The Fire and Smoke Model Evaluation Experiment—A Plan for Integrated, Large Fire–Atmosphere Field Campaigns

The Fire and Smoke Model Evaluation Experiment (FASMEE) is designed to collect integrated observations from large wildland fires and provide evaluation datasets for new models and operational systems. Wildland fire, smoke dispersion, and atmospheric chemistry models have become more sophisticated, and next-generation operational models will require evaluation datasets that are coordinated and comprehensive for their evaluation and advancement. Integrated measurements are required, including ground-based observations of fuels and fire behavior, estimates of fire-emitted heat and emissions fluxes, and observations of near-source micrometeorology, plume properties, smoke dispersion, and atmospheric chemistry. To address these requirements the FASMEE campaign design includes a study plan to guide the suite of required measurements in forested sites representative of many prescribed burning programs in the southeastern United States and increasingly common high-intensity fires in the western United States. Here we provide an overview of the proposed experiment and recommendations for key measurements. The FASMEE study provides a template for additional large-scale experimental campaigns to advance fire science and operational fire and smoke models

Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire: an expert assessment

As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%–85% of permafrost carbon release can still be avoided if human emissions are actively reduced

Perspectives on land-change science and carbon management

© Cambridge University Press 2013. In response to the need to understand the drivers, processes, and consequences of human activities that change the land surface, the developing science of land change is addressing observations, explanations, and predictions of these land-surface changes (Gutman et al. 2004; Rindfuss et al. 2004; Turner, Lambin, and Reenberg 2007). In that context, this volume synthesizes recent advances from multiple disciplines that contribute to our understanding of how land changes affect the cycling of carbon (C) between the land surface and the atmosphere. Observations about changes in C stocks and fluxes on land and in the atmosphere, and about the contributions of the former to the latter (see Sections I and II of this volume), have played a role in motivating a wide range of economic, political, and social responses to the problem of increasing atmospheric C concentrations (see Sections IV and V). Many of the most important approaches to mitigating these increases have to do with the technological, behavioral, and regulatory innovations regarding C emissions from the use of fossil fuels. However, the secondary role of land-use and land-cover change (LUCC) and land management in causing increases in atmospheric C, as well as the potential to direct these activities toward enhanced sequestration (referred to as biological sequestration), justify attention to land-related policies and management that can respond to these challenges and opportunities. Analyses of these management and policy options are informed by both the observations that undergird our understanding of C stocks and fluxes and by results from mathematical, statistical, and computational models that encode our understanding of land-system processes and their impacts on land-based C. What we hope to have advanced by bringing together the work presented in this volume is an integrated, interdisciplinary, cross-sectoral, and cross-scale perspective on the issues surrounding land-related C. This understanding comes from advances in the theoretical and empirical bases of land-change and C cycle sciences, as well as cross-fertilization among them. Integrating these sciences brings findings from several scientific disciplines into closer alignment with the needs of decision makers in various settings and informs those decisions in ways that consider the physical, biological, and social contexts of multiple land-related decisions. Included within these pages are numerous examples of (1) results from measurements and models of land–C interactions and (2) implications of these results for land management and policy for affecting C stocks and fluxes

Quantifying How Sources of Uncertainty in Combustible Biomass Propagate to Prediction of Wildland Fire Emissions

Smoke emissions from wildland fires contribute to concentrations of atmospheric particulate matter and greenhouse gases, influencing public health and climate. Prediction of emissions is critical for smoke management to mitigate the effects on visibility and air quality. Models that predict emissions require estimates of the amount of combustible biomass. When measurements are unavailable, fuel maps may be used to define the inputs for models. Mapped products are based on averages that poorly represent the inherent variability of wildland fuels, but that variability is an important source of uncertainty in predicting emissions. We evaluated the sensitivity of emissions estimates to wildland fuel biomass variability using two models commonly used to predict emissions: Consume and the First Order Fire Effects Model (FOFEM). Flaming emissions were consistently most sensitive to litter loading (Sobol index 0.426–0.742). Smouldering emissions were most often sensitive to duff loading (Sobol 0.655–0.704) under the extreme environmental scenario. Under the moderate environmental scenario, FOFEM-predicted smouldering emissions were similarly sensitive to sound and rotten coarse woody debris (CWD) and duff fuel components (Sobol 0.193–0.376). High variability in loading propagated to wide prediction intervals for emissions. Direct measurements of litter, duff and coarse wood should be prioritised to reduce overall uncertainty

