1989, Kaufmann 1993). Evidence from the past .... (Kaufman 1993, Tausch et al. 1993). Although we ..... making your contribution to the worldâAndy Granatelli.
RANGELANDS15(5), October 1993
Viewpoint: Lessons from the Past for Managing Tomorrow's
Range Ecosystems Robin J. Tausch, J. Wayne Burkhardt, Cheryl L. Nowak, and Peter E. Wigand
Editor's Note: Thispaper is a condensedversion ofthe paper'Viewpoint: Plant Community Thresholds, Multiple Steady States, and Multiple Successional Pathways; Legacy of the Quaternary" published in the September1993 issueof the Journal ofRange Management.
0
Range ecosystems have seen dramatic changes over the last centuryand a half (Young et al. 1978, West1983). —2 Manystudieshave shown that thechanges in the affected communitieshave not followed traditional concepts of -4 plant succession (Johnsonand Mayeux 1992).Thesetraditional concepts were based on assumptions of envi-6 ronmental stability and eventual equilibrium conditions. 1000 800 600 400 200 0 What managers have been observing has been much Thousands of years(B.P.) more complex and without much evidence of environmental stability or long-termequilibrium (Westoby et al. Fig. 1. Reconstructionof the history of surface temperaturedeviationsfor the last850,000years. Mean annual temperaturedevia1989, Kaufmann 1993). Evidence from the pastprovided tionsarefor the mean valueofthepresentcentury ofabout 15° C. by paleoecological research is indicatingthat suchcomFigure adapted fromEddy and Bradley,Earthquest, Spring 1991, Vol. 15, No. I, Office for Interdisciplinary Earth Studies. plex and dynamicsituationsare morethe norm than the exception. 1500
Lessons from the Past Paleoecological research providesinformationon both past variationsin climate and theassociated changes in plant communities. Recordsof temperature (Eddy and Bradley 1991, Webb 1991,Winogradet al. 1992,Taylor et al. 1993) and lake level fluctuationsover the last 2 million years (Smileyet al. 1991) indicatethat climatic variations in the past werehighly complex(Tausch et al. 1993).Over the last 850,000 years, for example, there have been w approximately10 major glacial-interglacialcycles (Fig. 1). Duringthis period temperatures have fluctuated by as much as 8° C. Averagetemperatures that are equivalent to those of today totaled only 10 to 15 percent of the period. On a geologic time scale this represents periods
of drought in an otherwiseglacial climate.The effectsof these temperature variations on climate is evident, such as in the changes in pluvial Lake Lahontan in western Nevada (Fig.2), which has had several fluctuationsin lake level in only the last 35,000 years (Thompsonet al. 1986,
PluvialLake Lahontan
1400
1300
1200
9 ?
1100
10
20
30
Years B.P. (xl000)
Fig. 2. Reconstructedpluvial Lake Lahontan levels for the past 35,000years. RedrawnfromThompson et a!. (1986)and Benson (1991).
Vegetation data forthe last 45,000yearscollectedfrom woodratmiddens (Betancourtet al. 1990) and forthelast 200,000+ years from the analysisof pollen from lakes, First and third authors are project leader and paleobiologist, bogs, and ocean sediments (Schoonmaker and Foster lntermountain Research Station, USDA Forest Service, 920 Valley 1989, 1991) shows that vegetationresponses to climate Road, Reno, Nev. 89512. Second author is associate professor, Departmentof EnvironmentalandResourceSciences,University of variations have been equally complex. At each point in Nevada,Reno, Reno 89512, andthe lastauthor isassociateresearch spaceand time the combinationof species and environprofessor, Desert Research institute, Universityof Nevada System, ment has been in some way unique (Tausch et al. 1993). Reno 89506. Benson 1991).
