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.

scholarly journals ASSESSING THE CANOPY INTEGRITY USING CANOPY DIGITAL IMAGES IN SEMIDECIDUOUS FOREST FRAGMENT IN SÃO CARLOS - SP- BRAZIL1

2017 ◽  
Vol 41 (5) ◽  
Author(s):  
Thiago Yamada ◽  
Emerson Carlos Pedrino ◽  
João Juares Soares ◽  
Maria do Carmo Nicoletti
Keyword(s):  
Digital Image Analysis ◽  
Digital Images ◽  
Research Work ◽  
Canopy Structure ◽  
Canopy Cover ◽  
Relevant Information ◽  
Canopy Closure ◽  
Forest Fragment ◽  
Semideciduous Forest

ABSTRACT It is well-known that conducting experimental research aiming the characterization of canopy structure of forests can be a difficult and costly task and, generally, requires an expert to extract, in loco, relevant information. Aiming at easing studies related to canopy structures, several techniques have been proposed in the literature and, among them, various are based on canopy digital image analysis. The research work described in this paper empirically compares two techniques that measure the integrity of the canopy structure of a forest fragment; one of them is based on central parts of canopy cover images and, the other, on canopy closure images. For the experiments, 22 central parts of canopy cover images and 22 canopy closure images were used. The images were captured along two transects: T1 (located in the conserved area) and T2 (located in the naturally disturbance area). The canopy digital images were computationally processed and analyzed using the MATLAB platform for the canopy cover images and the Gap Light Analyzer (GLA), for the canopy closure images. The results obtained using these two techniques showed that canopy cover images and, among the employed algorithms, the Jseg, characterize the canopy integrity best. It is worth mentioning that part of the analysis can be automatically conducted, as a quick and precise process, with low material costs involved.

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.

scholarly journals Rapid response of habitat structure and above-ground carbon storage to altered fire regimes in tropical savanna

2019 ◽  
Vol 16 (7) ◽  
pp. 1493-1503 ◽  
Author(s):  
Shaun R. Levick ◽  
Anna E. Richards ◽  
Garry D. Cook ◽  
Jon Schatz ◽  
Marcus Guderle ◽  
...  
Keyword(s):  
Carbon Storage ◽  
Vegetation Structure ◽  
Habitat Structure ◽  
Canopy Structure ◽  
Three Dimensional ◽  
Canopy Cover ◽  
Fire Regimes ◽  
Dry Season ◽  
Airborne Lidar ◽  
Climate Conditions

Abstract. Fire regimes across the globe have been altered through changes in land use, land management, and climate conditions. Understanding how these modified fire regimes impact vegetation structure and dynamics is essential for informed biodiversity conservation and carbon management in savanna ecosystems. We used a fire experiment at the Territory Wildlife Park (TWP), northern Australia, to investigate the consequences of altered fire regimes for vertical habitat structure and above-ground carbon storage. We mapped vegetation three-dimensional (3-D) structure in high spatial resolution with airborne lidar across 18 replicated 1 ha plots of varying fire frequency and season treatments. We used lidar-derived canopy height and cover metrics to extrapolate field-based measures of woody biomass to the full extent of the experimental site (R2=0.82, RMSE = 7.35 t C ha−1) and analysed differences in above-ground carbon storage and canopy structure among treatments. Woody canopy cover and biomass were highest in the absence of fire (76 % and 39.8 t C ha−1) and lowest in plots burnt late in the dry season on a biennial basis (42 % and 18.2 t C ha−1). Woody canopy vertical profiles differed among all six fire treatments, with the greatest divergence in height classes <5 m. The magnitude of fire effects on vegetation structure varied along the environmental gradient underpinning the experiment, with less reduction in biomass in plots with deeper soils. Our results highlight the large extent to which fire management can shape woody structural patterns in savanna landscapes, even over time frames as short as a decade. The structural profile changes shown here, and the quantification of carbon reduction under late dry season burning, have important implications for habitat conservation, carbon sequestration, and emission reduction initiatives in the region.

scholarly journals Forest Cover Change within the Russian European North after the Breakdown of Soviet Union (1990–2005)

