Postglacial Fire Frequency and its Relation to Long- Term Vegetational and Climatic Changes in Yellowstone Park

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1 University of Wyoming National Park Service Research Center Annal Report Volme 16 16th Annal Report, 1992 Article Postglacial Fire Freqency and its Relation to Long- Term Vegetational and Climatic Changes in Yellowstone Park Cathy Whitlock University of Oregon Follow this and additional works at: Recommended Citation Whitlock, Cathy (1992) "Postglacial Fire Freqency and its Relation to Long-Term Vegetational and Climatic Changes in Yellowstone Park," University of Wyoming National Park Service Research Center Annal Report: Vol. 16, Article 35. Available at: This Yellowstone National Park Report is broght to yo for free and open access by Wyoming Scholars Repository. It has been accepted for inclsion in University of Wyoming National Park Service Research Center Annal Report by an athorized editor of Wyoming Scholars Repository. For more information, please contact

2 Whitlock: Postglacial Fire Freqency and its Relation to Long-Term Vegetati - POSTGLACIAL FIRE FREQUENCY AND ITS RELATION TO LONG-TERM VEGETATIONAL AND CLIMATIC CHANGES IN YELLOWSTONE PARK CATHY WHITLOCK t DEPARTMENT OF GEOGRAPHY UNIVERSITY OF OREGON + EUGENE t OBJECTIVES. The primary research objective has been to stdy the vegetational history of Yellowstone and its sensitivity to changes in climate and fire freqency. To establish a seqence of vegetational changes, a network of pollen records spanning the last 14, years has been stdied from different types of vegetation within the Park. The relationship between modem pollen rain, modem vegetation and presentday climate in the northern Rocky Montains has been the basis for interpreting past vegetation and climate from the fossil records. Changes in fire regime dring the past 14, years have been inferred from sedimentary charcoal and other fire proxy in lake sedime~ts. Calibration of the fire signal is based on a stdy that measres the inpt of charcoal into lakes following the 1988 fires in Yellowstone. The research project has been divided into for parts: 1. A stdy of the modem charcoal accmlation into lake sediments. At reglar time intervals, we are collecting srface sediments from different water depths in lakes that lie both within the 1988 brned region and at varying distances from the bm. We are relating charcoal abndance in these samples to basin size, water depth, and fire size and proximity t An analysis of fire events dring th~--past ca. 5 years. We are examining charcoal abndance, pollen composition, and paleomagnetic characteristics at closely spaced intervals in meter-long sediment cores to determine if the stratigraphic evidence of fire correlates well with the fire chronology based on dendrological stdies (Romme 1992, npblished data). An analysis of fire history from a lake with annally laminated (varved) sediments. To reconstrct fire history on an annal time scale and to extend the fire chronology beyond the limits of Lead-21 dating, we are stdying a 6-year varved record from Crevice Lake in the Northern Range. An analysis of vegetational history and fire freqency of the last 14, years. Or crrent research focses on the vegetational and fire history of the Central Platea and sothern Yellowstone region, the Bechler region, and the Northern Range. METHODS Detailed methodology for this research has been described in Millspagh (1991) and Whitlock (199), and only tasks accomplished since May 1992 are described. Pblished by Wyoming Scholars Repository,

