scholarly journals How to consider the effects of time of day, beam strength, and snow cover in ICESat-2 based estimation of boreal forest biomass?

2022 ◽  
Author(s):  
Petri Varvia ◽  
Lauri Korhonen ◽  
André Bruguière ◽  
Janne Toivonen ◽  
Petteri Packalen ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Laser Scanning ◽  
Forest Canopy ◽  
Spatial Scales ◽  
Forest Biomass ◽  
3D Structure ◽  
Time Of Day ◽  
Forest Zone ◽  
Weak Beam ◽  
Power Difference

Spaceborne lidar sensors have potential to improve the accuracy of forest above-ground biomass (AGB) estimates by providing direct measurements of 3D structure of forests over large spatial scales. The ICESat-2 (Ice, Cloud and land Elevation Satellite 2), launched in 2018, provides a good coverage of the boreal forest zone and has been previously shown to provide good estimates of forest canopy height and AGB. However, spaceborne lidar data are affected by various conditions, such as presence of snow, solar noise, and in the case of ICESat-2, the power difference between the so-called strong and weak beams. The aim of this study was to explore the effects of these conditions on the performance of AGB modeling using ICESat-2 photon data in a boreal forest area. The framework of the study is multiphase modeling, where AGB field data and wall-to-wall airborne laser scanning (ALS) data are used to produce proxy ALS plots on ICESat-2 track positions. Models between the ALS-predicted AGB and the ICESat-2 photon data are then formulated and evaluated by subsets, such as only strong beam data captured in snowy conditions.Our results indicate that, if possible, strong beam night data from snowless conditions should be used in AGB estimation, because our models showed clearly smallest RMSE (27.0%) for this data subset. If more data are needed, we recommend using only strong beam data and constructing separate models for the different data subsets. In the order of increasing RMSE\%, the next best options were snow/night/strong (30.5%), snow/day/strong (33.6%), and snowless/day/strong (34.2%). Weak beam data from snowy night conditions could also be used if necessary (31.1%).

scholarly journals Predicting Occurrence, Abundance, and Fruiting of a Cultural Keystone Species to Inform Landscape Values and Priority Sites for Habitat Enhancements

Forests ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 783
Author(s):  
Scott E. Nielsen ◽  
Jacqueline M. Dennett ◽  
Christopher W. Bater
Keyword(s):  
Laser Scanning ◽  
Forest Canopy ◽  
Prescribed Burning ◽  
Spatial Scales ◽  
Keystone Species ◽  
Natural Disturbance ◽  
Fold Increase ◽  
Fruit Production ◽  
Timber Species ◽  
Environmental Niche

Environmental niche modeling is an increasingly common tool in conservation and management of non-timber species. In particular, models of species’ habitats have been aided by new advances in remote sensing and it is now possible to relate forest structure variables to understory species at a relatively high resolution over large spatial scales. Here, we model landscape responses for a culturally-valued keystone shrub, velvet-leaf blueberry (Vaccinium myrtilloides Michaux), in northeast Alberta, Canada, to better understand the environmental factors promoting or limiting its occurrence, abundance, and fruit production, and to guide regional planning. Occurrence and abundance were measured at 845 and 335 sites, respectively, with both strongly related to land cover type and topo-edaphic factors. However, their influence varied widely, reflecting differences in the processes affecting occurrence and abundance. We then used airborne laser scanning (ALS) to characterize horizontal forest canopy cover for the study area, and related this and other geospatial variables to patterns in fruit production where we demonstrated a five-fold increase in fruit production from closed to open forest stands. We then simulated forest canopy thinning across the study area to identify places where gains in fruit production would be greatest following natural disturbance or directed management (e.g., thinning, prescribed burning). Finally, we suggest this approach could be used to identify sites for habitat enhancements to offset direct (land use change) or indirect (access) losses of resources in areas impacted with resource extraction activities, or simply to increase a culturally-valued resource through management.

scholarly journals Airborne measurements of nucleation mode particles II: boreal forest nucleation events

