Comparison of Hyperspectral Versus Traditional Field Measurements of Fractional Ground Cover in the Australian Arid Zone

The collection of high-quality field measurements of ground cover is critical for calibration and validation of fractional ground cover maps derived from satellite imagery. Field-based hyperspectral ground cover sampling is a potential alternative to traditional in situ techniques. This study aimed to develop an effective sampling design for spectral ground cover surveys in order to estimate fractional ground cover in the Australian arid zone. To meet this aim, we addressed two key objectives: (1) Determining how spectral surveys and traditional step-point sampling compare when conducted at the same spatial scale and (2) comparing these two methods to current Australian satellite-derived fractional cover products. Across seven arid, sparsely vegetated survey sites, six 500-m transects were established. Ground cover reflectance was recorded taking continuous hyperspectral readings along each transect while step-point surveys were conducted along the same transects. Both measures of ground cover were converted into proportions of photosynthetic vegetation, non-photosynthetic vegetation, and bare soil for each site. Comparisons were made of the proportions of photosynthetic vegetation, non-photosynthetic vegetation, and bare soil derived from both in situ methods as well as MODIS and Landsat fractional cover products. We found strong correlations between fractional cover derived from hyperspectral and step-point sampling conducted at the same spatial scale at our survey sites. Comparison of the in situ measurements and image-derived fractional cover products showed that overall, the Landsat product was strongly related to both in situ methods for non-photosynthetic vegetation and bare soil whereas the MODIS product was strongly correlated with both in situ methods for photosynthetic vegetation. This study demonstrates the potential of the spectral transect method, both in its ability to produce results comparable to the traditional transect measures, but also in its improved objectivity and relative logistic ease. Future efforts should be made to include spectral ground cover sampling as part of Australia’s plan to produce calibration and validation datasets for remotely sensed products.

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Extracting Fractional Vegetation Cover from Digital Photographs: A Comparison of In Situ, SamplePoint, and Image Classification Methods

Sensors ◽

10.3390/s21217310 ◽

2021 ◽

Vol 21 (21) ◽

pp. 7310

Author(s):

Xiaolei Yu ◽

Xulin Guo

Keyword(s):

Image Classification ◽

Vegetation Cover ◽

Field Measurements ◽

Unsupervised Classification ◽

Classification Methods ◽

Mean Values ◽

Fractional Cover ◽

Fractional Vegetation Cover ◽

Object Based

Fractional vegetation cover is a key indicator of rangeland health. However, survey techniques such as line-point intercept transect, pin frame quadrats, and visual cover estimates can be time-consuming and are prone to subjective variations. For this reason, most studies only focus on overall vegetation cover, ignoring variation in live and dead fractions. In the arid regions of the Canadian prairies, grass cover is typically a mixture of green and senescent plant material, and it is essential to monitor both green and senescent vegetation fractional cover. In this study, we designed and built a camera stand to acquire the close-range photographs of rangeland fractional vegetation cover. Photographs were processed by four approaches: SamplePoint software, object-based image analysis (OBIA), unsupervised and supervised classifications to estimate the fractional cover of green vegetation, senescent vegetation, and background substrate. These estimates were compared to in situ surveys. Our results showed that the SamplePoint software is an effective alternative to field measurements, while the unsupervised classification lacked accuracy and consistency. The Object-based image classification performed better than other image classification methods. Overall, SamplePoint and OBIA produced mean values equivalent to those produced by in situ assessment. These findings suggest an unbiased, consistent, and expedient alternative to in situ grassland vegetation fractional cover estimation, which provides a permanent image record.

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LIGHTER-THAN-AIR (LTA) UNMANNED AERIAL SYSTEM (UAS) CARRIER CONCEPT FOR SURVAILLANCE AND DISASTER MANAGEMENT

Seminar Nasional Geomatika ◽

10.24895/sng.2018.3-0.1051 ◽

2019 ◽

Vol 3 ◽

pp. 1255

Author(s):

Ahmad Salahuddin Mohd Harithuddin ◽

Mohd Fazri Sedan ◽

Syaril Azrad Md Ali ◽

Shattri Mansor ◽

Hamid Reza Jifroudi ◽

...

