Proceedings brand creation for a prescribed fire culture – utilizing key social media parameters. Lars Coleman*1, J. Kelly Hoffman1, Thomas McDaniel1, R. Patrick Bixler2, Urs P. Kreuter1, Morgan Russell3

Monitoring herbage that exists in the fall after grazing or during drought situations on large rangeland pastures is an important but time-consuming process. The HARPER process improves the accuracy and efficiency of field time required for monitoring of rangelands by utilizing LANDSAT 8 satellite imagery to identify areas of unacceptably low herbage and areas of high herbage. The process is somewhat similar to the widely used comparative-yield herbage assessment process. The difference is that instead of identifying herbage classes and training rangeland managers to estimate the percent of a limited number of small 1 foot square plots that are within a given herbage class, the rangeland manager uses information that is generated by a satellite that has been trained to estimate the percent of ¼ acre plots for the entire pasture that are within each identified herbage class.

Larkspurs (Delphinium, Ranunculaceae) are poisonous plants found on rangelands throughout Western North America.  Two main structural groups of norditerpene alkaloids, the N-(methylsuccinimido) anthranoyllycoctonine type (MSAL-type) and the non-MSAL type, are responsible for larkspur-induced poisoning.  Information on the alkaloid composition is lacking for a number of Delphinium species.  The objective of this study was to profile the alkaloid composition of several Delphinium species.  Not all Delphinium species contain alkaloid profiles that pose the same toxic risk.  Two species, D. ramosum and D. occidentale, are represented each by two alkaloid profiles, where one profile from each species contained significantly greater concentrations of the MSAL-type alkaloids than the other.  Plants containing each respective alkaloid profile were unique in their geographical distribution.  Populations of these chemotypes will likely differ in their toxic potential and consequently pose different risks of poisoning when grazed by livestock species.  This information has important implications in grazing management decisions on Delphinium-infested rangelands and demonstrates that botanical classification alone is not an adequate indicator of relative risk of toxicity.

STUDY USING SOIL SURVEY TO HELP PREDICT SONORAN DESERT TORTOISE POPULATION

We completed a soils and vegetation attribute study, in relation to Sonoran Desert Tortoise (SDT) (Gopherus morafkai) habitat, from December 5, 2009 to January 19, 2010 and again from March 29 to April 1, 2015 in Mojave County, Arizona on behalf of the Mojave Livestock Association. The survey covered approximately 956 square miles or 611,840 acres located from 5 to 80 plus miles south of Kingman, Arizona. The objectives of this study were to compare site specific landform, soils and vegetative characteristics to SDT density and distribution and attempt to identify detailed and quantifiable soils and landform characteristics that may be used to predict the distribution and densities of resident SDT, overlapping inhabitant Mojave Desert Tortoise (MDT)1 and any hybrids produced from the union of the SDT and MDT2 . An assessment of livestock use and potential competition for forage or habitat were considered. Similar efforts were completed in 19923 in Piute Valley, Clark County, Nevada for the MDT and in 19974 for 10 MDT study plots and surrounding areas located in Nye, Clark and Lincoln Counties in Nevada showing clear and definable relationships between soils, geomorphic surfaces (geomorphology), vegetation, and the distribution and densities of burrowing animals such as the MDT.

The resultant soils classification criteria were evaluated by the National Resources Conservation Service (NRCS) who developed soils criteria and a soils report called WLF-Desert Tortoise.

The information collected and analyzed from the Piute Valley study in the 1997 effort as revised in 20104 were compared with four existing SDT study plots that had previously been established on federal land within this study area in Mojave County, Arizona by the Bureau of Land Management (BLM) and the Arizona Game and Fish Department (AGFD). The agency study plots are named East Bajada, Buck Mountain, Hualapai Foothills and Arrastra Mountain.

