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Environmental factors often limit plant establishment and survival through increased seedling mortality. Understanding plant growth and the causes of mortality can be helpful in developing solutions that enhance seeding success and improve restoration monitoring. The purpose of our research was to assess the efficacy of time lapse and motion sensing cameras for monitoring seedling height, density, and fate. We conducted this study in a salt desert shrub community in northwest Utah, USA. In spring 2017, we placed 28 cameras in fenced and unfenced plots seeded with bottlebrush squirreltail and collected hourly images of the seedlings’ development for the initial four months post-seeding. The seedling attributes were recorded in-field and compared with camera images to determine accuracy and reliability. We found that the optimal period for capturing imagery occurred near the sun’s zenith when shadows were minimized. We were able to detect both the timing of the plant emergence, plant height, density, growth rate, and seedling death. The average seedling height and density were underestimated by 14% and 30% between the camera and field estimates, respectively. We recognize that it could be beneficial to adjust for the effect of the date. The reduced seedling density improved the measurement accuracy through a lower visual obscurity. Managers can utilize remote cameras to effectively measure vegetation that can provide an insight into environmental influences.

Small unmanned aircraft systems (sUAS) offer key benefits over manned aircraft and satellite platforms used for remote sensing research, such as high spatial resolution, portability, simplicity of ...

For centuries, humans occupying arid regions of North America have maintained an intricate relationship with Agave (Agavoideae, Asparagaceae). Today Agave cultivation, primarily for beverage production, provides an economic engine for rural communities throughout Mexico. Among known dryland-farming methods, the use of rock piles and cattle-grazed areas stand out as promising approaches for Agave cultivation. Identifying new cultivation areas to apply these approaches in Arizona, USA and Sonora, Mexico warrants a geographic assessment of areas outside the known ranges of rock piles and grasslands. The objective of this study was to predict areas for dryland-farming of Agave and develop models to identify potential areas for Agave cultivation. We used maximum entropy (MaxEnt) ecological-niche-modeling algorithms to predict suitable areas for Agave dryland farming. The model was parameterized using occurrence records of Hohokam rock piles in Arizona and grassland fields cultivated with Agave in Sonora. Ten environmental-predictor variables were used in the model, downloaded from the WorldClim 2 climate database. The model identified potential locations for using rock piles as dryland-farming methods from south-central Arizona to northwestern Sonora. The Agave-grassland model indicated that regions from central to southern Sonora have the highest potential for cultivation of Agave, particularly for the species Agave angustifolia. Results suggest that there are many suitable areas where rock piles can be used to cultivate Agave in the Sonoran Desert, particularly in the border of southeastern Arizona and northwest Sonora. Likewise, cattle-grazing grasslands provide a viable environment for cultivating Agave in southern Sonora, where the expanding bacanora-beverage industry continues to grow and where different Agave products (e.g., syrups, fructans, saponins, and medicinal compounds) can potentially strengthen local economies.

PurposeThe purpose of this study is to evaluate the vulnerability of the important rangeland shrub,Atriplex leucoclada(Boiss) to both climate change and livestock grazing, within the Syrian rangelands as a representative landscape type of West Asia.Design/methodology/approachEcologically based quantitative niche models were developed for both shrub species using maximum entropy and 13 spatially explicit GIS-based layers to predict current and future species distribution scenarios. Climatic variables varied over time in line with the predictions created from the HADCM3 global circulation model.FindingsResults indicate that with grazing and climate change, the distribution ofA. leucocladawill be reduced by 54 per cent in 2050, with the mean annual and minimum temperatures of the coldest month having the highest contribution in the model (28.7 and 21.2 per cent, respectively). The contribution of the grazing pressure, expressed by the overgrazing index, was estimated at 8.2 per cent.Originality/valueThese results suggest that the interaction of climate and increased grazing has the potential to favor the establishment of unpalatable species, while reducing the distribution of preferred plant species on western Asia rangelands.

Semi‐arid rangeland degradation is a reoccurring issue throughout the world. In the Great Basin of North America, seeds sown in the fall to restore degraded sagebrush (Artemisia spp.) steppe plant communities may experience high mortality in winter due to exposure of seedlings to freezing temperatures and other stressors. Delaying germination until early spring when conditions are more suitable for growth may increase survival. We evaluated the use of BioNik™ (Valent BioSciences LLC) abscisic acid (ABA) to delay germination of bluebunch wheatgrass (Pseudoroegneria spicata). Seed was either left untreated or coated at five separate rates of ABA ranging from 0.25 to 6.0 g 100 g−1 of seed. Seeds were incubated at five separate constant temperatures from 5 to 25°C. From the resultant germination data, we developed quadratic thermal accumulation models for each treatment and applied them to 4 years of historic soil moisture and temperature data across six sagebrush steppe sites to predict germination timing. Total germination percentage remained similar across all temperatures except at 25°C, where high ABA rates had slightly lower values. All ABA doses delayed germination, with the greatest delays at 5–10°C. For example, the time required for 50% of the seeds to germinate at 5°C was increased by 16–46 d, depending on the amount of ABA applied. Seed germination models predicted that the majority of untreated seed would germinate 5–11 weeks after a 15 October simulated planting date. In contrast, seeds treated with ABA were predicted to delay germination to late winter or early spring. These results indicate that ABA coatings may delay germination of fall planted seed until conditions are more suitable for plant survival and growth.

