NM Ranch Study Shows Improved Grazing Strategy Increases Forage Production
The following is an excerpt from an article by Rick Danvir, Gregg Simonds, and Eric Sant in the journal IN PRACTICE titled “Using Remote Sensing to Compare Ground Cover—Comparing the Effectiveness of Grazing Strategies.” The authors investigated the effects of grazing management practices, at a landscape scale on upland bare ground and riparian vegetative cover. They compared cover on four eastern New Mexico ranches managed for ten or more years by Holistic Management-trained ranchers using ‘Strategic Grazing Management’ (SGM) with neighboring pastures seasonally or continuous stocked (CS) or multi-year rest (3 or more years of rest). Their question was, does management make a difference? The short answer was yes. The full article can be viewed in the scientific publication Rangelands.In 2015 Western Landowners Alliance (WLA) and the Thornburg Foundation partnered with Open Range Consulting (ORC), applying ORC’s remote sensing technology to compare ground cover attributes under different management styles. ORC’s Gregg Simonds and Eric Sant developed and have used their remote sensing technology to measure land cover characteristics like bare ground, litter, herbaceous and woody cover on western riparian and upland range sites for years. Rick Danvir, a wildlife and range advisor for WLA coordinated the research and reporting.
The Ranches
With the help of a Science Advisory team (a team of experienced range professors) the research team settled on four selection criteria to narrow our focus. First, both the subject ranches must be in the livestock grazing business. Second, only ranches managed with Holistic Management principles (like SGM) for ten or more years were selected. Third, only ranches who began using Holistic Management grazing principles after 1972 (when Landsat satellite imagery first became available) were selected.
Four ranches in eastern New Mexico, ranging in size from 7,000-70,000 acres, met the criteria and research begin in September 2015, following a very wet growing season (150% of average precipitation). These ranches provide 3-12-month recovery periods, running 1-3 herds through 10-30 pastures per herd each year. They plan relatively short (< 15 day) grazing periods during the growing season, and vary pasture season of use through time. As a result, pastures are grazed ≤ 10% and recovering from grazing for ≥ 90% of the calendar year.
Information from ranch records and interviews suggests maximum stocking rates of the subject ranches and neighboring ranches over the past decade were in the 40-60 acres/AU range. The JX Ranch is currently stocked a bit higher, having increased from 58 ac/AU in the late 1990s to about 35 ac/AU.
Field work consisted of collecting 70-130 ground-based vertical photographs (GBVP) on each subject ranch. These images were obtained from a high-resolution camera on a boom, linked to a laptop, mounted on a four-wheeler. Photo sites were selected to capture the full range of variability in cover variation on each ranch. Back in the lab, ORC’s Eric Sant used the GBVP’s and self-learning software to ‘train’ the computer to interpret cover characteristics on 0.5-m Pleaides satellite imagery in synch with the GBVP’s.
Since two of the ranches also had streams and riparian habitat, ORC used satellite imagery to determine the amount of each potential riparian area (PRA) along the streams containing riparian vegetation. In addition, they correlated the Pleaides imagery with Landsat satellite imagery (which are available every year since 1972) to compare riparian cover through time, on both the subject ranches and on neighboring stream ‘reaches’.
Comparing Upland Bare GroundShows 27% Decrease
The research focused on percent bare ground to compare upland range condition, as bare ground is believed to reflect management over many years. Gregg and Eric then devised a way to compare grazing management effects on upland bare ground values. Using the continuous cover maps, they compared bare ground on 100-meter-wide strips on either side of the ranch boundary fence, completely around each ranch. Within these strips, they compared bare ground values on soil polygons of the same soil types, on each side of the fence (Fig. 1). Since these adjacent polygons were of identical soil types, and received virtually identical weather, any difference in bare ground was attributed to management.
Bare ground values varied with soil type and ranch geographic location with bare ground sometimes less on the SGM side of the fence and sometimes less on the paired CS or rested polygons across the fence. However, the data indicated that on each ranch bare ground averaged less on the SGM subject ranches than on adjacent, neighboring pastures (Fig. 2).
