Andy Hudak - Academia.edu (original) (raw)

Papers by Andy Hudak

Research paper thumbnail of Supplementary material to "Understanding the effect of fire on vegetation composition and gross primary production in a semi-arid shrubland ecosystem using the Ecosystem Demography (EDv2.2) model&quot

Research paper thumbnail of Got shrubs? Precipitation mediates long-term shrub and introduced grass dynamics in chaparral communities after fire

Fire Ecology, Apr 29, 2019

Research paper thumbnail of Boreal forest vegetation and fuel conditions 12 years after the 2004 Taylor Complex fires in Alaska, USA

Fire Ecology, Aug 26, 2019

Research paper thumbnail of Spatial and temporal drivers of post-fire tree establishment and height growth in a managed forest landscape

Fire Ecology, Dec 5, 2022

Research paper thumbnail of Multitemporal lidar captures heterogeneity in fuel loads and consumption on the Kaibab Plateau

Fire Ecology, Aug 9, 2022

Research paper thumbnail of Integrating active fire behavior observations and multitemporal airborne laser scanning data to quantify fire impacts on tree growth: A pilot study in mature Pinus ponderosa stands

Forest Ecology and Management

Research paper thumbnail of Land use/cover spatiotemporal dynamics, and implications on environmental and bioclimatic factors in Chingola district, Zambia

Geomatics, Natural Hazards and Risk

Research paper thumbnail of Accurate Ground Positioning Obtained From 3d Data Matching Between Airborne and Terrestrial Data for Ground Validation of Satellite Laser

IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium

GEDI Satellite laser mission will take 3D data globally from International Space Station. The sen... more GEDI Satellite laser mission will take 3D data globally from International Space Station. The sensor has an improved navigation system to position laser shooting areas accurately. However, the ground validation is still difficult due to the misalignment caused by poor reception of GPS signals under the thick forest. This study introduces a new way to get more accurate ground positioning of trees in tropical forest using 3D data matching technique between airborne and terrestrial data. Our study site is in tropical forest at Robson Creek, Australia. RMSE of XY directions was 0.5 m in and Z direction was 0.6 m, which was impossible to achieve efficiently from the traditional positioning by GPS under dense canopy. The 3D data taken by terrestrial laser is not only useful for capturing structure data for the validation of the waveform analysis of satellite laser but also helps to position accurate ground coordinates in tropical forest through this technique.

Research paper thumbnail of Comparison of fire-produced gases from wind tunnel and small field experimental burns

International Journal of Wildland Fire

Composition of pyrolysis gases for wildland fuels is often determined using ground samples heated... more Composition of pyrolysis gases for wildland fuels is often determined using ground samples heated in non-oxidising environments. Results are applied to wildland fires where fuels change spatially and temporally, resulting in variable fire behaviour with variable heating. Though historically used, applicability of traditional pyrolysis results to the wildland fire setting is unknown. Pyrolytic and flaming combustion gases measured in wind tunnel fires and prescribed burns were compared using compositional data techniques. CO2 was dominant in both. Other dominant gases included CO, H2 and CH4. Relative amounts of CO, CO2 and CH4 were similar between fire phases (pyrolysis, flaming combustion); relatively more H2 was observed in pyrolysis samples. All gas log-ratios with CO2 in pyrolysis samples were larger than in flaming combustion samples. Presence of live plants significantly affected gas composition. A logistic regression model correctly classified 76% of the wind tunnel samples a...

Research paper thumbnail of Stand Replacing Disturbance History from Object-Based Image Analysis (OBIA) of LiDAR Data

AGU Fall Meeting Abstracts, Dec 1, 2016

Research paper thumbnail of Quantifying Fuel Consumption for Two Western U.S. Fires using Repeat LiDAR

AGU Fall Meeting Abstracts, Dec 1, 2018

Research paper thumbnail of Mapping Heterogeneous Fuel Characteristics and Fuel Consumption Using AVIRIS, LiDAR, and Field Data for Fire Emissions Modeling

AGU Fall Meeting Abstracts, Dec 1, 2020

Research paper thumbnail of Author response for "Treetop: A Shiny‐based Application and R package for Extracting Forest Information from LiDAR data for Ecologists and Conservationists

Research paper thumbnail of Forest soil microbial communities: Using metagenomic approaches to survey permanent plots

Forest soil ecosystems include some of the most complex microbial communities on Earth (Fierer et... more Forest soil ecosystems include some of the most complex microbial communities on Earth (Fierer et al. 2012). These assemblages of archaea, bacteria, fungi, and protists play essential roles in biogeochemical cycles (van der Heijden et al. 2008) and account for considerable terrestrial biomass (Nielsen et al. 2011). Yet, determining the microbial composition of forest soils remains a great challenge due in part to their overwhelming diversity and variability. Until recently, studies of microbial diversity in natural systems have relied on clonal cultures. Early environmental gene sequencing, which cloned specific genes to produce a profile of diversity in a natural sample, revealed that the vast majority of microbial diversity had been overlooked using these direct cultivation methods.