2008 ◽  
Vol 8 (1) ◽  
pp. 2821-2848 ◽  
Author(s):  
C. D. O'Dowd ◽  
Y. J. Yoon ◽  
W. Junkerman ◽  
P. Aalto ◽  
M. Kulmala ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Forest Canopy ◽  
Particle Production ◽  
Spatial Scales ◽  
Source Region ◽  
Free Troposphere ◽  
Airborne Measurements ◽  
Nucleation Mode ◽  
Gulf Of Bothnia ◽  
Nocturnal Inversion

Abstract. Airborne measurements of nucleation mode aerosol concentrations during nucleation events over the boreal forest of southern Finland are reported. Three case studies are analysis in an attempt to characterise the spatial scales over which these events occur and to identify the source region for particle production. For the cases presented, there is no evidence of nucleation mode particles in the Free Troposphere. Nucleation mode particles are first detected in the surface layer as the nocturnal inversion breaks up and develops into the current-day's new boundary layer. In terms of spatial variability, significant variability in the concentration of nucleation mode particles was observed and was attributed to changes in the topography which comprised a mix of forest canopy and frozen lakes. Measurements over the Gulf of Bothnia indicated no nucleation mode over the sea and confirm that the scale of the events is associated with the boreal forest scale and that the new particles are produced directly above the forest canopy.

scholarly journals Do Ovenbirds (Seiurus Aurocapillus) Avoid Boreal Forest Edges? A Spatiotemporal Analysis in an Agricultural Landscape

The Auk ◽  
2003 ◽  
Vol 120 (1) ◽  
pp. 152-162
Author(s):  
Daniel F. Mazerolle ◽  
Keith A. Hobson
Keyword(s):  
Home Range ◽  
Boreal Forest ◽  
Forest Canopy ◽  
Time Of Day ◽  
Habitat Characteristics ◽  
Home Ranges ◽  
Forest Fragments ◽  
Forest Edges ◽  
Seiurus Aurocapillus ◽  
The Mean

Abstract Previous studies suggest that Ovenbirds (Seiurus aurocapillus) are area sensitive and apparently avoid forest edges. In 1999 and 2000, we used radiotelemetry to investigate how breeding male Ovenbirds respond to forest edges. Twenty-one males with home ranges abutting edges of seven forest fragments surrounded by agriculture were tracked for an average of two weeks. We found that sightings of males were situated 8 ± 10 m closer to edges than random locations within each home range. However, the mean time of day for edge sightings (1139 hours, 95% CI = 1052–1227 hours) occurred significantly later than the mean for sightings in the interior of forest fragments (0936 hours, 95% CI = 0856–1016 hours). That indicates that previous studies focusing on morning singing locations to delineate home-range use have likely underestimated use of edges by birds. Habitat characteristics also varied in relation to edges. Forest canopy was lower, shrubs were denser, leaf-litter thicker, and soils dryer near edges than in the portion of home ranges facing the interior of forest fragments. Arthropod biomass varied little in relation to edges, except biomass of larvae, which was greatest at edges. Boreal forest edges abutting agricultural fields do not appear to reduce habitat use or quality for breeding male Ovenbirds, and so we suggest that the generalized association between area sensitivity and edge avoidance for Ovenbirds in forest fragments be reassessed.

scholarly journals Where there is smoke there is mercury: Assessing boreal forest fire mercury emissions using aircraft and highlighting uncertainties associated with upscaling emissions estimates

2020 ◽  
Author(s):  
David S. McLagan ◽  
Geoff W. Stupple ◽  
Andrea Darlington ◽  
Katherine Hayden ◽  
Alexandra Steffen
Keyword(s):  
Boreal Forest ◽  
Biomass Burning ◽  
Vegetation Type ◽  
Spatial Scales ◽  
Forest Biomass ◽  
Fire Intensity ◽  
Retrieval Algorithm ◽  
Concentration Data ◽  
Mercury Emissions ◽  
Research Aircraft

