The influence of ground- and lidar-derived forest structure metrics on snow accumulation and ablation in disturbed forests

2010 ◽  
Vol 40 (4) ◽  
pp. 812-821 ◽  
Author(s):  
Andrés Varhola ◽  
Nicholas C. Coops ◽  
Christopher W. Bater ◽  
Pat Teti ◽  
Sarah Boon ◽  
...  
Keyword(s):  
Forest Structure ◽  
Mountain Pine Beetle ◽  
Forest Canopy ◽  
Forest Cover ◽  
Three Dimensional ◽  
Ablation Rate ◽  
Snow Accumulation ◽  
Innovative Technology ◽  
Spring Runoff ◽  
Structure Metrics

The current mountain pine beetle infestation in British Columbia’s lodgepole pine forests has raised concerns about potential impacts on water resources. Changes in forest structure resulting from defoliation, windthrow, and salvage harvesting may increase snow accumulation and ablation (i.e., spring runoff and flooding risk) below the forest canopy because of reduced snow interception and higher levels of radiation reaching the surface. Quantifying these effects requires a better understanding of the link between forest structure and snow processes. Light detection and ranging (lidar) is an innovative technology capable of estimating forest structure metrics in a detailed, three-dimensional approach not easily obtained from manual measurements. While a number of previous studies have shown that increased snow accumulation and ablation occur as forest cover decreases, the potential improvement of these relationships based on lidar metrics has not been quantified. We investigated the correlation between lidar-derived and ground-based traditional canopy metrics with snow accumulation and ablation indicators, demonstrating that a lidar-derived forest cover parameter was the strongest predictor of peak snow accumulation (r2 = 0.70, p < 0.001) and maximum snow ablation rate (r2 = 0.59, p < 0.01). Improving our ability to quantify changes in forest structure in extensive areas will assist in developing more robust models of watershed processes.

scholarly journals Observations of a Coniferous Forest at 9.6 and 17.2 GHz: Implications for SWE Retrievals

2018 ◽  
Vol 11 (1) ◽  
pp. 6 ◽  
Author(s):  
Aaron Thompson ◽  
Richard Kelly
Keyword(s):  
Forest Canopy ◽  
Forest Cover ◽  
Snow Water Equivalent ◽  
Incidence Angle ◽  
Coniferous Forest ◽  
Snow Accumulation ◽  
Ancillary Data ◽  
Volume Scattering ◽  
Component Decomposition ◽  
Forested Landscapes

UWScat, a ground-based Ku- and X-band scatterometer, was used to compare forested and non-forested landscapes in a terrestrial snow accumulation environment as part of the NASA SnowEx17 field campaign. Field observations from Trail Valley Creek, Northwest Territories; Tobermory, Ontario; and the Canadian Snow and Ice Experiment (CASIX) campaign in Churchill, Manitoba, were also included. Limited sensitivity to snow was observed at 9.6 GHz, while the forest canopy attenuated the signal from sub-canopy snow at 17.2 GHz. Forested landscapes were distinguishable using the volume scattering component of the Freeman–Durden three-component decomposition model by applying a threshold in which values ≥50% indicated forested landscape. It is suggested that the volume scattering component of the decomposition can be used in current snow water equivalent (SWE) retrieval algorithms in place of the forest cover fraction (FF), which is an optical surrogate for microwave scattering and relies on ancillary data. The performance of the volume scattering component of the decomposition was similar to that of FF when used in a retrieval scheme. The primary benefit of this method is that it provides a current, real-time estimate of the forest state, it automatically accounts for the incidence angle and canopy structure, and it provides coincident information on the forest canopy without the use of ancillary data or modeling, which is especially important in remote regions. Additionally, it enables the estimation of forest canopy transmissivity without ancillary data. This study also demonstrates the use of these frequencies in a forest canopy application, and the use of the Freeman–Durden three-component decomposition on scatterometer observations in a terrestrial snow accumulation environment.

scholarly journals The use of laser scanning technology of accounting for wood

2015 ◽  
Vol 5 (4) ◽  
pp. 114-122
Author(s):  
Стариков ◽  
Aleksandr Starikov ◽  
Батурин ◽  
Kirill Baturin
Keyword(s):  
Laser Scanning ◽  
Forest Canopy ◽  
Forest Cover ◽  
Three Dimensional ◽  
Terrestrial Laser Scanning ◽  
Monitoring And Evaluation ◽  
Digital Processing ◽  
Forest Plantations ◽  
Three Dimensional Model ◽  
Individual Trees

