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Gillan, Jeffrey K., Jason W. Karl, Michael Duniway, Ahmed Elaksher. 2014. Modeling vegetation heights from high resolution stereo aerial photography: An application for broad-scale rangeland monitoring. Journal of Environmental Management, 144, 226–235.

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This collection of articles represents the geographic extent of the cited literature for this publication.

latest article added on August 2013

ArticleFirst AuthorPublished
Testing sagebrush allometric relationships across three fire chronosequences in Wyoming, USACleary, M. B.2008

Testing sagebrush allometric relationships across three fire chronosequences in Wyoming, USA

Keywords

aboveground biomass; Artemisia tridentate; plant allometry; root biomass; universal scaling

Abstract

Aboveground and coarse root allometric relationships were tested across three mountain big sagebrush (Artemisia tridentata var. vaseyana (Rydb.) chronosequences at three stages of recovery from fire (establishment, expansion, and mature) in Wyoming, USA. Big sagebrush shrubs dominate North American rangelands and are critical components of habitat for threatened species such as sage grouse. There were no differences in regression relationships estimating biomass over space and time, which reduces the need to destructively sample sagebrush for local studies and supports regional carbon modeling and biomass estimates. Crown volume (CV) explained the most variability (R-2 > 0.75) in aboveground biomass, and crown area (CA) explained the most variability for coarse roots (R-2 >0.87). Analyses supported both the 2/3 power universal scaling rules between leaf and stem biomass, but did not support global models of seed plant and reproductive part biomass. This study provides compelling evidence that simple field measurements may be used to estimate biomass over large regions and that universal scaling rules are valid for semiarid shrubs. (c) 2007 Elsevier Ltd. All rights reserved.

Authors

Cleary, M. B.; Pendall, E.; Ewers, B. E.

Year Published

2008

Publication

Journal of Arid Environments

Locations
DOI

10.1016/j.jaridenv.2007.07.013

A Technique for Estimating Rangeland Canopy-Gap Size Distributions From High-Resolution Digital ImageryKarl, Jason W.2012

A Technique for Estimating Rangeland Canopy-Gap Size Distributions From High-Resolution Digital Imagery

Keywords

digital aerial photography, image classification, photo interpretation, remote sensing

Abstract

The amount and distribution of gaps in vegetation canopy is a useful indicator of multiple ecosystem processes and functions. In this paper, we describe a semiautomated approach for estimating canopy-gap size distributions in rangelands from high-resolution (HR) digital images using image interpretation by observers and statistical image classification techniques. We considered two different classification methods (maximum-likelihood classification and logistic regression) and both pixel-based and object-based approaches to estimate canopy-gap size distributions from 2- to 3-cm resolution UltraCamX color infrared aerial photographs for arid and semiarid shrub sites in Idaho, Nevada, and New Mexico. We compare our image-based estimates to field-based measurements for the study sites. Generally, percent of input points correctly classified and kappa coefficients of agreement for plot image classifications was very high. Plots with low kappa values yielded canopy gap estimates that were very different from field-based estimates. We found a strong relationship (R2 > 0.9 for all four methods evaluated) between image- and field-based estimates of the total percent of the plot in canopy gaps greater than 50 cm for plots with a classification kappa of greater than 0.5. Performance of the remote sensing techniques varied for small canopy gaps (25 to 50 cm) but were very similar for moderate (50 to 200 cm) and large (> 200 cm) canopy gaps. Our results demonstrate that canopy-gap size distributions can be reliably estimated from HR imagery in a variety of plant community types. Additionally, we suggest that classification goodness-of-fit measures are a potentially useful tool for identifying and screening out plots where precision of estimates from imagery may be low. We conclude that classification of HR imagery based on observer-interpreted training points and image classification is a viable technique for estimating canopy gap size distributions. Our results are consistent with other research that has looked at the ability to derive monitoring indicators from HR imagery.