Current methods for determining plant age of shrub species require destructive sampling and annual growth ring analysis on the primary stem. Although individual plant ages can frequently be determined in this manner, the method is time consuming and of limited value for plants that have lost stem wood from stem splitting and rot. Nondestructive methods for estimating big sagebrush (Artemisia tridentata Nutt.) plant age would be useful in assessing stand age structure and population dynamics at variable spatial scales. The purpose of this study was to test a suite of traits for potential use in estimating mountain big sagebrush (Artemisia tridentata ssp. vaseyana [Rydb.] Beetle) age. We evaluated traits including plant height, crown area, subcanopy litter depth, percent crown mortality, bark furrow depth, bark fiber length, circumference and diameter of plant basal stem, and circumference of secondary and tertiary branches. We measured and harvested basal cross-sections from 163 plants of varying sizes from five locations in central and south-central Utah. Plant age was determined from annual growth rings. Linear regression analyses revealed that stem diameter (r2 = 0.507 P

Exotic annual grasses are transforming native arid and semi-arid ecosystems globally by accelerating fire cycles that drive vegetation state changes. Cheatgrass (Bromus tectorum), a particularly widespread and aggressive exotic annual grass, is a key management target in national parks of the western United States due to its impacts on wildfire and biodiversity loss. Cheatgrass is known for its high interannual variability and can grow in a wide range of conditions. The objectives were to (1) map the presence and persistence of cheatgrass in national park units across a 11-year period using remote sensing, and (2) identify the biophysical parameters that correlate with cheatgrass persistence. We used remote sensing and GIS tools to develop a systematic model to characterize the status and environmental correlates of cheatgrass invasions in seven national park units in the western United States. On average cheatgrass covered 3.8% of park areas, each park ranging from 0.8 to 24.8% coverage. Where cheatgrass was detected, persistent populations across time (hotspots) made up on average 13% of cheatgrass areas. Hotspots were found in areas with deeper plant-available water, lower elevations, colder mean winter temperatures, flatter slopes, higher soil clay content, and lower mean fall precipitation. Study results identified spatiotemporal patterns of plant invasions and key environmental drivers that influence invasion patterns. GIS tool development and analysis from this study were used to generate invasion maps for each park, which can be used to mitigate wildfire and biodiveristy loss.

This is the final version. Available from the Ecological Society of America via the DOI in this record

Obtaining accurate plant population estimates has been integral in listing, recovery, and delisting species under the U.S. Endangered Species Act of 1973 and for monitoring vegetation in response to livestock grazing. Obtaining accurate population estimates remains a daunting and labor-intensive task. Small unmanned aircraft systems (sUASs or drones) may provide an effective alternative to ground surveys for rare and endangered plants. The objective of our study was to evaluate the efficacy of sUASs (DJI Phantom 4 Pro) for surveying the Wright fishhook cactus (Sclerocactus wrightiae), a small (1–8 cm diameter) endangered species endemic to grazinglands in the southwest desert of Utah, USA. We assessed sUAS-based remotely sensed imagery to detect and count individual cacti compared to ground surveys and estimated optimal altitudes (10 m, 15 m, or 20 m) for collecting imagery. Our results demonstrated that low altitude flights provided the best detection rates (p < 0.001) and counts (p < 0.001) compared to 15 m and 20 m. We suggest that sUASs can effectively locate cactus within grazingland areas, but should be coupled with ground surveys for higher accuracy and reliability. We also acknowledge that these technologies may have limitations in effectively detecting small, low-growing individual plants such as the small and obscure fishhook cactus species.

Cultivation of C3 and C4 crops in semi-arid regions will be severely constrained as global temperatures rise. Consequently, alternative crops need to be sought out that adapt well to heat and drought and are productive despite limited access to water. Traits, such as crassulacean acid metabolism (CAM), enable economically important species such as those in the Agave genus adapt to drought and high temperatures. The succulence and high efficiency of agaves, which enables them to produce biomass with little water, underscores their feasibility as an alternative crop for semi-arid regions, such as the Sonoran Desert in the southwestern U.S. In this paper, we offer a review of the suitability for cultivation of agaves via dryland farming, particularly by rock mulching techniques used by pre-Columbian, Sonoran Desert farmers. This analysis dovetails with information also provided on the biological traits of Agave and its historical and present utilization. Pre-Columbian, Hohokam dryland farmers used rock mulching in the form of rock piles to cultivate agaves. Rock piles acted as a type of mulch to harvest rainfall and to retain soil moisture, which allowed the Hohokam to intensively cultivate agaves during multi-year droughts. Remains of Hohokam rock mulching for agave production can be found at archaeological sites in central Arizona, which provides evidence of the utility of dryland farming and ancient agricultural innovation to reconcile water scarcity in the region. Moreover, the use of rock piles likely bolstered Agave productivity in marginal lands. Although little is known of historic rock mulching to cultivate agaves and its biological implications on plant productivity we suggest its application as a dryland farming model could be a sustainable strategy in the U.S. Southwest.

In situ measurements of sagebrush have traditionally been expensive and time consuming. Currently, improvements in small Unmanned Aerial Systems (sUAS) technology can be used to quantify sagebrush morphology and community structure with high resolution imagery on western rangelands, especially in sensitive habitat of the Greater sage-grouse (Centrocercus urophasianus). The emergence of photogrammetry algorithms to generate 3D point clouds from true color imagery can potentially increase the efficiency and accuracy of measuring shrub height in sage-grouse habitat. Our objective was to determine optimal parameters for measuring sagebrush height including flight altitude, single- vs. double- pass, and continuous vs. pause features. We acquired imagery using a DJI Mavic Pro 2 multi-rotor Unmanned Aerial Vehicle (UAV) equipped with an RGB camera, flown at 30.5, 45, 75, and 120 m and implementing single-pass and double-pass methods, using continuous flight and paused flight for each photo method. We generated a Digital Surface Model (DSM) from which we derived plant height, and then performed an accuracy assessment using on the ground measurements taken at the time of flight. We found high correlation between field measured heights and estimated heights, with a mean difference of approximately 10 cm (SE = 0.4 cm) and little variability in accuracy between flights with different heights and other parameters after statistical correction using linear regression. We conclude that higher altitude flights using a single-pass method are optimal to measure sagebrush height due to lower requirements in data storage and processing time.

