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Using fire regimes to delineate zones in a high-resolution lake sediment record from the western United States

Published online by Cambridge University Press:  20 January 2017

Jesse L. Morris ,
Andrea Brunelle ,
R. Justin DeRose ,
Heikki Seppä ,
Mitchell J. Power ,
Vachel Carter  and
Ryan Bares
Jesse L. Morris*
Affiliation:
Department of Geosciences and Geography, University of Helsinki, 00014 Helsinki, Finland
Andrea Brunelle
Affiliation:
Department of Geography, University of Utah, Salt Lake City, UT 84112, USA
R. Justin DeRose
Affiliation:
USDA Forest Service, Forest Inventory Analysis, Rocky Mountain Research Station, Ogden, UT 84401, USA
Heikki Seppä
Affiliation:
Department of Geosciences and Geography, University of Helsinki, 00014 Helsinki, Finland
Mitchell J. Power
Affiliation:
Department of Geography, University of Utah, Salt Lake City, UT 84112, USA Utah Museum of Natural History, Garrett Herbarium, University of Utah, Salt Lake City, UT 84112, USA
Vachel Carter
Affiliation:
Department of Geography, University of Utah, Salt Lake City, UT 84112, USA
Ryan Bares
Affiliation:
Department of Geography, University of Utah, Salt Lake City, UT 84112, USA
*
*Corresponding author. E-mail address:jesse.morris@helsinki.fi (J.L. Morris).
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Abstract

Paleoenvironmental reconstructions are important for understanding the influence of long-term climate variability on ecosystems and landscape disturbance dynamics. In this paper we explore the linkages among past climate, vegetation, and fire regimes using a high-resolution pollen and charcoal reconstruction from Morris Pond located on the Markagunt Plateau in southwestern Utah, USA. A regime shift detection algorithm was applied to background charcoal accumulation to define where statistically significant shifts in fire regimes occurred. The early Holocene was characterized by greater amounts of summer precipitation and less winter precipitation than modern. Ample forest fuel and warm summer temperatures allowed for large fires to occur. The middle Holocene was a transitional period between vegetation conditions and fire disturbance. The late Holocene climate is characterized as cool and wet reflecting an increase in snow cover, which reduced opportunities for fire despite increased availability of fuels. Similarities between modern forest fuel availability and those of the early Holocene suggest that warmer summers projected for the 21st century may yield substantial increases in the recurrence and ecological impacts of fire when compared to the fire regime of the last millennium.

Keywords

CharcoalFire regimeFire seasonForest disturbanceLake sedimentsPollenPaleoecologyRegime shiftSpruce-fir forestWildfire
Type
Research Article
Information
Quaternary Research , Volume 79 , Issue 1 , January 2013 , pp. 24 - 36
Copyright
University of Washington

