Comparison of laser and field measurements of vegetation height and canopy cover

1994 ◽  
Vol 30 (5) ◽  
pp. 1311-1319 ◽  
Author(s):  
Mark A. Weltz ◽  
Jerry C. Ritchie ◽  
H. Dale Fox
Keyword(s):  
Canopy Cover ◽  
Field Measurements ◽  
Vegetation Height

scholarly journals Accuracy Assessment of GEDI Terrain Elevation and Canopy Height Estimates in European Temperate Forests: Influence of Environmental and Acquisition Parameters

2020 ◽  
Vol 12 (23) ◽  
pp. 3948
Author(s):  
Markus Adam ◽  
Mikhail Urbazaev ◽  
Clémence Dubois ◽  
Christiane Schmullius
Keyword(s):  
Laser Scanning ◽  
Temperate Forests ◽  
Accuracy Assessment ◽  
Canopy Cover ◽  
Global Scale ◽  
Canopy Height ◽  
Ecosystem Dynamics ◽  
Vegetation Height ◽  
Height Estimates ◽  
Terrain Elevation

Lidar remote sensing has proven to be a powerful tool for estimating ground elevation, canopy height, and additional vegetation parameters, which in turn are valuable information for the investigation of ecosystems. Spaceborne lidar systems, like the Global Ecosystem Dynamics Investigation (GEDI), can deliver these height estimates on a near global scale. This paper analyzes the accuracy of the first version of GEDI ground elevation and canopy height estimates in two study areas with temperate forests in the Free State of Thuringia, central Germany. Digital terrain and canopy height models derived from airborne laser scanning data are used as reference heights. The influence of various environmental and acquisition parameters (e.g., canopy cover, terrain slope, beam type) on GEDI height metrics is assessed. The results show a consistently high accuracy of GEDI ground elevation estimates under most conditions, except for areas with steep slopes. GEDI canopy height estimates are less accurate and show a bigger influence of some of the included parameters, specifically slope, vegetation height, and beam sensitivity. A number of relatively high outliers (around 9–13% of the measurements) is present in both ground elevation and canopy height estimates, reducing the estimation precision. Still, it can be concluded that GEDI height metrics show promising results and have potential to be used as a basis for further investigations.

NASA Cold Land Processes Experiment (CLPX 2002/03): Field Measurements of Snowpack Properties and Soil Moisture

2009 ◽  
Vol 10 (1) ◽  
pp. 320-329 ◽  
Author(s):  
Kelly Elder ◽  
Don Cline ◽  
Glen E. Liston ◽  
Richard Armstrong
Keyword(s):  
Soil Moisture ◽  
Canopy Cover ◽  
Field Measurements ◽  
Near Surface ◽  
Surface Wetness ◽  
North Park ◽  
Soil Measurements ◽  
Snowpack Properties ◽  
Fraser Valley ◽  
Rabbit Ears

Abstract A field measurement program was undertaken as part NASA’s Cold Land Processes Experiment (CLPX). Extensive snowpack and soil measurements were taken at field sites in Colorado over four study periods during the two study years (2002 and 2003). Measurements included snow depth, density, temperature, grain type and size, surface wetness, surface roughness, and canopy cover. Soil moisture measurements were made in the near-surface layer in snow pits. Measurements were taken in the Fraser valley, North Park, and Rabbit Ears Pass areas of Colorado. Sites were chosen to gain a wide representation of snowpack types and physiographies typical of seasonally snow-covered regions of the world. The data have been collected with rigorous protocol to ensure consistency and quality, and they have undergone several levels of quality assurance to produce a high-quality spatial dataset for continued cold lands hydrological research. The dataset is archived at the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado.

scholarly journals Regional Scale Dryland Vegetation Classification with an Integrated Lidar-Hyperspectral Approach

2019 ◽  
Vol 11 (18) ◽  
pp. 2141 ◽  
Author(s):  
Hamid Dashti ◽  
Andrew Poley ◽  
Nancy F. Glenn ◽  
Nayani Ilangakoon ◽  
Lucas Spaete ◽  
...  
Keyword(s):  
Regional Scale ◽  
Imaging Spectroscopy ◽  
Canopy Structure ◽  
Canopy Cover ◽  
Vegetation Classification ◽  
Large Contribution ◽  
Spectral Angle Mapper ◽  
Vegetation Height ◽  
Sparse Canopy ◽  
Spectral Mixture

