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latest article added on December 2013

ArticleFirst AuthorPublished
Spatial and temporal variability of plant-available water in calcium carbonate-cemented soils and consequences for arid ecosystem resilienceDuniway, Michael Cohrs2010

Spatial and temporal variability of plant-available water in calcium carbonate-cemented soils and consequences for arid ecosystem resilience

Keywords

Calcic; Petrocalcic; Chihuahuan Desert; Desert grassland; Climate change

Abstract

Increased variability in precipitation, including frequency of drought, is predicted for many arid and semiarid regions globally. The ability of soils to retain water can increase resilience by buffering vegetation communities against precipitation extremes. Little is known, however, about water retention by carbonate-cemented soil horizons, which occur extensively in arid and semiarid ecosystems. It has been speculated that they may significantly modify vertical and temporal distribution of plant-available water (PAW). To investigate this hypothesis, PAW was monitored at three sites in a mixed shrub-grass community in southern New Mexico, USA, across soils with differing degrees of carbonate horizon development: no carbonate horizon, a horizon partially cemented with carbonates (calcic), and a horizon continuously cemented with carbonates (petrocalcic). Results are presented from 3 years that included extremely dry and wet periods. Both carbonate-cemented horizons absorbed and retained significantly greater amounts of PAW for several months following an extremely wet winter and summer compared to the non-carbonate soil. Following a wet summer, continuously cemented horizons retained very high PAW (16-18% volumetric or similar to 72-80% of soil water holding capacity) through early spring of the following year, more than double the PAW retained by similar depths in the non-carbonate soil. Drying dynamics indicate both carbonate-cemented horizons release stored water into the grass rooting zone during growing seasons following extreme wet events. Water dynamics of these horizons during extreme events provide a mechanism to explain previous observations that perennial grasses exhibit greater resilience to drought when carbonate-cemented horizons occur at shallow depths (< 50 cm). Water holding capacity of the entire profile, including horizons cemented with carbonates, should be considered when evaluating the potential resilience of vegetation communities to disturbance, including the increased variability in precipitation expected to occur as a result of global climate change.

Authors

Duniway, Michael Cohrs; Herrick, Jeffrey E.; Monger, H. Curtis

Year Published

2010

Publication

Oecologia

Locations
DOI

10.1007/s00442-009-1530-7

Assessing Transportation Infrastructure Impacts on Rangelands: Test of a Standard Rangeland Assessment ProtocolDuniway, Michael C.2010

Assessing Transportation Infrastructure Impacts on Rangelands: Test of a Standard Rangeland Assessment Protocol

Keywords

disturbance; indicators; off-highway vehicles; oil and gas; rangeland health; roads

Abstract

Linear disturbances associated with on-and off-road vehicle use on rangelands has increased dramatically throughout the world in recent decades. This increase is due to a variety of factors including increased availability of all-terrain vehicles, infrastructure development (oil, gas, renewable energy, and ex-urban), and recreational activities. In addition to the direct impacts of road development, the presence and use of roads may alter resilience of adjoining areas through indirect effects such as altered site hydrologic and eolian processes, invasive seed dispersal, and sediment transport. There are few standardized methods for assessing impacts of transportation-related land-use activities on soils and vegetation in arid and semi-arid rangelands. Interpreting Indicators of Rangeland Health (IIRH) is an internationally accepted qualitative assessment that is applied widely to rangelands. We tested the sensitivity of IIRH to impacts of roads, trails, and pipelines on adjacent lands by surveying plots at three distances from these linear disturbances. We performed tests at 16 randomly selected sites in each of three ecosystems (Northern High Plains, Colorado Plateau, and Chihuahuan Desert) for a total of 208 evaluation plots. We also evaluated the repeatability of IIRH when applied to road-related disturbance gradients. Finally, we tested extent of correlations between IIRH plot attribute departure classes and trends in a suite of quantitative indicators. Results indicated that the IIRH technique is sensitive to direct and indirect impacts of transportation activities with greater departure from reference condition near disturbances than far from disturbances. Trends in degradation of ecological processes detected with qualitative assessments were highly correlated with quantitative data. Qualitative and quantitative assessments employed in this study can be used to assess impacts of transportation features at the plot scale. Through integration with remote sensing technologies, these methods could also potentially be used to assess cumulative impacts of transportation networks at the landscape scale.

