Progress report for LNC21-450
Project Information
The Nebraska Sandhills region is one of the largest (20,179 miles2) and the most intact native grasslands in the world. Sandhills grasslands are used primarily for beef cattle production, but these native environments also provide important wildlife and plant species habitat, wetlands and water infiltration for recharge of the Great Plains aquifer, and other ecosystem services such as recreation. Vegetation management typically includes a combination of grazing strategies, mechanical and chemical control of invasive plants, and, less frequently, prescribed fire. Tradeoffs that occur among competing ecosystem services (e.g., soil health, cattle weight gain, economic return, wildlife diversity) and disservices (e.g., invasive species, low plant diversity, compromised soils) must be evaluated and quantified when making management decisions that have consequences for sustaining livelihoods.
The collaborative adaptive management (CAM) project at Barta Brothers Ranch began its research by evaluating alternative, stakeholder-designed approaches to grassland management in the Sandhills and surrounding north-central Great Plains. Preliminary meetings with the CAM Project Team (ranchers, land managers, researchers) broadly identified management of invasive species, enhancing livestock performance, and managing for multifunctionality, or managing for multiple ecosystem services on the same land area, as key uncertainties and primary goals for the research. A modified patch-burn grazing system was recommended as a management practice that could address these areas of concern.
Utilizing the adaptive management framework, researchers then established protocols to monitor changes in livestock performance, landscape and species heterogeneity, and forage productivity before, during, and after the grazing season. In the spring of 2022, through cooperation among stakeholders in the region, Barta Brothers Ranch completed a prescribed burn in one, 160-acre pasture in the system. Based on initial observations in forage recovery, an addendum was adopted to allow cattle to openly graze all four pastures in the system (i.e., no pastures were deferred).
Animals (spayed heifers) were put out to pasture in mid-May and removed in mid-September. Stocking rates (.62 AUMs/acre) reflected real-world conditions and were held constant throughout the grazing season despite an ongoing regional drought. As a control, a similarly stocked four-pasture deferred system was also established at Barta Brothers Ranch. Animals were weighed three times during the grazing season with some heifers (n=8) tracked via GPS collars.
During the sampling period, researchers also monitored: landscape cover change via geospatial monitoring and remote sensing, livestock behavior and performance, annual plant production, erosion, grassland bird diversity, and group learning among the CAM project team.
Quarterly meetings along with phone and email communication took place throughout the growing season. This active engagement among stakeholders is also foundational to the CAM approach. Through the co-production of science, shared learning and trust are fostered among the CAM Project Team. There were no other revisions to the management strategy for the 2022 grazing season. Data in the aforementioned areas were collected, analyzed and preliminary results were presented to the CAM project team in late October (see research results for detailed summaries).
As of this report, the 2023 grazing season will proceed similarly to that of 2022. A prescribed burn will be conducted in an adjacent pasture in early spring. Conditions will be monitored until May during which a stocking rate will be determined. The research team will monitor variables throughout the grazing season and quarterly meetings with the CAM project will continue. Contrasts among year 1 and year 2 data will be a key exercise for the Project Team this year.
CAM requires stakeholder involvement from inception to completion. We will: 1) Establish a CAM program in the Sandhills to identify management challenges and goals; 2) Establish Barta Brothers Ranch (BBR), a University-owned ranch, as a location for “learning-by-management” experiments, where stakeholders voice and test management hypotheses in an environment that does not affect their livelihoods; 3) Compare alternative, stakeholder-identified approaches and evaluate their effects; 4) Develop monitoring and tradeoff tools for assessing tradeoffs among alternative management approaches and informing decisions that affect the attainment of economic and environmental goals; and 5) Evaluate progress, success and uptake of the CAM for rangelands.
In 2020, the University of Nebraska’s Barta Brothers Ranch launched a collaborative adaptive management (CAM) project to address risks and uncertainties related to grassland management in the Sandhills. This project focuses on evaluating stakeholder-designed management plans in a collaborative research setting. This emphasis on co-producing science ensures CAM reflects real-world ranching conditions of the Sandhills and the north-central Great Plains. This publication highlights preliminary results from year 1 of the study (2022 grazing season).
Cooperators
Research
The results from the first year of data help validate the project’s working hypothesis that burn/graze systems can increase livestock performance and rancher profitability while minimizing tradeoffs to other desired functions of the landscape.
Adaptive Management Framework
The foundation of the CAM Project at Barta Brother Ranch comes from its linkage to the adaptive management framework. Adaptive management is an iterative process with aims to increase understanding of a system through a structured decision-making process. This includes: 1) defining the problem, 2) identifying objectives, 3) formulating evaluation criteria, estimating outcomes, 4) evaluating trade-offs, 5) decide on actions to be taken, 6) implement action plan, 7) monitor system behavior, 8) evaluate management outcomes, 9) adjust management.
