Light Detection and Ranging (LiDAR) has demonstrated potential for forest inventory at the individual tree-level. The aim in this study was to predict individual tree height (Ht; m), basal area (BA; m 2 ) and stem volume (V; m 3 ) attributes using Random Forest k-nearest neighbor (RF k-NN) imputation and individual tree-level based metrics extracted from a LiDAR-derived canopy height model (CHM) in a longleaf pine (Pinus palustris Mill.) forest in southwestern Georgia, USA. We developed a new framework for modeling tree-level forest attributes that was comprised of three steps: (1) individual tree detection, crown delineation and tree-level based metrics computation from LiDAR-derived CHM; (2) automatic matching of LiDAR-derived trees and field-based trees for a regression modeling step using a novel algorithm; and (3) RF k-NN imputation modeling for estimating tree-level Ht, BA, and V, and subsequent summarization of these metrics at the plot-and stand-levels. RMSDs for tree-level Ht, BA and V were 2.96%, 58.62% and 8.19%, respectively. Although BA estimation accuracy was poor because of the longleaf pine growth habit, individual tree locations, Ht, and V were estimated with high accuracy, especially in low canopy cover conditions. Future efforts based on the findings could help to improve the estimation accuracy of individual tree-level attributes like BA. RésuméLe lidar a démontré son potentiel pour l'inventaire forestier à l'échelle de l'arbre. Le but de cette étude était de prédire la hauteur individuelle des arbres (Ht; m), la surface terrière (BA; m 2 ) et le volume des tiges (V; m 3 ) en utilisant une imputation basée sur la méthode des forêts aléatoires et des k plus proches voisins (RF k-NN; Random Forest k-nearest neighbor) et de mesures à l'échelle de l'arbre extraites à partir d'un modèle de la hauteur de la canopée (MHC) Downloaded by [Boston University] at 03:50 29 June 2016 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 3 dérivés du lidar dans une forêt de pins des marais (Pinus palustris Mill.) dans le sud-ouest de laGéorgie, aux États-Unis. Nous avons développé un nouveau cadre pour la modélisation des attributs forestiers à l'échelle de l'arbre composé de trois étapes : 1. la détection des arbres individuels, la délimitation des couronnes et le calcul de paramètres à l'échelle de l'arbre à partir de modèles MHC obtenus à partir du lidar; 2. la mise en correspondance automatique entre les arbres obtenus à partir du lidar et les arbres observés sur le terrain pour une étape de modélisation de régression en utilisant un nouvel algorithme; et 3. l'imputation par modélisation en utilisant RF k-NN pour estimer la Ht, la BA et le V à l'échelle de l'arbre et la synthèse ultérieure de ces mesures à l'échelle de la parcelle et du peuplement. Les REQM pour la Ht, la BA et le V à l'échelle de l'arbre étaient de 2,96 %, 58,62 % et 8,19 %, respectivement. Bien que la précision de l'estimation de la BA fût faible en raison du port et du mode de croissance des pins des marais, l'emplacement des arbres individuels, la...

In ecosystems with frequent surface fire regimes, fire and fuel heterogeneity has been largely overlooked owing to the lack of unburned patches and the difficulty in measuring fire behavior at fine scales (0.1–10 m). The diverse vegetation in these ecosystems varies at these fine scales. This diversity could be driven by the influences of local interactions among patches of understorey vegetation and canopy-supplied fine fuels on fire behavior, yet no method we know of can capture fine-scale fuel and fire measurements such that these relationships could be rigorously tested. We present here an original method for inventorying of fine-scale fuels and in situ measures of fire intensity within longleaf pine forests of the south-eastern USA. Using ground-based LIDAR (Light Detection and Ranging) with traditional fuel inventory approaches, we characterized within-fuel bed variation into discrete patches, termed wildland fuel cells, which had distinct fuel composition, characteristics, and architecture that became spatially independent beyond 0.5 m2. Spatially explicit fire behavior was measured in situ through digital infrared thermography. We found that fire temperatures and residence times varied at similar scales to those observed for wildland fuel cells. The wildland fuels cell concept could seamlessly connect empirical studies with numerical models or cellular automata models of fire behavior, representing a promising means to better predict within-burn heterogeneity and fire effects.