Keyword(s):

Unmanned Aerial Vehicles ◽

Disaster Management ◽

Unmanned Aerial Systems ◽

Unmanned Aerial System ◽

Border Control ◽

Aerial Vehicles ◽

Operational Safety ◽

In Situ Methods ◽

Aerial Systems

Unmanned aerial systems (UAS) has many advantages in the fields of SURVAILLANCE and disaster management compared to space-borne observation, manned missions and in situ methods. The reasons include cost effectiveness, operational safety, and mission efficiency. This has in turn underlined the importance of UAS technology and highlighted a growing need in a more robust and efficient unmanned aerial vehicles to serve specific needs in SURVAILLANCE and disaster management. This paper first gives an overview on the framework for SURVAILLANCE particularly in applications of border control and disaster management and lists several phases of SURVAILLANCE and service descriptions. Based on this overview and SURVAILLANCE phases descriptions, we show the areas and services in which UAS can have significant advantage over traditional methods.

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Underwater Holographic Sensor for Plankton Studies In Situ Including Accompanying Measurements

Sensors ◽

10.3390/s21144863 ◽

2021 ◽

Vol 21 (14) ◽

pp. 4863

Author(s):

Victor Dyomin ◽

Alexandra Davydova ◽

Igor Polovtsev ◽

Alexey Olshukov ◽

Nikolay Kirillov ◽

...

Keyword(s):

World Ocean ◽

Field Tests ◽

Field Measurements ◽

Measuring Systems ◽

Water Turbidity ◽

Background Data ◽

Average Size ◽

Size Dispersion

The paper presents an underwater holographic sensor to study marine particles—a miniDHC digital holographic camera, which may be used as part of a hydrobiological probe for accompanying (background) measurements. The results of field measurements of plankton are given and interpreted, their verification is performed. Errors of measurements and classification of plankton particles are estimated. MiniDHC allows measurement of the following set of background data, which is confirmed by field tests: plankton concentration, average size and size dispersion of individuals, particle size distribution, including on major taxa, as well as water turbidity and suspension statistics. Version of constructing measuring systems based on modern carriers of operational oceanography for the purpose of ecological diagnostics of the world ocean using autochthonous plankton are discussed. The results of field measurements of plankton using miniDHC as part of a hydrobiological probe are presented and interpreted, and their verification is carried out. The results of comparing the data on the concentration of individual taxa obtained using miniDHC with the data obtained by the traditional method using plankton catching with a net showed a difference of no more than 23%. The article also contains recommendations for expanding the potential of miniDHC, its purpose indicators, and improving metrological characteristics.

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Laboratory and In Situ Determination of Hydraulic Conductivity and Their Validity in Transient Seepage Analysis

Water ◽

10.3390/w13081131 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1131

Author(s):

Soonkie Nam ◽

Marte Gutierrez ◽

Panayiotis Diplas ◽

John Petrie

Keyword(s):

Hydraulic Conductivity ◽

Field Measurements ◽

Natural Soil ◽

In Situ Tests ◽

Seepage Analysis ◽

Soil Deposits ◽

Seepage Modeling ◽

Sample Disturbance

This paper critically compares the use of laboratory tests against in situ tests combined with numerical seepage modeling to determine the hydraulic conductivity of natural soil deposits. Laboratory determination of hydraulic conductivity used the constant head permeability and oedometer tests on undisturbed Shelby tube and block soil samples. The auger hole method and Guelph permeameter tests were performed in the field. Groundwater table elevations in natural soil deposits with different hydraulic conductivity values were predicted using finite element seepage modeling and compared with field measurements to assess the various test results. Hydraulic conductivity values obtained by the auger hole method provide predictions that best match the groundwater table’s observed location at the field site. This observation indicates that hydraulic conductivity determined by the in situ test represents the actual conditions in the field better than that determined in a laboratory setting. The differences between the laboratory and in situ hydraulic conductivity values can be attributed to factors such as sample disturbance, soil anisotropy, fissures and cracks, and soil structure in addition to the conceptual and procedural differences in testing methods and effects of sample size.