Monitoring
The CAM Project Team will continue to refine what and how to monitor, and to develop expectations of responses to stakeholder-implemented management. Below are methods encapsulated in monitoring Yr. 1 management (2022 grazing season).
Vegetation
1: Vegetation data will be collected each year, including the year prior to application of treatments. Plant community species composition and dry weight rank will be assessed using a 40 by 40 cm monitoring frame placed at multiple locations within the study areas at each CAM project. Trained technicians will locate multiple monitoring points based on ecological site, topography, and aspect. Technicians will record all rooted plant species within each monitoring frame placement. These data will provide species richness, species frequency of occurrence and diversity, spatial variability of plant groupings, and relative importance of species across the locations and management alternatives. Multiple grazing exclosures will be placed throughout the study pastures and annual net primary plant production will be collected at peak standing crop during the growing season by clipping all plant material at ground level, separating by functional plant group, drying to a consistent weight, and recording weights.
2. Remotely-Sensed Monitoring Data: at broader scales, remote sensing technology will be utilized to evaluate ground cover, tree cover, shrub cover, perennial forb and grass cover and biomass (i.e., productivity), and annual forb and grass cover and biomass using the Rangeland Analysis Platform (rangelands.app). Percent cover values are available in an online user interface, for download, and on Google Earth Engine (Gorelick et al. 2017) annually at 30-meter grain, whereas biomass is available annually or over 16-day intervals at 30-meter grain. Additional remote sensing products for early identification and tracking of vegetation state-transitions at multiple scales (state-transition screening, Uden et al. 2019, www.rangelands.app) will supplement monitoring of vegetation cover and biomass. These metrics will be used to evaluate changes in functional group ground cover and biomass continuously across the ranch. Additionally, data from airplane imagery will be incorporated into the baseline data to explain the available resource and track departures based on management strategies.
Grassland birds
Each experimental unit or pasture will have 24 plots laid out in a grid with sampling points spaced 250 m apart. To measure songbird abundance and composition, we will conduct 150-m fixed-radius point counts 3 times at each point in each year. At each point, an observer will record all birds seen or heard for 6 minutes and the estimated distance from the observer to the bird. Species, sex, and behavior (observed singing, observed calling, heard singing, heard calling, observed only) of the bird will be recorded.
Livestock production and grazing behavior
Livestock production metrics will be calculated by beginning (prior to turn out on study pastures) and end (conclusion of the grazing period) weights of cows, calves, and/or yearling cattle. We will also measure differences in reproductive success of the cattle groups under different management practices. Additionally, GPS tracking collars will be placed on a portion of the study animals to evaluate shifts in cattle grazing behavior (i.e., grazing and resting times) and grazing distribution (i.e., where animals are grazing) in the study pastures.
Soil erosion
To monitor this effect, pins are driven into the ground in a grid (n=38) in a burned and unburned/control pasture. Initial depths are recorded and periodically remeasured throughout the grazing season. The difference in these measurements is the amount of erosion or deposition that had occurred at that pin location.
Soil health
Soil samples will be collected to arrive at estimations of patterns of nutrient return in relation to management practices and the influence on soil N, C, and P. Soil samples on the zones generated from the mapping at the treatment sites will be collected during late March. We anticipate taking soil samples from a maximum of three pastures in each treatment area. In each pasture, 30 soil samples from 0-20 cm depth will be collected at fixed intervals in a 100-m transect. Samples of each transect will be air dried and analyzed for available P (Mehlich III), soil organic matter (loss on ignition), total N, ammonium, and nitrate. Potential N mineralization will be determined using a short term (14 days) aerobic incubation with destructive sampling made 1, 3, 5, 7, and 14 days to measure nitrate and ammonium.
The management action in the spring of 2022 was to burn pasture N-5 which has typically been managed as part of a traditional four-pasture rotation (Figure 1). Instead of a closed-gate rotation through the four pastures during the grazing season, the gates were left open and open grazing by spayed heifers (.62 AUMs/acre) was allowed. Researchers targeted livestock behavior, landscape heterogeneity and species diversity (e.g., spatial composition of vegetation and richness of birds), and livestock performance (e.g., weight gain) for evaluation. Below are preliminary results from year 1 of the study along with discussions of the research.