RANGELANDS 15(5), October 1993
Throughouttheperiod in Figure1, with theexceptionof aboutthelast 10,000years, southwestern plantcommunities supportedmany differentspecies of large grazing or browsing animals(Grayson 1991). Today's plant communitiesare the resultof their constituent species surviving over2 millionyears ofcontinual climateand other environmental variation(Schoonmaker and Foster 1991). These environmental variationshave had a major influencein the on-goingevolutionof plants in response to their environment (Conkle 1992). Each plant species has responded individuallyto the climatic changes (Nowak 1991, Tausch etal. 1993). Manyspecies have migratedhundredsof miles in the last 12,000years, buttheratesand directionshave differedamongspecies. The species present in a particular plant community today often arrivedat differenttimes,came fromdifferent locations,and had to copewith differentadversities during migration (Davis 1986, Huntley 1991). The result has been continual changes in community compositionand many modern communitiesthat have no analog in the past (Webb 1987, Anderson et al. 1989). Many Southwestern communitieshave dramaticallychanged injustthe last century and a half. Some of thesecommunities may have been relics from a previous climatethat weresensitive to recent environmental changes and to the impacts of western settlement(Neilson 1986, 1987; Tausch et al.
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The present30 percentincrease in CO2 over pre-industrial levels isalready changing the productivitypatterns of plants (Polleyet al. 1993) andthisis alteringthecompetitive interactions between plant species (Johnson et al. 1993).The future outcomeof these competitivechanges on communitycompositionis mostlyunknown. Research is needed to measure and understand these changes.
Combining Past and Present
Several importantconceptscanbe developed by combining current ecologicalresearch results and management experiencewith the extended time-line and perspective provided by paleoecological information. These concepts need to beconsideredin thedevelopment of the longer-term aspects of the management of rangeecosystems. Although effects vary between locations, no communityor ecosystem is now without some level of human impact(West 1993). Communities of the future can never beexactlywhattheywere in the past (Box 1992). Because our knowledge is still insufficient to fully grasp or to accurately predict the outcome of future vegetationclimate interactions (Mooney 1991), these interactions need to be a priority of research. The many influenceswe havediscussed are global in nature and representvarious aspects of what is called global change. All communitieson the earthare in some 1993). way managed systems, intendedor not. Because we are The legacy of this past climate change is that plant indirectly as well as directly affecting the future of all communitiesare far less stable than they appear to be ecosystems, a hands off approach is also management from our generally short-termhistoric perspective (Davis (Kaufman 1993, Tausch et al. 1993). Although we can't 1986). Models of ecosystem dynamics based on long- eliminate our influence, we can control and direct our term equilibrium conditions have limited applicability. actions to minimize undesirableresults or accentuate Such models are based on observationsfromtoo narrow desirable changes. a time base (Tauschet al. 1993). The principlesand conAs recent paleoecological and ecological research cepts of ecosystem management, and the ecosystem results have shown, continualvariation in ecosystems is paradigms or models from which they are developed, not new. Only our awareness of the changes and their need to incorporatethe past, aswell asthe present condi- potential magnitude is new because the timescales at tions, to successfully project long-termfuture variation which we have been observing ecosystem variation have over both space and time (Johnsonand Mayeux 1992, not matched the timescales at which the changes are Tausch et al. 1993). occurring (Scholes 1990). Short-terminformationmakes it difficult to recognize and estimate the magnitude of Experiencefrom the Present changes that take decades or longerto occur. Time lags, Additional evidencefordynamiccommunities isaccumu- commonin ecologicalsystems, can concealevidenceof lating from management experience. We are finding that mismanagement and thelinks between cause and effect, communitieshave multiple possible steady states, each further confusingour interpretation(Scholes 1990). The with differentspecies composition(Westoby et al. 1989, management of rangeecosystems needs to considerthe Friedel1991,Laycock 1991). Between thedifferentsteady many global change problems and the perspective prostates are thresholdsrepresenting variouslevels ofsensi- vided by paleoecological informationin the development tivityto physicaland biologicaldisturbance. Oncedistur- of long-termplanning. bance pushes the community across a threshold, the The paleoecologicalrecord and the history of the last two After the centuries of land use are clear. If we manage for the communitycompositionchanges. composition has changed, it often does not reverse when the distur- future by tryingto recreate communitiesof the past, most bance is removed. Thesedynamics, plusthe presence of ofour effortswill notsucceed becausetheconditionsthat similar patternsthroughout the paleoecological record made those past communitiespossible no longer exist. (Tausch et al. 1993), are affecting how we can define The resulting community may resemble a community long-termmanagement goals by defining thecommuni- present on the site at some past time, but it also maynot. ties that are possiblein the future. To determine a desired future condition for a site will Climatic variations of the past have continuedto the require an understandingof the future capabilities or present, includingthe last 150 years (Neilsori 1986,1987).