Abstract. Mercury (Hg) emitted from biomass burning is an important source of the contaminant to the atmosphere and an integral component of the global Hg biogeochemical cycle. In 2018, measurements of gaseous elemental Hg (GEM) were taken on-board a research aircraft along with a series of co-emitted contaminants in the emissions plume of an 88 km2 boreal forest wildfire on the Garson Lake Plain (GLP) in NW Saskatchewan, Canada. A series of four flight tracks were made perpendicular to the emissions plume at increasing distances from the fire each with 3–5 passes at different altitudes at each downwind location. The maximum GEM concentration measured on the flight was 2.88 ng m−3, which represents a ≈2.4x increase in concentration above background. GEM concentrations were significantly correlated with the co-emitted carbon species (CO, CO2, and CH4). Emissions ratios (ERs) were calculated from measured GEM and carbon co-contaminants data. Using the least uncertain of these ratios (GEM : CO), GEM concentrations were estimated at the higher 0.5 Hz time resolution of the CO measurements resulting in maximum GEM concentrations and enhancements of 6.75 ng m−3 and ≈5.6x, respectively. Extrapolating the estimated maximum 0.5 Hz GEM concentration data from each downwind location back to source, 1 km and 1 m (from fire) concentrations were predicted to be 12.9 and 29.9 ng m−3, or enhancements of ≈11x and ≈25x, respectively. ERs and emissions factors (EFs) derived from the measured data and literature values were also used to calculate Hg emissions estimates on three spatial scales: (i) the GLP fires themselves, (ii) all boreal forest biomass burning, and (iii) global biomass burning. The most robust estimate was of the GLP fires (21 ± 10 kg of Hg) using calculated EFs that used minimal literature derived data. Using a Top-down Emission Rate Retrieval Algorithm (TERRA) we were able to determine a similar emission estimate of 22 ± 7 kg of Hg. The elevated uncertainties of the other estimates and high variability between the different methods used in the calculations highlight concerns with some of the assumptions that have been used in calculating Hg biomass burning in the literature. Among these problematic assumptions are variable ERs of contaminants based on vegetation type and fire intensity, differing atmospheric lifetimes of emitted contaminants, the use of only one co-contaminant in emissions estimate calculations, and the paucity of atmospheric Hg species concentration measurements in biomass burning plumes.

scholarly journals Where there is smoke there is mercury: Assessing boreal forest fire mercury emissions using aircraft and highlighting uncertainties associated with upscaling emissions estimates

2021 ◽  
Vol 21 (7) ◽  
pp. 5635-5653
Author(s):  
David S. McLagan ◽  
Geoff W. Stupple ◽  
Andrea Darlington ◽  
Katherine Hayden ◽  
Alexandra Steffen
Keyword(s):  
Boreal Forest ◽  
Biomass Burning ◽  
Vegetation Type ◽  
Spatial Scales ◽  
Forest Biomass ◽  
Fire Intensity ◽  
Retrieval Algorithm ◽  
Background Concentration ◽  
Concentration Data ◽  
Mercury Emissions

Abstract. Emissions from biomass burning are an important source of mercury (Hg) to the atmosphere and an integral component of the global Hg biogeochemical cycle. In 2018, measurements of gaseous elemental Hg (GEM) were taken on board a research aircraft along with a series of co-emitted contaminants in the emissions plume of an 88 km2 boreal forest wildfire on the Garson Lake Plain (GLP) in NW Saskatchewan, Canada. A series of four flight tracks were made perpendicular to the plume at increasing distances from the fire, each with three to five passes at different altitudes at each downwind location. The maximum GEM concentration measured on the flight was 2.88 ng m−3, which is ≈ 2.4× background concentration. GEM concentrations were significantly correlated with the co-emitted carbon species (CO, CO2, and CH4). Emissions ratios (ERs) were calculated from measured GEM and carbon co-contaminant data. Using the most correlated (least uncertain) of these ratios (GEM:CO), GEM concentrations were estimated at the higher 0.5 Hz time resolution of the CO measurements, resulting in maximum GEM concentrations and enhancements of 6.76 ng m−3 and ≈ 5.6×, respectively. Extrapolating the estimated maximum 0.5 Hz GEM concentration data from each downwind location back to source, 1 km and 1 m (from fire) concentrations were predicted to be 12.9 and 30.0 ng m−3, or enhancements of ≈ 11× and ≈ 25×, respectively. ERs and emissions factors (EFs) derived from the measured data and literature values were also used to calculate Hg emissions estimates on three spatial scales: (i) the GLP fires themselves, (ii) all boreal forest biomass burning, and (iii) global biomass burning. The most robust estimate was of the GLP fires (21 ± 10 kg of Hg) using calculated EFs that used minimal literature-derived data. Using the Top-down Emission Rate Retrieval Algorithm (TERRA), we were able to determine a similar emission estimate of 22 ± 7 kg of Hg. The elevated uncertainties of the other estimates and high variability between the different methods used in the calculations highlight concerns with some of the assumptions that have been used in calculating Hg biomass burning in the literature. Among these problematic assumptions are variable ERs of contaminants based on vegetation type and fire intensity, differing atmospheric lifetimes of emitted contaminants, the use of only one co-contaminant in emissions estimate calculations, and the paucity of atmospheric Hg species concentration measurements in biomass burning plumes.