Livestock Behavior
The boost in nutrient value of grasses and forbs due to prescribed burning is well documented in rangeland research. Fire helps remove standing dead plant material buildup, which increases access to a more nutritious diet for grazing animals. As a result, cattle will focus grazing on burned sites and reduce grazing pressure on unburned areas of the pastures. As the grazing season goes on, animals will spread out to other areas of the pasture but still return periodically to selectively graze certain species in the burned patches within the pasture. GPS tracking collars were placed on a portion of the study animals to evaluate shifts in cattle grazing behavior (i.e., grazing and resting times) and grazing distribution (i.e., where animals are grazing) in the study pastures. Our first-year results aligned with previous studies with cattle spending 1.5 to 2 times more time in the burned patches compared to unburned areas within the pastures.
Annual Plant Production
Developing a better understanding of how burning and grazing effects vegetation growth over time is a key outcome of the BBR CAM project’s research. In 2022, plant samples were collected in the burned area of the study and compared to Barta Brother’s Ranch long-term grazing systems data which has evaluated plant production for over 20 years. At this point, data is still being analyzed and multiple years of data are needed to draw conclusions, but there was no difference in the total annual plant production on the burned compared to unburned pastures. The main difference between the burned and unburned areas was the amount of standing dead and litter plant material. While seasonal conditions will vary production, year one suggests that burning and grazing can occur in the same season with minimal effects on the total forage produced.
Livestock Performance
The animals were weighed three times during the year, pre-turnout in May, mid-season in July, and before pull-off in late September. As a control, heifers grazing in the management pastures (N-5 through N-8) were compared to other spayed heifers stocked at a similar rate in a standard 4-pasture deferred rotation system at the Barta Brothers Ranch. At the end of the grazing season in 2022, cattle in the burn/graze management system were 43 lbs. heavier than those in the standard deferred system. These gains were not consistent throughout the grazing season. The cattle in the burn/graze system tended to gain more weight in June and July but later tracked closely with gains of the animals in the standard deferred rotation. At market, the heifers from the burned/grazed system returned an additional $86.96 per head. This is based on one year of data in a relatively high cattle price scenario.
Landcover Monitoring
Field observations were taken at Barta Brothers Ranch in mid-June. Sampling was carried out in three locations on the ranch: burned, unburned, and a neutral site formerly used to study biocomplexity. Researchers detected an increase in the burned treatment's reflectance, likely arising from increased albedo affecting the surface energy balance. This team also found decreases in key energy absorption bands, likely resulting from the loss of standing biomass. These two observations may explain a possible surface cooling effect resulting from the use of prescribed fire.
Cognitive Models
The CAM approach is a participatory process by which management decisions are made collaboratively. The purpose of this research is to chronicle this exercise, primarily by focusing on how stakeholders make initial decisions, learn from relevant data, and adapt their thinking about system dynamics. The significance of the research is both practical and theoretical because knowledge of the system is evaluated through hands-on experimentation and implementation of the adaptive management framework. The figure (right) reflects the beginnings of an operational framework based on mental modeling exercise conducted with stakeholders in the summer of 2022.
Erosion
Another key stakeholder concern in the use of prescribed burning is how exposed landscapes respond to wind-blown erosion. To monitor this effect, erosion measurements were taken at both burned and unburned pastures before and after the grazing season. On average, the unburned/grazed pasture lost 0.0986 cm of soil and burned/grazed pastures lost 0.3595 cm. While more erosion was observed in the burned pasture, there was also more deposition compared to the unburned control pasture. These preliminary results suggest that while soil did move in the burned pasture, it was not lost from the system. This is in aliment with previous research performed in the Sandhills that found 4-5 years of repeated vegetation suppression was required before significant movement of soil occurred.
Grassland bird diversity
Across most of the species observed and in total, there were slightly more observations of grassland birds in the burned/grazed system compared to the standard deferred system. For species that prefer bare ground and less dense vegetation (e.g., Dickcissel, Horned Lark), observations were between 2.0 - 6.0 times higher for these species in the burned/grazed system. The burned/grazed system also had a more uniform distribution in total species present, likely reflecting the increased heterogeneity of the habitat created through the use of prescribed fire.