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References

Adams, D.K., and Comrie, A.C. The North American Monsoon. Bulletin of the American Meteorological Society 78, (1997). 2197–2213.2.0.CO;2>CrossRefGoogle Scholar
Ali, A.A., Higuera, P.E., Bergeron, Y., and Carcaillet, C. Comparing fire-history interpretations based on area, number and estimated volume of macroscopic charcoal in lake sediments. Quaternary Research 72, (2009). 462–486.Google Scholar
Alley, R.B., and Ágústsdóttir, A.M. The 8k event: cause and consequences of a major Holocene abrupt climate change. Quaternary Science Reviews 24, (2005). 1123–1149.CrossRefGoogle Scholar
Anderson, L.A. Holocene record of precipitation seasonality from lake calcite δ18O in the central Rocky Mountains, United States. Geology 39, (2011). 211–214.CrossRefGoogle Scholar
Anderson, L.A. Rocky Mountain hydroclimate: Holocene variability and the role of insolation, ENSO, and the North American Monsoon. Global and Planetary Change 92–93, (2012). 198–208.CrossRefGoogle Scholar
Anderson, R.S., Hasbargen, J., Koehler, P.A., and Feiler, E.J. Late Wisconsin and Holocene subalpine forests of the Markagunt Plateau of Utah, southwest Colorado Plateau, USA. Arctic, Antarctic, and Alpine Research 31, (1999). 366–378.Google Scholar
Anderson, R.S., Betancourt, J.L., Mead, J.I., Hevly, R.H., and Adam, D.P. Middle- and late-Wisconsin paleobotanic and paleoclimatic records from the southern Colorado Plateau, USA. Palaeogeography, Palaeoclimatology, Palaeoecology 155, (2000). 31–57.Google Scholar
Appleby, P.G., Oldfield, F., Thompson, R., Huttunen, P., and Tolonen, K. 210Pb dating of annually laminated lake sediments from Finland. Nature 280, (1979). 53–55.CrossRefGoogle Scholar
Arno, S.F., and Hammerly, R.P. Timberline: Mountain and Arctic Forest Frontiers. (1984). The Mountaineers, Seattle.Google Scholar
Bartlein, P.J., Anderson, K.H., Anderson, P.M., Edwards, M.E., Mock, C.J., Thompson, R.S., Webb, R.S., Webb, T. III, and Whitlock, C. Paleoclimate simulations for North America over the past 21,000 years: features of the simulated climate and comparisons with paleoenvironmental data. Quaternary Science Reviews 17, (1998). 549–585.Google Scholar
Bassett, I.J., Crompton, C.W., and Parmlee, J.A. An Atlas of Airborne Pollen Grains and Common Fungal Spores. (1978). Biosystematics Research Institute, Ottawa.Google Scholar
Bennett, K.D. Determination of the number of zones in a biostratigraphical sequence. New Phytologist 132, (1996). 155–170.Google Scholar
Berger, A., and Loutre, M.F. Insolation values for the climate of the last 10 million years. Quaternary Science Reviews 10, (1991). 297–317.Google Scholar
Biondi, F., Gershunov, A., and Cayan, D. North Pacific decadal climate variability since 1661. Journal of Climate 14, (2001). 5–10.Google Scholar
Braconnot, P., Otto-Bliesner, B., Harrison, S., Joussaume, S., Peterchmitt, J.-Y., Abe-Ouchi, A., Crucifix, M., Driesschaert, E., Fichefet, T., Hewitt, C.D., Kageyama, M., Kitoh, A., Laıne, A., Loutre, M.F., Marti, O., Merkel, U., Ramstein, G., Valdes, P., Weber, S.L., Yu, Y., and Zhao, Y. Results of PMIP2 coupled simulations of the Mid-Holocene and Last Glacial Maximum — parts 1 and 2: experiments and large-scale features. Feedbacks with emphasis on the location of the ITCZ and mid- and high latitudes heat budget. Climate of the Past 3, (2007). 261–296.Google Scholar
Brown, P.M., Heyerdahl, E.K., Kitchen, S.G., and Weber, M.H. Climate effects on historical fires (1630–1900) in Utah. International Journal of Wildland Fire 17, (2008). 28–39.Google Scholar
Brunelle, A.R., Rehfeldt, J., Bentz, B.J., and Munson, A.S. Holocene records of mountain pine beetle infestation in the U.S. Northern Rocky Mountains. Forest Ecology and Management 255, (2008). 836–846.CrossRefGoogle Scholar
Cable, D.R. Soil water changes in the creosote bush and bursage during a dry period in southern Arizona. Journal of the Arizona Academy of Science 12, (1977). 15–20.CrossRefGoogle Scholar