Horses have been associated with human societies for millennia, and for many have come to symbolize wildness, power, resilience, and freedom. Although equids were extirpated from North America 10,000–12,000 years ago, descendants of domestic horses now roam freely in the USA and 17 other countries across six continents. In landscape-scale and experimental investigations, free-roaming horses ( Equus caballus ) have been shown to induce numerous alterations to native-ecosystem components and processes through influences on soil, water, plants, and other aspects of biodiversity. However, we argue that the management of free-roaming horses both in the U.S. and globally has been complicated by “socio-ecological mismatches.” Such mismatches arise from an inability to reconcile conflicting processes and functions in a social-ecological system, often reflecting differences in the spatio-temporal scales at which diverse components operate. Here, we describe three types of mismatches, and illustrate how the ecological dynamics of aridlands generally fit poorly with existing approaches to horse management and policy. Such mismatches complicate cost-effective management of free-roaming horses and the ecosystems they inhabit, and reduce the palette of potential solutions.

Seed production is an essential component of postdisturbance recovery for mountain big sagebrush (Artemisia tridentata Nutt, ssp vaseyana [Rydb] Beetle; MBS). We tested a method for rapid estimation of MBS seed production using measurements of inflorescence morphology. We measured total stem length, stem length from first branchlet to stem tip, stem diameter, fresh weight, and number of stem branchlets for 750 inflorescences collected from five central and southern Utah sites. Florets per inflorescence were counted to provide an estimate of seed production potential. We used regression analysis to assess associations between morphological traits and potential seed production and evaluated the efficiency and scalability of each measure for field application. Site means for morphological measures varied ∼2 to 11-fold while mean number of florets per inflorescence varied ∼ 8-fold. Inflorescence weight was the best predictor of seed production potential (P < 0.0001, r2 = 0.897), although correlations for all tested variables were highly significant. Among-site differences in regression equations for this relationship were not significant (P = 0.226), suggesting that a single conversion factor may have broad application. However, validation will require additional testing across a broader range of sites and field conditions. Scalable methods for efficient estimation of sagebrush seed production potential, such as those evaluated in this study, could be useful for managers charged with assessing variability in sagebrush community stability.

Feral horses ( Equus callabus ) occur throughout the world on all continents except Antarctica. In North America, feral horses occupy 31.6 million acres throughout western North America. Throughout their range, feral horses often share habitat with American pronghorn ( Antilocapra americana) . Since horses are larger and more aggressive than pronghorn, they are considered socially dominant. In the Great Basin of western North America, pronghorn often access water sources where horses occur since habitat preferences are similar. If pronghorn are excluded where water is used by both species, pronghorn fitness may be impaired, especially during dry or droughty periods. The purpose of this study was to investigate interference competition between pronghorn and feral horses at water sources within the Great Basin. We observed horses and pronghorn at high-use water sources and recorded all occurrences and outcomes of pronghorn/horse interactions. We assessed differences in pronghorn behavior in the presence or absence of horses. Pronghorn invested more time on vigilance behavior and less time foraging or drinking in the presence of horses than in their absence. Nearly half of pronghorn/horse interactions resulted in pronghorn exclusion from water. We conclude that as feral horse numbers increase, competition for water will subsequently increase.

Encroachment of pinyon (Pinus spp) and juniper (Juniperus spp.) woodlands in western North America is considered detrimental due to its effects on ecohydrology, plant community structure, and soil stability. Management plans at the federal, state, and private level often include juniper removal for improving habitat of sensitive species and maintaining sustainable ecosystem processes. Remote sensing has become a useful tool in determining changes in juniper woodland structure because of its uses in comparing archived historic imagery with newly available multispectral images to provide information on changes that are no longer detectable by field measurements. Change in western juniper (J. occidentalis) cover was detected following juniper removal treatments between 1995 and 2011 using panchromatic 1-meter NAIP and 4-band 1-meter NAIP imagery, respectively. Image classification was conducted using remotely sensed images taken at the Roaring Springs Ranch in southeastern Oregon. Feature Analyst for ArcGIS (object-based extraction) and a supervised classification with ENVI 5.2 (pixel-based extraction) were used to delineate juniper canopy cover. Image classification accuracy was calculated using an Accuracy Assessment and Kappa Statistic. Both methods showed approximately a 76% decrease in western juniper cover, although differing in total canopy cover area, with object-based classification being more accurate. Classification results for the 2011 imagery were much more accurate (0.99 Kappa statistic) because of its low juniper density and the presence of an infrared band. The development of methods for detecting change in juniper cover can lead to more accurate and efficient data acquisition and subsequently improved land management and monitoring practices. These data can subsequently be used to assess and quantify juniper invasion and succession, potential ecological impacts, and plant community resilience.

Rangeland monitoring is important for evaluating and assessing semi-arid plant communities. Remote sensing provides an effective tool for rapidly and accurately assessing rangeland vegetation and other surface attributes such as bare soil and rock. The purpose of this study was to evaluate the efficacy of remote sensing as a surrogate for field-based sampling techniques in detecting ground cover features (i.e., trees, shrubs, herbaceous cover, litter, surface), and comparing results with field-based measurements collected by the Utah Division of Wildlife Resources Range Trent Program. In the field, five 152 m long transects were used to sample plant, litter, rock, and bare-ground cover using the Daubenmire ocular estimate method. At the same location of each field plot, a 4-band (R,G,B,NIR), 25 cm pixel resolution, remotely sensed image was taken from a fixed-wing aircraft. Each image was spectrally classified producing 4 cover classes (tree, shrub, herbaceous, surface). No significant differences were detected between canopy cover collected remotely and in the field for tree (P = 0.652), shrub (P = 0.800), and herbaceous vegetation (P = 0.258). Surface cover was higher in field plots (P < 0.001), likely in response to the methods used to sample surface features by field crews. Accurately classifying vegetation and other features from remote sensed information can improve the efficiency of collecting vegetation and surface data. This information can also be used to improve data collection frequency for rangeland monitoring and to efficiently quantify ecological succession patterns.