Authors

Karl, Jason W., Duniway, Michael C. and Schrader, T. Scott

Year Published

2012

Publication

Rangeland Ecology & Management

Locations
DOI

10.2111/REM-D-11-00006.1

Rangeland and pasture monitoring: an approach to interpretation of high-resolution imagery focused on observer calibration for repeatabilityDuniway, Michael C.2012

Rangeland and pasture monitoring: an approach to interpretation of high-resolution imagery focused on observer calibration for repeatability

Keywords

remote sensing, image interpretation, aerial photography, repeatability, assessment and monitoring, large-scale

Abstract

Collection of standardized assessment and monitoring data is critically important for supporting policy and management at local to continental scales. Remote sensing techniques, including image interpretation, have shown promise for collecting plant community composition and ground cover data efficiently. More work needs to be done, however, evaluating whether these techniques are sufficiently feasible, cost-effective, and repeatable to be applied in large programs. The goal of this study was to design and test an image-interpretation approach for collecting plant community composition and ground cover data appropriate for local and continental-scale assessment and monitoring of grassland, shrubland, savanna, and pasture ecosystems. We developed a geographic information system image-interpretation tool that uses points classified by experts to calibrate observers, including point-by-point training and quantitative quality control limits. To test this approach, field data and high-resolution imagery (∼3 cm ground sampling distance) were collected concurrently at 54 plots located around the USA. Seven observers with little prior experience used the system to classify 300 points in each plot into ten cover types (grass, shrub, soil, etc.). Good agreement among observers was achieved, with little detectable bias and low variability among observers (coefficient of variation in most plots  0.9), suggesting regression-based adjustments can be used to relate image and field data. This approach could extend the utility of expensive-to-collect field data by allowing it to serve as a validation data source for data collected via image interpretation.

Authors

Karl, Jason W., Duniway, Michael C., Schrader, Scott, Baquera, Noemi and Herrick, Jeffrey E.

Year Published

2012

Publication

Environmental Monitoring and Assessment

Locations
DOI

10.1007/s10661-011-2224-2

Measuring Plant Cover in Sagebrush Steppe Rangelands: A Comparison of MethodsSeefeldt, Steven S.2006

Measuring Plant Cover in Sagebrush Steppe Rangelands: A Comparison of Methods

Keywords

Image analysis; Digital imagery; Vegetation measurement; Sagebrush steppe

Abstract

Methods that are more cost-effective and objective are needed to detect important vegetation change within acceptable error rates. The objective of this research was to compare visual estimation to three new methods for determining vegetation cover in the sagebrush steppe. Fourteen management units at the US Sheep Experiment Station were identified for study. In each unit, 20 data collection points were selected for measuring plant cover using visual estimation, laser-point frame (LPF), 2 m above-ground-level (AGL) digital imagery, and 100-m AGL digital imagery. In 11 of 14 management units, determinations of vegetation cover differed (P < 0.05). However, when combined, overall determinations of vegetation cover did not differ. Standard deviation, corrected sums of squares, coefficient of variation, and standard error for the 100 m AGL method were half as large as for the LPF and less than the 2-m AGL and visual estimate. For the purpose of measuring plant cover, all three new methods are as good as or better than visual estimation for speed, standard deviation, and cost. The acquisition of a permanent image of a location is an important advantage of the 2 and 100 m AGL methods because vegetation can be reanalyzed using improved software or to answer different questions, and changes in vegetation over time can be more accurately determined. The reduction in cost per sample, the increased speed of sampling, and the smaller standard deviation associated with the 100-m AGL digital imagery are compelling arguments for adopting this vegetation sampling method.

Authors

Seefeldt, Steven S. and Booth, D. Terrance

Year Published

2006

Publication

Environmental Management

Locations
DOI

10.1007/s00267-005-0016-6

Image-based monitoring to measure ecological change in rangelandBooth, D Terrance2008

Image-based monitoring to measure ecological change in rangeland

Keywords

No keywords available

Abstract

High-resolution, image-based methods can increase the speed and accuracy of ecological monitoring while reducing monitoring costs. We evaluated the efficacy of systematic aerial and ground sampling protocols to detect stocking-rate differences across 130 ha of shortgrass prairie. Manual (SamplePoint) and automated (spectral) image-analysis methods were compared for both aerial and ground data. Vegetative cover changes due to grazing were detectable from 1-mm ground sample distance (GSD, a measure of resolution) digital aerial photography with as few as 30 samples yielding enough data to predict bare ground within ± 5%. We found poor agreement between automated and manual image-analysis methods, but good agreement between manual analyses of imagery from the air (100 m above ground level [AGL]) and from the ground (2 m AGL). We conclude that cover measurements made using SamplePoint from 1-mm GSD images (from 2 or 100 m AGL) can detect ecologically important changes in key indicators such as bare ground. The costs of ground and aerial methods differ markedly, and we suggest that aerial imagery is most cost effective for areas larger than 200 ha.