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Peter Potapov ◽  
Svetlana Turubanova ◽  
Ilona Zhuravleva ◽  
Matthew Hansen ◽  
Alexey Yaroshenko ◽  
...  
Keyword(s):  
Soviet Union ◽  
Forest Cover ◽  
Spatial Information ◽  
Regional Scale ◽  
Canopy Cover ◽  
Tree Canopy ◽  
Forest Cover Change ◽  
European North ◽  
Tree Canopy Cover ◽  
Forest Cover Loss

Forest cover dynamics (defined as tree canopy cover change without regard to forest land use) within the Russian European North have been analyzed from 1990 to 2005 using a combination of results from two Landsat-based forest cover monitoring projects: 1990–2000 and 2000–2005. Results of the forest cover dynamics analysis highlighted several trends in forest cover change since the breakdown of the Soviet planned economy. While total logging area decreased from the 1990–2000 to the 2000–2005 interval, logging and other forms of anthropogenically-induced clearing increased within the Central and Western parts of the region. The most populated regions of European Russia featured the highest rates of net forest cover loss. Our results also revealed intensive gross forest cover loss due to forest felling close to the Russian-Finland border. The annual burned forest area almost doubled between the two time intervals. The 2000–2005 gross forest cover gain results suggest that tree encroachment on abandoned agriculture land is a wide-spread process over the region. The analysis demonstrates the value of regional-scale Landsat-based forest cover and change quantification. Our results supplemented official data by providing independently derived spatial information that could be used for assessing on-going trends and serve as a baseline for future forest cover monitoring.

Disentangling the Control of Canopy Structure and Plant Physiology on the Diurnal Dynamics of SIF and Photosynthesis

2020 ◽  
Author(s):  
Christine Chang ◽  
Jiaming Wen ◽  
Ruiqing Zhou ◽  
Ying Sun
Keyword(s):  
Plant Physiology ◽  
Chlorophyll Fluorescence ◽  
Regional Scale ◽  
Canopy Structure ◽  
Hyperspectral Reflectance ◽  
Diurnal Dynamics ◽  
Promising Tool ◽  
Leaf Level ◽  
Biological Context

&lt;p&gt;Solar-induced chlorophyll fluorescence (SIF) offers a promising tool to remotely monitor photosynthesis from the canopy to regional scale. However, in order to interpret instantaneous satellite SIF measurements in a biological context, there needs to be a better understanding of the diurnal dynamics of SIF and photosynthesis. Using two maize sites with contrasting row orientations, we acquired canopy scale SIF and hyperspectral reflectance using a tower and UAV, in conjunction with concurrent leaf-level measurements of photosynthesis and chlorophyll fluorescence. We show that SIF dynamics are impacted by a combination of canopy structure and plant physiology, which can lead to a divergent SIF-photosynthesis relationship, particularly at certain times of day. These findings have significant implications for upscaling and interpreting satellite SIF retrievals, which rely on daily mean integrals.&lt;/p&gt;

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.

scholarly journals Floristic and structural patterns in South Brazilian coastal grasslands

2015 ◽  
Vol 87 (4) ◽  
pp. 2081-2090 ◽  
Author(s):  
LUCIANA S. MENEZES ◽  
SANDRA C. MÜLLER ◽  
GERHARD E. OVERBECK
Keyword(s):  
Coastal Plain ◽  
Management Practices ◽  
Regional Scale ◽  
Coastal Region ◽  
Bare Soil ◽  
Livestock Grazing ◽  
Paspalum Notatum ◽  
Southern Brazil ◽  
Important Species ◽  
Vegetation Height

ABSTRACT The natural vegetation of Southern Brazil's coastal region includes grasslands formations that are poorly considered in conservation policy, due to the lack of knowledge about these systems. This study reports results from a regional-scale survey of coastal grasslands vegetation along a 536 km gradient on southern Brazil. We sampled 16 sites along the coastal plain with 15 plots (1 m²) per site. All sites were grazed by cattle. We estimated plant species cover, vegetation height, percentage of bare soil, litter and manure, and classified species according to their growth forms. We found 221 species, 14 of them exotic and two threatened. The prostate grasses: Axonopus aff.affinis, Paspalum notatum and P. pumilumwere among the most important species. Prostrate graminoids species represented the most important vegetation cover, followed by cespitose grasses. Vegetation height, bare soil, litter and manure were similar among all areas, highlighting the homogeneity of sampling sites due to similar management. In comparison to other grasslands formations in Southern Brazil, the coastal grasslands presented rather low species richness. The presence of high values for bare soil at all sampling sites indicates the need to discuss management practices in the region, especially with regard to the intensity of livestock grazing.