Research paper thumbnail of Anomalous increasing annual streamflows driven by the demise of western white pine dominated ecosystems

Research paper thumbnail of A comparison of four individual tree height prediction methods for forest inventory

Research paper thumbnail of Linking Wildfire and Climate as Drivers of Plant Species and Community-level Change

Research paper thumbnail of Influence of flight parameters on UAS-based monitoring of tree height, diameter, and density

Remote Sensing of Environment, 2021

Abstract Increased focus on restoring forest structural variation and spatial pattern in dry coni... more Abstract Increased focus on restoring forest structural variation and spatial pattern in dry conifer forests has led to greater emphasis on forest monitoring strategies that can be summarized across scales. To inform restoration objectives with data sources that can characterize individual trees, groups of trees, and the entire stand, different remote sensing strategies such as aerial and terrestrial light detection and ranging (LiDAR) have been explored. Unfortunately, high equipment and operational costs of aerial systems, along with limited spatial extent of terrestrial scanners, have restricted widespread adoption of these technologies for repeated forest monitoring. This study investigates applications of unmanned aerial system (UAS) imagery for Structure from Motion derived modeling of individual tree and stand-level metrics. Specifically, we evaluate how flight parameters impact UAS extracted height and imputed DBH accuracies against field stem-mapped values. In total, 30 UAS image datasets collected from combinations of three altitudes, two flight patterns, and five camera orientations were assessed. Tree heights were extracted using a variable window function that searched UAS-derived canopy height models, while DBH was sampled from point cloud slices at 1.32–1.42 m using a least squares circle fitting algorithm. The sample trees were then filtered against National Forest Inventory data from the study region to ensure reasonable matching of extracted heights and diameters. The matched values were used to create a height to diameter relationship for predicting missing DBH values. Extracted and imputed tree values were compared against stem-mapped values to determine tree commission and omission rates, the accuracy and precision of extracted tree height, DBH, as well as overstory and understory stand density. Finding that, 1) tree extraction accuracy and correctness was maximized (F-score = 0.77) for nadir crosshatch UAS flight designs; 2) extracted tree height R2 with stem-mapped values was high (R2 ≥ 0.98) for all UAS flight parameters, but the quality (mean error = 0.79 cm) and quantity (~10% of all trees) of extracted DBH values was maximized for lower altitude, nadir crosshatch acquisitions; 3) the distribution of predicted DBH values most closely matched field observed values for off-nadir crosshatch flight designs; 4) using either off-nadir or crosshatch flight designs at lower altitudes maximized correlation (r > 0.70) and accuracy (basal area within 2 m2 ha−1) of stand density estimates. This study demonstrates a novel UAS-based inventory strategy for estimating individual tree structural attributes (i.e., location, height, and DBH) in dry conifer forests, without the need for in situ field observations.

Research paper thumbnail of Field attributes and satellite data for "How vegetation recovery and fuel conditions in past fires influences fuels and future fire management in five western U.S. ecosystems

Forest Service Research Data Archive

Research paper thumbnail of Corrigendum to: Use of ordinary kriging and Gaussian conditional simulation to interpolate airborne fire radiative energy density estimates

International Journal of Wildland Fire, 2018

Fire radiative energy density (FRED, Jm-2) integrated from fire radiative power density (FRPD, Wm... more Fire radiative energy density (FRED, Jm-2) integrated from fire radiative power density (FRPD, Wm-2) observations of landscape-level fires can present an undersampling problem when collected from fixed-wing aircraft. In the present study, the aircraft made multiple passes over the fire at ~3min intervals, thus failing to observe most of the FRPD emitted as the flame front spread. We integrated the sparse FRPD time series to obtain pixel-level FRED estimates, and subsequently applied ordinary kriging (OK) and Gaussian conditional simulation (GCS) to interpolate across data voids caused by the undersampling. We compared FRED interpolated via OK and GCS with FRED estimated independently from ground measurements of biomass consumed from five prescribed burns at Eglin Air Force Base, Florida, USA. In four of five burns considered where undersampling prevailed, OK and GCS effectively interpolated FRED estimates across the data voids, improving the spatial distribution of FRED across the b...

