The Effects of Post Fire Grazing on Species

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ABSTRACT

The objective of this study was to determine the effect of burn status and grazing post-fire on species composition of annual- grass rangeland in northern California. Using single factor, completely randomized design, 1×1 meter plots were established on burned and unburned (control) sites (6 replications per treatments). Plant community composition based on relative species frequency was determined at each study site by sampling years 1,5, and 10. Vegetation was measured by type of percent coverage in the two treatments. E. moschatum, Taeniatherum caput- medusae, and Vicia sativa were significant (P< 0.

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05) for percent coverage. Bare ground (P= 0.119), Hordeum murinum (P=0.067), and Trifolium hirtum (P=0.073) were not significant (P>0.05) for percent coverage collected. Data were analyzed using complete randomized design ANOVA.

Results suggest that grazing livestock should be allowed back on rangeland allotments in California sooner than the two-year blanket policy used by many land managers. California’s Mediterranean climate makes for a unique environment different from other rangelands in the united States. A different policy for different rangeland locations such as in northern California would reduce fuel loads as a preventative to fire season and invasive species post fires.

Introduction

In California, 15 million acres is public land of allowing for 6.1 million acres to be permitted livestock grazing land. The BLM permitted about 553 lessees in 2017 to graze on the that land. There are many benefits to allowing livestock grazing on public lands. Not only is it beneficial for the ranchers, but livestock grazing promotes woody plant growth by suppressing competition from herbaceous plants through preferential grazing of grasses and forbs (Roselle et.

al 2010). Previous research has explored grazing post fire and the effects of vegetation recovery, but not commonly as combination.

A major issue affecting California livestock grazers according to BLM is fire. According to an article in Science journal, burned area per annum are all increasing across much of the western United States (Westerling and others 2006). Not only is this impacting the people who live in these areas, it is impacting the ranchers who have livestock grazing the land. In 2017, 30,299 acres of the 15 million acres were affected by wildfire (BLM, 2017). Stephens (2007) claims massive fire-fighting has reduced forest fire activity to levels far below those that characterized many western landscapes before Euro- American settlement began in the mid-19th century, but fire season used to be just that, a season. Now the fires affecting California are considered super fires that happen all year round. These super fires are caused by fuel build up. This is not an issue that has recently happened. It has been developing over decades of poor land management because of strict environmental and land laws. Logging and grazing practices are being observed and studied more now as a better option to try to control and prevent fires.

Learning more about the benefits of fire and allowing grazing soon after a fire will aid in better management practices for grazing and fire. As oofow the federal government does not allow re- entry of livestock to graze on public land until 2 years have passed. The reasoning behind this policy is absent. The Public Rangeland Management Act of 1995, Section 114d 1A states In general—use may be suspended in whole or in part on a temporary basis to facilitate (i) recovery from drought, fire, or another natural event. The Act of 1995 does not state a specific time constraint to suspend grazing operations, generally a two-year blanket policy has been used.

The two-year policy does not have a direct source, but early research done by John Valentine shows he recommended it. Valentine was known for his intermountain region research. The two-year rest period recommended by Valentine and other texts such as Range Management was based on a combination of biology and field experience (Stoddard, Box and Smith, 1975). Although not all geographic areas are the same, the policy for two-year wait period for regeneration and recovery has stuck for all regions as a simple and easy solution.

Vegetation is not only different in various locations but does not grow at the same rate as others. There are different planting seasons along with different temperatures and climates; precipitation is key, followed by soil characteristics, season, andntensity of grazing, and species of grazing herbivore. (Roselle et. al 2010). All vegetation grows differently, some need fire to survive which is the case for species in California. California has a unique Mediterranean climate which favors annual grass growth. Annual plant carcasses (i.e., thatch, residual dry matter) can contribute to fine wildfire fuel load more so than the perennial grasses of the great basin and grassland areas (DeAtley, 2018). Fire helps with elimination of old or death growth and sometimes with seeding depending on the plant. With the destruction of fire, comes invasive species such as medusa head which is said to have no to reasonably palativeity to grazing livestock. It is not easily burned in a fire when green, and if burned some the of the seeds usually survive. The objective of this study being to determine the effect of burn status and grazing post-fire on species composition of annual-grass rangeland in northern California.

Material and Methods

The study site was located in the northeast corner of the CSU, Chico Beef Unit Range (latitude 39.847606 and longitude -121.896172), Chico, CA, Butte County. Study experiment consisted of 1×1 meter plots in burned (1.1 acres) and unburned area (2.2 acres) with a total of 3.3 acres. The burned plots were because of a wildfire that sparked 31 October 2015. In the unburned plots, 66.4 % of the soil consisted of red sluff gravelly loam soil. The burned plots consisted 33.6% of red tough- red swale soil. The site consists of cool- season annual grass and forbs from fall to mid- spring with a mean annual precipitation is 23 to 28 inches.

Although the grazing scheme is continuous, there is Angus, Red Angus, and Hereford cows grazing between November to mid- April with a stocking rate of about 2.02 hectares per animal unit. Calving season starts about February 10.