Authors

Duniway, Michael C.; Herrick, Jeffrey E.; Pyke, David A.; Toledo, David P.

Year Published

2010

Publication

Rangeland Ecology & Management

Locations
DOI

10.2111/REM-D-09-00176.1

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

Assessing Impacts of Roads: Application of a Standard Assessment ProtocolDuniway, Michael C.2013

Assessing Impacts of Roads: Application of a Standard Assessment Protocol

Keywords

adaptive management, assessment, monitoring, off-highway vehicles, oil and gas, rangeland health

Abstract

Adaptive management of road networks depends on timely data that accurately reflect the impacts those systems are having on ecosystem processes and associated services. In the absence of reliable data, land managers are left with little more than observations and perceptions to support management decisions of road-associated disturbances. Roads can negatively impact the soil, hydrologic, plant, and animal processes on which virtually all ecosystem services depend. The Interpreting Indicators of Rangeland Health (IIRH) protocol is a qualitative method that has been demonstrated to be effective in characterizing impacts of roads. The goal of this study were to develop, describe, and test an approach for using IIRH to systematically evaluate road impacts across large, diverse arid and semiarid landscapes. We developed a stratified random sampling approach to plot selection based on ecological potential, road inventory data, and image interpretation of road impacts. The test application on a semiarid landscape in southern New Mexico, United States, demonstrates that the approach developed is sensitive to road impacts across a broad range of ecological sites but that not all the types of stratification were useful. Ecological site and road inventory strata accounted for significant variability in the functioning of ecological processes but stratification based on apparent impact did not. Analysis of the repeatability of IIRH applied to road plots indicates that the method is repeatable but consensus evaluations based on multiple observers should be used to minimize risk of bias. Landscape-scale analysis of impacts by roads of contrasting designs (maintained dirt or gravel roads vs. non- or infrequently maintained roads) suggests that future travel management plans for the study area should consider concentrating traffic on fewer roads that are well designed and maintained. Application of the approach by land managers will likely provide important insights into minimizing impacts of road networks on key ecosystem services.

Authors

Duniway, Michael C. and Herrick, Jeffrey E.

Year Published

2013

Publication

Rangeland Ecology & Management

Locations
DOI

10.2111/rem-d-11-00130.1

The High Water-Holding Capacity of Petrocalcic HorizonsDuniway, Michael C.2007

The High Water-Holding Capacity of Petrocalcic Horizons

Keywords

CHIHUAHUAN DESERT, SOIL-QUALITY, REPLACEMENT, CALICHE, PLANTS, ROCK

Abstract

Petrocalcic soil horizons occur in most arid and semiarid ecosystems around the world, often within the plant rooting zone. Little is known, however, about the water-holding characteristic of soils indurated with CaCO3. We conducted a replicated experiment to define the soil-water release curve (SWRC) for a range of petrocalcic horizon materials. Samples from both plugged and laminar zones of two Stage V petrocalcic horizons in southern New Mexico were characterized. Wetter soil-water potentials were measured using a pressure plate; more negative potentials (down to less than < -10 MPa) were measured using a chilled mirror water activity meter. Measured SWRC data were fitted to the van Genuchten equation. The SWRC methods used were found to be both reliable and repeatable. Plant-available water-holding capacity (AWHC) for desert species (with wilting point set at -4.0 MPa) ranged from 0.26 m3 m-3 in plugged zones to 0.06 m3 m-3 in some laminar zones in contrast to about 0.07 m3 m-3 in the loamy sand parent material. Correlation analyses across morphologies of AWHC and soil properties resulted in significant statistical relationships only with bulk density and porosity. The AWHC and CaCO3 content, however, were significantly negatively correlated within the laminar and positively correlated within the plugged petrocalcic horizon morphologies. Cementation by CaCO3 dramatically alters the water-holding characteristics of soils and understanding these horizons is crucial to understand patterns of soil water in desert systems throughout the world.