EXPERIMENTAL DROUGHT IMPACTS ON COLORADO PLATEAU ECOSYSTEMS. Michael C. Duniway*¹, David Hoover², Alix Pfennigwerth¹, Jayne Belnap¹; ¹US Geological Survey, Moab, UT, ²USDA-ARS, Fort Collins, CO

ABSTRACT

Increasingly severe drought and associated reductions in water availability to plants and ecosystems have emerged as predominant climate characteristics of the southwestern U.S. (SW) at the beginning of the 21st century.  This growing aridity and likely changes in precipitation seasonality and intensity represent substantial challenges to SW land managers tasked with sustaining or restoring these important ecosystems. These challenges are further complicated by significant landscape-level heterogeneity in soil-geomorphic properties that mediate vegetation responses to multi-temporal climate drivers. Understanding how broad-scale climate drivers will impact ecosystems at local scales is therefore of paramount importance for designing effective management strategies to mitigate and minimize undesired ecosystem changes.  The response of SW ecosystems to droughts of the 20th and 21st centuries provides clear examples of variability in climate-plant relationships that are mediated by soil-geomorphic unit vulnerability.  Here, we present results from two ongoing drought experiments near Moab, UT.   In one study, we are imposing a chronic but subtle drought (35% precipitation reduction) using passive removal shelters, across a wide geographic region. Over seven years, we have been examining plant cover changes and mortality of four dominant plant functional types: C3 grasses, C4 grasses, C3 shrubs and C4 shrubs.  Results from this long-term experiment show varying resistance and resilience to chronic drying among dominant functional types, with cool season grasses showing lowest resistance and resilience.  Second, we report results from a more recent study in which we are imposing extreme seasonal drought (66% reductions in the summer or winter) in a grassland system and have found dramatic shifts in species abundance following only two years of seasonal droughts. Taken together, results from these experiments suggest that both chronic and seasonal changes in water availability can alter the structure and function of the Colorado Plateau ecosystem by differentially impacting key plant functional types.  

POTENTIAL CONSEQUENCE OF REPEATED SEVERE DROUGHT FOR SHORTGRASS STEPPE SPECIES. Renee J. Rondeau*¹, Karin Decker², Georgia Doyle²; ¹Colorado State University, Hesperus, CO, ²Colorado State University, Fort Collins, CO

ABSTRACT

Future climate projections indicate temperatures in the shortgrass steppe region are likely to warm by up to 3°C by mid-century, with a corresponding reduction in soil moisture even without precipitation deficit. Although periodic drought is a natural disturbance in shortgrass rangeland, negative effects on characteristic shortgrass species are likely as the frequency and severity of drought events increase in comparison to recent historic norms. As part of a study intended to detect vegetation changes at a shortgrass steppe site on Colorado’s eastern plains, frequency and canopy cover percentage were measured in 37 permanently marked plots over a period of 17 years. The study period included the two lowest total annual precipitation years (2002 and 2012) in the period of record for regional weather stations, exceeding even the lowest precipitation years of the extended 1930s drought. Growing season mean temperatures during those drought years were 1°C and 1.6°C above the 1971-2000 average, respectively. Three of the six perennial grass species monitored showed a decline over the period of the study. Blue grama (Bouteloua gracilis), a dominant and important forage species in the shortgrass steppe, declined in both cover and frequency, while alkali sacaton (Sporobolus airoides), not an important forage species, slightly increased. In addition to changes in graminoid dominance, we observed an increase in cholla (Cylindropuntia imbricata) and a decrease in sandsage (Artemisia filifolia) and Rabbitbrush (Chrysothamnus nauseousus) shrub densities between 1999 and 2015. Even if total productivity of the shortgrass steppe is maintained under warming and drying conditions, changes in species composition have implications for rangeland quality with regard to its use for livestock grazing.

