In the grip of drought, livestock producers often must deal with the additional impact of wildfire. While drought conditions develop gradually and can be anticipated, losses due to wildfire are sudden and devastating

Gates, Roger N.

Richter, Heather

Smart, Alexander J.

English

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South Dakota State UniversityOpen PRAIRIE: Open Public Research Access InstitutionalRepository and Information ExchangeExtension Extra SDSU Extension1-1-2007After Wildfire: Range RecoveryAlexander J. SmartSouth Dakota State UniversityRoger N. GatesSouth Dakota State UniversityHeather RichterSouth Dakota State UniversityFollow this and additional works at: http://openprairie.sdstate.edu/extension_extraThis Other is brought to you for free and open access by the SDSU Extension at Open PRAIRIE: Open Public Research Access InstitutionalRepository and Information Exchange. It has been accepted for inclusion in Extension Extra by an authorized administrator of Open PRAIRIE: OpenPublic Research Access Institutional Repository and Information Exchange. For more information, please contact michael.biondo@sdstate.edu.Recommended CitationSmart, Alexander J.; Gates, Roger N.; and Richter, Heather, "After Wildfire: Range Recovery" (2007). Extension Extra . Paper 80.http://openprairie.sdstate.edu/extension_extra/80ExEx2057C o l l e g e o f A g r i c u l t u r e & B i o l o g i c a l S c i e n c e s / U S D AIn the grip of drought, livestock producers often must dealwith the additional impact of wildfire. While drought con-ditions develop gradually and can be anticipated, losses dueto wildfire are sudden and devastating.Because fire is a natural component of Northern GreatPlains grassland ecosystems, prairie vegetation is very welladapted to recover following a fire. With prescribed burn-ing you choose the conditions that make fire a beneficialmanagement tool. Unfortunately, those conditions areabsent in many wildfires.A fire prescription or burn plan designed to reduce onespecies or group and encourage another would include spe-cific conditions such as a target fuel load, favorable growingconditions, good moisture, and acceptable wind speed, winddirection, and relative humidity. These conditions mostoften exist early in the growing season. If prescribed condi-tions are not met, the burn is not conducted.In contrast, wildfires occur when conditions may be veryunfavorable for vegetation.Wildfire has impacts on the soil as well as on the vegeta-tion. Under normal conditions, the soil surface is protectedby a layer of litter—old plant material undergoing the decayprocess. This litter layer and standing vegetation reduceevaporation and protect the surface from soil movementcaused by wind or rain. Litter also promotes rainwaterinfiltration, reducing runoff and enhancing soil moisture.During winter, standing vegetation is important in capturingsnow that later contributes to soil moisture.Standing vegetation and litter are removed, sometimes com-pletely, by a wildfire.Wildfires also remove whatever live plant tissue is presentat the time of the burn. As plants initiate new growth fol-lowing the fire, they will draw down stored reserves toreestablish photosynthetic leaf tissue in the same manner aswhen putting on new growth in the spring. If reserves havenot been replenished by the time autumn freezes occur, theplant's reserve status will be compromised and recovery thefollowing spring may be less vigorous.Although the landscape may appear devastated following afire, grassland species are adapted to fire. They will recov-er.In contrast to woodland fires where fuel loads may lead toextended periods of very hot temperatures, grassland firesgenerally move over individual plants very rapidly, minimiz-ing the duration and intensity of elevated temperatures. Therate of post-fire recovery is controlled primarily by the con-dition of the vegetation before the fire and moisture condi-tions following the burn. Healthy, vigorous rangeland willrecover rapidly following a fire. Recovery of rangelandvegetation stressed by long-term overgrazing will be muchslower.While tame grasses introduced for forage production maybe less well adapted to fire, if they have reached dormancyby the time of a summer wildfire, they are unlikely to beseverely damaged. With fall moisture and cooler tempera-tures they should begin regrowth rapidly.When favorable growing conditions return, the first plantsto respond will be annual broadleaves. These weedy speciesare nature's mechanism to protect the soil surface as rapidlyas possible. While this flush of growth is normally transientand