On the Ground • Spatial data is valuable to researchers for locating studies that occur in a particular area of interest, or one with similar attributes. • Without a standard in publishing protocol, spatial data largely goes unreported, or is difficult to find without searching the publication. • Assigning location data and displaying points on a public web map makes locating publications based on spatial location possible.

Expansion of Pinus L. (pinyon) and Juniperus L. (juniper) (P-J) trees into sagebrush (Artemisia L.) steppe communities can lead to negative effects on hydrology, loss of wildlife habitat, and a decrease in desirable understory vegetation. Tree reduction treatments are often implemented to mitigate these negative effects. In order to prioritize and effectively plan these treatments, rapid, accurate, and inexpensive methods are needed to estimate tree canopy cover at the landscape scale. We used object based image analysis (OBIA) software (Feature AnalystTM for ArcMap 10.1®, ENVI Feature Extraction®, and Trimble eCognition Developer 8.2®) to extract tree canopy cover using NAIP (National Agricultural Imagery Program) imagery. We then compared our extractions with ground measured tree canopy cover (crown diameter and line point intercept) on 309 plots across 44 sites in Utah. Extraction methods did not consistently over- or under-estimate ground measured P-J canopy cover except where tree cover was >45%. Estimates of tree canopy cover using OBIA techniques were strongly correlated with estimates using the crown diameter method (r = 0.93 for ENVI, 0.91 for Feature AnalystTM, and 0.92 for eCognition). Tree cover estimates using OBIA techniques had lower correlations with tree cover measurements using the line-point intercept method (r = 0.85 for ENVI, 0.83 for Feature AnalystTM, and 0.83 for eCognition). All software packages accurately and inexpensively extracted P-J canopy cover from NAIP imagery when the imagery was not blurred, and when P-J cover was not mixed with Amelanchier alnifolia (Utah serviceberry) and Quercus gambelii (Gambel’s oak), which had similar spectral values as P-J.

The recent introduction of low cost small unmanned aircraft systems (sUAS) to remote sensing has provided a significant improvement in the quantity and quality of high resolution imagery. The purpose of this research was to describe the acquisition of very high resolution imagery using sUAS (drones) and assess the effectiveness of spectral-based classification for distinguishing vegetation (species, total cover), percent bare ground, litter, and rock from this data. Images were obtained from a semiarid rangeland site in central Nevada, USA. Flight missions were flown 15 m above ground level using automated flight paths, and individual images were processed into orthomosaics using the Pix4D software. Features were classified using a spectral unsupervised classification. Ground-based measurements were collected in the field to compare rangeland structure with generated classification output. Results indicate that very high resolution imagery can be effectively used to assess rangeland ecosystems that can aid in rangeland assessment and monitoring. The ability to use sUAS to monitor ecosystem structure and condition can be an important resource for rangeland managers, as they improve their ability to access high quality data for making informed management decisions within and across multiple years.

Broadcast seeding is one of the most commonly applied rehabilitation treatments for the restoration of burned pinon and juniper woodlands, but the success rate of this treatment is notoriously low. In pinon-juniper woodlands, postfire soil—water repellency can impair seeding success by reducing soil—water content and increasing soil erosion. Implementing anchor chaining immediately after seeding can improve establishment of seeded species by enhancing seed-to-soil contact and may improve restoration success by decreasing soil—water repellency through soil tillage. The objectives of this research were to 1) determine if anchor chaining in postfire pinyon-juniper woodlands diminishes soil—water repellency, and 2) determine meaningful relationships between soil—water repellency, unsaturated hydraulic conductivity [K(h)], and the establishment of seeded and invasive species. Research was conducted on two study sites, each located on a burned pinon-juniper woodland that had severe water repellency and...

Numerous studies have been conducted that evaluate the utility of remote sensing for monitoring and assessing vegetation and ground cover to support land management decisions and complement ground measurements. However, few comparisons have been made that evaluate the utility of object-based image analysis (OBIA) to accurately classify a landscape where rule sets (models) have been developed at various scales. In this study, OBIA rule sets used to estimate land cover from high–spatial resolution imagery (0.06-m pixel) on Pinus L. (pinyon) and Juniperus L. (juniper) woodlands were developed using eCognition Developer at four scales with varying grains—1) individual plot, 2) individual sites, 3) regions (western juniper vs. Utah juniper sites), and 4) pinyon-juniper woodland network (all plots)—that were within the same study extent. Color-infrared imagery was acquired over five sites in Oregon, California, Nevada, and Utah with a Vexcel UltraCamX digital camera in June 2009. Ground cover measurements were also collected at study sites in 2009 on 80 0.1-ha plots. Correlations between OBIA and ground measurements were relatively high for individual plot and site rule sets (ranging from r¼0.52 to r¼0.98). Correlations for regional and network rule sets were lower (ranging from r¼0.24 to r¼0.63), which was expected due to radiance differences between the images as well as vegetation differences found at each site. All site and plot OBIA average cover percentage estimates for live trees, shrubs, perennial herbaceous vegetation, litter, and bare ground were within 5% of the ground measurements, and all region and network OBIA average cover percentage estimates were within 10%. The trade-off for decreased accuracy over a larger area (region and network rule sets) may be useful to prioritize management strategies but will unlikely capture subtle shifts in understory plant communities that site and plot rule sets often capture.