Authors

Duniway, Michael C., Herrick, Jeffrey E. and Monger, H. Curtis

Year Published

2007

Publication

Soil Science Society of America Journal

Locations
DOI

10.2136/sssaj2006.0267

Hierarchical analysis of vegetation dynamics over 71 years: soil-rainfall interactions in a Chihuahuan Desert ecosystemBrowning, Dawn M.2012

Hierarchical analysis of vegetation dynamics over 71 years: soil-rainfall interactions in a Chihuahuan Desert ecosystem

Keywords

aerial photography; Chihuahuan Desert, New Mexico, USA; cross-scale linkages; ecological-state mapping; hierarchy theory; Jornada Basin LTER; object-based change detection; petrocalcic soil; Prosopis glandulosa; shrub patch dynamics; shrub proliferation; soil depth

Abstract

Proliferation of woody plants in grasslands and savannas is a persistent problem globally. This widely observed shift from grass to shrub dominance in rangelands worldwide has been heterogeneous in space and time largely due to cross-scale interactions among soils, climate, and land-use history. Our objective was to use a hierarchical framework to evaluate the relationship between spatial patterns in soil properties and long-term shrub dynamics in the northern Chihuahuan Desert of New Mexico, USA. To meet this objective, shrub patch dynamics from 1937 to 2008 were characterized at patch and landscape scales using historical imagery and a recent digital soils map. Effects of annual precipitation on patch dynamics on two soils revealed strong correlations between shrub growth on deep sandy soils and above-average rainfall years (r = 0.671, P = 0.034) and shrub colonization and below-average rainfall years on shallow sandy soils (r = 0.705, P = 0.023). Patch-level analysis of demographic patterns revealed significant differences between shrub patches on deep and shallow sandy soils during periods of above-and below-average rainfall. Both deep and shallow sandy soils exhibited low shrub cover in 1937 (1.0% +/- 2.3% and 0.3% +/- 1.3%, respectively [mean +/- SD]) and were characterized by colonization or appearance of new patches until 1960. However, different demographic responses to the cessation of severe drought on the two soils and increased frequency of wet years after 1960 have resulted in very different endpoints. In 2008 a shrubland occupied the deep sandy soils with cover at 19.8% +/- 9.1%, while a shrub-dominated grassland occurred on the shallow sandy soils with cover at 9.3% +/- 7.2%. Present-day shrub vegetation constitutes a shifting mosaic marked by the coexistence of patches at different stages of development. Management implications of this long-term multi-scale assessment of vegetation dynamics support the notion that soil properties may constrain grassland remediation. Such efforts on sandy soils should be focused on sites characterized by near-surface water-holding capacity, as those lacking available water-holding capacity in the shallow root zone pose challenges to grass recovery and survival.

Authors

Browning, Dawn M.; Duniway, Michael C.; Laliberte, Andrea S.; Rango, Albert

Year Published

2012

Publication

Ecological Applications

Locations
This article contributed by:

Ecological Society of America

Revolutionary Land Use Change in the 21st Century: Is (Rangeland) Science Relevant?Herrick, J. E.2012

Revolutionary Land Use Change in the 21st Century: Is (Rangeland) Science Relevant?

Keywords

No keywords available

Abstract

Rapidly increasing demand for food, fiber, and fuel together with new technologies and the mobility of global capital are driving revolutionary changes in land use throughout the world. Efforts to increase land productivity include conversion of millions of hectares of rangelands to crop production, including many marginal lands with low resistance and resilience to degradation. Sustaining the productivity of these lands requires careful land use planning and innovative management systems. Historically, this responsibility has been left to agronomists and others with expertise in crop production. In this article, we argue that the revolutionary land use changes necessary to support national and global food security potentially make rangeland science more relevant now than ever. Maintaining and increasing relevance will require a revolutionary change in range science from a discipline that focuses on a particular land use or land cover to one that addresses the challenge of managing all lands that, at one time, were considered to be marginal for crop production. We propose four strategies to increase the relevance of rangeland science to global land management: 1) expand our awareness and understanding of local to global economic, social, and technological trends in order to anticipate and identify drivers and patterns of conversion; 2) emphasize empirical studies and modeling that anticipate the biophysical (ecosystem services) and societal consequences of large-scale changes in land cover and use; 3) significantly increase communication and collaboration with the disciplines and sectors of society currently responsible for managing the new land uses; and 4) develop and adopt a dynamic and flexible resilience-based land classification system and data-supported conceptual models (e.g., state-and-transition models) that represent all lands, regardless of use and the consequences of land conversion to various uses instead of changes in state or condition that are focused on a single land use.