scholarly journals Remote Sensing-Based Extraction and Analysis of Temporal and Spatial Variations of Winter Wheat Planting Areas in the Henan Province of China

2018 ◽  
Vol 13 (1) ◽  
pp. 533-543 ◽  
Author(s):  
Jinqiu Zou ◽  
Yinlan Huang ◽  
Lina Chen ◽  
Shi Chen
Keyword(s):  
Remote Sensing ◽  
Winter Wheat ◽  
Goodness Of Fit ◽  
Regional Scale ◽  
Spatial Variations ◽  
Henan Province ◽  
Spectral Angle Mapper ◽  
Temporal And Spatial Variations ◽  
Temporal And Spatial ◽  
Crop Planting

AbstractThe aim of this study is to assess the winter wheat planting (WWP) area in Henan Province and investigate its temporal and spatial variations by using remote sensing (RS) technology. A spectral angle mapper (SAM) was adopted to identify the WWP area of each district divided by the hierarchical grades of land surface drought index during 2001-2015. The results obtained show the expediency of monitoring the WWP areas at the regional scale via drought regionalization, which provides a goodness-of-fit R2 =0.933, a mean relative error MRE=49,118 ha, and an overall accuracy up to 90.24%. The major WWP areas in Henan Province were located in Zhoukou, Zhumadian, Shangqiu, Nanyang, and Xinxiang prefecture-level cities. Two representative sites are mountainous districts, with rich water resources or high urbanization rate, which have a low probability of WWP. Both sites exhibited a strongly manifested evolution of WWP areas, which could be attributed to extremely cold weather conditions, crop alternation, the popularization of new varieties, and fast expansion of built-up areas. The results of this study are instrumental in the analysis of crop planting variation characteristics, which should be taken into account in the further decision-making process related to the crop planting strategies.

scholarly journals CHROMITITE PROSPECTING USING LANDSAT TM AND ASTER REMOTE SENSING DATA

2015 ◽  
Vol II-2/W2 ◽  
pp. 99-103 ◽  
Author(s):  
A. Beiranvand Pour ◽  
M. Hashim ◽  
M. Pournamdari
Keyword(s):  
Remote Sensing ◽  
Satellite Data ◽  
Host Rock ◽  
Regional Scale ◽  
High Potential ◽  
Landsat Tm ◽  
Band Ratio ◽  
Spectral Angle Mapper ◽  
Spectral Transform ◽  
Ophiolitic Rock

Studying the ophiolite complexes using multispectral remote sensing satellite data are interesting because of high diversity of minerals and the source of podiform chromitites. This research developed an approach to discriminate lithological units and detecting host rock of chromitite bodies within ophiolitic complexes using the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Landsat Thematic Mapper (TM) satellite data. Three main ophiolite complexes located in south of Iran have been selected for the study. Spectral transform techniques, including minimum noise fraction (MNF) and specialized band ratio were employed to detect different rock units and the identification of high-potential areas of chromite ore deposits within ophiolitic complexes. A specialized band ratio (4/1, 4/5, 4/7) of ASTER, MNF components and Spectral Angle Mapper (SAM) on ASTER and Landsat TM data were used to distinguish ophiolitic rock units. Results show that the specialized band ratio was able to identify different rock units and serpentinized dunite as host rock of chromitites within ophiolitic complexes, appropriately. MNF components of ASTER and Landsat TM data were suitable to distinguish ophiolitic rock complexes at a regional scale. The integration of SAM and Feature Level Fusion (FLF) used in this investigation discriminated the ophiolitic rock units and prepared detailed geological map for the study area. Accordingly, high potential areas (serpentinite dunite) were identified in the study area for chromite exploration targets.The approach used in this research offers the image processing techniques as a robust, reliable, fast and cost-effective method for detecting serpentinized dunite as host rock of chromitite bodies within vast ophiolite complexes using ASTER and Landsat TM satellite data.

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