J. Kevin Hiers’s research while affiliated with Texas A&M University and other places

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Publications (26)


Fig. 1 Conceptual figure showing the different levels of forest structural metrics and ignition patterns used in this study. A total of 42 simulations were completed that encompassed variation in each of these conditions
Fig. 2 Computational domain design showing areas with surface fuels (light gray), areas where surface fuels have been removed (dark gray), and the three initial fire lines (red). The arrow shows the streamwise wind direction, pointing towards the direction wind is going (blue). The area of interest (AOI) for this simulation is the light gray area (204 m × 200 m × 560 m) in the center of the domain
Fig. 3 Histogram showing the means of crown scorch and consumption for prescribed fire simulations in 14 representative forests. Standard deviations for overall crown damage (i.e., the sum of crown scorch and consumption) are shown
Fig. 4 The forest structural complexity index (FSCI) plotted against the proportion of a crown consumption, b crown scorch, and c crown damage observed within each simulation. The three linear regression lines show linear fits for simulations ignited with strip-head (red), dot (green), and alternating dot (blue) ignition patterns. The points show the simulation results
Forest structural characteristics of 14 representative forests simulated in the fire simulation software, HIGRAD-FIRETEC
Forest structural complexity and ignition pattern influence simulated prescribed fire effects
  • Article
  • Full-text available

September 2024

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91 Reads

Fire Ecology

Sophie R. Bonner

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J. Kevin Hiers

Background Forest structural characteristics, the burning environment, and the choice of ignition pattern each influence prescribed fire behaviors and resulting fire effects; however, few studies examine the influences and interactions of these factors. Understanding how interactions among these drivers can influence prescribed fire behavior and effects is crucial for executing prescribed fires that can safely and effectively meet management objectives. To analyze the interactions between the fuels complex and ignition patterns, we used FIRETEC, a three-dimensional computational fluid dynamics fire behavior model, to simulate fire behavior and effects across a range of horizontal and vertical forest structural complexities. For each forest structure, we then simulated three different prescribed fires each with a unique ignition pattern: strip-head, dot, and alternating dot. Results Forest structural complexity and ignition pattern affected the proportions of simulated crown scorch, consumption, and damage for prescribed fires in a dry, fire-prone ecosystem. Prescribed fires in forests with complex canopy structures resulted in increased crown consumption, scorch, and damage compared to less spatially complex forests. The choice of using a strip-head ignition pattern over either a dot or alternating-dot pattern increased the degree of crown foliage scorched and damaged, though did not affect the proportion of crown consumed. We found no evidence of an interaction between forest structural complexity and ignition pattern on canopy fuel consumption, scorch, or damage. Conclusions We found that forest structure and ignition pattern, two powerful drivers of fire behavior that forest managers can readily account for or even manipulate, can be leveraged to influence fire behavior and the resultant fire effects of prescribed fire. These simulation findings have critical implications for how managers can plan and perform forest thinning and prescribed burn treatments to meet risk management or ecological objectives.

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Fig. 1. Overview of the FastFuels modeling pipeline showing the interaction between user inputs, FastFuels, and fire behavior simulations. Green boxes are user inputs, blue boxes are processes internal to FastFuels, yellow boxes are intermediate inputs and outputs, and red boxes are fire simulators.
Fig. 7. Voxelized trees placed within a grid representing a forest area spanning 200 m by 200 m by 40 m. The grid's voxel resolution is 0.5 m by 0.5 m by 0.5 m. Distinct colors within the grid indicate individual trees.
FastFuels: Advancing wildland fire modeling with high-resolution 3D fuel data and data assimilation

September 2024

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74 Reads

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1 Citation

Environmental Modelling & Software

Acquiring detailed 3D fuel data for advanced fire models remains challenging, particularly at large scales. To address this need, we present FastFuels, a novel platform designed to generate detailed 3D fuel data and accelerate the use of advanced fire models. FastFuels integrates existing fuel and spatial data with innovative modeling techniques to represent complex 3D fuel arrangements across landscapes. It leverages data sources including the Forest Inventory and Analysis (FIA) database and plot imputation maps, and incorporates advanced features such as data assimilation from LiDAR. This research demonstrates FastFuels’ capabilities through two applications: evaluating fuel treatment effectiveness with the Fire Dynamics Simulator and simulating a prescribed fire operation using QUIC-Fire. FastFuels provides previously unavailable 3D fuel data at landscape scales, empowering informed decision-making, detailed investigations of fuel treatment impacts, and higher-resolution risk assessments. Its flexible data assimilation and model-agnostic outputs accelerate advanced fire science and support fire management decisions.