3 University of Wyoming National Park Service Research Center Annal Report, Vol. 16 [1992], Art. 35 CHARCOAL ACCUMULATION FROM THE 1988 FIRES Srface sediment samples have been taken from brned and nbrned sites biannally since In Agst, we collected a site of samples from Dck, Goose, Cascade, Grizzly, Dryad, and Sylvan lakes, and Lake of the Woods. FIRE HISTORY OF THE LAST CA. 5 YEARS One-m-long cores were obtained from Cb Creek Pond and Slogh Creek Pond in Agst and sbsamples were taken at 1-cm intervals. Charcoal abndance and magnetic ssceptibility were analyzed in short cores from Grizzly, Goose, and Cygnet lakes. FIRE HISTORY FROM A VARVED-LAKE RECORD A frozen-sediment core from Crevice Lake has been photographed and the laminations have been conted. Analysis of the charcoal from this core follows the thin-section method of Clark (1988). To learn these techniqes, Sarah Millspagh went to the Limnological Research Center, University of Minnesota. The procedre involves replacing the water in the core with acetone and then epoxy to harden the sediments; ctting slices of the hardened core along transverse srfaces; and grinding these slices into thin sections so that they can be monted on glass slides for microscopic analysis. Or first efforts to impregnate the Crevice Lake core in epoxy were nsccessfl. In September, we modified the procedre and achieved good reslts. In the next 6 months, the rest of the core will be prepared by the epoxy method, and slabs will be sent to a commercial lab to be thin-sectioned and monted on petrographic slides. POSTGLACIAL VEGETATIONAL AND FIRE HISTORY Long cores were collected from Robinson Lake in the Bechler region and Cb Creek Pond in the Yellowstone Lake drainage. Pollen analysis of a core from Loon Lake in the Bechler region is nearly completed. Charcoal and magnetic ssceptibility analyses of cores taken from Cygnet Pond in 1991 are also nderway. RESULTS The reslts of this research appear in several recent and forthcoming isses of Ecological Monographs (Whitlock, 1993); Ecology (Millspagh and Whitlock, in review); Qaternary Research (Whitlock and Bartlein, 1993); Jornal of Paleolimnology (Engstrom and others, 1991); and Proceedings of the National Park Service (Whitlock, in press; Millspagh, in press). The findings have been discssed in book chapters (Whitlock and others, 1991; Thompson and others 1993), and they have been the basis for two M.S. theses (Sherrod, 1989; Millspagh, 1991), and a Ph.D. dissertation (Millspagh, to be completed in 1994). In addition, papers have been presented at national meetings of the Ecological Society of America, the Association of American Geographers, and the Geological Societj.'_of America and at the International -Palynology Conference (e.g., Millspagh and Whitlock Barnosky, 199; Whitlock and Bartlein, 1991). Some specific reslts of the last six months are discssed below: CHARCOAL ACCUMULATION FROM THE 1988 FIRES Charcoal profiles for Dck, Goose, Cascade, and Grizzly lakes for March 1992 are shown in Figre 1. Charcoal particles between 125 and 25 microns have proven to be a reliable indicator of local catchment fire. Charcoal qantities have increased in the sediments of brned lakes and nbrned lakes between 1989 and The initial sorce of charcoal was airborne fall-ot dring the fire, and this is still the primary component in nbrned watersheds. Lakes with brned catchments have received additional charcoal from two sorces: (1) slopewash processes and (2) sediment focsing of material from shallow water to deep water. It is probable that qantities of charcoal from these secondary sorces will contine to increase as charcoal is introdced from brned slopes and moved from shallow to deep water. Paleoecologists generally collect cores in deep water at the center of the lake. Ths, information on the lag between a fire and its registration as a charcoal peak in deep-water sediments is of critical importance in paleoecologic stdies. The type of vegetation that brned, as well as the characteristics of the lake catchment and

4 Whitlock: Postglacial Fire Freqency and its Relation to Long-Term Vegetati 214 Goose Lk NN E...._..r:. ~.. Cascade Lk NN E... - o f:...c - c (, Dck Lk NN. E...._..r:. Grizzly Lk NN E...._..r:: Depth (m) Figre 1. Charocoal abndance in the srface sediments in March At each site, samples were collected along a transect from shallow to deep water. Pblished by Wyoming Scholars Repository,