Direct seeding techniques often result in unsatisfactory outcomes in rangeland rehabilitation, primarily because of low seedling emergence and poor establishment. Seed processing techniques aimed at improving seedling emergence have gained interest by pasture managers. The purpose of this study was to investigate the combined effects of bracteole removal and seeding rate on seedling emergence in seven halophytic species: Atriplex halimus, A. canescens, A. leucoclada, A. nummularia, A. lentiformis, Salsola vermiculata and Haloxylon aphyllum under semi-arid conditions in Tel Hadya (Syria). Each of these species was evaluated for seedling emergence under two seed treatments (bracteoles removed and non-removed bracteoles) with three seeding rates (10, 30 and 60 seeds per pot), in a completely randomised block design. The results showed a positive effect of seed treatment on seedling emergence for all studied species. The native A. halimus had the highest emergence percentages whereas the introduced A. mummularia, had the lowest. However, there were no significant effects of seeding rates on seedling emergence. These results showed that bracteole removal could improve germination and seedling emergence, and potentially increase the rate of establishment of the species studied. Therefore, when implementing rangeland rehabilitation projects, bracteole removal needs to be considered. The native S. vermiculata should be recommended for direct seeding in the West Asia and North Africa region given its high seedling emergence, known high palatability, nutritive value, and high auto-regeneration performance.

More effective methods for counting greater sage-grouse (Centrocercus urophasianus) are needed to better assess population trends through enumeration or location of new leks. We describe an aerial infrared technique for conducting sage-grouse lek counts and compare this method with conventional ground-based lek count methods. During the breeding period in 2010 and 2011, we surveyed leks from fixed-winged aircraft using cryogenically cooled mid-wave infrared cameras and surveyed the same leks on the same day from the ground following a standard lek count protocol. We did not detect significant differences in lek counts between surveying techniques. These findings suggest that using a cryogenically cooled mid-wave infrared camera from an aerial platform to conduct lek surveys is an effective alternative technique to conventional ground-based methods, but further research is needed. We discuss multiple advantages to aerial infrared surveys, including counting in remote areas, representing greater spatial variation, and increasing the number of counted leks per season. Aerial infrared lek counts may be a valuable wildlife management tool that releases time and resources for other conservation efforts. Opportunities exist for wildlife professionals to refine and apply aerial infrared techniques to wildlife monitoring programs because of the increasing reliability and affordability of this technology.

Land managers need to rapidly assess vegetation composition and bare ground to effectively evaluate and manage shrub steppe communities that have been encroached by pinyon and juniper trees. We used an object-based image analysis (OBIA) approach to estimate land cover classes found in pinyon-juniper woodlands, and evaluated the relationship between ground measurements and OBIA land cover measurements. We acquired high-spatial resolution color-infrared imagery for five sites with a Vexcel UltraCamX digital camera in June 2009. We simultaneously collected ground-based cover measurements within 30 m × 33 m subplots. OBIA mean land cover class differences by site ranged from underestimating litter by 3 percent to overestimating live trees by 1 percent when compared to ground-based measurements. Overall accuracy for thematic maps was 84 percent with a Kappa statistic of 0.80. Although OBIA cover estimates varied slightly from ground cover estimates, methods provide land managers with options for prioritizing management practices and enabling monitoring at an operational scale.

The ancient polity of Tikal has been extensively studied by archaeologists and soil scientists, but more information is needed to determine the specific subsistence and ancient farming techniques that sustained its inhabitants for more than eight centuries. Recent settlement, soil resource, and vegetation surveys were completed during a re-evaluation of the earthworks of Tikal. The objective of this research was to combine non-parametric multiplicative regression, stable carbon isotopes, soil properties, and remote-sensing data for cost-effective, predictive modelling of ancient maize Zea mays L. agricultural areas. The study area is positioned within a 300 km2 region surrounding the Tikal site centre 17° 13′ 19.0″ N, 89° 27′ 25.2″ W. In the study area, ancient maize agriculture was determined using carbon C isotopic signatures of C4 vegetation that were incorporated into the soil humin fraction. Probability models predicting C isotopic enrichment were used to outline areas of potential long-term maize agriculture. A binomial model predicted areas mainly along the bajo margins, indicating that these areas may have been used for sustained ancient maize agriculture. Upland areas with shallow Rendolls soil were found to lack strong C4 isotopic signatures. They showed a long-term C3 vegetation signature that could have supported native forest, silvicultural activities, or C3 cropping practices i.e. forest gardens. The mosaic of C3 and C4 signatures within the study site soils suggests that the Tikal area supported a variety of food production systems.

Greater sage-grouse (GSG; Centrocercus urophasianus) selectively utilize portions of sagebrush and sagebrush associated habitats within broad and heterogeneous landscapes. Until recently, sage-grouse research has generally focused on fine-scale vegetation structure and composition and less on landscape-scale habitat requirements. Insufficient information at broad scales limits a manager’s ability to interpret and predict habitat use patterns, assess habitat suitability, and target areas for conservation and ecological rehabilitation. We identified environmental attributes associated with GSG habitat use at broad spatial scales. In 2006, we captured 50 GSG, radio-collared each bird, and tracked each bird’s position within a 31,416 ha study area in central Oregon, USA. We monitored birds year-long between March 2006 and March 2008 across the study area. Each time a bird was located, we collected a coordinate position at the point where it was observed. We generated spatially explicit predictor variables in a Geographic Information System to quantify the association between landscape structure and GSG occurrence. Predictor variables included elevation, slope, aspect, curvature, solar radiation, landscape ruggedness, orientation, distance from roads, distance from leks, distance from mesic habitats, and cover type. We used spatial modeling (Maximum Entropy) to 1) develop predictive models of GSG seasonal resource use, 2) generate probability maps for visual assessment, and 3) characterize response curves associated with GSG habitat preference based on individual landscape predictor variables. Results indicate that during the breeding season GSG will use big sagebrush, low sagebrush or complexes of low and mountain big sagebrush cover types. During the summer season, GSG use low sagebrush, mountain big sagebrush, and mesic areas. Additionally, summer season use areas include higher elevation sites within or in close proximity to habitats that sustain succulent forbs throughout most of the growing season. Maps of modeled data identify spatially explicit areas of preferred habitat and predicted bird use patterns. This information can help managers identify and protect important GSG habitat across heterogeneous landscapes.