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Did Ground Cover Change Over Geologic Time?

The Paleontological Society Papers ◽

10.1017/s1089332600000759 ◽

2000 ◽

Vol 6 ◽

pp. 171-182 ◽

Cited By ~ 4

Author(s):

Ben A. LePage ◽

Hermann W. Pfefferkorn

Keyword(s):

Fossil Record ◽

Ground Cover ◽

The Other ◽

Detailed Account ◽

Geologic Time ◽

The Past ◽

Other Hand ◽

Plant Fossil

When one hears the term “ground cover,” one immediately thinks of “grasses.” This perception is so deep-seated that paleobotanists even have been overheard to proclaim that “there was no ground cover before grasses.” Today grasses are so predominant in many environments that this perception is perpetuated easily. On the other hand, it is difficult to imagine the absence or lack of ground cover prior to the mid-Tertiary. We tested the hypothesis that different forms of ground cover existed in the past against examples from the Recent and the fossil record (Table 1). The Recent data were obtained from a large number of sources including those in the ecological, horticultural, and microbiological literature. Other data were derived from our knowledge of Precambrian life, sedimentology and paleosols, and the plant fossil record, especially in situ floras and fossil “monocultures.” Some of the data are original observations, but many others are from the literature. A detailed account of these results will be presented elsewhere (Pfefferkorn and LePage, in preparation).

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Sustainable use of wildlife in western New South Wales: Possibilities and problems.

The Rangeland Journal ◽

10.1071/rj0000088 ◽

2000 ◽

Vol 22 (1) ◽

pp. 88 ◽

Cited By ~ 12

Author(s):

DB Croft

Keyword(s):

Arid Zone ◽

Sustainable Use ◽

Ex Situ ◽

Animal Products ◽

Wildlife Tourism ◽

South Wales ◽

Wild Progenitors ◽

Ecologically Sustainable ◽

New Evidence

Sustainable use of wildlife has become equated with exploitation of animal products (meat, skin or feathers) and/or removal of wild progenitors into the pet trade. This consumption of the wildlife is therefore largely ex situ and so removes nutrients and energy from the rangelands. Demand for lethal or a removal action is often driven by the severity of the perceived conflict between the wildlife and other enterprises, especially agriculture, rather than for the resulting products. Such uses also raise community concerns about humane treatment of animals and a valuing of the natural heritage. Wildlife-based tourism, as part of the valuable and growing nature-based or ecotourism industry in Australia, is an in situ use that may be a more ecologically sustainable and economically twble option for use of rangeland wildlife. This paper examines these possibilities and their problems with a focus on the commercial kangaroo industry and the use of arid-zone mammals, birds and reptiles for pets. It provides new evidence that wildlife-tourism based on free-living kangaroos in the rangelands is both feasible and in demand. This industry should be given advocacy in the on-going debate on the management and future of the rangelands. Key words: kangaroos, wildlife management, wildlife tourism, game harvesting

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Is fire a threatening process for Liopholis kintorei, a nationally listed threatened skink?