will be replaced by perennial plants, you must be alertAfter Wildfire: Range RecoveryAlexander J. Smart and Roger N. Gates, associate professors, Animal and Range Sciences Department,andHeather Richter, student, Animal and Range Sciences Departmentto the invasion of troublesome weeds during the early stagesof post-fire recovery. Early treatment of small plants orpatches will be much more effective than later treatment ofwell established weeds.Best management for rangeland following a burn is restfrom grazing.Unfortunately, regrowth following a burn is both palatableand nutritious. Exclude livestock from burned areas for aslong as possible. For example, if only a portion of a pasturehas burned, a temporary fence to exclude grazing should beestablished.The greatest benefit for vegetation following a fire will be acomplete growing season rest, perhaps grazing again aftervegetation is dormant in the fall. If an area must be grazed,delaying at least until important plants have reached maturi-ty and set seed will be beneficial. Productivity of plantssurviving after a fire will be reduced.For example, we monitored recovery by measuring forageproduction from unburned and burned areas following theSeptember wildfire at the South Dakota Grassland Coalitionmanaged intensive grazing demonstration site. We set upfive exclosures on the burn line in May 2006 and measuredforage biomass and soil temperatures in the burned andunburned areas in May, June, and July. Green biomass andlitter portions of each sample were separated and ovendried.Green forage biomass was reduced by 43% in the burnedarea compared to the unburned area at the May samplingdate (Table 1). However, both burned and unburned areashad similar green biomass at the June sampling date. At theJuly sampling date the burned area had 20% less green bio-mass compared to the unburned area. Averaged over thesummer, the burned areas had 25% less green biomasscompared to the unburned areas.These data indicate that wildfire reduces forage productionthe following year, especially if it is a dry year (April-May2006 precipitation was 59% below normal compared to the6-year average, 2000-2005, of 2,500 lb/acre.Protective litter was 6 times greater in the unburned site(Table 1). However this did not translate into the expectedtemperature differences between the burned and unburnedareas. The dry and hot summer may have minimized anyprotective advantage the abundant litter in the unburnedarea could have provided.Season-long stocking rates, at the very minimum, should bereduced by 25% to reduce the risk of overgrazing.Delaying turnout until later in the summer would also beadvisable because the differences in green biomass betweenthe burned and unburned areas decreased later in the sum-mer.It is apparent from this example, that a wildfire followed bya dry spring limited forage production.While there is a strong desire to “do something” following afire, there is no evidence that tillage or other soil treatmentsor reseeding will be of any benefit. In fact, some researchindicates they can be detrimental.Management following a fire boils down to matching ani-mal demand and feed supply by reducing animal numbersand/or identifying alternative sources of feed. Delaying areturn to grazing on burned areas will benefit the vegetationand restore its productivity.Table 1. Average green forage biomass, litter, and soil temperatures at the South Dakota Grassland Coalition management intensive grazingdemonstration site near Highmore, S.D., May–July 2006.May 15 June 15 July 14Measurement Burned Unburned Burned Unburned Burned UnburnedGreen biomass, lb/acre 610b 1070a 890a 990a 750b 930aLitter, lb/acre 200b 2040a 260b 1590a 330b 1390aSoil temp at 0.5-inch depth, oF - - 105a 102a 112a 107aSoil temp at 2-inch depth, oF - - 90a 85a 93a 88aa,b Means followed by different letters within a row and common sampling date are significantly different (P<0.05).South Dakota State University, South Dakota counties, and U.S. Department of Agriculture cooperating. South Dakota State University is an AffirmativeAction/Equal Opportunity Employer and offers all benefits, services, education, and employment opportunities without regard for race, color, creed, religion,national origin, ancestry, citizenship, age, gender, sexual orientation, disability, or Vietnam Era veteran status.EXEX2057, 2007. Access at http://agbiopubs.sdstate.edu/articles/ExEx2057.pdf. Or go to http://sdces.sdstate.edu/drought

After Wildfire: Range Recovery

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After Wildfire: Range Recovery

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