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PHASE 1: Define the Problem |
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Focus |
Objectives for BBR CAM |
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· Woody encroachment/invasive species · Heterogeneity/diversity · Economic and ecological trade-offs
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· Reduce woody encroachment · Increase landscape heterogeneity and species diversity · Improve livestock performance |
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PHASE 2: Decide |
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Management for grazing season (2022) |
CAM Project Team selects modified-patch burn grazing for management of the four-pasture grazing system. |
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PHASE 3: Monitor |
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Focus |
Approach |
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Woody encroachment |
Control of eastern redcedar via geospatial and ground monitoring |
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Heterogeneity/diversity
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Vegetation cover, composition, and diversity; grassland bird abundance |
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Livestock performance
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Weight gains, patch selectivity (GPS-tracked cattle), nutritional content of forage |
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Soils
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Erosion (loss/gain), sampling of organic matter |
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PHASE 4: Evaluate |
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Focus |
Results* |
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Woody encroachment |
N/A: absent in ’22 burned pasture |
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Heterogeneity/diversity |
Vegetation cover, composition, and diversity: Currently under review |
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Grassland bird abundance |
Greater number of bird species present in the burn grazing system. Species richness in burned/unburned pastures was similar. Birds that preferred bare ground (e.g., horned lark) were between 2.0 - 6.0 times more likely to be observed in the burned system. |
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Livestock performance |
Weight gains: Cattle in burn grazed system averaged 43 lbs. more than control animals. This resulted in approximately $86.96 per animal at sale. |
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Patch selectivity: Animals spent 1.5 - 2.0 more time in burned areas compared to unburned pastures. |
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Forage utilization: Currently under review |
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Soils |
Erosion: Increases in soil movement were detected in the burned pasture (.3595cm) compared to unburned (.0986cm). |
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Profile: Currently under review |
*All results shown are considered preliminary.
The stakeholders of the BBR CAM project were encouraged by the first-year results and recommended a continuation of the burn/grazing management plan. This year will target pasture N-6 for burning, followed by season-long grazing across all four pastures. The results from the first year of weight gains and livestock movement data help validate the project’s working hypothesis that burn/graze systems can increase livestock performance and rancher profitability, while controlling invasive eastern red cedar encroachment into the pastures. Analysis of other key data will continue along with a second season of site monitoring.
Education
The CAM Project utilizes a tiered-approach to learning and education Through the adaptive management framework, we emphasize collaboration in our structured decision-making process to guide management of the experiment. This setting allows for group participation, enhanced learning outcomes through cognitive modeling, and provides a rich environment for the co-production of science. We also look to expertise from Nebraska's Extension Educators who possess a breadth and depth of practical experience alongside their innovative approach to collaboration and education in the agricultural community. Lastly, we rely on the outreach efforts from the entire University research team as individual members conduct field tours, consultations, presentations, author media articles, and host training and networking opportunities throughout the year. This diversified approach allows the CAM Project to have immediate relevance within the Sandhills region (focal point of study), but it also allows CAM to communicate and coordinate with stakeholders statewide on the implications of the CAM Project.
Project Activities
Educational & Outreach Activities
Participation Summary:
The first year of the CAM project at Barta Brothers Ranch was active with education and outreach. To summarize, these included regular CAM project team meetings, articles in University newsletters, the establishment of a web presence for the Barta Brothers Ranch and the CAM Project, presentations to audiences of ranchers, natural resource managers, and researchers, and several on-site field exercises and tours.
CAM Project Team Meetings
The CAM Project Team (ranchers, natural resource managers, and researchers) began a regular cadence of meetings at the ranch (3-4 x per year). These meetings are a steady stream of CAM project updates, research design or analysis, and the selection and weighting of indicators to evaluate the outcomes. These team meetings also combine field tours to the pastures to inspect and discuss conditions firsthand. These meetings and associated exercises are critical to the structured decision-making process established in an adaptive management approach. These meetings result in approximately 600 hours of combined continuing education for the CAM Project Team.
Education
The University research team was active with both its education and outreach in year one of the CAM Project. Presentations were delivered to the Nebraska Grazing Conference, Society of Range Management-Nebraska Chapter, the Nebraska Cattlemen Association, a University of Nebraska Agricultural Resilience Forum, and the national meeting of the Society for Range Management.
These efforts were matched with tours, consultations, and other educational activities. For example, CAM researchers led a group of area ranchers on a tour of the modified patch-burn grazing system at Barta Brothers Ranch during the grazing season. CAM researchers consulted with a ranching family on their successful use of prescribed burning in their management plan. CAM researchers also led an educational session with Nebraska's Extension Educators on the CAM project's objectives and how to get involved.
Outreach
The establishment and revision of University webpages were important contributions in heightening the awareness of the CAM Project in Nebraska and beyond. This included new webpages for the Center for Resilience and an associated page about CAM as well as revisions to Nebraska Extension website. CAM researchers produced five web-based articles, three articles for University newsletters, and one short-form podcast for statewide media distribution. The team is currently developing a standalone publication summarizing the CAM Project and year 1 results.
Learning Outcomes
- adaptive management
- modified patch burn grazing system
- ecosystem services
- management of tradeoffs