Authors

Karl, Jason W., Herrick, J. E., Brown, J. R., Bestelmeyer, B. T., Andrews, S. S., Baldi, G., Davies, J., Duniway, M., Havstad, K. M., Karlen, D. L., Peters, D. P. C., Quinton, J. N., Riginos, C., Shaver, P. L., Steinaker, D. and Twomlow, S.

Year Published

2012

Publication

Rangeland Ecology & Management

Locations
    DOI

    10.2111/REM-D-11-00186.1

    Modeling Vegetation Heights from High Resolution Stereo Aerial Photography: An Application for Broad-Scale Rangeland MonitoringGillan, Jeffrey K.2014

    Modeling Vegetation Heights from High Resolution Stereo Aerial Photography: An Application for Broad-Scale Rangeland Monitoring

    Keywords

    rangeland monitoring, photogrammetry, vegetation height, digital terrain model, remote sensing

    Abstract

    Vertical vegetation structure in rangeland ecosystems can be a valuable indicator for assessing rangeland health and monitoring riparian areas, post-fire recovery, available forage for livestock, and wildlife habitat. Federal land management agencies are directed to monitor and manage rangelands at landscapes scales, but traditional field methods for measuring vegetation heights are often too costly and time consuming to apply at these broad scales. Most emerging remote sensing techniques capable of measuring surface and vegetation height (e.g., LiDAR or synthetic aperture radar) are often too expensive, and require specialized sensors. An alternative remote sensing approach that is potentially more practical for managers is to measure vegetation heights from digital stereo aerial photographs. As aerial photography is already commonly used for rangeland monitoring, acquiring it in stereo enables threedimensional modeling and estimation of vegetation height. The purpose of this study was to test the feasibility and accuracy of estimating shrub heights from high-resolution (HR, 3-cm ground sampling distance) digital stereo-pair aerial images. Overlapping HR imagery was taken in March 2009 near Lake Mead, Nevada and 5-cm resolution digital surface models (DSMs) were created by photogrammetric methods (aerial triangulation, digital image matching) for twenty-six test plots. We compared the heights of individual shrubs and plot averages derived from the DSMs to field measurements. We found strong positive correlations between field and image measurements for several metrics. Individual shrub heights tended to be underestimated in the imagery, however, accuracy was higher for dense, compact shrubs compared with shrubs with thin branches. Plot averages of shrub height from DSMs were also strongly correlated to field measurements but consistently underestimated. Grasses and forbs were generally too small to be detected with the resolution of the DSMs. Estimates of vertical structure will be more accurate in plots having low herbaceous cover and high amounts of dense shrubs. Through the use of statistically derived correction factors or choosing field methods that better correlate with the imagery, vegetation heights from HR DSMs could be a valuable technique for broad-scale rangeland monitoring needs.

    Authors

    Gillan, Jeffrey K., Karl, Jason W., Duniway, Michael and Elaksher, Ahmed

    Year Published

    2014

    Publication

    Journal of Environmental Management

    Locations
    DOI

    10.1016/j.jenvman.2014.05.028

    Interpretation of high-resolution imagery for detecting woodland cover composition change after fuels reduction treatmentsKarl, Jason W.2014

    Interpretation of high-resolution imagery for detecting woodland cover composition change after fuels reduction treatments

    Keywords

    image interpretation, rangeland monitoring, remote sensing, high-resolution, land cover, change detection