RANGELANDS 15(5), October 1993
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possibilities of that site along with its potential uses. (Tausch et al. 1993). These decisions also need to be based on an increased understanding and sustainment of ecosystem function and biodiversityso as not to foreclose on future options. Often there is more than one communitythat canachievethe same management goals (Johnsonand Mayeux 1992). Knowledge of past climate variation and the associated changes in environments and communitiesis equal in importance to knowledge of present conditions for understanding the management implications ofsuchcomplex ecosystemdynamics (Tausch et al. 1993). While it is one thing to recognize the need for new methods and models, it is another to produce them (Keddy 1992). The hardest part of management for sustaining ecosystem function will be the extrapolationof the trajectories of change from the past,, through the present, and into the future (Mooney 1991, Tausch et al. 1993). A promising way to accomplish this is to gather information in a way that facilitates the verification of general predictivehypotheses that canbe assembledinto general models applicable to landscapes. This requires sufficiently large numbers of sampled species to (1) statistically test correlationsbetween specifictraits representing basic functions of organismsand environmental parameters; and (2) determine whether the observed patterns representwidespread responses or are specific to only a few species (Keddy 1992). Examples of efforts beginningthe movement in this direction inclue Bosch and Booysen (1992), Georgeetal. (1992), and Leonardet al. (1992).
Grayson, D.K. 1991. Late Pleistocene mammalian extinction in NorthAmerica:taxonomy, chronologyand explanations.J.World Prehistory5:193-232. Huntley, B. 1991. Howplants respondtoclimate change:Migration rates, individualism and the consequencesfor plant comunities. Ann. Bot. 67:15—22. Johnson, H.B.,andH.S.Mayeux.1992. Viewpoint:Aviewonspecies additions anddeletions andthe balanceof nature.J. Range Manage. 45:322-333. Johnson, H.B.,H.W. Polly, and H.S. Mayeux. 1993. IncreasingCO2 and plant-plantinteractions: effects on natural vegetation. Vegetatio 104/105:157—170.
Kaufmann, W. 1993. How nature really works. American Forests March/April 1993 p. 17-19. Keddy, P.A. 1992. A pragmatic approach to functional ecology. Func. Ecol. 6:621-626. Laycock, W.A. 1991. Stable states and thresholds of rangeconditionson North Americanrangelands:A viewpoint.J. Range Manage. 44:427-433.