The sparse canopy cover and large contribution of bright background soil, along with the heterogeneous vegetation types in close proximity, are common challenges for mapping dryland vegetation with remote sensing. Consequently, the results of a single classification algorithm or one type of sensor to characterize dryland vegetation typically show low accuracy and lack robustness. In our study, we improved classification accuracy in a semi-arid ecosystem based on the use of vegetation optical (hyperspectral) and structural (lidar) information combined with the environmental characteristics of the landscape. To accomplish this goal, we used both spectral angle mapper (SAM) and multiple endmember spectral mixture analysis (MESMA) for optical vegetation classification. Lidar-derived maximum vegetation height and delineated riparian zones were then used to modify the optical classification. Incorporating the lidar information into the classification scheme increased the overall accuracy from 60% to 89%. Canopy structure can have a strong influence on spectral variability and the lidar provided complementary information for SAM’s sensitivity to shape but not magnitude of the spectra. Similar approaches to map large regions of drylands with low uncertainty may be readily implemented with unmixing algorithms applied to upcoming space-based imaging spectroscopy and lidar. This study advances our understanding of the nuances associated with mapping xeric and mesic regions, and highlights the importance of incorporating complementary algorithms and sensors to accurately characterize the heterogeneity of dryland ecosystems.

Fine-scale habitat use by the southern emu-wren (Stipiturus malachurus)

2006 ◽  
Vol 33 (2) ◽  
pp. 137 ◽  
Author(s):  
Grainne S. Maguire
Keyword(s):  
Habitat Use ◽  
Plant Species ◽  
Habitat Structure ◽  
Canopy Cover ◽  
Ground Level ◽  
Fine Scale ◽  
Vegetation Height ◽  
Vertical Density ◽  
Foliage Density ◽  
Floristic Characteristics

Fine-scale variation in habitat structure and composition is likely to influence habitat use by avian species with limited flight capabilities. I investigated proportional use of available habitat and microhabitat by the southern emu-wren (Stipiturus malachurus), a threatened, flight-limited passerine, at three sites in Victoria, in relation to vegetation structure and composition. Emu-wrens appeared to discriminate between habitats with regard to structural rather than floristic characteristics. Habitats with dense vertical foliage of shrubs, grasses and sedges/rushes between ground level and 100 cm, and dense horizontal cover of medium to tall shrubs, were used most frequently. However, when availability of habitat was taken into account, habitat use was negatively correlated with the vertical density of low shrub foliage and species richness. Within habitats, emu-wrens more frequently used plant species that had a dense canopy cover (26 ± 2% of total cover, crown diameter 93 ± 5 cm), high foliage density between 50 and 100 cm, and average heights of ~1 m. Plant species in which the birds nested comprised ~14% of total canopy cover and were densest between ground level and 50 cm. Canopy cover, vegetation height and vertical foliage density were consistently important variables correlated with emu-wren habitat use at multiple fine-scales. This study provides valuable information for conservation management of the species; in particular, the restoration of degraded habitats.

Effects of overtopping vegetation on light availability and growth of Engelmann spruce (Piceaengelmannii) seedlings

1993 ◽  
Vol 23 (10) ◽  
pp. 2044-2048 ◽  
Author(s):  
Philip G. Comeau ◽  
Thomas F. Braumandl ◽  
Chang-Yi Xie
Keyword(s):  
Seedling Growth ◽  
Objective Assessment ◽  
Light Availability ◽  
Field Measurements ◽  
Percent Cover ◽  
Competition Index ◽  
Full Sunlight ◽  
Vegetation Height ◽  
Engelmann Spruce ◽  
Neighborhood Studies

To examine the effects of overtopping vegetation on solar irradiance reaching Engelmann spruce (Piceaengelmannii Parry) seedlings and on crop seedling performance, neighborhood studies were established at six sites in mixed shrub–herb and fireweed communities of the Interior Cedar–Hemlock zone of southern British Columbia. These communities were dominated by mixtures of fireweed (Epilobiumangustifolium L.), thimbleberry (Rubusparviflorus Nutt.), red raspberry (Rubusidaeus L.), and (or) bracken fern (Pteridiumaquilinum (L.) Kuhn). Three hundred and eighty-eight planted Engelmann spruce seedlings, between 1 and 5 years of age, served as plot centers for measurements in 1990 and 1991. Vegetation had been clipped around 109 of these seedlings in 1988, 1989, and 1990. Seedling diameter and height were measured in the autumn of 1990 and 1991. Vegetation cover, vegetation height, and the fraction of full sunlight reaching the top branches of each spruce seedling were measured in midsummer of 1991. A simple competition index (CI), based on visually estimated percent cover, height of each species present within 1.26 m of the crop seedling, and crop-seedling height, can be used to estimate the fraction of full sunlight reaching crop seedlings. Measurements of transmittance through vegetation canopies are correlated with this competition index and could be useful as a separate, objective assessment of competition levels. Seedling growth was related to both seedling-needle biomass (at the beginning of the year) and either CI or the amount of light reaching crop seedlings during midsummer. Growth increased as needle biomass or irradiance reaching the seedling increased and decreased as CI increased. Since CI can be calculated from simple field measurements and since seedling growth is related to CI, this index has potential utility in evaluating the need for operational release treatments. Transmittance measurement provides an equally useful, and potentially more objective approach to evaluating the need for release treatment. Results from this study suggest that cumulative effects of competition result at least in part from effects on growth of seedling leaf mass.

scholarly journals ¿Refleja Formicidae el impacto de la degradación de los bosques ribereños en la Amazonía Oriental?