Land use and the carbon cycle: Advances in integrated science, management, and policy

© Cambridge University Press 2013. As governments and international institutions work to ameliorate the effects of anthropogenic carbon dioxide emissions on global climate, there is an increasing need to understand how land-use and land-cover change is coupled to the carbon cycle, and how land management can be used to mitigate their effects. This book brings an interdisciplinary team of fifty-six international researchers to share novel approaches, concepts, theories, and knowledge on land use and the carbon cycle. The book examines how the social, political, economic, and ecosystem processes associated with land use and land management drive carbon flux and storage in terrestrial ecosystems. The central theme is that land use and land management are tightly integrated with the carbon cycle, and thus it is necessary to study these processes as a single natural-human system to improve carbon accounting and mitigate climate change. Land Use and the Carbon Cycle is an invaluable resource for advanced students, researchers, land-use planners, and policymakers in natural resources, geography, forestry, agricultural science, ecology, atmospheric science, and environmental economics

Linking land use and the carbon cycle

© Cambridge University Press 2013. The last few millennia have seen significant human intervention in the Earth system. For most of this time, the influence of humans on ecological processes, including the carbon (C) cycle, was limited to local-scale impacts through hunting and gathering and then through cultivation and animal husbandry. However, the start of the Industrial Revolution in the eighteenth century saw the collective action of humans begin to alter the C cycle at a global scale by changing the composition of the Earth’s atmosphere (Hegerl et al. 2007). It is arguable that human impacts on global levels of atmospheric methane (CH4) and carbon dioxide (CO2) can be traced back thousands (not just hundreds) of years, largely driven by extensive land management through use of fire (Ruddiman 2003). Although the dominant anthropogenic influence on the global C cycle has resulted from the burning of fossil fuels, it has been estimated that land changes and land degradation have directly affected 39 to 50 percent of the land surface (Vitousek et al. 1997) and contributed to 30 percent of the total anthropogenic efflux of CO2 to the atmosphere (see Chapter 3). Humans have become integral actors in the C cycle – at both local and global scales – to such a degree that many now argue that no point on the surface of the Earth, or ecosystem, has escaped the effects of human activity (e.g., Ellis et al. 2010; Turner, Lambin, and Reenberg 2007). Central to the theme of this book is the notion that as humans alter the surface of the land through land use and land management, they change the pools and fluxes of C across the Earth. Human actions affect the fundamental structure and function of the ecosystems, therefore altering the amount of C stored above- and belowground; the rate of transfer between the surface and the atmosphere; and how much ends up in the rivers, streams, lakes, and oceans. For example, when a forest is burned to clear the land, a large portion of the aboveground C is released to the atmosphere, some remains on site, and some is leached into the hydrological system. Not all of these fractions are known with a high degree of precision, but they vary by ecological context and frequency, duration, and intensity of fire

Next‐generation biomass mapping for regional emissions and carbon inventories: Incorporating uncertainty in wildland fuel characterization

Biomass mapping is used in variety of applications including carbon assessments, emission inventories, and wildland fire and fuel planning. Single values are often applied to individual pixels to represent biomass of classified vegetation, but each biomass estimate has associated uncertainty that is generally not acknowledged nor quantified. In this study, we developed a geospatial database of wildland fuel biomass values to characterize the inherent variability within and across major vegetation types of the United States and Canada. For vegetation types that had sufficient quantification of biomass by fuel type (e.g., canopy, shrub, herbaceous, fine downed wood, coarse downed wood, and organic soil layers), we developed empirical distribution estimates. Based on available data, fitted distributions will be useful for informing the first‐generation biomass mapping that incorporates variability in loading by vegetation and fuel type and to evaluate potential errors in point estimates given in current map products. Because combustible biomass is a common input in fire and smoke models, variability estimated for fitted distributions can be used to inform data input uncertainty in predictions of wildland fuel consumption and emissions and to provide stochastic inputs of biomass to ensemble simulation models