Now for the decision of tasks of monitoring and evaluation of forest plantations the use of methods and means of laser scanning is one of the most act-sexual and priorities. Laser scanning can be performed independently, or in combination with digital aerial and space photos and video, and can also be carried out ground research on the sample areas. A number of indicators laser scanning is superior to other, currently known, remote evaluation methods qualitative and quantitative characteristics of the forest Fund Laser scanning of forest cover based on the use of modern tech-nologies of digital photogrammetry and geoinformation systems, as well as methods of digital processing and multidimensional modeling of the reflected signals. The article provides analysis of modern methods and means of aerial and terrestrial laser scanning of forest stands. The use of air-borne laser scanning will allow achieving high precision in the determination of basic inventory pa-rameters that are comparable to land-based taxation. Main advantages of laser ranging to other me-thods of monitoring of forest plantations is that the laser beam is able to penetrate the forest canopy, thereby scanning all the tiers of the stand. High density scanning (5-10 points per 1 m2) allows ob-taining three-dimensional images of individual trees with high accuracy. The obtained three-dimensional model requires no processing, unlike aerospace methods of remote sensing that are as-sociated with long and arduous races-encryption of the images. Terrestrial laser scanning, in fact, similar to traditional photogrammetric methods, but it allows you to get the coordinates from one point of standing with the possibility of control measurements directly in the field, while providing higher measurement accuracy, compared with photogrammetric methods.

scholarly journals Estimation of forest structure metrics relevant to hydrologic modelling using coordinate transformation of airborne laser scanning data

2012 ◽  
Vol 16 (10) ◽  
pp. 3749-3766 ◽  
Author(s):  
A. Varhola ◽  
G. W. Frazer ◽  
P. Teti ◽  
N. C. Coops
Keyword(s):  
Solar Radiation ◽  
Forest Structure ◽  
Laser Scanning ◽  
Forest Canopy ◽  
Airborne Laser Scanning ◽  
Water Dynamics ◽  
Hydrologic Models ◽  
Hydrologic Modelling ◽  
Airborne Laser ◽  
Structure Metrics

Abstract. An accurate characterisation of the complex and heterogeneous forest architecture is necessary to parameterise physically-based hydrologic models that simulate precipitation interception, energy fluxes and water dynamics. While hemispherical photography has become a popular method to obtain a number of forest canopy structure metrics relevant to these processes, image acquisition is field-intensive and, therefore, difficult to apply across the landscape. In contrast, airborne laser scanning (ALS) is a remote-sensing technique increasingly used to acquire detailed information on the spatial structure of forest canopies over large, continuous areas. This study presents a novel methodology to calibrate ALS data with in situ optical hemispherical camera images to obtain traditional forest structure and solar radiation metrics. The approach minimises geometrical differences between these two techniques by transforming the Cartesian coordinates of ALS data to generate synthetic images with a polar projection directly comparable to optical photography. We demonstrate how these new coordinate-transformed ALS metrics, along with additional standard ALS variables, can be used as predictors in multiple linear regression approaches to estimate forest structure and solar radiation indices at any individual location within the extent of an ALS transect. We expect this approach to substantially reduce fieldwork costs, broaden sampling design possibilities, and improve the spatial representation of forest structure metrics directly relevant to parameterising fully-distributed hydrologic models.

scholarly journals Comparison of LiDAR and Digital Aerial Photogrammetry for Characterizing Canopy Openings in the Boreal Forest of Northern Alberta

2019 ◽  
Vol 11 (16) ◽  
pp. 1919 ◽  
Author(s):  
Annette Dietmaier ◽  
Gregory J. McDermid ◽  
Mir Mustafizur Rahman ◽  
Julia Linke ◽  
Ralf Ludwig
Keyword(s):  
Boreal Forest ◽  
Forest Structure ◽  
Forest Canopy ◽  
Canopy Structure ◽  
Three Dimensional ◽  
Canopy Cover ◽  
Aerial Photogrammetry ◽  
Northern Alberta ◽  
Height Model ◽  
Economical Alternative