Projecting the long‐term effects of large‐scale human influence on the spatial and functional persistence of extant longleaf pine ecosystems in the Florida Flatwoods Pyrome

July 2024

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49 Reads

Decades of human activities and fire suppression have adversely affected longleaf pine (Pinus palustris) ecosystems, which are home to high levels of diversity and endemism. These iconic ecosystems also now face challenges from urbanization and climate change, which will alter conservation outcomes over the remainder of the 21st century. To explore how long‐term, large‐scale human influences could affect the spatial and functional persistence of extant longleaf pine ecosystems in the Florida Flatwoods Pyrome, we extracted a set of 2400 longleaf pine patches ≥40 ha in size from the Florida Longleaf Pine Ecosystem Geodatabase. Projections from the FUTURES urban growth model and the Florida 2070 project indicate that development will lead to losses of existing longleaf pine habitat, reductions in longleaf pine patch size, and patches that are predominantly located in close proximity to developed areas. Finer‐scale patterns of longleaf pine loss in three focal landscapes highlighted differences in land protection, ecological setting, and development pressure and the value of using of multiple urbanization iterations. The occurrence of suitable conditions to conduct prescribed fires, a crucial tool for maintaining, improving, and restoring longleaf pine ecosystems, is projected to decrease seasonally throughout the study area. As a result, the functional persistence of ecosystems is at risk due to climate changes that increase barriers to the safe and reliable application of intentional fire. The long‐term viability of this critical ecosystem will warrant the evaluation of adaptive strategies that explicitly account for the individual and compounding effects of urban development and changing fire management conditions when considering options for ecosystem protection, management, and restoration.


Prescribed Fire Reduces Wildfire Damages to Valued Resources Within the Okefenokee National Wildlife Refuge

July 2024

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48 Reads

Prescribed fire is increasingly utilized for conservation and restoration goals, yet there is limited empirical evidence supporting its effectiveness in reducing wildfire-induced damages to valued resources of significant worth—whether natural, cultural, or economic. This study evaluates the efficacy of prescribed fire in reducing wildfire severity to LANDFIRE-defined vegetation classes and valued resources impacted by the 2017 West Mims event. Wildfire severity, measured using the differenced normalized burn ratio (dNBR) index, was highly heterogeneous both within and between vegetation classes; however, profound differences between treated and untreated areas were evident. The beneficial effects of prescribed fire were most pronounced within ca. two-years post-treatment but remained evident beyond three-years relative to untreated areas. For example, actively managed areas that were treated with prescribed fire just one month prior to the West Mims event exhibited an 88% reduction in mean wildfire severity relative to unmanaged areas. When post-treatment duration reached 38 months, mean wildfire severity remained 17% lower than untreated areas. Findings from this study reveal significant reductions in both average and peak wildfire severities in areas treated with frequent fire, supporting burn rotations of one to two years to balance fuel reduction and ecological conservation.



