Kevin K. Sedivec

Effects of Grazing Pressure on Efficiency of Grazing on North American Great Plains Rangelands

Abstract Comparisons of stocking rates across sites can be facilitated by calculating grazing pressure. We used peak standing crop and stocking rates from six studies in the North American Great Plains (Cheyenne, Wyoming; Cottonwood, South Dakota; Hays, Kansas; Nunn, Colorado; Streeter, North Dakota; and Woodward, Oklahoma) to calculate a grazing pressure index and develop relationships for harvest efficiency, utilization, grazing efficiency, and animal performance and production. Average grazing pressures for heavy, moderate, and light stocking across the study sites were 40, 24, and 14 animal unit days · Mg−1, respectively. These grazing pressures resulted in average harvest efficiency values of 38%, 24%, and 14% and grazing efficiencies of 61%, 49%, and 39% for heavy, moderate, and light stocking rates, respectively. Utilization increased quadratically as grazing pressure index increased, whereas grazing and harvest efficiencies exhibited a linear increase with grazing pressure. The latter indicates that nonlivestock forage losses (e.g., weathering, senescence, wildlife, insects) were disproportional across stocking rates. Average daily gain of livestock decreased linearly as grazing pressure index increased across study sites. Prediction equations reaffirm assumptions of 50% grazing efficiency and 25% harvest efficiency associated with moderate stocking. Novel here, however, is that harvest and grazing efficiencies increased at high grazing pressures and decreased at low grazing pressures. Use of grazing pressure index to “standardize” stocking rates across rangeland ecosystems in the North American Great Plains should improve communication among scientists, resource managers, and the public, and thus better achieve both production and conservation goals on these lands.

Potential Management Alternatives for Invaded Rangelands in the Northern Great Plains

Potential Management Alternatives for Invaded Rangelands in the Northern Great Plains DOI:10.2458/azu_rangelands_v32i5_dekeyser

Comparison of soil-to-water suspension ratios for determining electrical conductivity of oil-production-water-contaminated soils

Abstract: Soil salinity caused by oil-production-water (brine) contamination is a major issue in regions of oil and gas development. However, rapid site assessment tools such as soil-to-water suspension electrical conductivity (EC) methods and conversion equations have not been previously calibrated and validated for brine-contaminated soils. Our objective was to compare three soil EC methods and derive conversion equations for EC values commonly observed at brine-spill sites. Brine-contaminated soils from western North Dakota were assessed for salinity. Electrical conductivity was determined using 1:1 and 1:5 soil-to-water suspensions (EC1:1, EC1:5) and saturated paste extracts (ECe). Soil EC equilibration times for soil-to-water suspensions were also assessed. Significant relationships (r2 = 0.91 to 0.97, P < 0.0001) existed among all methods for EC values ranging between 0 and 126 dS m-1. Conversion equations were developed based on these relationships and then validated with an independent data set. These new equations reduced ECe prediction errors by 2 to 4.5 times when compare with 14 predictive equations reported in the literature. The conversion equations developed here are recommended for use in remediation efforts when converting EC1:1 and EC1:5 data to ECe on brine-contaminated and noncontaminated soils where ECe is highly correlated to Na concentrations.

Use of Kendall's coefficient of concordance to assess agreement among observers of very high resolution imagery

Ground-based vegetation monitoring methods are expensive, time-consuming and limited in sample size. Aerial imagery is appealing to managers because of the reduced time and expense and the increase in sample size. One challenge of aerial imagery is detecting differences among observers of the same imagery. Six observers analysed a set of 1-mm ground sample distance aerial imagery for graminoid species composition and important ground-cover characteristics. Kendalls coefficient of concordance (W) was used to measure agreement among observers. The group of six observers was concordant when assessed as a group. When each of the observers was assessed independently against the other five, lack of agreement was found for those graminoid species that were difficult to identify in the aerial images.

Ring-necked Pheasant Use of Post − Conservation Reserve Program Lands

ABSTRACT The Conservation Reserve Program (CRP) has provided millions of ha of cover for numerous wildlife species. Many CRP contracts have expired or will expire, resulting in the loss of critical wildlife cover. The purpose of the current study was to evaluate the potential response of ring-necked pheasant (Phasianus colchicus) to future changes in land use. We selected four land uses that may potentially occur on CRP lands being converted back to agriculture: 1) season-long grazing, 2) hay land, 3) no-till corn (Zea mays), and 4) no-till barley (Hordeum spp.). As a control, 32 ha of CRP grasslands were left idle to mimic land in CRP. Using data from 193 ring-necked pheasant nests, we found nest density was different among land uses (P < 0.01). The control and season-long grazing treatment did not differ from one another (P = 0.42; 0.43 and 0.24 nests-ha-1, respectively), but both had greater nest densities than no-till corn and no-till barley treatments (P < 0.01; 0.04 and 0.03 nests-ha-1, respectively). The nest density in the hay treatment (0.16 ± 0.04 nests-ha-1) and control were different (P = 0.02). Ring-necked pheasant nest site selection was influenced by visual obstruction and vegetation height as hens chose nest sites with taller vertical structure and vegetation heights. Daily survival rates of nests were not influenced by treatment but did increase with greater visual obstruction, increased as a nest aged and throughout the nesting season, and were negatively affected by precipitation events. Our results suggest that maintaining CRP-type grasslands will be beneficial for ring-necked pheasants because of the nesting cover they provide. However, the conversion of CRP to livestock production may be a viable option that provides nesting opportunities for ring-necked pheasant, given vertical structure is available for nesting hens.