UNCOVERING THE RELATIONSHIP BETWEEN DROUGHT INDICES AND RANGELAND PRODUCTION. Matt C. Reeves*; USDA Forest Service, Florence, MT

ABSTRACT

Drought is a normal experience for rangelands of the United States and poses one of the primary risks faced by managers and producers. Drought planning is therefore an important tool for minimizing drought-related losses, for both managers, planners and policy makers. Approaches to responding to drought are highly variable given the complexity of landscapes and operations and due to the different types and intensities of droughts. Drought indices are often used as indicators for extent and intensity of drought but relationships between the various monitors and rangeland production at regional scales is relatively undescribed.  In this paper we quantify relations between 6 drought monitors including the U.S. Drought Monitor (USDM), Evaporative Demand Drought Index (EDDI), Standardized Precipitation-Evapotranspiration Index 12, (SPEI12), Standardized Precipitation-Evapotranspiration Index 6, (SPEI6), Palmer Drought Severity Index (PDSI) and the Self-Calibrated Palmer Drought Severity Index (PDSIsc) with annual rangeland productivity from 2000 to 2016. In this assessment we answer 5 basic questions including:

1. 
   What vegetation types exhibit the highest correlation between drought monitors and annual production?
   
2. 
   What monitor exhibits the highest correlation with rangeland production?
   
3. 
   What combination of monitors produces the best correlation between rangeland production and drought monitors?
   
4. 
   What lag times exhibit the highest correlation between rangeland production and drought monitors?
   
5. 
   What vegetative and regional characteristics enable high correlations between rangeland production and drought monitors?
   

Drought is a common occurrence in the Great Plains and an understanding how temporal precipitation patterns affect range plant communities is critical in grazing management decisions. Current rainfall models project that rainfall events will increase in intensity and decrease in frequency. Our objective was to evaluate the effects of differing rainfall amounts at different time intervals on above-ground plant production and plant community composition on Nebraska Sandhills rangelands. Using rainout shelters, total exclusion of rainfall was implemented from May 9 through August 22 during the 2017 growing season. Using an irrigation system, simulated rainfall was applied to individual rainout shelters on a sands ecological site to determine the effects of temporal distribution of precipitation. Water amounts were applied at 50% of average annual rainfall and at 125% of average annual rainfall at intervals of once every week, once every three weeks, and once every five weeks. There were five replications of all intensity-by-frequency combinations. A control treatment of excluding all rainfall (0% of average annual rainfall) also was included as a baseline. Plant response was measured as basal cover by plant species, using the line-intercept method, and above-ground plant production as measured by hand-clipping in August. Soil moisture was measured weekly in each plot using Time-Domain Reflectometry (TDR) at depths of 0-20 cm, 21-40 cm, 41-60 cm, 61-80cm and 81-100 cm. The volumetric water content of the once-per-week plots were similar or greater than the three and five-week plots through the growing season for both watering intensities. Treatment plots steadily decreased across all treatments through the duration of the experiment except for the 125% weekly watering treatment. Plant production data is in the process of being analyzed and will be presented.

INCREASED SOIL WATER AND SPECIES CHANGE COMBINE TO ENHANCE GRASSLAND BIOMASS-CO2 RESPONSE
. Wayne Polley*¹, Michael Aspinwall², Harold Collins¹, Anne Gibson¹, Richard Gill³, Robert Jackson⁴, Virginia Jin⁵, Albina Khasanova⁶, Lara Reichmann⁷, Philip Fay¹; ¹USDA/Agricultural Research Service, Temple, TX, ²University of North Florida, Jacksonville, FL, ³Brigham Young University, Provo, UT, ⁴Stanford University, Stanford, CA, ⁵USDA/Agricultural Research Service, Lincoln, NE, ⁶University of Texas, Austin, TX, ⁷University of California Berkeley, Berkeley, CA