Evaluating the potential of Landsat TM/ETM+ imagery for assessing fire severity in Alaskan black spruce forests

Satellite remotely sensed data of fire disturbance offers important information; however, current methods to study fire severity may need modifications for boreal regions. We assessed the potential of the differenced Normalized Burn Ratio (dNBR) and other spectroscopic indices and image transforms derived from Landsat TM/ETM+ data for mapping fire severity in Alaskan black spruce forests (Picea mariana) using ground measures of severity from 55 plots located in two fire events. The analysis yielded low correlations between the satellite and field measures of severity, with the highest correlation (R2adjusted ≤ 0.52, P \u3c 0.0001) between the dNBR and the composite burn index being lower than those found in similar studies in forests in the conterminous USA. Correlations improved using a ratio of two Landsat shortwave infrared bands (Band 7/Band 5). Overall, the satellite fire severity indices and transformations were more highly correlated with measures of canopy-layer fire severity than ground-layer fire severity. High levels of fire severity present in the fire events, deep organic soils, varied topography of the boreal region, and variations in solar elevation angle may account for the low correlations, and illustrate the challenges faced in developing approaches to map fire and burn severity in high northern latitude regions. © IAWF 2008

Evaluation of the composite burn index for assessing fire severity in Alaskan black spruce forests

We evaluated the utility of the composite burn index (CBI) for estimating fire severity in Alaskan black spruce forests by comparing data from 81 plots located in 2004 and 2005 fire events. We collected data to estimate the CBI and quantify crown damage, percent of trees standing after the fire, depth of the organic layer remaining after the fire, depth of burning in the surface organic layer (absolute and relative), and the substrate layer exposed by the fire. To estimate pre-fire organic layer depth, we collected data in 15 unburned stands to develop relationships between total organic layer depth and measures of the adventitious root depth above mineral soil and below the surface of the organic layer. We validated this algorithm using data collected in 17 burned stands where pre-fire organic layer depth had been measured. The average total CBI value in the black spruce stands was 2.46, with most of the variation a result of differences in the CBI observed for the substrate layer. While a quadratic equation using the substrate component of CBI was a relatively strong predictor of mineral soil exposure as a result of fire (R2 ≤ 0.61, P \u3c 0.0001, F ≤ 60.3), low correlations were found between the other measures of fire severity and the CBI (R2 ≤ 0.00-0.37). These results indicate that the CBI approach has limited potential for quantifying fire severity in these ecosystems, in particular organic layer consumption, which is an important factor to understand how ecosystems will respond to changing climate and fire regimes in northern regions. © IAWF 2008

Fire in arctic tundra of Alaska: Past fire activity, future fire potential, and significance for land management and ecology

© IAWF 2015. A multidecadal analysis of fire in Alaskan Arctic tundra was completed using records from the Alaska Large Fire Database. Tundra vegetation fires are defined by the Circumpolar Arctic Vegetation Map and divided into five tundra ecoregions of Alaska. A detailed review of fire records in these regions is presented, and an analysis of future fire potential was performed based on future climate scenarios. The average size of tundra fire based on the data record is 22km2 (5454 acres). Fires show a mean size of 10km2 (2452 acres) and median of 0.064km2 (16 acres), indicating small fires are common. Although uncommon, 16 fires larger than 300km2 (74132 acres) have been recorded across four ecoregions and all five decades. Warmer summers with extended periods of drying are expected to increase fire activity as indicated by fire weather index. The implications of the current fire regime and potential changes in fire regime are discussed in the context of land management and ecosystem services. Current fire management practices and land-use planning in Alaska should be specifically tailored to the tundra region based on the current fire regime and in anticipation of the expected change in fire regime projected with climate change