Leonard, S.G., G.J. Staldi, K.A. Gebhardt,and D.E. Prichard. 1992. Viewpoint: Range site/ecological site information requirements for classificationof riverine riparian systems. 45:431 -435. Mooney, H.A. 1991. Biological response to climate change: An agendafor research. Ecol.App. 1:112-117. Nelison, R.P. 1986. High-resolutionclimatic analysisand southwest biogeography.Science 232:27-34. NeUson, R.P. 1967. Biotic regionalization and climatic controls in western North America. Vegetatio70:135-147. Nowak, C.L. 1991. Reconstruction of post-glacial vegetation and climate historyinwesternNevada: Evidencefrom plant macrofossils in Neotomamiddens. M.S. Thesis, Univ. of Nevada, Reno. Policy, H.W., H.B. Johnson, B.D. Marlno, and H.S. Mayeux. 1993. Increasein C3 plantwater-useefficiency and biomassover glacial to presentCO2 concentrations.Nature 361:61—64. Scholes, D.J. 1990. Change in nature and the nature of change: Interactions between terrestrial ecosystemsandtheatmosphere. S. African J. Sci. 86:350-354. Schoonmaker,P.K.,andDR.Foster.1989. Stand-levelforest history incentral NewEnglandinvestigatedby pollenanalysis.Bull. Ecol. Soc. Amer.70:256. References Schoonmaker,P.K., and D.R. Foster. 1991. Some implications of paleoecologyfor contemporaryecology. Bot. Rev. 57:204-244. Anderson, P.M.,P.J. Bartlein, L.B. Brubaker,K. Gajeuski, and J.C. Smiley, T.H., R.A. Bryson, J.E. King, G.J. Kukia, and G.l. Smith. Ritchle.1989. Modernanaloguesoflate Quaternarypollenspectra 1991. Quaternarypaleoclimates,p. 13-44. In: R.B. Morrison (ed.), from the western interior of North America. J. Biogeography Quaternary Nonglacial Geology: ConterminousU.S. Geol. Soc. 16:573-596. Amer., Boulder, Cob. Benson,LV. 1991.Timing ofthe lasthighstandof LakeLahontan.J. Tausch, R.J., P.E. Wlgand, and J.W. Burkhardt. 1993. Viewpoint: Paleolimnology5:115-126. Plant community thresholds, multiple study states, and multiple Betancourt,J.L., TA. VanDevender, and P.S. Martin. 1990. Packrat successionalpathways;legacyofthe Quaternary?.J. Range Manmiddens: The last 40,000 years of biotic change. Univ. of Ariz. age. 46:439-447. Press, Tucson. Taylor, K.C., G.W. Lamorey, G.A. Doyle, R.B. Alley, P.M. Grootes, BIllings, W.D. 1990. Bromus tectorum, a bioticcauseofecosystem P.A. Mayewaki, J.W.C. White, andL.K.Barlow.1993. The flickering impoverishmentin the Great Basin.p.30l-322.In:G.M.Woodwell switch of late Pleistoceneclimate change.Nature 361:432-436. (ed.) The Earth in Transition: Patterns and Processes of Biotic Thompson,R.S.,L. Benson. and E.M.Hattore. 1986. A revised chroImpoverisement.Cambridge Univ. Press, N.Y. nology for thelast Pleistocenelake cycle in the central Lahontan Bosch, O.J.H., and J. Booysen. 1992. An integrative approach to Basin.Quat. Res. 25:1-10. rangelandcondition andcapability assessment. J.RangeManage. Webb, T., iii. 1987. The appearanceand disappearanceof major 45:116—122. vegetational assemblages: Long term vegetational dynamics in Box,T.W. 1992. Rangelands,desertification,and Clements'ghost, a eastern North America. Vegetatio69:177-187. viewpoint paper. Rangelands14:329-331. Webb, T., III. 1991. The spectrum of temporal climatic variability: Conkle, M.T. 1992. Genetic diversity—seeingtheforest through the Currentestimatesandthe needforglobal and regionaltimeseries, trees. New Forests6:5-22. p. 61-81. In: R.S. Bradely (ed.),Global Changesofthe Past. UniDavIs, MB. 1986. Climatic instability, time lags, and community versity Corp. for Atmos. Res., Office of Interdisciplinary Earth disequilibrium, p. 269-284. In: J. Diamond and T.J. Case (eds.). Studies, Boulder, Cob. Community Ecology. Harper and Row, N.Y. N.E. 1983. Great Basin-Colorado Plateau sagebrush semiWest, Eddy,J.A.,and R.S. Bradley.1991. Sciencecapsule,UniversityCordesert, p. 331 -349. In: N.E. West (ed.) Temperate Deserts and for poration Atmospheric Research, Office of Interdisciplinary Semi-Deserts.ElsevierSci. Pub. Co., N.Y. Earth Studies. Earth Quest5(1): supplement. West, N.E. 1993. Biodiversity on rangelands. J. Range Manage. Frledel,M.H. 1991. Rangecondition assessment and the concept of 46:2-13. thresholds:A viewpoint. J. Range Manage. 44:422-426. Westoby,M., B. Walker,and I. Noy-Meier.1989. Opportunistic manJ.R. and W.J. Clawson. 1992. of Brown, George, M.R., Application agement for rangelands not at equilibrium. J. Range Manage. nonequilibrium ecology to managementof Mediterrean grass42:266-274. lands.J. Range Manage. 45:436-440.