Research paper thumbnail of Supplementary material to "Understanding the effect of fire on vegetation composition and gross primary production in a semi-arid shrubland ecosystem using the Ecosystem Demography (EDv2.2) model&quot

Research paper thumbnail of Got shrubs? Precipitation mediates long-term shrub and introduced grass dynamics in chaparral communities after fire

Fire Ecology, Apr 29, 2019

Research paper thumbnail of Boreal forest vegetation and fuel conditions 12 years after the 2004 Taylor Complex fires in Alaska, USA

Fire Ecology, Aug 26, 2019

Research paper thumbnail of Spatial and temporal drivers of post-fire tree establishment and height growth in a managed forest landscape

Fire Ecology, Dec 5, 2022

Research paper thumbnail of Multitemporal lidar captures heterogeneity in fuel loads and consumption on the Kaibab Plateau

Fire Ecology, Aug 9, 2022

Research paper thumbnail of Integrating active fire behavior observations and multitemporal airborne laser scanning data to quantify fire impacts on tree growth: A pilot study in mature Pinus ponderosa stands

Forest Ecology and Management

Research paper thumbnail of Land use/cover spatiotemporal dynamics, and implications on environmental and bioclimatic factors in Chingola district, Zambia

Geomatics, Natural Hazards and Risk

Research paper thumbnail of Accurate Ground Positioning Obtained From 3d Data Matching Between Airborne and Terrestrial Data for Ground Validation of Satellite Laser

IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium

GEDI Satellite laser mission will take 3D data globally from International Space Station. The sen... more GEDI Satellite laser mission will take 3D data globally from International Space Station. The sensor has an improved navigation system to position laser shooting areas accurately. However, the ground validation is still difficult due to the misalignment caused by poor reception of GPS signals under the thick forest. This study introduces a new way to get more accurate ground positioning of trees in tropical forest using 3D data matching technique between airborne and terrestrial data. Our study site is in tropical forest at Robson Creek, Australia. RMSE of XY directions was 0.5 m in and Z direction was 0.6 m, which was impossible to achieve efficiently from the traditional positioning by GPS under dense canopy. The 3D data taken by terrestrial laser is not only useful for capturing structure data for the validation of the waveform analysis of satellite laser but also helps to position accurate ground coordinates in tropical forest through this technique.

Research paper thumbnail of Comparison of fire-produced gases from wind tunnel and small field experimental burns

International Journal of Wildland Fire

Composition of pyrolysis gases for wildland fuels is often determined using ground samples heated... more Composition of pyrolysis gases for wildland fuels is often determined using ground samples heated in non-oxidising environments. Results are applied to wildland fires where fuels change spatially and temporally, resulting in variable fire behaviour with variable heating. Though historically used, applicability of traditional pyrolysis results to the wildland fire setting is unknown. Pyrolytic and flaming combustion gases measured in wind tunnel fires and prescribed burns were compared using compositional data techniques. CO2 was dominant in both. Other dominant gases included CO, H2 and CH4. Relative amounts of CO, CO2 and CH4 were similar between fire phases (pyrolysis, flaming combustion); relatively more H2 was observed in pyrolysis samples. All gas log-ratios with CO2 in pyrolysis samples were larger than in flaming combustion samples. Presence of live plants significantly affected gas composition. A logistic regression model correctly classified 76% of the wind tunnel samples a...

Research paper thumbnail of Stand Replacing Disturbance History from Object-Based Image Analysis (OBIA) of LiDAR Data

AGU Fall Meeting Abstracts, Dec 1, 2016

Research paper thumbnail of Quantifying Fuel Consumption for Two Western U.S. Fires using Repeat LiDAR

AGU Fall Meeting Abstracts, Dec 1, 2018

Research paper thumbnail of Mapping Heterogeneous Fuel Characteristics and Fuel Consumption Using AVIRIS, LiDAR, and Field Data for Fire Emissions Modeling

AGU Fall Meeting Abstracts, Dec 1, 2020

Research paper thumbnail of Author response for "Treetop: A Shiny‐based Application and R package for Extracting Forest Information from LiDAR data for Ecologists and Conservationists

Research paper thumbnail of Forest soil microbial communities: Using metagenomic approaches to survey permanent plots

Forest soil ecosystems include some of the most complex microbial communities on Earth (Fierer et... more Forest soil ecosystems include some of the most complex microbial communities on Earth (Fierer et al. 2012). These assemblages of archaea, bacteria, fungi, and protists play essential roles in biogeochemical cycles (van der Heijden et al. 2008) and account for considerable terrestrial biomass (Nielsen et al. 2011). Yet, determining the microbial composition of forest soils remains a great challenge due in part to their overwhelming diversity and variability. Until recently, studies of microbial diversity in natural systems have relied on clonal cultures. Early environmental gene sequencing, which cloned specific genes to produce a profile of diversity in a natural sample, revealed that the vast majority of microbial diversity had been overlooked using these direct cultivation methods.