Forest canopy openings are a key element of forest structure, influencing a host of ecological dynamics. Light detection and ranging (LiDAR) is the de-facto standard for measuring three-dimensional forest structure, but digital aerial photogrammetry (DAP) has emerged as a viable and economical alternative. We compared the performance of LiDAR and DAP data for characterizing canopy openings and no-openings across a 1-km2 expanse of boreal forest in northern Alberta, Canada. Structural openings in canopy cover were delineated using three canopy height model (CHM) alternatives, from (i) LiDAR, (ii) DAP, and (iii) a LiDAR/DAP hybrid. From a point-based detectability perspective, the LiDAR CHM produced the best results (87% overall accuracy), followed by the hybrid and DAP models (47% and 46%, respectively). The hybrid and DAP CHMs experienced large errors of omission (9–53%), particularly with small openings up to 20m2, which are an important element of boreal forest structure. By missing these, DAP and hybrid datasets substantially under-reported the total area of openings across our site (152,470 m2 and 159,848 m2, respectively) compared to LiDAR (245,920 m2). Our results illustrate DAP’s sensitivity to occlusions, mismatched tie points, and other optical challenges inherent to using structure-from-motion workflows in complex forest scenes. These under-documented constraints currently limit the technology’s capacity to fully characterize canopy structure. For now, we recommend that operational use of DAP in forests be limited to mapping large canopy openings, and area-based attributes that are well-documented in the literature.

scholarly journals Forest impacts on snow accumulation and ablation across an elevation gradient in a temperate montane environment

2016 ◽  
Author(s):  
Travis R. Roth ◽  
Anne W. Nolin
Keyword(s):  
Forest Canopy ◽  
Forest Cover ◽  
Snow Accumulation ◽  
Forest Site ◽  
Canopy Interception ◽  
Study Region ◽  
Wind Speeds ◽  
Open Site ◽  
Forest Sites ◽  
Energy Inputs

Abstract. Forest cover modifies snow accumulation and ablation rates via canopy interception and changes in sub-canopy energy balance processes. However, the ways in which snowpacks are affected by forest canopy processes vary depending on climatic, topographic and forest characteristics. Here we present results from a 4 year study of snow-forest interactions in the Oregon Cascades. We continuously monitored snow and meteorological variables at paired forested and open sites at three elevations representing the Low, Mid, and High seasonal snow zones in the study region. On a monthly to bi-weekly basis, we surveyed snow depth and snow water equivalent across 900 m transects connecting the forested and open pairs of sites. Our results show that the dense, relatively warm on forests at Low and Mid sites impede snow accumulation through increased canopy snow interception and increase energy inputs to the sub-canopy snowpack. Compared with the Forest sites, snowpacks are deeper and last longer in the Open site at the Low and Mid sites (4 – 26 days and 11 – 33 days, respectively). However, we see the opposite relationship at the relatively colder High sites with the Forest site maintaining snow longer into the spring by 15 – 29 days relative to the nearby Open site. Over a 4 year study, canopy interception efficiency (CIE) values in the Low- and Mid-Forest sites, were 79 % and 76 % of the total event snowfall, whereas CIE was 31 % at the lower density High-Forest site. At all elevations, longwave radiation in forested environments appears to be the primary energy component due to the maritime climate and forest presence, accounting for 82 %, 88 %, and 59 % of total energy inputs to the snowpack at the Low-, Mid-, and High-Forest sites, respectively. Higher wind speeds in the High-Open site significantly increase turbulent energy exchanges and snow sublimation. Lower wind speeds in the High-Forest site create preferential snowfall deposition. These results show the importance of understanding the effects of forest cover on sub-canopy snowpack evolution and highlight the need for improved forest cover model representation to accurately predict water resources in maritime forests.

Seasonal snow accumulation in the mid-latitude forested catchment

Biologia ◽  
2014 ◽  
Vol 69 (11) ◽  
Author(s):  
Václav Šípek ◽  
Miroslav Tesař
Keyword(s):  
Snow Cover ◽  
Forest Canopy ◽  
Forest Cover ◽  
Snow Water Equivalent ◽  
Elevation Gradient ◽  
Snow Accumulation ◽  
Forested Catchment ◽  
Seasonal Snow ◽  
Snow Water ◽  
Fagus Sylvatica L