Wildlife Research ◽

10.1071/wr14227 ◽

2015 ◽

Vol 42 (3) ◽

pp. 207 ◽

Cited By ~ 9

Author(s):

Danae Moore ◽

Michael Ray Kearney ◽

Rachel Paltridge ◽

Steve McAlpin ◽

Adam Stow

Keyword(s):

Breeding Success ◽

Prescribed Burning ◽

Arid Zone ◽

Ground Cover ◽

Management Tool ◽

Burrow System ◽

Spatial And Temporal Scales ◽

Key Sites ◽

Primary Habitat ◽

Experimental Burns

Context Prescribed burning is widely adopted as a conservation-management tool, with priorities largely being the protection of fire-sensitive plant communities, threatened fauna habitat and minimising the risk and impacts of broad-scale wildfire. However, an improved understanding of the ecological mechanisms that underpin species responses to fire will assist the development and refinement of prescribed-burning practice. Aims To examine the effect of fire on burrow-system occupancy and breeding success at different spatial and temporal scales for a threatened skink, Liopholis kintorei. Methods Experimental burns simulating different fire types (clean burn, patchy burn and no burn) were conducted at 30 L. kintorei burrow systems that were selected from within a 75-ha focal study area. Burrow-system occupancy was monitored daily for 1 month, then monthly for an additional 3 months. Breeding success was assessed once at all 30 burrow systems. Eight additional 1-km2 sites within L. kintorei habitat that had experienced some degree of fire 2 years earlier were selected from across Newhaven Wildlife Sanctuary. Burrow-system occupancy and breeding success of L. kintorei at these sites was assessed once. Key results There was no significant effect of fire on burrow-system occupancy 1 month after experimental burns; however, burrow-system occupancy was significantly higher at unburnt sites 4 months after experimental burns and 2 years post-fire. Breeding success was significantly higher at unburnt sites than at clean-burnt and patchy-burnt sites. Conclusions Fire adversely affects L. kintorei, as demonstrated by a higher proportion of unoccupied burrow systems and fewer successful breeding events post-fire, particularly when all ground cover is lost. Implications Because fire is an inevitable and natural process within arid-zone spinifex grasslands, the primary habitat for L. kintorei, we recommend prescribed-burning practices that aim to maximise ground cover by reducing the frequency, intensity and size of fires. More specifically, we recommend fire exclusion from key sites within distinct localities where L. kintorei is known to be locally abundant. Depending on the size of these key sites, there may also be a need to construct strategic fire breaks within sites to ensure that any unwanted ignitions do not result in the loss of all vegetation cover.

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Assessment of Moisture Content in Sandy Beach Environments from Multispectral Satellite Imagery

Canadian Geotechnical Journal ◽

10.1139/cgj-2020-0624 ◽

2021 ◽

Author(s):

Julie Paprocki ◽

Nina Stark ◽

Hans C Graber ◽

Heidi Wadman ◽

Jesse E McNinch

Keyword(s):

Moisture Content ◽

Laboratory Data ◽

Field Measurements ◽

Weather Conditions ◽

Sandy Beaches ◽

Percent Error ◽

Moisture Contents ◽

Multispectral Satellite Imagery ◽

Factor C

A framework for estimating moisture content from satellite-based multispectral imagery of sandy beaches was tested under various site conditions and sensors. It utilizes the reflectance of dry soil and an empirical factor c relating reflectance and moisture content for specific sediment. Here, c was derived two ways: first, from in-situ measurements of moisture content and average NIR image reflectance; and second, from laboratory-based measurements of moisture content and spectrometer reflectance. The proposed method was tested at four sandy beaches: Duck, North Carolina, and Cannon Beach, Ocean Cape, and Point Carrew, Yakutat, Alaska. Both measured and estimated moisture content profiles were impacted by site geomorphology. For profiles with uniform slopes, moisture contents ranged from 3.0%-8.0% (Zone 1) and from 8.0%-23.0% (Zone 2). Compared to field measurements, the moisture contents estimated using c calibrated from in-situ and laboratory data resulted in percent error of 3.6%-44.7% and 2.7%-58.6%, respectively. The highest percent error occurred at the transition from Zone 1 to Zone 2. Generally, moisture contents were overestimated in Zone 1 and underestimated in Zone 2, but followed the expected trends based on field measurements. When estimated moisture contents in Zone 1 exceeded 10%, surface roughness, debris, geomorphology, and weather conditions were considered.

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