Lidar-derived estimates of forest structure in response to fire frequency

May 2024

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123 Reads

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3 Citations

Fire Ecology

Background Longleaf pine ( Pinus palustris ) ecosystems are recognized as biodiversity hotspots, and their sustainability is tightly coupled to a complex nexus of feedbacks between fire, composition, and structure. While previous research has demonstrated that frequent fire is often associated with higher levels of biodiversity, relationships between fire frequency and forest structure are more nuanced because structure can be difficult to measure and characterize. We expanded on this body of research by using lidar to characterize vegetation structure in response to fire frequency at a long-term prescribed-fire experiment. We asked (1) how does prescribed fire frequency affect structure and (2) how do structural metrics vary in the strength of their relationships with fire frequency. Results Our results indicated that forest structure varied significantly in response to fire frequency, with more frequent fire reducing vegetation structural complexity. Metrics that characterized the central tendency of vegetation and/or the variance of canopy-related properties were weakly to moderately correlated with prescribed fire frequency, while metrics that captured the vertical dispersion or variability of vegetation throughout the forest strata were moderately to strongly correlated with fire frequency. Of all the metrics evaluated, the understory complexity index had the strongest correlation with fire frequency and explained 88% of the structural variation in response to prescribed fire treatments. Conclusions The findings presented in this study highlight the usefulness of lidar technology for characterizing forest structure and that structural complexity cannot be fully characterized by a single metric. Instead, a range of diverse metrics is required to refine scientific understanding of the feedbacks between fire, composition, and structure in support of longleaf pine sustainability. Furthermore, there is a need for further research to broaden structural assessments beyond the overstory and incorporate more understory components, particularly within the realm of prescribed fire science and land management.


How will future climate change impact prescribed fire across the contiguous United States?

April 2024

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129 Reads

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3 Citations

npj Climate and Atmospheric Science

As of 2023, the use of prescribed fire to manage ecosystems accounts for more than 50% of area burned annually across the United States. Prescribed fire is carried out when meteorological conditions, including temperature, humidity, and wind speed are appropriate for its safe and effective application. However, changes in these meteorological variables associated with future climate change may impact future opportunities to conduct prescribed fire. In this study, we combine climate projections with information on prescribed burning windows for ecoregions across the contiguous United States (CONUS) to compute the number of days when meteorological conditions allow for the safe and effective application of prescribed fire under present-day (2006–2015) and future climate (2051–2060) conditions. The resulting projections, which cover 57% of all vegetated area across the CONUS, indicate fewer days with conditions suitable for prescribed burning across ecoregions of the eastern United States due to rising maximum daily temperatures, but opportunities increase in the northern and northwestern United States, driven primarily by rising minimum temperatures and declining wind speeds.


Principles of fire ecology

April 2024

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968 Reads

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10 Citations

Fire Ecology

Fire ecology is a complex discipline that can only be understood by integrating biological, physical, and social sciences. The science of fire ecology explores wildland fire’s mechanisms and effects across all scales of time and space. However, the lack of defined, organizing concepts in fire ecology dilutes its collective impact on knowledge and management decision-making and makes the discipline vulnerable to misunderstanding and misappropriation. Fire ecology has matured as a discipline and deserves an enunciation of its unique emergent principles of organization. Most scientific disciplines have established theories, laws, and principles that have been tested, debated, and adopted by the discipline’s practitioners. Such principles reflect the consensus of current knowledge, guide methodology and interpretation, and expose knowledge gaps in a coherent and structured way. In this manuscript, we introduce five comprehensive principles to define the knowledge fire ecology has produced and provide a framework to support the continued development and impact of the fire ecology discipline.


Figure 3. Conceptual diagram of the tiered TLS Monitoring Protocol. QAQC: Quality Assurance Quality Control. (Courtesy: Emily Link, USFWS).
Figure 4. Plot layout for TLS monitoring field data collection methods. (Courtesy: Pokswinski and others 2021).
Figure 5. IntELiMon Interactive Viewer dashboard (as of March 2024) (USGS 2023).
Specifications and performance of the Leica BLK360 G1 terrestrial laser scanner.
Examples of what is directly measured (using Tier 1) or predicted (using either Tier 2 or Tier 3*) metrics from the TLS monitoring protocol. TBD means that the measurements or estimates could still be developed. N/A means that it is not applicable. The 'New category' represents the ability to add new categories/metrics/predictors as they are developed. d.b.h.: diameter at breast height, c.b.h.: canopy base height. The 'Other Nuanced Categories' represent the multitude of categories that are not necessarily directed related to a known vegetative feature but quantify various portions of the point cloud using statistical measures. These measures quantify the structure of the vegetation, space between vegetation, and occlusion behind vegetation.
Terrestrial 3D Laser Scanning for Ecosystem and Fire Effects Monitoring