High intensity wildfires in semiarid shrub and woodland plant communities can leave ecosystems incapable of self-repair and susceptible to weed invasion. Subsequently, land managers need effective restoration tools to reseed native vegetation back into these degraded systems. In order to develop successful post-fire restoration approaches in these communities, it is critical that we understand the mechanisms that impair reseeding success. Our objective was to quantify the influence of soil water repellency on seedling emergence and plant growth in a greenhouse study using soil cores obtained from beneath burned Juniperus osteosperma trees. Soil cores were seeded with either Elymus wawawaiensis or Agropyron cristatum, and watered with either a high (watered daily) or a low water regime (watered every 5 days). During the first watering event, water repellency was ameliorated in half the cores by adding a wetting-agent comprised of alkylpolyglycoside-ethylene oxide/propylene oxide block copolymers. Results s...

Usnea hirta, an important member of the lichen family Parmeliaceae, has long been used as a bio-monitor of air pollution, particularly of sulphur dioxide in North America. Although U. hirta has a wide geographical distribution, it is important to be able to identify accurately the optimal habitat conditions for air pollution-sensitive species, thus making it possible to more effectively and efficiently establish air quality bio-monitoring stations. We modelled the distribution of U. hirta as a function of nine variables, five macroclimatic variables: average monthly precipitation, average monthly minimum temperature, average monthly maximum temperature, solar radiation, and integrated moisture index, and four topographic variables: elevation, slope, aspect, and land forms and uses for the White River National Forest, Colorado. The response variable was developed based on the presence or absence of U. hirta at each of 72 bio-monitoring baseline sites established in selected portions of four intermountain area states. Our model was developed using Non-Parametric Multiplicative Regression (NPMR) analysis, a modelling approach that analyzes environmental gradients, or predictor variables, against known locations for individuals of the model species. Finally, we evaluated our model on the basis of log β values and overall improvement over a naïve model and the Monte Carlo Permutation Test with 1000 randomized runs. The best model for U. hirta included four variables – solar radiation, average monthly precipitation, and average monthly minimum and maximum temperatures (log β=3·68). Among these four variables, average monthly maximum temperature was the most influential predictor (sensitivity=0·71) for the distribution of U. hirta. The occurrence rate for U. hirta, based on field validation, was 45·5%, 65·4%, and 70·4% for low, medium, and high probability areas, respectively. This study showed that our model was successful in predicting the distribution of U. hirta in the White River National Forest. Based on these results, the north-eastern and western portions of the forest appear to offer the most favourable conditions for the installation of future air quality bio-monitoring baseline sites.

The arid rangelands of Syria cover over half of the nation's landmass. Punctuating this landscape are broad, dry basins, or wadis, and gentle landscape depressions that exhibit localized elevated vegetation productivity and unique edaphic and hydrologic properties. Historically, continuous heavy grazing and aggressive agricultural activities resulted in excessive ecological degradation within these sensitive environments. Information is needed to determine the influence of livestock grazing on plant communities in landscape depressions and the impact that this has on ecosystem resilience. The purpose of this research is to evaluate the effect of short-term sheep grazing on vegetation characteristics and plant community structure within depressions, and to provide recommendations for improved grazing management. Study plots were randomly located within paired topographic depressions located in northwestern Syria. Vegetation samples were collected along transects including plant biomass, plant density, herbaceous cover, and species diversity. In grazed plots, plant biomass was 49 g DM/m2 compared to 234.4 g DM/m2 in protected plots. Average plant density was 65 plants/m2 in grazed plots compared to 1013 plants/m2 in protected plots (P = 0.001). Herbaceous cover was 175% higher on protected sites compared to grazed plots. Average diversity (Shannon–Wiener index value) was 0.8 in grazed plots compared to 2.3 in protected plots. These results suggest that plant community structure will be impacted from short-term grazing and that a site's ability to positively respond to disturbance over time may be limited. We conclude that carefully planned grazing management should result in greater plant productivity and diversity.

Soil water repellency can limit postfire reseeding efforts and thus increase the susceptibility of a site to weed invasion. We evaluated the effectiveness of wetting agents and simulated anchor chaining for improving seedling growth and survival in water-repellent soil, for the native perennial bluebunch wheatgrass (Pseudoroegneria spicata) and invasive annual cheatgrass (Bromus tectorum). Research was performed in a glasshouse, on 20-cm-diameter soil cores that were excavated from underneath burned Utah juniper (Juniperus osteosperma) trees. The experiment was arranged as a randomized split-plot design, with the two grass species sown separately under four soil treatments: 1) no treatment (control), 2) simulated anchor chaining (hereafter referred to as “till”), 3) wetting agent, and 4) till plus wetting agent. Soil water content was highest in the wetting agent treatment, lower for till, and lowest in the control. Overall, the response of bluebunch wheatgrass and cheatgrass was similar among treatments. At the conclusion of the study, wetting agent cores had twice as many seedlings as the control, while the till and control were similar. Despite a lower number of seedlings, tilling in general resulted in the same level of biomass as the wetting agent treatment. Overall, biomass in the till and wetting agent treatments was at least twofold higher than the control. No benefit was found in applying both till and wetting agent treatments together in comparison to just applying wetting agent. Because of a lack of correlation between glasshouse and field settings the results of this study need to be interpreted with caution. Our data may indicate that if cheatgrass is not already present on the site, anchor chaining or treating the soil with wetting agent can increase establishment of seeded species.