Understanding how climate change may influence forest carbon (C) budgets requires knowledge of forest growth relationships with regional climate, long-term forest succession, and past and future disturbances, such as wildfires and timber harvesting events. We used a landscape-scale model of forest succession, wildfire, and C dynamics (LANDIS-II) to evaluate the effects of a changing climate (A2 and B1 IPCC emissions; Geophysical Fluid Dynamics Laboratory General Circulation Models) on total forest C, tree species composition, and wildfire dynamics in the Lake Tahoe Basin, California, and Nevada. The independent effects of temperature and precipitation were assessed within and among climate models. Results highlight the importance of modeling forest succession and stand development processes at the landscape scale for understanding the C cycle. Due primarily to landscape legacy effects of historic logging of the Comstock Era in the late 1880s, C sequestration may continue throughout the current century, and the forest will remain a C sink (Net Ecosystem Carbon Balance > 0), regardless of climate regime. Climate change caused increases in temperatures limited simulated C sequestration potential because of augmented fire activity and reduced establishment ability of subalpine and upper montane trees. Higher temperatures influenced forest response more than reduced precipitation. As the forest reached its potential steady state, the forest could become C neutral or a C source, and climate change could accelerate this transition. The future of forest ecosystem C cycling in many forested systems worldwide may depend more on major disturbances and landscape legacies related to land use than on projected climate change alone.

Ground-based LIDAR (also known as laser ranging) is a novel technique that may precisely quantify fuelbed characteristics important in determining fire behavior. We measured fuel properties within a south-eastern US longleaf pine woodland at the individual plant and fuelbed scale. Data were collected using a mobile terrestrial LIDAR unit at sub-cm scale for individual fuel types (shrubs) and heterogeneous fuelbed plots. Spatially explicit point-intercept fuel sampling also measured fuelbed heights and volume, while leaf area and biomass measurements of whole and sectioned shrubs were determined from destructive sampling. Volumes obtained by LIDAR and traditional methods showed significant discrepancies. We found that traditional means overestimated volume for shrub fuel types because of variation in leaf area distribution within shrub canopies. LIDAR volume estimates were correlated with biomass and leaf area for individual shrubs when factored by species, size, and plant section. Fuelbed heights were found to be highly variable among the fuel plots, and ground LIDAR was more sensitive to capturing the height variation than traditional point intercept sampling. Ground LIDAR is a promising technology capable of measuring complex surface fuels and fuel characteristics, such as fuel volume.

The realm of wildland fire science encompasses both wild and prescribed fires. Most of the research in the broader field has focused on wildfires, however, despite the prevalence of prescribed fires and demonstrated need for science to guide its application. We argue that prescribed fire science requires a fundamentally different approach to connecting related disciplines of physical, natural, and social sciences. We also posit that research aimed at questions relevant to prescribed fire will improve overall wildland fire science and stimulate the development of useful knowledge about managed wildfires. Because prescribed fires are increasingly promoted and applied for wildfire management and are intentionally ignited to meet policy and land manager objectives, a broader research agenda incorporating the unique features of prescribed fire is needed. We highlight the primary differences between prescribed fire science and wildfire science in the study of fuels, fire behavior, fire weather, fire effects, and fire social science. Wildfires managed for resource benefits ("managed wildfires") offer a bridge for linking these science frameworks. A recognition of the unique science needs related to prescribed fire will be key to addressing the global challenge of managing wildland fire for long-term sustainability of natural resources.Keywords: fire behavior, fire effects, fire weather, fireline interactions, fuels characterization, post-fire tree mortality, prescribed burning, wildland fire research Resumen El ámbito de la ciencia del fuego comprende tanto a los incendios de vegetación no controlados como a las quemas prescriptas. La mayoría de las investigaciones en este amplio campo se han enfocado en los incendios de vegetación, a pesar de la prevalencia de las quemas prescriptas y la probada necesidad de que la ciencia guíe su aplicación. Argüimos que la ciencia de las quemas prescriptas requiere de un enfoque fundamentalmente diferente para conectarse con las disciplinas relacionadas de la ciencias físicas, sociales y naturales. También postulamos que la investigación enfocada a preguntas relevantes para las quemas prescriptas va a mejorar la ciencia de fuegos de vegetación en general y estimular el desarrollo del conocimiento útil sobre el manejo de fuegos de vegetación. Dado que las quemas prescriptas son propuestas y aplicadas de manera incremental para para el manejo de fuegos (Continued on next page) de vegetación, y que son intencionalmente iniciadas para lograr metas y objetivos de manejo de tierras, una agenda más amplia de investigación, incorporando aspectos únicos de las quemas prescriptas, se hace necesaria. Ilustramos las diferencias primarias entre la ciencia de las quemas prescriptas y la de la ciencia de fuegos naturales de vegetación en lo que hace al estudio de los combustibles, el comportamiento del fuego, la meteorología, los efectos del fuego, y las ciencias sociales relacionadas con el fuego. Los incendios manejados para beneficio de los recursos ("fuegos manejados") ofrecen un puente para li...