2019 ◽  
Vol 67 (4) ◽  
Author(s):  
Stefania Pinzon Triana ◽  
Guillaume Xavier Rousseau ◽  
Jhonatan Andrés Muñoz Gutiérrez ◽  
Alexandra Rocha da Piedade ◽  
Heder Braun
Keyword(s):  
Riparian Forest ◽  
Similarity Index ◽  
Canopy Cover ◽  
Dry Season ◽  
Riparian Forests ◽  
Sampling Effort ◽  
Anthropogenic Pressure ◽  
Successional Stage ◽  
Vegetation Height ◽  
The Impact

The increasing anthropogenic pressure on the Eastern Amazon makes the diagnostic of forest degradation imperative, particularly, the effect on key communities within the riparian ecosystems. Formicidae is commonly used in diagnostic and monitoring studies in areas under restoration. This study aimed to determine the impact of riparian forest successional stages (open areas, and, early, intermediate, and advanced succession) on the richness, frequency, and composition of Formicidae. Sampling was performed during both dry and wet seasons, with the TSBF (Tropical Soil Biological and Fertility) method. Collected organisms were identified to species and morphospecies level and the analysis of collector curves determined the method efficiency to represent the ant sub-community. Ant richness and frequency were submitted to generalized linear mixed models to evaluate the effects of season, local, and successional stage. We used linear regressions model to investigate the relationship between richness and frequency of ants with canopy cover and vegetation height. Species composition was represented by the Jaccard similarity index. In total, we observed 1940 individuals grouped into 86 (morpho)species. Analysis of sampling effort suggested that we obtained more than 80% of the probable species richness. Frequency and richness significantly increased following the advanced succession in comparison with the open areas during the dry season. Canopy cover and vegetation height seemed to moderately affect both richness and frequency of Formicidae during the dry season. Intermediate and advanced succession areas presented similar composition with 50 shared species, followed by the areas of early succession with 43, and, anthropic use with 34 shared species. We conclude that the elimination of riparian forests results in a substantial effect on the richness and frequency of Formicidae, with minimum values in open areas during the dry season. Forest areas transformed to agricultural systems suffered losses of 41% and 56% of richness and frequency respectively. Succession restores forest structure and functions thus, favoring re-colonization of ant species. Formicidae reflects forests degradation, and is a key group in monitoring programs for the conservation/restoration of local riparian forests. Agroforestry and silvopastoral systems should be promoted as low impact practices for adjacent lands to riparian forests.

scholarly journals Airborne laser scanning proxies of canopy light transmission in forests

2021 ◽  
Author(s):  
Adam Erickson ◽  
Nicholas Coops
Keyword(s):  
Laser Scanning ◽  
Light Transmission ◽  
Canopy Cover ◽  
Field Measurements ◽  
Airborne Laser Scanning ◽  
Validation Data ◽  
Cloud Models ◽  
Airborne Laser ◽  
Gap Fraction ◽  
And Function

Reliable estimates of canopy light transmission are critical to understanding the structure and function of vegetation communities but are difficult and costly to attain by traditional field inventory methods. Airborne laser scanning (ALS) data uniquely provide multi-angular vertically resolved representation of canopy geometry across large geographic areas. While previous studies have proposed ALS indices of canopy light transmission, new algorithms based on theoretical advancements may improve existing models. Herein, we propose two new models of canopy light transmission (i.e., gap fraction, or Po, the inverse of angular canopy closure). We demonstrate the models against a suite of existing models and ancillary metrics, validated against convex spherical densiometer measurements for 950 field plots in the foothills of Alberta, Canada. We also tested the effects of synthetic hemispherical lens models on the performance of the proposed hemispherical Voronoi gap fraction (Phv) index. While vertical canopy cover metrics showed the best overall fit to field measurements, one new metric, point-density-normalized gap fraction (Ppdn), outperformed all other gap fraction metrics by two-fold. We provide suggestions for further algorithm enhancements based on validation data improvements. We argue that traditional field measurements are no longer appropriate for ‘ground-truthing’ modern LiDAR or SfM point cloud models, as the latter provide orders of magnitude greater sampling and coverage. We discuss the implications of this finding for LiDAR applications in forestry.