Controlling Kentucky Bluegrass with Herbicide and Burning Is Influenced by Invasion Level

Kentucky bluegrass (Poa pratensis L.) invades northern Great Plains rangelands. On the Sheyenne National Grassland in southeastern North Dakota, three research sites, each with a different level of Kentucky bluegrass invasion, were chosen to evaluate effectiveness of burning and burning—herbicide combinations to control Kentucky bluegrass. Initial Kentucky bluegrass invasion levels were 37%, 77%, and 91% for LOW, MODERATE, and HIGH invaded sites, respectively. Within each invaded site, four replicated strips (20 by 60 m) were established, with half of each strip burned in late October 2005 and the other half burned in early May 2006. Herbicide treatments of (1) no herbicide, (2) 2.24 kg ha-1 of glyphosate, and (3) 0.43 kg ha-1 of imazapic were randomly assigned to 10 by 20 m subplots within each burn. Control plots were established at the same time. Relative basal cover of native grass, native forb, and Kentucky bluegrass was estimated annually using 50 10-point frames within each subplot. On the HIGH site in 2006, fall-burned plots with a spring glyphosate application had three times the native grass cover and only one fourth of the Kentucky bluegrass cover compared with controls. Similar results with the same treatment occurred at the MODERATE site. Native grasses became the most abundant plant community on these plots in the MODERATE and HIGH sites within 1 yr. Treatment differences were transitory, and the LOW site differed from the MODERATE and HIGH sites. In 2007, on fall-burned plots with spring glyphosate application, the amount of Kentucky bluegrass was 14% and 30%, and native grass species were 52% and 42% on the MODERATE and HIGH sites, respectively, which was similar to the initial values on the LOW site. These data emphasize the importance of initial invasion level in developing restoration strategies and provide evidence burning and herbicide combinations can be valuable management tools even on heavily invaded grasslands. Nomenclature: Glyphosate; imazapic; Kentucky bluegrass, Poa pratensis L. POAPR.

Use of Ecological Sites in Managing Wildlife and Livestock: An Example with Prairie Dogs

On the Ground The perception of prairie dogs among Native Americans living on the Standing Rock Sioux Reservation is mixed. Some Native Americans focus on the loss of forage productivity, whereas others are interested in the cultural and ecological aspects of prairie dogs. The use of ecological sites may provide a mechanism for developing a management framework that would consider both livestock and prairie dogs. The three ecological sites we surveyed had large differences in off-colony standing crop, but in 2 of the 3 years we surveyed, there were no differences between standing crop on-colony. This suggests that management of prairie dogs on rangelands should focus on limiting prairie dogs on more productive ecological sites with less productive sites receiving less emphasis.

Effects of Short-Term Cattle Exclusion on Plant Community Composition: Prairie Dog and Ecological Site Influences

On the Ground Maintaining cattle and prairie dogs on rangelands is important ecologically, economically, and culturally. However, competition between these species, both actual and perceived, has led to conflict. We explored the effects of short-term (2-year) cattle exclusion on plant communities both on and off prairie dog towns and among three common ecological sites. Plant communities were different between on-town and off-town plots and among ecological sites but were similar between cattle-excluded and nonexcluded plots. Plant community composition did not differ between rangeland targeted for moderate forage utilization and that in which cattle had been excluded for 2 years.

Seasonal prescribed fire variation decreases inhibitory ability of Poa pratensis L. and promotes native plant diversity

Global biodiversity is threatened by invasive plant species. Without a thorough understanding of effective management strategies, minimizing their impacts while improving native species diversity will be challenging. Burning in fire-prone landscapes has been successful for managing invasive species and increasing native biodiversity, but it is unclear how specific fire regimes improve restoration practices in novel ecosystems where invasive plants have a similar growth phenology to native plants. We investigated fire as a restoration practice in the Northern Great Plains to decrease the cover of Kentucky bluegrass Poa pratensis (bluegrass), a perennial cool-season invasive grass phenologically similar to dominant native cool-season grasses, by 1) evaluating season of burn (early-growing season, late-growing season, and dormant season) in a field experiment to test differences in plant community composition and 2) manipulating fine fuels (3000-5000 kg ha-1) in an experimental approach to determine the effects of fire on plant survivability of selected native grasses and bluegrass. Bluegrass cover decreased 27% on all field burned plots the first year post-fire. Three years post-fire, late-growing season and dormant season treatments had 35% less bluegrass, whereas the early-growing season treatment was not significantly different from the control. Overall, fire altered the native plant community, with native plants more associated with burned plots. However, native plant community changes were only evident three years post-fire in late-growing season and dormant season burn treatments. In the experimental approach, native grasses and bluegrass experienced high rates of mortality (40-50%) at fuel loads above 4000 kg ha-1 and heat dosages above 30,000 °C·sec, features commonly associated with early-growing season burns. Therefore, early-growing season burns meant to reduce bluegrass may also impact native plants dominant in the region. Invasive species management is complicated in novel ecosystems when invasive plants have similar growth phenologies to native species. Control efforts should consider how different management strategies impact invasive and native plants alike. We found that late-growing season and dormant season burns, along with higher fuel loads, decreased bluegrass cover. Determining mechanisms of control in fire-prone landscapes is a crucial step to improving invasive plant control and increasing native biodiversity.

History of Occurrence and Present Home Territory Sizes for Black-Tailed Prairie Dogs on the Standing Rock Sioux Reservation

On the Ground Past management and historic occupation by black-tailed prairie dogs will affect the vegetation responses to changes in management. Ecological sites have different production potential and may influence colonization by black-tailed prairie dogs. Thin Claypan ecological sites had the largest coterie home territory size at 1.8 ha but also had coteries among the smallest at 0.5 ha.