Authors

Booth, D Terrance and Cox, Samuel E

Year Published

2008

Publication

Frontiers In Ecology And The Environment

Locations
DOI

10.1890/070095

This article contributed by:

Ecological Society of America

LiDAR-Based Classification of Sagebrush Community TypesSankey, Temuulen Tsagaan2011

LiDAR-Based Classification of Sagebrush Community Types

Keywords

active sensors, laser data, rangeland classification, vegetation height

Abstract

Sagebrush (Artemisia spp.) communities constitute the largest temperate semidesert in North America and provide important rangelands for livestock and habitat for wildlife. Remote sensing methods might provide an efficient method to monitor sagebrush communities. This study used airborne LiDAR and field data to measure vegetation heights in five different community types at the Reynolds Creek Experimental Watershed, southwestern Idaho: herbaceous-dominated, low sagebrush (Artemisia arbuscula) –dominated, big sagebrush (Artemisia tridentata spp.) –dominated, bitterbrush (Purshia tridentata) -dominated, and other vegetation community types. The objectives were 1) to quantify the correlation between field-measured and airborne LiDAR-derived shrub heights, and 2) to determine if airborne LiDAR-derived mean vegetation heights can be used to classify the five community types. The dominant vegetation type and vegetation heights were measured in 3 × 3 m field plots. The LiDAR point cloud data were converted into a raster format to generate a maximum vegetation height map in 3-m raster cells. The regression relationship between field-based and airborne LiDAR-derived shrub heights was significant (R2  =  0.77; P value < 0.01), except for herbaceous-dominated communities compared to low sagebrush-dominated communities. Although LiDAR measurements consistently underestimated vegetation heights in all community types, shrub heights at some locations were overestimated due to adjacent taller vegetation. We recommend for future studies a smaller rasterized pixel size that is consistent with the target vegetation canopy diameter.

Authors

Sankey, Temuulen Tsagaan and Bond, Pamela

Year Published

2011

Publication

Rangeland Ecology & Management

Locations
DOI

10.2111/REM-D-10-00019.1

Field Test of Digital Photography Biomass Estimation Technique in Tallgrass PrairieLeis, Sherry A.2011

Field Test of Digital Photography Biomass Estimation Technique in Tallgrass Prairie

Keywords

fire, fuel load, grassland, photo board, techniques

Abstract

Fuel loading information is important for prescribed fire planning, evaluating wildfire risk, and understanding fire effects in grassland. Yet fuel loads in grasslands often go unmeasured because of the time required to clip plots and process samples, as well as limited access or proximity to a drying oven. We tested the digital photography biomass estimation technique for measuring fuel load in grasslands in two national parks in the eastern Great Plains. The method consists of using percentage image obstruction, as determined by digital photography, to estimate vegetation biomass based on a linear transformation (i.e., regressing dry clipped weights against percent digital obstruction). We used the technique with some modification and measured digital obstruction at two sites at Wilson's Creek National Battlefield, Missouri (WICR), and three sites at Tallgrass Prairie National Preserve, Kansas (TAPR). The method did not result in strong correlations at either of the two sites at WICR (Site 1: r2  =  0.02; Site 2: r2  =  0.32), but performed relatively well at TAPR (Site 1 [ 0.05). In general, the denser the vegetation, the weaker the relationship between the vegetation biomass of clip plots and the percentage image obstruction of digital images. The digital photography technique may not be useful for estimating fuel loads in grasslands with relatively high biomass (> 80 g · 0.1 m−2) or digital image obstruction > 50%. Large amounts of litter may also potentially reduce the accuracy of the technique.

Authors

Leis, Sherry A. and Morrison, Lloyd W.

