources, such as the Rothermel model and its variants.
- Fire Effects on Specific Cultural Materials: Chapters 3–7 examine the effects of fire on ceramics, lithic artifacts, rock art, historical materials, and underground archaeological deposits. It is highlighted how high temperatures and duration of exposure can cause damage to these materials, including fractures, chemical alterations, and changes in structure. For example, thermal variations can alter the hydration bands of obsidian.
- Intangible Cultural Resources and the Landscape Approach: Chapter 8 focuses on the importance of cultural landscapes to Indigenous Peoples and the need to actively involve local communities in the development of collaborative management plans. It highlights how fire affects the connection between people and place and suggests moving beyond a purely material science-based approach.
- Implications of fire management on cultural resources: Chapter 9 discusses planning, risk management and recommendations for fire management to protect cultural resources, including prescribed burning and fire suppression. A tool, a decision matrix, is introduced to assess risks and plan appropriate actions to protect cultural heritage.
The paper highlights that fire is a natural element that has shaped human cultures for millennia, but at the same time it can pose a threat to archaeological sites and cultural artefacts. The key to effective management is to find a balance between the need to control fire and the protection of cultural resources. This requires a solid understanding of fire processes, careful planning and close collaboration between all stakeholders. The paper also includes a glossary and index to facilitate understanding and reference. Finally, this is the first comprehensive study of the effects of fire on cultural resources, including both Canada and the United States.
How the document helps stakeholders
The Report is designed to help both fire managers and archaeologists by providing a common knowledge base and practical tools for more effective management of cultural resources in fire contexts. Specifically:
For fire managers, the paper provides:
- An understanding of fire processes and their effects. The Report provides an introduction to key concepts in fire science, such as fire behavior, burning patterns, and the effects of different fire intensities. This knowledge allows managers to better predict how a fire might spread and what its impacts on cultural resources might be.
- A guide to planning: The Report introduces models and decision matrices for risk assessment and response planning, for both prescribed and uncontrolled fires. These tools help managers integrate cultural resource protection into their operational plans.
- Information on the effects of fire on specific types of resources: The Report provides details on the effects of fire on different types of cultural materials such as ceramics, lithic artefacts, rock art and historical materials. This knowledge allows managers to understand which sites or artefacts are most vulnerable and what protective measures can be taken.
- Mitigation and protection strategies: The Report includes practical recommendations on how to mitigate the negative effects of fire and suppression activities on cultural resources, such as fuel removal, use of retardants and structural protection techniques. The importance of considering the landscape context and local cultural dynamics is highlighted.
- The importance of collaboration: The Report highlights the need for close collaboration between fire managers and cultural resource specialists. This collaboration ensures that fire management decisions take into account the conservation needs of cultural heritage.
- An integrated approach: The Report promotes an integrated approach that considers both the need to manage fires and the need to protect cultural resources.
For archaeologists and cultural resources specialists, the document offers:
- An understanding of fire processes and fire dynamics. The Report provides scientific information on fire behavior, enabling archaeologists to understand how fires affect archaeological sites and artifacts.
- A basis for risk assessment. The Report offers a conceptual framework for assessing the direct and indirect effects of fire on cultural resources. This framework helps archaeologists determine which sites are at risk and what protective measures should be implemented.
- An analysis of the effects of fire on specific materials. Chapters 3 to 7 describe in detail how fire affects specific materials such as ceramics, lithics, rock art, historical artifacts, and underground archaeological deposits. This helps archaeologists to recognize fire damage and correctly interpret finds.
- Post-fire assessment guidelines. The Report provides guidance on how to conduct post-fire assessments to determine the impact of fire on archaeological sites and artefacts. These assessments are essential for planning mitigation and recovery interventions.
- Consideration of intangible resources. The Report highlights the importance of intangible cultural values for local and indigenous communities, promoting a participatory approach to fire and cultural resource management.
- The importance of a holistic view: The Report challenges archaeologists to move beyond a material science-only approach and to consider landscape context and cultural values when planning heritage management and protection interventions.
- Research methodologies: The Report highlights the need to standardize the collection and presentation of data related to fire effects, including the fire environment, its severity and the alterations of artefacts, for better interpretation and comparison of data from different studies.
Limits of the simulation models
One of the most important considerations of the Report concerns the limits of the ability to model the effects of fire, particularly on cultural resources. In this regard, the report highlights that, although models exist to predict fire behaviour, predicting specific effects on cultural resources still presents challenges. The limitations highlighted in the Report include:
- Spatial and Temporal Variations. Fire varies significantly in space and time, making accurate modeling difficult. Environmental and combustion conditions are constantly changing, influencing the intensity and duration of fire, and therefore its effects. Models tend to simplify these variables.
- Fuel Complexity. Fire behavior models often focus on surface fuels, neglecting the effects of fire on soil, deep underground, and on fuels such as roots or buried wood. Burning of woody debris and organic layers in the soil can have a significant impact on underground cultural resources, and its modeling is limited.
- Lack of Specific Data. Many studies of fire effects are conducted ex post facto, that is, after a fire, without comparative pre-fire data. The lack of specific data on temperature and duration of heat exposure for different cultural materials makes it difficult to accurately predict effects.
- Difficulties in Measurement. Precise measurement of fire behavior, such as intensity and heat transfer, requires sophisticated instruments and is often impractical in real-world situations. Estimates based on visual observation are often inaccurate and can lead to less reliable models.
- Models focused on fire behavior. Existing models were developed primarily to predict the spread of fire, not its specific effects. This makes it difficult to use these models to estimate the impact of fire on artifacts and archaeological sites.
- Simplifications in models. Fire models use simplifications to represent reality, such as stylized fuel models and static weather conditions. These simplifications can lead to less accurate results for cultural resources.
- Cumulative effects. Models often do not consider the cumulative effects of multiple fire events on a given site or archaeological material, and the consequences of the combined action of heat with other factors, such as weathering.
- Material variability. Cultural materials vary greatly in their composition and thermal properties. Current models do not always account for these variations and how they influence the response of materials to fire.
- Indirect and tertiary effects. Models tend to focus on the direct effects of fire, but do not always account for indirect effects (such as soil erosion after fire) or tertiary effects (such as human responses to fire or management activities).
In summary:
- the management of cultural resources in fire contexts requires a holistic and collaborative approach, integrating scientific and traditional knowledge, and taking into account both the tangible and intangible aspects of cultural heritage. The Report provides a framework for effective management, highlighting that the key is to find a balance between the need to manage fire and the responsibility to protect cultural heritage;
- modeling the effects of fire on cultural resources is limited by the variability of fire, the lack of specific data on materials and sites, the difficulty in accurately measuring it, and the focus of existing models on the behavior of fire rather than its effects. The Report highlights the need for further research and interdisciplinary approaches to improve the modeling and management of fire risks for cultural resources. A better understanding of heat transfer mechanisms and the response of cultural materials to heat is essential for more effective management.
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