scholarly journals Airborne measurements of nucleation mode particles II: boreal forest nucleation events

2009 ◽  
Vol 9 (3) ◽  
pp. 937-944 ◽  
Author(s):  
C. D. O'Dowd ◽  
Y. J. Yoon ◽  
W. Junkermann ◽  
P. Aalto ◽  
M. Kulmala ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Forest Canopy ◽  
Particle Production ◽  
Spatial Scales ◽  
Source Region ◽  
Free Troposphere ◽  
Airborne Measurements ◽  
Nucleation Mode ◽  
Gulf Of Bothnia ◽  
Nocturnal Inversion

Abstract. Airborne measurements of nucleation mode aerosol concentrations during nucleation events over the boreal forest of southern Finland are reported. Three case studies are analyzed in an attempt to characterise the spatial scales over which these events occur and to identify the source region for particle production. For the cases presented, there is no evidence of nucleation mode particles in the Free Troposphere. Nucleation mode particles are first detected in the surface layer as the nocturnal inversion breaks up and develops into the current-day's new boundary layer. In terms of spatial variability, significant variability in the concentration of nucleation mode particles was observed and was attributed to changes in the topography which comprised a mix of forest canopy and frozen lakes. Measurements over the Gulf of Bothnia indicated no nucleation mode over the sea and confirm that the scale of the events is associated with the boreal forest scale and that the new particles are produced directly above the forest canopy.

scholarly journals Terrestrial Laser Scanning for Vegetation Analyses with a Special Focus on Savannas

2021 ◽  
Vol 13 (3) ◽  
pp. 507
Author(s):  
Tasiyiwa Priscilla Muumbe ◽  
Jussi Baade ◽  
Jenia Singh ◽  
Christiane Schmullius ◽  
Christian Thau
Keyword(s):  
Remote Sensing ◽  
Vegetation Structure ◽  
Laser Scanning ◽  
Spatial Scales ◽  
Terrestrial Laser Scanning ◽  
Point Clouds ◽  
Parameter Extraction ◽  
Airborne Lidar ◽  
Special Focus ◽  
Vegetation Parameter

Savannas are heterogeneous ecosystems, composed of varied spatial combinations and proportions of woody and herbaceous vegetation. Most field-based inventory and remote sensing methods fail to account for the lower stratum vegetation (i.e., shrubs and grasses), and are thus underrepresenting the carbon storage potential of savanna ecosystems. For detailed analyses at the local scale, Terrestrial Laser Scanning (TLS) has proven to be a promising remote sensing technology over the past decade. Accordingly, several review articles already exist on the use of TLS for characterizing 3D vegetation structure. However, a gap exists on the spatial concentrations of TLS studies according to biome for accurate vegetation structure estimation. A comprehensive review was conducted through a meta-analysis of 113 relevant research articles using 18 attributes. The review covered a range of aspects, including the global distribution of TLS studies, parameters retrieved from TLS point clouds and retrieval methods. The review also examined the relationship between the TLS retrieval method and the overall accuracy in parameter extraction. To date, TLS has mainly been used to characterize vegetation in temperate, boreal/taiga and tropical forests, with only little emphasis on savannas. TLS studies in the savanna focused on the extraction of very few vegetation parameters (e.g., DBH and height) and did not consider the shrub contribution to the overall Above Ground Biomass (AGB). Future work should therefore focus on developing new and adjusting existing algorithms for vegetation parameter extraction in the savanna biome, improving predictive AGB models through 3D reconstructions of savanna trees and shrubs as well as quantifying AGB change through the application of multi-temporal TLS. The integration of data from various sources and platforms e.g., TLS with airborne LiDAR is recommended for improved vegetation parameter extraction (including AGB) at larger spatial scales. The review highlights the huge potential of TLS for accurate savanna vegetation extraction by discussing TLS opportunities, challenges and potential future research in the savanna biome.