A 30 meter transect line was established in each of the two sites. The plots were located one meter from the center of the transect with two meters between each plot. Along each transect, 2 quadrats were established at 1 m intervals for a total of 60 quadrats per study site. All plant species rooted within each 0.01 m quadrat were identiﬁed following Baldwin et al. (Baldwin et al. 2012). Percentage samples of bare ground, Hordeum pusillum (Hordeum), Taeniatherum caput-medusae (medusa head), Bromus hordeaceus (soft chess) cover, Vicia americana (vetch) cover, Bromus diandrus (rip gut) cover, Amsinckia (fiddleneck) cover, and Trifolium hirtum (rose clover) cover were taken. Species composition data were collected each on 20 April 2018 using the procedures of: https://www.researchgate.net/publication/262532064_Montane_Meadow_Plant_Community_ Response_to_Livestock_Grazing.

The experimental design is single factor, complete random design, using single factor ANOVA procedures in Excel (Microsoft, Inc.; Seattle, WA).

Results

The effect of the burn status of the plant species percent coverage show only three had significance. In the statistical model, vegetation was measured by type of percent coverage in two treatments unburned (control) and burned. Filaree, Medusahead, and Vetch were significant (P < 0.05) for percent coverage (Table 1). Bare ground (P = 0.119), Hordeum (P=0.067), Fiddleneck (P = 0.102), Ripgut (P = 0.223), and Rose Clover (P = 0.073) were not significant (P > 0.05) for percent coverage collected. Filaree is the only species collected that was not present in the control (0% coverage) but grew post fire (0.148% coverage).

Filaree is the only species collected that was not present in the control (0% coverage) but grew post fire (14.8% coverage). Hordeum (7.7% coverage) and Ripgut (1.7% coverage) grew before the fire and did not recover to grow post fire (0% coverage). Medusahead and Filaree thrived in the post fire environment. Medusahead showed an increase of 17.8% post fire and Filaree showed an increase of 14.8%. Vetch on the other hand did not thrive in post fire environment decreasing by 45.8%.

Discussion

With recent wildlife burning hundreds of thousands of acres more and more consistently, law makers to land managers have been looking into better management practices for mountainous areas to grass and rangelands. One common idea from land and livestock owners has been adjusting the 2-year post fire grazing rule.

Many studies have examined plant species response to wildfire, but not invasive species regarding allowing grazing animals to return on land. Fuel loads increase with a lack of understanding of land management and because little research has been conducted on the effects of earlier re introduction of grazers to rangeland, it has been a battle for landowners and livestock owners.

In a previous study of a fire in 2000 showed sheep re introduction had little to no effect on vegetation recovery (Roselle, L. 2010 et. al,). The results of that study showed the cover of annual grasses was not affected by the grazer re introductions of 1 to 3 years. This also showed true for perennial coverage, but annual plant coverage was varied.

It is hard to compare this exact study to previous because there has been little done as a combination of grazing post fire and the effects of vegetation recovery. Although during this study there was nothing that blatantly went wrong, future research needs to continue to strive for a better understanding of ecosystem influences (including grazing, fires, and plant species).

Conclusion

Land managers need to reconsider allowing grazing livestock back on rangeland sooner than two- year “recovery” period in California. This study determined invasive species such as E. moschatum (Filaree) and Taeniatherum caput- medusae (medusa head) showed significant coverage and produced additional fuel load post fire. In summary, grazing livestock should be allowed back onto rangeland sooner than two years to help prevent invasive species and lower fuel load.

References

California Statewide Fire Map. (208, January 24). Retrieved from http://cdfdata.fire.ca.gov/incidents/incidents_stats?year=2017
DeAtley, K. (2018, Fall). Overview of Range Project. Retrieved October 23, 2018, from https://learn.csuchico.edu/webapps/blackboard/execute/content/file?cmd=view&content_id=_3421094_1&course_id=_134079_1
Holechek, J. L. (1981). Livestock Grazing Impacts on Public Lands: A Viewpoint. Journal of Range Management,34(3), 251.
Johnson, E. A., Miyanishi, K., & Bridge, S. R. (2001). Wildfire Regime in the Boreal Forest and the Idea of Suppression and Fuel Buildup. Conservation Biology,15(6), 1554-1557.
Miller, J. D., Safford, H. D., Crimmins, M., & Thode, A. E. (2008). Quantitative Evidence for Increasing Forest Fire Severity in the Sierra Nevada and Southern Cascade Mountains, California and Nevada, USA. Ecosystems,12(1), 16-32.
Roselle, L., Seefeldt, S. S., & Launchbaugh, K. (2010). Delaying sheep grazing after wildfire in sagebrush steppe may not affect vegetation recovery. International Journal of Wildland Fire,19(1), 115.
S. Rept. 104-123 – PUBLIC RANGELANDS MANAGEMENT ACT OF 1995. (n.d.). Retrieved from https://www.congress.gov/congressional-report/104th-congress/senate-report/123/1
Stephens, S. L., Martin, R. E., & Clinton, N. E. (2007). Prehistoric fire area and emissions from Californias forests, woodlands, shrublands, and grasslands. Forest Ecology and Management,251(3), 205-216.
Stoddart, L. A. (1975). Range management(3rd ed.). New York: McGraw-Hill.
Westerling, A., Hidalgo, H., Cayan, D., & Swetnam, T. (2006, August 18). Warming and earlier spring increase western U.S. forest wildfire activity. Science, 313(5789), 940-943.