5 University of Wyoming National Park Service Research Center Annal Report, Vol. 16 [1992], Art bathymetry seem to be significant in determining the amont of charcoal in deep-water sediments. As an example, Goose Lake lies in a low-gradient catchment that was covered by open Pins contorta forest and 95% brned by grond fire in Despite the size of the catchment fire, Goose Lake contains the lowest amont of sedimentary charcoal of any of the brned sites. We think that the type of forest prodced little charcoal (see Renkin and Despain 1991) and that the low gradient of the catchment has limited the amont of charcoal to the site throgh secondary processes. In contrast, the catchment of Dck Lake spported fores~ of Picea, 4bies, and Pins contorta and a dense shrb nderstory. Abot 6% of the catchment brned in 1988 as a mixed canopy/grond fire. The amont of charcoal in lake sediments was higher than-other sites in 1989 and charcoal qantities. in deep-water sediments have increased since Or data sggest that the brning of this forest prodce4 abndant charcoal and that steep slopes and bathymetry have allowed charcoal to be introdced to the system throgh erosion and sediment focsing. At present, qantities of charcoal in deepwater sediments are not above the level of significance that wold indicate a local fire event at either Goose or Dck lakes. We hypothesis that charcoal abndance in the sediments will contine to increase in brned lakes in the next few years and that charcoal evidence of a fire event in 1988 will be more obvios in the ftre. FIRE HISTORY OF THE LAST CA. 5 YEARS Charcoal and magnetic ssceptibility have been analyzed in lead-21-dated short cores from Dck, Mallard, and Dryad lakes (Millspagh and Whitlock, in review). Stratigraphic levels that featre abndant charcoal and high vales of magnetic ssceptibility are interpreted as times of local catchment fire accompanied by significant erosion. Dck, Mallard, and Dryad lakes all record major fires between ca , a period that was also identified in the fire chronology developed by Romme and Despain (1989) from dendrologic records. Fire events occrred on a 4-6 year freqency from ca. 15 to ca. 175, bt they have been relatively rare since that time. Charcoal and magnetic ssceptibility measrements from Grizzly Lake, Goose Lake, and Cygnet Lake have been completed, and samples for lead-21 dating have been sbmitted. The profiles show changes in charcoal and clastic material that record past fires and erosion at each site (Figre 2). All the sites record the 1988 fire and a fire at ca em depth in the core, which we think dates to ca. 17. The preliminary data sggest changes in the longer fire recrrence interval in the last centry. Pollen percentages associated with historic fire events at Dck Lake show noticeable variations in the abndance of conifer pollen and total herb pollen~ The increase in total herb pollen associated with fire events may reflect an increase in herbaceos _ taxa that rapidly colonize a brned area. The flctations in coniferos pollen probably reflect;ihe,.. brning of late-scce$sional sprce, fir~ - and pine forests. - A FIRE HISTORY FROM VARVED SEDIMENTS High resoltion photographs have been taken of the Crevice Lake core, and ca. 6 varves layers have been conted. This core is being sbsampled for charcoal; no reslts are available at this time. STUDY OF POSTGLACIAL VEGETATION AND FIRE HISTORY As part of a stdy of the vegetation and climate history of the Bechler region, a 12.3 m core from Loon Lake (Targhee National Forest) was collected in the smmer Pollen analysis of the core sggests that Popls tremloides and Hapoxylon-type Pins have been components of the vegetation throghot the Holocene. The bottommost sediments at the site contain abndant Picea and herb pollen, which sggests a period of sprce parkland vegetation. Comparison with other radiocarbon-dated records in Yellowstone indicates that the Loon Lake core spans the last ca. 11, years. Radiocarbon dates will be sbmitted this fall. A 6.5 m core was taken from the floating mat at Robinson Lake to stdy the history of the wetland endemics there. At the base of the core was Mazama ash, sggesting that the site is ca. 7 years old. Frther cores will be collected next smmer. 4

6 to-) ~ Whitlock: Postglacial Fire Freqency and its Relation to Long-Term Vegetati Pblished by Wyoming Scholars Repository, 1992 ~ ~.~'\ Cygnet Lk.; >" Goose Lk ~" Grizzly Lk ~ 1 2 ~ ~ ~" (J(Q~ (J(Q~ (J(Q~ ~Cj --Cj ~Cj Cj Cj Cj ~ ~(J ~ ~c., ~ ~(J d) (J() (J() ~~ ~~ ~~ ~(:i.~~~ ~ & & <J' ~~~,<J'.~~~',G I J~ 1 2~ ~ I 2 - ]: 3 ~ l ~ I E.., c..c fr 4 <1) 4._. r- I 5 51 ~ 6~~ I I ~ i ~ I 6 6 j.. I I ~I ~ If ~ I 7 1 ~ I I ' 2 em IIU. I {.;IIIL em no./ cm2 em 7 Figre 1. Charcoal abndance and magnetic ssceptibility measrements in ndated cores from Grizzly, Goose, and Cygnet lake. All sites contain a peak of charcoal from the 1988 fires, as well as a peak at ca em depth..,. J";