scholarly journals HABITAT UTILIZATION BY THE TEXAS HORNED LIZARD (PHRYNOSOMA CORNUTUM) FROM TWO SITES IN CENTRAL TEXAS

2017 ◽  
pp. 28-33
Author(s):  
Wesley M. Anderson ◽  
David B. Wester ◽  
Christopher J. Salice ◽  
Gad Perry
Keyword(s):  
Habitat Use ◽  
Canopy Cover ◽  
Ground Cover ◽  
Plant Species Richness ◽  
Phrynosoma Cornutum ◽  
Vegetation Height ◽  
Blue Mountain ◽  
Texas Horned Lizard ◽  
Central Texas ◽  
Vegetation Encroachment

The Texas Horned Lizard (Phrynosoma cornutum) is found in a variety of habitats. Although several studies have been conducted on habitat use by this species, none have been performed in central Texas, a more mesic habitat than most of those previously studied. This area is of special interest because horned lizard populations have been experiencing sharp declines in central Texas over the last approximately 50 years. We collected habitat data at two sites in central Texas, Camp Bowie and Blue Mountain Peak Ranch. Microhabitat data included canopy cover and ground cover from digitized photographs of Daubenmire quadrats; macrohabitat variables included vegetation height and length, cactus height, soil penetrability, woody plant species richness, tree density, tree diameter at breast height (DBH), and density of ant mounds collected along 100-m by 2-m transects. Similar patterns of habitat use were observed between the two sites. At Blue Mountain Peak Ranch, lizards appeared to be located in areas with a diversity of ground cover types, as observed in previous studies. At Camp Bowie, vegetation encroachment limited lizards in some areas to the use of roads and road margins. Implementation of prescribed burns or other vegetation management could create the preferred ground cover mosaic at such sites.

Estimating vegetation height and canopy cover from remotely sensed data with machine learning

2010 ◽  
Vol 5 (4) ◽  
pp. 256-266 ◽  
Author(s):  
Daniela Stojanova ◽  
Panče Panov ◽  
Valentin Gjorgjioski ◽  
Andrej Kobler ◽  
Sašo Džeroski
Keyword(s):  
Machine Learning ◽  
Canopy Cover ◽  
Remotely Sensed ◽  
Remotely Sensed Data ◽  
Vegetation Height

scholarly journals Enhancing Methods for Under-Canopy Unmanned Aircraft System Based Photogrammetry in Complex Forests for Tree Diameter Measurement

2020 ◽  
Vol 12 (10) ◽  
pp. 1652
Author(s):  
Sean Krisanski ◽  
Mohammad Sadegh Taskhiri ◽  
Paul Turner
Keyword(s):  
Forest Canopy ◽  
Measurement Techniques ◽  
Digital Terrain Model ◽  
Canopy Cover ◽  
Field Measurements ◽  
Point Clouds ◽  
3D Models ◽  
Unmanned Aircraft ◽  
Global Navigation Satellite Systems ◽  
Diameter Measurement

The application of Unmanned Aircraft Systems (UAS) beneath the forest canopy provides a potentially valuable alternative to ground-based measurement techniques in areas of dense canopy cover and undergrowth. This research presents results from a study of a consumer-grade UAS flown under the forest canopy in challenging forest and terrain conditions. This UAS was deployed to assess under-canopy UAS photogrammetry as an alternative to field measurements for obtaining stem diameters as well as ultra-high-resolution (~400,000 points/m2) 3D models of forest study sites. There were 378 tape-based diameter measurements collected from 99 stems in a native, unmanaged eucalyptus pulchella forest with mixed understory conditions and steep terrain. These measurements were used as a baseline to evaluate the accuracy of diameter measurements from under-canopy UAS-based photogrammetric point clouds. The diameter measurement accuracy was evaluated without the influence of a digital terrain model using an innovative tape-based method. A practical and detailed methodology is presented for the creation of these point clouds. Lastly, a metric called the Circumferential Completeness Index (CCI) was defined to address the absence of a clearly defined measure of point coverage when measuring stem diameters from forest point clouds. The measurement of the mean CCI is suggested for use in future studies to enable a consistent comparison of the coverage of forest point clouds using different sensors, point densities, trajectories, and methodologies. It was found that root-mean-squared-errors of diameter measurements were 0.011 m in Site 1 and 0.021 m in the more challenging Site 2. The point clouds in this study had a mean validated CCI of 0.78 for Site 1 and 0.7 for Site 2, with a mean unvalidated CCI of 0.86 for Site 1 and 0.89 for Site 2. The results in this study demonstrate that under-canopy UAS photogrammetry shows promise in becoming a practical alternative to traditional field measurements, however, these results are currently reliant upon the operator’s knowledge of photogrammetry and his/her ability to fly manually in object-rich environments. Future work should pursue solutions to autonomous operation, more complete point clouds, and a method for providing scale to point clouds when global navigation satellite systems are unavailable.

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