ABSTRACT

Atmospheric carbon dioxide (CO2) concentration has risen by 40% since industrialization and is projected to exceed 2X the pre-industrial level this century.  Across regional gradients in precipitation, elevated CO2 stimulates grassland primary productivity more when precipitation is relatively scarce by increasing plant production per unit of transpiration (water use efficiency; WUE).  At local scales, however, the productivity-CO2 response to seasonal or inter-annual declines in precipitation may be positive, negative, or neutral, dependent on variation in other mediators of ecosystem CO2 responses.  Integrating mediators of CO2 responses, such as soil texture and plant species abundances, into predictive models is crucial to forecasting primary productivity at the scales at which land managers operate.  We show that, in contrast with results from across spatial gradients in precipitation, increasing CO2 from pre-industrial to elevated concentrations increased aboveground net primary productivity (ANPP) of perennial C3/C4 grassland communities grown on clay, sandy loam, and silty clay soil types more when soil water was relatively plentiful.  Greater water availability contributed to increase ANPP by as much as 50% at elevated CO2 by both directly stimulating ANPP and amplifying an increase in abundance of a productive C4 tallgrass species, Sorghastrum nutans. Combined, positive effects of species shifts and increased water outweighed a negative legacy effect of prior-year ANPP on the ANPP-CO2 response across soil types and a decade of CO2 treatment.  Assessments that fail to account for positive water effects and compositional shifts may underestimate the magnitude of past and future CO2 effects on grassland productivity. 

COMPETITION OF NATIVE AND NON-NATIVE GRASSES IN TERMS OF BELOWGROUND BUD BANK AND TILLER DEMOGRAPHY

In the northern Great Plains, the resilience of perennial grasslands largely depends on successful tiller recruitment and establishment from belowground bud banks. However, over the decades, these grasslands are rapidly invaded by introduced perennial grasses Bromus inermis and transforming larger tracts of native prairies by replacing native perennial grasses, such as Pascopyrum smithii, reducing biodiversity and quality of habitats, and increasing vulnerability of grasslands to other environmental disturbances. Therefore, this study aimed to understand effects of intra-and inter-specific competition between native P. smithii and invasive B. inermis on belowground bud banks and tiller demography under frequent water and constant temperature condition.  A greenhouse experiment was consisted of five treatments including single B. smithii, single P. smithii, pairwise mono of B. inermis, pairwise mono of P. smithii, and pairwise mixed of B. inermis and P. smithii with 30 replications for each treatment. Double-leaf seedlings of each species were transplanted to individual potting-soil filled pot (16.5-cm dia.) based upon designated treatments. Each pot was watered every other day with 72-ml tap water for 98 days after transplanting. At the end of 98 days, plants within each pot were carefully harvested and underground structures were washed free of soil. Each plant was dissected and classified into different generations. Within each generation, crown tillers, rhizome tillers, and buds were counted, and rhizome lengths were measured. Relative interaction index (Rii) of bud and tiller demography was used to calculate the competitive effect of the intra-and inter-specific competition between two species. Results from this study will enhance our understanding the potential utilizing reproduction and demography traits as important attributes of plant in response to disturbance. It will provide insights for developing strategies for sustainably manage non-native invaded perennial grasslands in remnant prairies of northern Great Plains.

SEED DISPERSAL PATHWAYS OF WESTERN AND UTAH JUNIPER: ROLES OF FRUGIVOROUS BIRDS AND GRANIVOUS RODENTS. Lindsay A. Dimitri*¹, William S. Longland¹, Stephen B. Vander Wall²; ¹USDA-ARS, Reno, NV, ²University of Nevada, Reno, Reno, NV