7 University of Wyoming National Park Service Research Center Annal Report, Vol. 16 [1992], Art Charcoal and pollen from Cygnet Lake are nder stdy to provide a detailed 14,-year recordof fire history and vegetational change from the Central Platea. No reslts are available at this time. Cores collected from Cb Creek Pond are crrently being sbsampled for pollen analysis. This site will provide a detailed environmental reconstrction for NPS archeological investigations along the shores of Yellowstone Lake., PROBLEMS ENCOUNTERED DURING PROJECf We assmed that charcoal wold be well recorded in lake sediments in the first months after the 1988 fires. This assmption has proven false; charcoal amonts have been gradally increasing in lake srface sediments dring the last for years, and there is every reason to think the trend will contine in the ftre. Becase the rate of charcoal accmlation is slower than we anticipated, we plan to sample the sites once a year rather than biannally as originally proposed. Charcoal analysis of the Crevice Lake has been more complicated and costly than anticipated. Now that we have mastered the epoxy impregnation techniqe, we shold be able to make more progress. FUTURE WORK IN THE CONTRACf YEAR Charcoal samples collected in 1992 will be analyzed from all the stdy sites. Short cores from Grizzly, Goose, and Cygnet lakes will be lead-21 dated. The varve record from Crevice Lake will be sbsampled and analyzed for charcoal. Pollen analysis on Loon Lake will be completed. Pollen and charcoal analysis will be initiated on the long cores collected at Cygnet Lake and Cb Creek Pond. + ACKNOWLEDGE:MENTS I wish to thank John Varley and Don Despain (Yellowstone National Park) for their contined spport and stimlating discssions of this project. Jennifer Whipple and Rick Htchinson (Yellowstone National Park) helped core Robinson Lake. I also thank Ron Jones, Lynn Kaeding, Dan Mahoney, Dan Carty, and Glen Boltz of the USFWS for their tremendos logistical assistance. + LITERATURE CITED Clark, J. S Stratigraphic charcoal analysis on petrographic thin sections: applications to fire history in northwestern Minnesota. Qaternary Research 3: Engstrom, D. R., C. Whitlock, S. C. Fritz, and H. E. Wright, Jr Recent environmental changes inferred from the sediments of small lakes in Yellowstone's Northern Range. Jornal of Paleolimnology 5: Millspagh, S. H A record of fire in the sediments of small lakes from Yellowstone National Park. M.S. thesis. Department of Geology and Planetary Science, University of Pittsbrgh..,~, t.l( in press. Records of fire preserved in lakes sediments from the Central Platea of Yellowstone National Park. National Park Service Transactions and Proceedings. Millspagh, S. H., and C. Whitlock. in review. A 5-year fire history based on lake sediment records in Yellowstone National Park. Ecology. Millspagh, S. H., and C. Bamosky Whitlock Calibrating modem charcoal records to reconstrct prehistoric fires in Yellowstone National Park (abstract). Proceedings of the Ecological Society of America Annal Meeting, Snowbird. Renkin, R. A., and D. G. Despain Fel moistre, forest type, and lightning-cased fire in Yellowstone National Park. Canadian Jornal of Forest Research 22: Romme, W. H Fire and landscape diversity in sbalpine forests of Yellowstone National Park. Ecological Monographs 52: Romme, W. H. and D. G. Despain Historical perspective on the Yellowstone fires of Bioscience 39:

8 Whitlock: Postglacial Fire Freqency and its Relation to Long-Term Vegetati 218 Sherrod, B. L Paleolimnology of Alder Lake and its implications for Holocene tectonics in Yellowstone National Park, Wyoming. M.S. Thesis, Department of Ge9logy and Planetary Sciences, Umversity of Pittsbrgh. Thompson, R. S., G. Whitlock, S. P. Harrison, W. G. Spalding, and P. J. Bartelein. in press. Climatic changes in the western United States since 18, yr b.p. In: H. E. Wright, Jr., J. E. Ktzbach, W. F. Rddiman, F. A. St(eet-Perrott, and T. Webb III, eds. Global climates since the Last Glacial Maximm. University of Minnesota Press, Minneapolis. Whitlock-Barnosky, C Long-term vegetational changes at contrasting elevations in the northwestern U.S. (abstract). Proceedings of the Ecological Society of America, Snowbird. Whitlock, C Late-Qaternary vegetational and climatic history of the Yellowstone/Grand Teton region. UW -NPS Research Center Final Report Vegetational and climatic history of the northwestern U. W. since 2 ka (abstract). Proceedings of the VIII International Palynological Conference, Aixen-Provence, France Postglacial vegetational and climate of Grand Teton and sothern Yellowstone National Parks. Ecological Monographs. Whitlock, C., and P. J. Bartlein Analysis of the patterns of Hol<>cene climatic change in the Northern Rocky Montains (abstract). Proceedings of the Geological Society of. America Annal Meeting, San Diego. Whitlock, C., and P. J. Bartlein SpatiaL variations of Holocene climatic change in the Northern Rocky Montains. Qaternary Research. In press. Whitlock, C. and S. H. Millspagh Development of a fire history in Yellowstone National Park (abmract). Proceedings of Association of Ariierican Geographers Annal Meeting, Miami. Whitlock, C., S. C. Fritz, and D. R. Engstrom A prehistoric perspective on Yellowstone's Northern Range. In: R. B. Keiter and M. S. Boyce, editors. The Greater Yellowstone Ecosystem: Redefining America's Wilderness Heritage, pp Yale University Press Long-term vegetational response to climatic change and edaphic conditions in Yellowstone National Park. National Park Service Transactions and Proceedings. Pblished by Wyoming Scholars Repository,

Postglacial Fire Frequency and its Relation to Long- Term Vegetational and Climatic Changes in Yellowstone Park

University of Wyoming National Park Service Research Center Annual Report Volume 18 18th Annual Report, 1994 Article 25 1-1-1994 Postglacial Fire Frequency and its Relation to Long- Term Vegetational and