Greater Sage-Grouse (Centrocercus urophasianus) depend on sagebrush habitat for food and cover during winter, yet few sage-grouse winter ecology studies have been conducted. During January and February 2007, we monitored 22 radio-collared sage-grouse (7 females and 15 males) in central Oregon to characterize winter habitat use and movement patterns. We estimated distances traveled between locations on a weekly basis and quantified habitat characteristics at loca- tions used by male and female sage-grouse. The birds we collared moved extensively across the landscape, using approxi - mately 1480 km2. Sagebrush canopy height in sites used by sage-grouse varied from 0.25 to 0.75 m, with females tending to be found in sites with taller sagebrush and less foliar cover than in sites where we found males. The difference in foliar cover between sexes was related to a seasonal change in habitat use: 4 females found in little sagebrush (Artemisia arbuscula) in January and early February were no longer located nor found foraging in little sagebrush after 15 February. Also, by this date, most male sage-grouse had stopped using big sagebrush (Artemisia tridentata) as they migrated to leks. Sage-grouse mortality rates were low during our study, which may be attributed to the study area receiving half the long-term average amount of snow. The large area over which sage-grouse moved during winter indicates that conservation of Greater Sage-Grouse may require preservation of sagebrush at landscape scales (thousands of square kilometers).

A sample preparation sequence for actinide isotopic analysis by thermal ionization mass spectrometry (TIMS) is described that includes column-based extraction chromatography as the first separation step, followed by anion-exchange column separations. The sequence is designed to include a wet ashing step after the extraction chromatography to prevent any leached extractant or oxalic acid eluent reagents from interfering with subsequent separations, source preparation, or TIMS ionization. TEVA resin and DGA resin materials, containing extractants that consist only of C, N, O, and H atoms, were investigated for isolation of plutonium. Radiotracer level studies confirmed expected high yields from column-based separation procedures. Femtogram-level studies were carried out with TIMS detection, using multiple monoisotopic spikes applied sequentially throughout the separation sequence. Pu recoveries were 87% and 86% for TEVA and DGA resin separations, respectively. The Pu recoveries from 400 μL anion-exchange column separation sequences were 89% and 93% for trial sequences incorporating TEVA and DGA resin. Thus, a prior extraction chromatography step in the sequence did not interfere with the subsequent anion-exchange separation when a simple wet ash step was carried out in between these column separations. The average measurement efficiency for Pu, encompassing the chemical separation recoveries and the TIMS ionization efficiency, was 2.73% ± 0.77% (2σ) for the DGA resin trials and 2.67% ± 0.54% for the TEVA resin trials, compared to 3.41% and 2.37% (average 2.89%) for two control trials. These compare with an average measurement efficiency of 2.78% ± 1.70%, n = 33 from process benchmark analyses using Pu spikes processed through a sequence of oxalate precipitation, wet ash, iron hydroxide precipitation, and anion-exchange column separations. We conclude that extraction chromatography can be a viable separation procedure as part of a multistep sequence for TIMS sample preparation.

Western North America is experiencing a dra- matic expansion of pinon (Pinus spp.) and juniper (Juni- perus spp.) (P-J) trees into shrub-steppe communities. Feature extracted data acquired from remotely sensed imagery can help managers rapidly and accurately assess this land cover change in order to manage rangeland eco- systems at a landscape-scale. The objectives of this study were to: (1) develop an effective and efficient method for accurately quantifying P-J tree canopy cover and density directly from high resolution photographs and (2) compare feature-extracted data to typical in-situ datasets used by land managers. Tree cover was extracted from aerial-pho- tography using Feature Analyst. Tree density was calcu- lated as the sum of the total number of individual polygons (trees) within the tree cover output file after isolation using a negative buffer post-processing technique. Feature- extracted data were compared to ground reference mea- surements from Utah's Division of Wildlife Resources Range Trend Project (DWR-RTP). We found that the proposed feature-extraction techniques used for measuring cover and density were highly correlated to ground refer- ence and DWR-RTP datasets. Feature-extracted measure- ments of cover generally showed a near 1:1 relationship to these data, while tree density was underestimated; how- ever, after calibration for juvenile trees, a near 1:1 rela- tionship was realized. Feature-extraction techniques used in this study provide an efficient method for assessing important rangeland indicators, including: density, cover, and extent of P-J tree encroachment. Correlations found between field and feature-extracted data provide evidence to support extrapolation between the two approaches when assessing woodland encroachment.

Western juniper (Juniperus occidentalis subsp. occidentalis Hook.) woodlands are expanding from their historic range and causing significant declines of other plant communities. However, landscape-scale restoration projects are hindered by timeconsuming and expensive methods to inventory juniper cover and prioritize landscapes based on developmental phase of juniper encroachment. We investigated the ability of feature-extraction software to estimate western juniper cover from color aerial photographs obtained from the National Agriculture Imagery Program (NAIP) and explored the relationships between juniper cover at stand closure (potential juniper cover) and environmental/site indices (heat load, site exposure, and integrated moisture index) and characteristics measured from commonly available geospatial data layers. Estimates of juniper cover derived from NAIP imagery and ground measurements were similar (R 2 5 0.74; P , 0.01). Neither method consistently estimated juniper cover higher or lower than the other method (P 5 0.79). Environmental indices were either not correlated or weakly correlated with juniper cover at stand closure. However, the environmental/site characteristics (slope, aspect, and elevation) could be used to explain 40% of the variation in juniper cover at stand closure (R 2 5 0.40; P , 0.01). Thus, commonly available geospatial data layers can be used to assist in determining potential juniper cover. This information can then be compared to current juniper cover to determine juniper woodland developmental phase. Knowing the developmental phase is important because management strategies and effectiveness of restoration treatments differ among phases of juniper encroachment. Our results suggest that NAIP imagery can be a valuable tool to estimate juniper cover over large areas effectively to make landscape-scale restoration more feasible. The model of the relationship between environmental/site characteristics measured from commonly available geospatial data layers and potential juniper can be used to assist in restoration planning and prioritization, but could be improved with further refinement.

Tropical forests provide important habitat for a tremendous diversity of plant and animal species. However, limitations in measuring and monitoring the structure and function of tropical forests has caused these systems to remain poorly understood. Remote-sensing technology has provided a powerful tool for quantification of structural patterns and associating these with resource use. Satellite and aerial platforms can be used to collect remotely sensed images of tropical forests that can be applied to ecological research and management. The purpose of this article is to highlight the resources available for tropical forest remote sensing and to present a case-study that demonstrates its application to a neotropical forest located in the Peten region of northern Guatemala.