Western and Utah juniper (WJ and UJ) woodlands have been expanding in range and infilling. Extensive resources have been spent managing theses woodlands, so understanding seed dispersal is critical in identifying mechanisms behind expansion. Junipers produce female cones (“berries”) that are consumed by frugivorous birds and mammals in many species, but the role of scatterhoarding rodents is unclear. Juniper cone and seed traits vary, with some species producing juicy cones (WJ) while others are dry (UJ), and some cones having multiple, smaller seeds (WJ) while others have fewer, larger seeds (UJ). We hypothesized that this variation has favored differing seed dispersal pathways. In northeastern California, we compared removal of whole WJ cones, hand-cleaned WJ seeds and bird-passed WJ seeds by rodents and birds. Birds preferred whole WJ cones while rodents preferred seeds. We also performed a seedling emergence experiment with the same three seed treatments and found that successful establishment requires WJ seeds to be removed from cones and buried. Additionally, we documented distributions of WJ seeds in four microsites after bird dispersal and subsequent seed removal by rodents. Juniper canopies had the most WJ seeds, and rodents depleted most seeds between winter and summer. To understand the impact of seed and cone traits on dispersers, we monitored removal of WJ and UJ cones and hand-cleaned seeds at a WJ site and a UJ site. Dispersers preferred cones of the local juniper species but seed removal was similar. Finally, to clarify the role of rodents as dispersers, we followed removal of radioactively labeled WJ and UJ seeds and found that rodents, especially piñon mice, cached WJ and UJ seeds in microsites suitable for seedling establishment. Overall our research indicates that WJ seeds are dispersed by frugivorous birds and by scatterhoarding rodents, while UJ seeds are primarily dispersed by scatterhoarding rodents.

MUTUALISTIC INTERACTIONS BETWEEN GRANIVOROUS HETEROMYID RODENTS AND INDIAN RICEGRASS (ACHNATHERUM HYMENOIDES): IMPLICATIONS FOR ARID-LAND RESTORATION
. Bill Longland*¹, Lindsay A. Dimitri²; ¹USDA, ARS, Reno, NV, ²USDA-ARS, Reno, NV

ABSTRACT

Granivorous heteromyid rodent species and Indian ricegrass (Achnatherum hymenoides), a perennial grass common on sandy soils, are both widely distributed throughout North American deserts. Previous research demonstrated that the vast majority (~95%) of Indian ricegrass seedling recruitment occurs from seed clusters cached in shallowly-buried scatterhoards by heteromyids, especially Merriam’s kangaroo rat (Dipodomys merriami). Here, we discuss how emergence of seedlings in aggregated clusters from caches affects subsequent seedling survival and establishment. In two western Nevada field studies, we monitored single Indian ricegrass seedlings and clumped seedlings in caches over the course of a year. Individual seedlings within clumps generally had higher survival rates than seedlings growing singly, and whole caches routinely had higher survival than single seedlings. We followed these observational studies with a field experiment in which Indian ricegrass seedlings were transplanted inside fenced plots either singly or in clumps of 25 or 35 seedlings and survival was compared through their first winter. Individual seedlings within clumps had higher survival than seedlings growing singly, and seedlings within clumps of 35 generally had maximum survival. These results suggest a mutualism involving heteromyid rodents and Indian ricegrass. Indian ricegrass seeds provide a highly preferred food resource to heteromyids, while benefits to Indian ricegrass extend beyond seed dispersal and seedling emergence into the longer-term survival of the plant. Finally, by broadcast seeding commercial seeds (millet) as an alternate resource for rodents, we tested whether such ‘diversionary seeds’ can enhance seedling recruitment resulting from Indian ricegrass seeds that had been cached by rodents by reducing numbers of these caches that rodents recover for consumption. Seedling recruitment was greater where diversionary seeds were applied, indicating that this mutualism can be applied in an arid-land restoration context.

TALL FORB PLANT COMMUNITY AND GROUND COVER DYNAMICS - WITH AND WITHOUT LIVESTOCK GRAZING. Aimee M. Zobell-Cameron*¹, Sherel Goodrich², Aaron Zobell³; ¹Uinta-Wasatch-Cache National Forest, Mountain View, WY, ²Ashley National Forest, Vernal, UT, ³Bridger-Teton National Forest, Kemmerer, WY