Year Published

2011

Publication

Rangeland Ecology & Management

Locations
DOI

10.2111/REM-D-09-00180.1

National ecosystem assessments supported by scientific and local knowledgeHerrick, Jeffrey E2010

National ecosystem assessments supported by scientific and local knowledge

Keywords

No keywords available

Abstract

An understanding of the extent of land degradation and recovery is necessary to guide land-use policy and management, yet currently available land-quality assessments are widely known to be inadequate. Here, we present the results of the first statistically based application of a new approach to national assessments that integrates scientific and local knowledge. Qualitative observations completed at over 10 000 plots in the United States showed that while soil degradation remains an issue, loss of biotic integrity is more widespread. Quantitative soil and vegetation data collected at the same locations support the assessments and serve as a baseline for monitoring the effectiveness of policy and management initiatives, including responses to climate change. These results provide the information necessary to support strategic decisions by land managers and policy makers.

Authors

Herrick, Jeffrey E, Lessard, Veronica C, Spaeth, Kenneth E, Shaver, Patrick L, Dayton, Robert S, Pyke, David A, Jolley, Leonard and Goebel, J Jeffery

Year Published

2010

Publication

Frontiers In Ecology And The Environment

Locations
    DOI

    10.1890/100017

    This article contributed by:

    Ecological Society of America

    Use of stereo aerial photography for quantifying changes in the extent and height of mangroves in tropical AustraliaLucas, R.M.2002

    Use of stereo aerial photography for quantifying changes in the extent and height of mangroves in tropical Australia

    Keywords

    aerial photography, Australia, Digital Elevation Models, historical change, sea level rise, mangroves

    Abstract

    The study investigated the use of aerial photographs, acquired in 1950 and 1991, for assessing the temporal dynamics of mangroves along theWest Alligator River in Australia’s Northern Territory. For both years, mangrove extent was mapped using an unsupervised classification of the digital orthomosaic and Digital ElevationModels (DEMs), or height maps, of the mangrove canopy were derived from stereo pairs. Helicopter and field observations in 1998 and 1999 respectively provided ground truth for interpreting the derived datasets. The comparison of mangrove extent revealed a substantial movement over the 41-year period, perhaps in response to hydrological changes that have resulted in a landward extension of saline conditions. Changes in the height of mangroves were observed but were difficult to quantify due to the reduced quality of the 1950 DEM. The study demonstrated the viability of using time-series of aerial photography for monitoring and understanding the long-term response of mangroves to environmental change, including hydrological variations and sea level rise.

    Authors

    Lucas, R.M., Ellison, J.C., Mitchell, A., Donnelly, B., Finlayson, M. and Milne, A.K.

    Year Published

    2002

    Publication

    Wetlands Ecology and Management

    Locations
    DOI

    10.1023/A:1016547214434

    Assessment of temporal changes in aboveground forest tree biomass using aerial photographs and allometric equationsMassada, Avi Bar2006

    Assessment of temporal changes in aboveground forest tree biomass using aerial photographs and allometric equations

    Keywords

    No keywords available

    Abstract

    Studies of forest biomass dynamics typically use long-term forest inventory data, available in only a few places around the world. We present a method that uses photogrammetric measurements from aerial photographs as an alternative to time-series field measurements. We used photogrammetric methods to measure tree height and crown diameter, using four aerial photographs of Yatir Forest, a semi-arid forest in southern Israel, taken between 1978 and 2003. Height and crown-diameter measurements were transformed to biomass using an allometric equation generated from 28 harvested Aleppo pine (Pinus halepensis Mill.) trees. Mean tree biomass increased from 6.37 kg in 1978 to 97.01 kg in 2003. Mean plot biomass in 2003 was 2.48 kg/m(2) and aboveground primary productivity over the study period ranged between 0.14 and 0.21 kg/m(2) per year. There was systematic overestimation of tree height and systematic underestimation of crown diameter, which was corrected for at all time points between 1978 and 2003. The estimated biomass was significantly related to field-measured biomass, with an R-2 value of 0.78. This method may serve as an alternative to field sampling for studies of forest biomass dynamics, assuming that there is sufficient spatial and temporal coverage of the investigated area using high-quality aerial photography, and that the tree tops are distinguishable in the photographs

    Authors

    Massada, Avi Bar, Carmel, Yohay, Tzur, Gilad Even, Grünzweig, José M and Yakir, Dan

    Year Published

    2006

    Publication

    Canadian Journal of Forest Research

    Locations
    DOI

    10.1139/x06-152

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