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Winograd, I.J., TB. Coplen, J.M. Landwehr,A.C. Riggs, K.R. Ludwig,B.J. Szabo,P.1. Kolesar, andKM. Revesz. 1992. Continuous 500,000 year climate record from vein calcite in Devils, Hole, Nevada. Science258:255—260.
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Young, J.A., R.E. Eckert,Jr., and R.A. Evans.1978. Historical perspectives regarding the sagebrush ecosystem, p. 1-13. In: Anonymous (ed.), The Sagebrush Ecosystem:A Symposium. Utah State Univ.,College Natur. Res., Logan. Young, J.A., R.A. Evans,RE. Eckert Jr., andB.L. Kay. 1987. Cheatgrass. Rangelands 9:266-270.
Frasier's Philosophy in recent months I have had several people express concernabout the costs associatedwith theSociety's two journals, the Journal ofRange Management and Rangelands. The concerns are from both sides of the issue— how muchit costsan authorto publishan article, primarilywith respect totheJournalofRange Management, and should the membership dues be used to "subsidize"the publications,especiallyRangelands. With respect to page charges, specifically in the Journal of Range Management, there are several scientific publicationsthat do not assesstheauthorspage charges for publication.They use other sources—dues, subscriptions, etc.—topay the costs of their publications.Some people have used this criterion as the reason to publish their materialelsewhere. It is the authors'prerogative to select the outlet for their material. At the same time we (the Journal of Range Management) have developed a scientific credibilityto a point that some authorsare statingthattheJRMaudienceis the onetheywishto address. In the current economic times when a research project frequently coststensof thousandsof dollars to conduct, thefew hundred dollarsto publishin the JournalofRange Management maybea minor componentof thetotal cost. There Is also the statementthat "I wish I didn't haveto receive the JournalofRange Management. It is too technical and I don't read it." We must remember that the Societyfor Range Management was formedto provide a professional organizationto "...insurethe best management of our range resources." ('Our Range Society' by Joseph F. Pechanec, JournalofRange Management, Vol. 1, No. 1, Oct 1948; Rangelands Vol 15, No. 3, Jun 1993).
Our respect as protessionals is entirely based on me scientificcredibilityofthe informationwe usetomake our management decisions. Today, the Journal of Range Management is a scientificallycrediblejournal.When our Societyofficers make a statement about properresource management, thevalidity for the statements is frequently based on information published in the Journal of Range Management. Without a scientific background, the statements are opinions. When you receive the Journal of Range Management as a part of your membership, you have in your possession the scientific proof with which "you" can provide information to others on proper resource management. WIth respect tothe question "Shouldmembership dues be usedtosupportthepublications?", itall dependsupon what you want out of the Society. If we had no publications, many members wouldgetnothingfortheir"bucks." Rangelands is a means for gettingtechnical information to the readers who "do not understand"the Journal of Range Management. Rangelands provides information on the history of our great rangeland resources and the people who made it what it is (good or bad). Rangelands is a forum for expressing ideasand thoughts on the past, current, and future management of the rangeland resources. Is all of this worth a portion of your dues? This is for everyone to decide for themselves. When you are making a success ofsomething, it's not work.It'sa wayoflife. Youenjoyyourselfbecause youare makingyour contributionto the world—AndyGranatelli