scholarly journals Novel Application and Validation of a Method to Assess Visual Impacts of Rotating Wind Turbine Blades Within Woodland Areas

2021 ◽  
Vol 89 (1) ◽  
pp. 1-14
Author(s):  
U. Nopp-Mayr ◽  
F. Kunz ◽  
F. Suppan ◽  
E. Schöll ◽  
J. Coppes
Keyword(s):  
Environmental Impact ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Power Plants ◽  
Laser Scanning ◽  
Forest Canopy ◽  
Turbine Blades ◽  
Wind Turbine Blades ◽  
Environmental Impact Assessments ◽  
Independent Field

AbstractIncreasing numbers of wind power plants (WPP) are constructed across the globe to reduce the anthropogenic contribution to global warming. There are, however, concerns on the effects of WPP on human health as well as related effects on wildlife. To address potential effects of WPP in environmental impact assessments, existing models accounting for shadow flickering and noise are widely applied. However, a standardized, yet simple and widely applicable proxy for the visibility of rotating wind turbines in woodland areas was largely lacking up to date. We combined land cover information of forest canopy extracted from orthophotos and airborne laser scanning (LiDAR) data to represent the visibility of rotating wind turbines in five woodland study sites with a high spatial resolution. Performing an in-situ validation in five study areas across Europe which resulted in a unique sample of 1738 independent field observations, we show that our approach adequately predicts from where rotating wind turbine blades are visible within woodlands or not. We thus provide strong evidence, that our approach yields a valuable proxy of the visibility of moving rotor blades with high resolution which in turn can be applied in environmental impact assessments of WPP within woodlands worldwide.

scholarly journals Synthesizing published knowledge of boreal forest cover change for large-scale landscape dynamics modelling

2003 ◽  
Vol 79 (1) ◽  
pp. 132-146 ◽  
Author(s):  
Dennis Yemshanov ◽  
Ajith H Perera
Keyword(s):  
Boreal Forest ◽  
Large Scale ◽  
Forest Canopy ◽  
Forest Cover ◽  
Forest Succession ◽  
Simulation Models ◽  
Limiting Factors ◽  
Sources Of Information ◽  
Forest Cover Change ◽  
Discrete State

We reviewed the published knowledge on forest succession in the North American boreal biome for its applicability in modelling forest cover change over large extents. At broader scales, forest succession can be viewed as forest cover change over time. Quantitative case studies of forest succession in peer-reviewed literature are reliable sources of information about changes in forest canopy composition. We reviewed the following aspects of forest succession in literature: disturbances; pathways of post-disturbance forest cover change; timing of successional steps; probabilities of post-disturbance forest cover change, and effects of geographic location and ecological site conditions on forest cover change. The results from studies in the literature, which were mostly based on sample plot observations, appeared to be sufficient to describe boreal forest cover change as a generalized discrete-state transition process, with the discrete states denoted by tree species dominance. In this paper, we outline an approach for incorporating published knowledge on forest succession into stochastic simulation models of boreal forest cover change in a standardized manner. We found that the lack of details in the literature on long-term forest succession, particularly on the influence of pre-disturbance forest cover composition, may be limiting factors in parameterizing simulation models. We suggest that the simulation models based on published information can provide a good foundation as null models, which can be further calibrated as detailed quantitative information on forest cover change becomes available. Key words: probabilistic model, transition matrix, boreal biome, landscape ecology

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