April 2024

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220 Reads

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2 Citations

Long-term terrestrial ecosystem monitoring is a critical component of documenting outcomes of land management actions, assessing progress towards management objectives, and guiding realistic long-term ecological goals, all through repeated observation and measurement. Traditional monitoring methods have evolved for specific applications in forestry, ecology, and fire and fuels management. While successful monitoring programs have clear goals, trained expertise, and rigorous sampling protocols, new advances in technology and data management can help overcome the most common pitfalls in data quality and repeatability. This paper presents Terrestrial Laser Scanning (TLS), a specific form of LiDAR (Light Detection and Ranging), as an emerging sampling method that can complement and enhance existing monitoring methods. TLS captures in high resolution the 3D structure of a terrestrial ecosystem (forest, grassland, etc.), and is increasingly efficient and affordable (<$30,000). Integrating TLS into ecosystem monitoring can standardize data collection, improve efficiency, and reduce bias and error. Streamlined data processing pipelines can rigorously analyze TLS data and incorporate constant improvements to inform management decisions and planning. The approach described in this paper utilizes portable, push-button TLS equipment that, when calibrated with initial transect sampling, captures detailed forestry, fuels, and ecological features in less than 5 minutes per plot. We also introduce an interagency automated processing pipeline and dashboard viewer for instant, user-friendly analysis, and data retrieval of hundreds of metrics. Forest metrics and inventories produced with these methods offer effective decision-support data for managers to quantify landscape-scale conditions and respond with efficient action. This protocol further supports interagency compatibility for efficient natural resource monitoring across jurisdictional boundaries with uniform data, language, methods, and data analysis. With continued improvement of scanner capabilities and affordability, these data will shape the future of terrestrial ecosystem monitoring as an important means to address the increasingly fast pace of ecological change facing natural resource managers.



Citations (16)


... Prescribed fire treatments are increasingly incorporated into land management plans to reduce hazardous fuels, conserve critical habitat for endangered, threatened and/or endemic species, and to restore important ecological processes in fire-adapted ecosystems by altering forest structure [1][2][3][4]. While there is abundant evidence supporting the effectiveness of prescribed fire for fuels reduction and for the conservation and restoration of fire-dependent ecosystems, limited empirical evidence exists regarding the efficacy of prescribed fire in reducing the severity of wildfires to valued resources, which include natural, cultural, or economic assets that hold significant importance or worth to communities, ecosystems, or industries [5][6][7]. ...

Reference:

Prescribed Fire Reduces Wildfire Damages to Valued Resources Within the Okefenokee National Wildlife Refuge
Lidar-derived estimates of forest structure in response to fire frequency

Fire Ecology

... The variability of wildfire incidents is influenced by climate change, fuel types and distribution, and ignition sources. Among them, climate change is the predominant driver that significantly alters global wildfire dynamics by modifying weather conditions that govern fire behavior and affecting critical variables of wildfire activity, such as plant biomass accumulation and fuel moisture 6,7 . Extensive research indicates that the increasing frequency of extreme wildfire events associated with climate change in recent years is progressively becoming a significant threat to both global ecosystems and human societies [8][9][10] . ...

How will future climate change impact prescribed fire across the contiguous United States?

npj Climate and Atmospheric Science

... Microbial aerosolization and dispersal patterns are of interest across a diverse array of disciplines including agriculture [1][2][3], human health [4][5][6], meteorology [7][8][9], and biogeography [10]. Wildland fires (wildfires and prescribed fires) are well understood to have terrestrial biophysical and atmospheric physicochemical impacts [11], but the smoke they generate has only recently been explored as a driver of bioaerosol emissions and dissemination [12][13][14][15]. Smoke's role as a vector for bioaerosol transport shifts existing paradigms of a wildland fire's perimeter of biological impact [12,16,17]. ...

Principles of fire ecology

Fire Ecology

... We recognize the need for species-specific and regionally-calibrated parameters to improve model accuracy. To address this limitation, we aim to leverage the growing datasets from terrestrial laser scanning (TLS) efforts to estimate model parameters and perform rigorous validation across a range of forest conditions (Murphy et al., 2024). By incorporating high-resolution TLS data, we can refine our understanding of crown architecture variability and develop more nuanced parameterizations. ...