Questions: How does landscape position influence biotic and abiotic attributes of western juniper (Juniperus occidentalis) encroached ecosystems? How does intercanopy plant community structure respond to changes in soil moisture and temperature based on juniper cover and topographic position? Location: Steens Mountain, southeast Oregon, USA. Objectives: Competition with western juniper modifies plant community composition, alters soil hydrology, and reduces plant productivity. Research is needed to understand these influences across heterogeneous landscapes. This study characterizes the relationship between juniper encroachment and soil water, soil temperature, topographic position, and intercanopy plant community structure. Methods: Using a completely randomized block design, plant density and cover, percent bare ground, percent soil moisture, soil temperature, heat accumulation, and elevation were sampled in 10 m2 plots representing low (

For more than 20 years, countries and their agencies which monitor discharge sites and storage facilities have relied on the National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 4355 Peruvian Soil reference material. Its low fallout contamination makes it an ideal soil blank for measurements associated with terrestrial pathway to man studies. Presently, SRM 4355 is out of stock, and a new batch of the Peruvian soil is currently under development as future NIST SRM 4355A. Both environmental radioanalytical laboratories and mass spectrometry communities will benefit from this SRM. The former must assess their laboratory contamination and measurement detection limits by measurement of blank sample material. The Peruvian Soil is so low in anthropogenic radionuclides that it is a suitable virtual blank. On the other hand, mass spectrometric laboratories have high sensitivity instruments that are capable of quantitative isotopic measurements at low plutonium levels of the SRM 4355 (first Peruvian Soil SRM) that provided the mass spectrometric community with the calibration, quality control, and testing material needed for methods development, and legal defensibility. The quantification of the ultra-low plutonium content in the SRM 4355A was a considerable challenge for the mass spectrometric laboratories. Careful blank control andmore » correction, isobaric interferences, instrument stability, peak assessment, and detection assessment were necessary. Furthermore, a systematic statistical evaluation of the measurement results and considerable discussions with the mass spectroscopy metrologists were needed to derive the certified values and uncertainties. SRM 4355A will provide the mass spectrometric community with the quality control and testing material needed for higher sensitivity methods development, and legal defensibility.« less

A threshold represents a point in space and time at which primary ecological processes degrade beyond the ability to self-repair. In ecosystems with juniper (Juniperus L. spp.) encroachment, ecological processes (i.e., infiltration) are impaired as intercanopy plant structure degrades during woodland expansion. The purpose of this research is to characterize influences of increasing juniper on vegetation structure and hydrologic processes in mountain big sagebrush–western juniper (Artemisia tridentata Nutt. subsp. vaseyana [Rydb.] Beetle–Juniperus occidentalis Hook.) communities and to identify and predict states and thresholds. Intercanopy plant cover and infiltration rates were sampled in relation to juniper canopy cover. Study plots, arranged in a randomized complete-block design, represented low shrub–high juniper, moderate shrub–moderate juniper, and high shrub–low juniper percentage of canopy cover levels at four primary aspects. In field plots, percentage of plant cover, bare ground, and s...

Predictive modeling and mapping based on the quantitative relationships between a species and the biophysical features (predictor variables) of the ecosystem in which it occurs can provide fundamental information for developing sustainable resource management policies for species and ecosystems. To create management strategies with the goal of sustaining a species such as sage grouse (Centrocercus urophasianus), whose distribution throughout North America has declined by approximately 50%, land management agencies need to know what attributes of the range they now inhabit will keep populations sustainable and which attributes attract disproportionate levels of use within a home range. The objectives of this study were to 1) quantify the relationships between sage grouse nest-site locations and a set of associated biophysical attributes using Maximum Entropy, 2) find the best subset of predictor variables that explain the data adequately, 3) create quantitative sage grouse distribution maps representing the relative likelihood of nest-site habitat based on those relationships, and 3) evaluate the implications of the results for future management of sage grouse. Nest-site location data from 1995 to 2003 were collected as part of a long-term research program on sage grouse reproductive ecology at Hart Mountain National Antelope Refuge. Two types of models were created: 1) with a set of predictor variables derived from digital elevation models, a field-validated vegetation classification, and UTM coordinates and 2) with the same predictors and UTM coordinates excluded. East UTM emerged as the most important predictor variable in the first type of model followed by the vegetation classification which was the most important predictor in the second type of model. The average training gain from ten modeling runs using all presence records and randomized background points was used to select the best subset of predictors. A predictive map of sage grouse nest-site habitat created from the application of the model to the study area showed strong overlap between model predictions and nest-site locations.

During the past 130 years, western juniper (Juniperus occidentalis Hook.) has rapidly expanded into sagebrush communities impacting plant structure and function. Predictions of intercanopy shrub density and cover with woodland development can provide insight into site condition and ecological resiliency in western juniper encroached areas. The purpose of this study is to model shrub density and cover in relation to juniper competition across a heterogeneous landscape in a southeast Oregon watershed. Independent variables included in model development were derived from high-resolution color imagery, a 10 m digital elevation model, and field-based vegetation and soil moisture measurements. Juniper cover and three intercanopy classes, representing different levels of juniper competition, were delineated from 1:5000 scale color (RGB) imagery. A competition index was produced from the classified image representing a gradient of potential competition with juniper. An integrated moisture index was generated representing variability in soil moisture due to hillslope solar radiation, curvature of the landscape and flow path direction and flow accumulation (flow path density). Plant density, plant cover, and percent soil moisture (gravimetric) were measured from 10 m × 10 m plots located throughout the watershed study area. Multiple stepwise regression produced the best-fit model for predicting plant density or cover for mountain big sagebrush (Artemesia tridentata ssp. vaseyana Beetle), bluebunch wheatgrass (Pseudoroegneria spicata (Pursh)), and all shrub species combined. The prediction of total shrub density was significantly greater than expected by chance (p