AbstractThe study deals with the snow cover characteristics (snow depth — SD and snow water equivalent — SWE) concerning the mid-latitude forested catchment. Namely, the influence of the forest canopy (Picea abies (L.) Karst. and Fagus sylvatica L.) and altitude (ranging from 835 m a.s.l. to 1118 m a.s.l.) was investigated. Forest cover was proved to have a significant influence on the snow cover accumulation, reducing SWE by 50 % on average, compared to open sites. The elevation gradient concerning SWE ranged from 30 to 40 mm and from 5 to 20 mm per 100 m in open and forested sites, respectively. Its magnitude was found to be temporarily variable and positively related to the total seasonal snowfall amount. The SWE/SD variability among measurement sites (with different altitude) was higher in open sites compared to forested ones. The catchment SWE/SD variability increases significantly in the snowmelt period (March–April) both in open and forested locations. The differences among snow interception losses, concerning various elevations and the forest canopy, were not statistically significant.

scholarly journals Estimation of forest structure metrics relevant to hydrologic modeling using coordinate transformation of airborne laser scanning data

2012 ◽  
Vol 9 (4) ◽  
pp. 5531-5573 ◽  
Author(s):  
A. Varhola ◽  
G. W. Frazer ◽  
P. Teti ◽  
N. C. Coops
Keyword(s):  
Solar Radiation ◽  
Forest Structure ◽  
Laser Scanning ◽  
Forest Canopy ◽  
Canopy Structure ◽  
Airborne Laser Scanning ◽  
Water Dynamics ◽  
Hydrologic Models ◽  
Airborne Laser ◽  
Structure Metrics

Abstract. Accurate characterizations of the complex and heterogeneous forest architecture are necessary to parameterize physically-based hydrologic models that simulate precipitation interception, energy fluxes and water dynamics. While hemispherical photography has become a popular method to obtain a number of forest canopy structure metrics relevant to these processes, image acquisition is field-intensive and therefore difficult to apply across the landscape. In contrast, airborne laser scanning (ALS) is a remote sensing technique increasingly used to acquire detailed information on the spatial structure of forest canopies over large, continuous areas. This study presents a novel methodology to calibrate ALS data with in-situ optical hemispherical camera images to obtain traditional forest structure and solar radiation metrics. The approach minimizes geometrical differences between these two techniques by transforming the Cartesian coordinates of ALS data to generate synthetic images with a polar projection directly comparable to optical photography. We demonstrate how these new coordinate-transformed ALS metrics, along with additional standard ALS variables, can be used as predictors in multiple linear regression to estimate forest structure and solar radiation indices at any individual location within the extent of an ALS transect. This approach is expected to substantially reduce fieldwork costs, broaden sampling design possibilities, and improve the spatial representation of forest structure metrics directly relevant to parameterize hydrologic models.

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

scholarly journals Patterns and Drivers of Deforestation and Forest Degradation in Myanmar

2021 ◽  
Vol 13 (14) ◽  
pp. 7539
Author(s):  
Zaw Naing Tun ◽  
Paul Dargusch ◽  
DJ McMoran ◽  
Clive McAlpine ◽  
Genia Hill
Keyword(s):  
Remote Sensing ◽  
Change Detection ◽  
Local Governments ◽  
Forest Canopy ◽  
Forest Cover ◽  
Forest Degradation ◽  
Forest Monitoring ◽  
Map Algebra ◽  
Change Detection Analysis ◽  
Detection Analysis

Myanmar is one of the most forested countries of mainland Southeast Asia and is a globally important biodiversity hotspot. However, forest cover has declined from 58% in 1990 to 44% in 2015. The aim of this paper was to understand the patterns and drivers of deforestation and forest degradation in Myanmar since 2005, and to identify possible policy interventions for improving Myanmar’s forest management. Remote sensing derived land cover maps of 2005, 2010 and 2015 were accessed from the Forest Department, Myanmar. Post-classification change detection analysis and cross tabulation were completed using spatial analyst and map algebra tools in ArcGIS (10.6) software. The results showed the overall annual rate of forest cover loss was 2.58% between 2005 and 2010, but declined to 0.97% between 2010 and 2015. The change detection analysis showed that deforestation in Myanmar occurred mainly through the degradation of forest canopy associated with logging rather than forest clearing. We propose that strengthening the protected area system in Myanmar, and community participation in forest conservation and management. There needs to be a reduction in centralisation of forestry management by sharing responsibilities with local governments and the movement away from corruption in the timber trading industry through the formation of local-based small and medium enterprises. We also recommend the development of a forest monitoring program using advanced remote sensing and GIS technologies.

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