Terrestrial 3D Laser Scanning for Ecosystem and Fire Effects Monitoring

... A key data source is prescribed fire permit data collected from state forestry agencies 4 summarized in Cummins et al. (2023), which serves as the empirical foundation to identify the location and magnitude of prescribed fire usage. The authors' personal conversations with fire experts in the Forest Service and university fire extension experts confirmed that burn permit data is the most accurate data source for capturing prescribed fire activities on private land. ...

The Southeastern U.S. Prescribed Fire Permit Database: Hot Spots and Hot Moments in Prescribed Fire across the Southeastern U.S.A.

Fire

... We simulated surface fuel loading and moisture based on plot averaged data from real longleaf pine forests (Natural Fuels Photo Series 2016); however, we did not attempt to simulate any spatial aspects of these surface fuels. Real-world forest surface fuel distributions and moistures are formed from the arrangement of overstory canopy and local wind patterns, which direct litter-fall, affect grass growth and decay, and influence moisture contents (McDanold et al. 2023). The understory can represent a diversity of species and vegetative structures with fuel heterogeneity changing across multiple spatial scales. ...

DUET - Distribution of Understory using Elliptical Transport: A mechanistic model of leaf litter and herbaceous spatial distribution based on tree canopy structure
  • Citing Article
  • September 2023

Ecological Modelling

... Past studies demonstrate that, in addition to factors related to topography and soil burn severity, rainfall intensity over a 15 min duration (I 15 ) controls the likelihood of debris-flow initiation within a basin as well as debris-flow volume (Gartner et al., 2014). Forecasts of debris-flow volume are highly uncertain, especially when applied in settings not represented within their training datasets (Gorr et al., 2023;Wall et al., 2023), and may exceed a factor of 10 (Gartner et al., 2014). Debris-flow likelihood and volume both increase with I 15 , which indicates that variations in rainfall intensity, even over small spatial (i.e., a low-order basin) and temporal (15 min) scales, will play an important role in determining the likelihood and spatial extent of debris-flow impacts. ...

Predicting burn severity for integration with post-fire debris-flow hazard assessment: a case study from the Upper Colorado River Basin, USA

International Journal of Wildland Fire

... Fire scientists and land managers have long understood that forest structure is a key variable influencing fire behavior and effects (Rothermel 1972;Anderson 1981;Catchpole et al. 1993), although only recently has the importance of characterizing the structural complexity of the fuels been fully understood (Loudermilk et al. 2014;Banerjee et al. 2020;Skowronski et al. 2020;Gallagher et al. 2021). While most fuel descriptions are qualitative or summarize the mean fuel loadings (Keane 2012;Vakili et al. 2016;Bonner et al. 2021), recent advancements in modeling and remote sensing technologies are allowing for a more complete depiction of the inherent complexity of wildland fuel complexes (Burt et al. 2013;Loudermilk et al. 2023;Zhou et al. 2023). Forest structural complexity is a descriptive statistic of forest attributes and their relative abundance (McElhinney et al. 2005). ...

Terrestrial Laser Scan Metrics Predict Surface Vegetation Biomass and Consumption in a Frequently Burned Southeastern U.S. Ecosystem

Fire

... Additionally, the integration of PHSs has led to enhanced simulations of carbon dynamics (Niu et al., 2020;Wu et al., 2020), including plant community dynamics such as tree mortality and replacement (Simeone et al., 2019;Ruffault et al., 2022;Yao et al., 2023). Furthermore, PHS-enabled models have provided valuable insights into forest flammability during heatwaves (Dickman et al., 2023). ...

Integrating plant physiology into simulation of fire behavior and effects

... Alternatives to airborne LiDAR such as terrestrial laser scanning (TLS) may improve the accuracy of predictive fire severity models based on pre-fire vegetation structure. TLS typically offers a much higher point density and thus more detailed information than airborne LiDAR collections about fuel structure in the lower strata [101], precisely where low-to moderate-severity fire effects tend to concentrate [102]. However, compared to airborne LiDAR, the area coverage of TLS is small [103]. ...

Terrestrial laser scan metrics predict surface vegetation biomass and consumption in a frequently burned southeastern U.S. ecosystem