The data from all four ranches was then pooled together, and assessed using a statistical test that accounted for soil type and ranch. This analysis indicated the SGM polygons had significantly less bare ground (13% less) than the paired CS or rested polygons across the fence, supporting the idea the differences were due to management. Since the research knew the grazing history of JX Ranch and its adjoining pastures, we were able to separately compare the JX Ranch SGM polygons with polygons in neighboring pastures 1) grazed continuously or season-long, or 2) rested three or more years. The JX had significantly less bare ground (27% less) than the adjoining grazed pastures. The bare ground was also less (9%) than on the adjoining pastures rested three or more years.
Riparian ComparisonShows 19% Increase in Vegetation
The research team also compared the difference in riparian vegetation on adjacent stream reaches on-and-off the AM and CS ranches. Using Landsat data, they went back in time, comparing riparian vegetation differences on SGM ‘reaches’ (a length of stream) with paired CS reaches 1984-2015. Over this time period, riparian vegetation averaged significantly greater (19% greater) on SGM stream reaches than on paired CS reaches. Riparian vegetation was similar on both SGM and CS reaches in 1984 (before SGM began). However, after 1990 (after SGM began) riparian vegetation is consistently greater on SGM than CS reaches.
Ranch Study Outcomes
First, the results support the belief that SGM practices can improve a land manager’s ability to reduce upland bare ground and increase riparian herbaceous cover on rangelands. The SGM ranches had less bare ground and higher riparian cover than more traditionally managed lands. Of equal importance, we found little difference in bare ground between pastures receiving multi-year rest and SGM pastures, suggesting that periodic grazing, alternated with appropriate and effective recovery periods (strategic rest), is comparable to multi-year rest. The data suggests ranchers can achieve bare ground values as good or better than multi-year rest, while generating livestock grazing revenue to fund themselves and their stewardship.
Riparian cover in both SGM and CS reaches (1984-2015) changed significantly with precipitation, and were similar at precipitation extremes (Fig. 3). Managers must consider how precipitation affects cover values, and the length of time over which these fluctuations occur, to properly judge the effectiveness of management activities on range and habitat condition.
Cost Benefit Analysis
Are the benefits of SGM worth additional management complexity and infrastructure? The ranchers in the study believe it was. The change required water development, additional fencing, in some cases brush control, and a lot of planning. The upside is that bare ground declined while cover, forage, beef production and habitat improved. Tom Sidwell explained that the resultant higher forage production, higher average stocking rate and more calves to sell – plus planning for drought and innovative marketing – means ranch revenue is better and more dependable than ever. Equally important, the increased cover and soil carbon initiated a positive cascade – capturing more water, reducing runoff, increasing forage production and lengthening the ‘green’ period – good for livestock, wildlife and the bottom line.
Rick Danvir is a Wildlife and Range advisor to the Western Landowners Alliance and can be reached at basinwlc@gmail.com. Gregg Simonds (greggesimonds@gmail.com) and Eric Sant (eric@openrangeconsulting.com) work at Open Range Consulting. All photos credited to Rick Danvir. Thanks to the Thornburg Foundation for their support of the development of this case study.
References
Jacobo E.J., A.M. Rodríguez, N. Bartoloni, V.A. Deregibus. 2006. Rotational grazing effects on rangeland vegetation at a farm scale. Rangeland Ecology & Management, 59:249-257.
Danvir, R., G. Simonds, E. Sant, E. Thacker, R. Larsen, T. Svejcar, D. Ramsey, F. Provenza and C. Boyd. 2018. Upland bare ground and riparian vegetative cover under strategic grazing management, continuous stocking and multi-year rest in New Mexico mid-grass prairie. Rangelands. Vol. 40: in press.
Weber, K.T., Alados, C.L., Bueno, C.G., Gokhale, B., Komac, B. and Pueyo, Y. 2009. Modeling bare ground with classification trees in Northern Spain. Rangeland Ecol. Manage. 62:452–459.
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