Research paper thumbnail of Anomalous increasing annual streamflows driven by the demise of western white pine dominated ecosystems

Research paper thumbnail of A comparison of four individual tree height prediction methods for forest inventory

Research paper thumbnail of Linking Wildfire and Climate as Drivers of Plant Species and Community-level Change

Research paper thumbnail of Influence of flight parameters on UAS-based monitoring of tree height, diameter, and density

Remote Sensing of Environment, 2021

Abstract Increased focus on restoring forest structural variation and spatial pattern in dry coni... more Abstract Increased focus on restoring forest structural variation and spatial pattern in dry conifer forests has led to greater emphasis on forest monitoring strategies that can be summarized across scales. To inform restoration objectives with data sources that can characterize individual trees, groups of trees, and the entire stand, different remote sensing strategies such as aerial and terrestrial light detection and ranging (LiDAR) have been explored. Unfortunately, high equipment and operational costs of aerial systems, along with limited spatial extent of terrestrial scanners, have restricted widespread adoption of these technologies for repeated forest monitoring. This study investigates applications of unmanned aerial system (UAS) imagery for Structure from Motion derived modeling of individual tree and stand-level metrics. Specifically, we evaluate how flight parameters impact UAS extracted height and imputed DBH accuracies against field stem-mapped values. In total, 30 UAS image datasets collected from combinations of three altitudes, two flight patterns, and five camera orientations were assessed. Tree heights were extracted using a variable window function that searched UAS-derived canopy height models, while DBH was sampled from point cloud slices at 1.32–1.42 m using a least squares circle fitting algorithm. The sample trees were then filtered against National Forest Inventory data from the study region to ensure reasonable matching of extracted heights and diameters. The matched values were used to create a height to diameter relationship for predicting missing DBH values. Extracted and imputed tree values were compared against stem-mapped values to determine tree commission and omission rates, the accuracy and precision of extracted tree height, DBH, as well as overstory and understory stand density. Finding that, 1) tree extraction accuracy and correctness was maximized (F-score = 0.77) for nadir crosshatch UAS flight designs; 2) extracted tree height R2 with stem-mapped values was high (R2 ≥ 0.98) for all UAS flight parameters, but the quality (mean error = 0.79 cm) and quantity (~10% of all trees) of extracted DBH values was maximized for lower altitude, nadir crosshatch acquisitions; 3) the distribution of predicted DBH values most closely matched field observed values for off-nadir crosshatch flight designs; 4) using either off-nadir or crosshatch flight designs at lower altitudes maximized correlation (r > 0.70) and accuracy (basal area within 2 m2 ha−1) of stand density estimates. This study demonstrates a novel UAS-based inventory strategy for estimating individual tree structural attributes (i.e., location, height, and DBH) in dry conifer forests, without the need for in situ field observations.

Research paper thumbnail of Field attributes and satellite data for "How vegetation recovery and fuel conditions in past fires influences fuels and future fire management in five western U.S. ecosystems

Forest Service Research Data Archive

Research paper thumbnail of Corrigendum to: Use of ordinary kriging and Gaussian conditional simulation to interpolate airborne fire radiative energy density estimates

International Journal of Wildland Fire, 2018

Fire radiative energy density (FRED, Jm-2) integrated from fire radiative power density (FRPD, Wm... more Fire radiative energy density (FRED, Jm-2) integrated from fire radiative power density (FRPD, Wm-2) observations of landscape-level fires can present an undersampling problem when collected from fixed-wing aircraft. In the present study, the aircraft made multiple passes over the fire at ~3min intervals, thus failing to observe most of the FRPD emitted as the flame front spread. We integrated the sparse FRPD time series to obtain pixel-level FRED estimates, and subsequently applied ordinary kriging (OK) and Gaussian conditional simulation (GCS) to interpolate across data voids caused by the undersampling. We compared FRED interpolated via OK and GCS with FRED estimated independently from ground measurements of biomass consumed from five prescribed burns at Eglin Air Force Base, Florida, USA. In four of five burns considered where undersampling prevailed, OK and GCS effectively interpolated FRED estimates across the data voids, improving the spatial distribution of FRED across the b...