    Abstract

    The use of very high resolution (VHR; ground sampling distances < ~5cm) aerial imagery to estimate site vegetation cover and to detect changes from management has been well documented. However, as the purpose of monitoring is to document change over time, the ability to detect changes from imagery at the same or better level of accuracy and precision as those measured in situ must be assessed for image-based techniques to become reliable tools for ecosystem monitoring. Our objective with this study was to quantify the relationship between field-measured and image-interpreted changes in vegetation and ground cover measured one year apart in a savanna with increased woody vegetation cover in southern Utah, USA. The study area was subject to a variety of fuel removal treatments between 2009 and 2010. We measured changes in plant community composition and ground cover along transects in a control area and three different treatments prior to and following three woody removal. We compared these measurements to vegetation composition and change based on photo-interpretation of ~4 cm ground sampling distance imagery along similar transects. Estimates of cover were similar between field-based and image-interpreted methods in 2009 and 2010 for woody vegetation, no vegetation, herbaceous vegetation and litter (including woody litter). Image-interpretation slightly overestimated cover for woody vegetation and no-vegetation classes (average difference between methods of 1.34% and 5.85%) and tended to underestimate cover for herbaceous vegetation and litter (average difference of -5.18% and 0.27%), but the differences were significant only for litter cover in 2009. Level of agreement between the field-measurements and image-interpretation was good for woody vegetation and no-vegetation classes (r between 0.47 and 0.89), but generally poorer for herbaceous vegetation and litter (r between 0.18 and 0.81) likely due to differences in image quality by year and the difficulty in discriminating fine vegetation and litter in imagery. Our results show that image interpretation to detect vegetation changes has utility for monitoring fuels reduction treatments in terms of woody vegetation and bare ground. The benefits of this technique are that it provides objective and repeatable measurements of site conditions that could be implemented relatively inexpensively and easily without the need for highly specialized software or technical expertise. Perhaps the biggest limitations of image interpretation to monitoring fuels treatments are the difficulty in challenges in estimating litter and herbaceous vegetation cover and the sensitivity of herbaceous cover estimates to image quality and shadowing.

    Authors

    Karl, Jason W., Gillan, Jeffrey K., Barger, Nichole N., Herrick, Jeffrey E. and Duniway, Michael

    Year Published

    2014

    Publication

    Ecological Indicators

    Locations
    DOI

    10.1016/j.ecolind.2014.05.017

    Recent Articles

    Modeling Vegetation Heights from High Resolution Stereo Aerial Photography: an Application for Broad-Scale Rangeland Monitoring

    by Gillan, Jeffrey K., Karl, Jason W., Duniway, Michael and Elaksher, Ahmed

    Vertical vegetation structure in rangeland ecosystems can be a valuable indicator for assessing rangeland health and monitoring riparian areas, post-fire recovery, available forage for livestock, and wildlife habitat. Federal land management agencies are directed to monitor and manage rangelands at landscapes scales, but traditional field methods for measuring vegetation heights are often t...

    published 2014 in Journal of Environmental Management

    Interpretation of High-Resolution Imagery for Detecting Woodland Cover Composition Change After Fuels Reduction Treatments

    by Karl, Jason W., Gillan, Jeffrey K., Barger, Nichole N., Herrick, Jeffrey E. and Duniway, Michael

    The use of very high resolution (VHR; ground sampling distances &lt; ~5cm) aerial imagery to estimate site vegetation cover and to detect changes from management has been well documented. However, as the purpose of monitoring is to document change over time, the ability to detect changes from imagery at the same or better level of accuracy and precision as those measured in situ must be assesse...

    published 2014 in Ecological Indicators


    Interpretation of High-Resolution Imagery for Detecting Woodland Cover Composition Change After Fuels Reduction Treatments

    by Karl, Jason W., Gillan, Jeffrey K., Barger, Nichole N., Herrick, Jeffrey E. and Duniway, Michael C.

    The use of very high resolution (VHR; ground sampling distances &lt; ~5cm) aerial imagery to estimate site vegetation cover and to detect changes from management has been well documented. However, as the purpose of monitoring is to document change over time, the ability to detect changes from imagery at the same or better level of accuracy and precision as those measured in situ must be assesse...

    published 2014 in Ecological Indicators

    Assessing Impacts of Roads: Application of a Standard Assessment Protocol

    by Duniway, Michael C. and Herrick, Jeffrey E.

    Adaptive management of road networks depends on timely data that accurately reflect the impacts those systems are having on ecosystem processes and associated services. In the absence of reliable data, land managers are left with little more than observations and perceptions to support management decisions of road-associated disturbances. Roads can negatively impact the soil, hydrologic, plant,...

    published 2013 in Rangeland Ecology & Management