Clark, J.S. Particle motion and the theory of charcoal analysis: source area, transport, deposition, and sampling. Quaternary Research 30, (1988). 67–80.CrossRefGoogle Scholar
Conedera, M., Tinner, W., Neff, C., Meurer, M., Dickens, A.F., and Kerbs, P. Reconstructing past fire regimes: methods, applications, and relevance to fire management and conservation. Quaternary Science Reviews 28, (2009). 555–576.Google Scholar
Conroy, J.L., Overpeck, J.T., Cole, J.E., Shanahan, T.M., and Steinitz-Kannan, M. Holocene changes in eastern tropical Pacific climate inferred from a Galápagos lake sediment record. Quaternary Science Reviews 27, (2008). 1166–1180.CrossRefGoogle Scholar
Davis, O.K. Caves as sources of biotic remains in arid western North America. Palaeogeography, Palaeoclimatology, Palaeoecology 76, (1990). 331–348.Google Scholar
Davis, O.K., and Pitblado, B.L. Late glacial aridity in the Southern Rocky Mountains. Waugh, W.J., Petersen, K.L., Wigand, P.E., Louthan, B.D., and Walker, R.D. Climate Change in the Four Corners and Adjacent Regions: Implications for Environmental Restoration and Land-use Planning. (1995). USDOE: CONF-9409325, Springfield, 9–23.Google Scholar
Dean, W.E. Determination of carbonate and organic matter in calcerous sediments by loss on ignition comparison to other methods. Journal of Sedimentary Petrology 44, (1974). 242–248.Google Scholar
DeRose, R.J., and Long, J.N. Disturbance, structure, and composition: spruce beetle and Engelmann spruce forests on the Markagunt Plateau, Utah. Forest Ecology and Management 244, (2007). 16–23.CrossRefGoogle Scholar
DeRose, R.J., and Long, J.N. Drought driven disturbance history characterizes a southern Rocky Mountain subalpine forest. Canadian Journal of Forest Research 42, (2012). 1649–1660.Google Scholar
Diffenbaugh, N.S., Ashfaq, M., Shuman, B., Williams, J.W., and Bartlein, P.J. Summer aridity in the United States: response to mid-Holocene changes in insolation and sea surface temperature. Geophysical Research Letters 33, (2006). http://dx.doi.org/10.1029/2006GL028012CrossRefGoogle Scholar
Ely, L. Response of extreme floods in the southwestern United States to climatic variations in the late Holocene. Geomorphology 19, (1997). 175–201.Google Scholar
Erdtman, G. Pollen Morphology and Plant Taxonomy: Angiosperms. (1952). Almqvist and Wiksell, Stockholm.Google Scholar
Fægri, K., Kaland, P.E., and Kzywinski, K. Textbook of Pollen Analysis. (1989). John Wiley and Sons, New York.Google Scholar
Falk, D.A., and Swetnam, T.W. Scaling rules and probability models for surface fire regimes in ponderosa pine forests. USDA Forest Service Proceedings RMRSP 29, (2003). 301–318.Google Scholar
Fall, P.L. Timberline fluctuations and late Quaternary paleoclimates in the southern Rocky Mountains, Colorado. Geological Society of America Bulletin 109, (1997). 1306–1320.2.3.CO;2>CrossRefGoogle Scholar
Feiler, E.J., Anderson, R.S., and Koehler, P.A. Late Quaternary paleoenvironments of the White River Plateau, Colorado, USA. Arctic and Alpine Research 29, (1997). 53–62.CrossRefGoogle Scholar
Ford, D.C., and Williams, P.W. Karst Geomorphology and Hydrology. (2007). John Wiley and Sons, New York.Google Scholar
Gardner, J.J., and Whitlock, C. Charcoal accumulation following a recent fire in the Cascade Range, northwestern USA, and its relevance for fire-history studies. The Holocene 11, (2001). 541–549.Google Scholar
Gavin, D.G., Hu, F.S., Lertzman, K., and Corbett, P. Weak climatic control of stand-scale fire history during the Late Holocene in southeastern British Columbia. Ecology 87, (2006). 1722–1732.Google Scholar
Gedye, S.J., Jones, R.T., Tinner, W., Ammann, B., and Oldfield, F. The use of mineral magnetisms in the reconstruction of fire history: a case study from Lago di Origlio, Swiss Alps. Palaeogeography, Palaeoclimatology, Palaeoecology 164, (2000). 101–110.Google Scholar
Goldstrand, P.M. Tectonic development of Upper Cretaceous to Eocene strata of southwestern Utah. Geological Society of America Bulletin 106, (1994). 145–154.Google Scholar
Gregory, H.E. Geologic and geographic reconnaissance of eastern Markagunt Plateau, Utah. Geological Society of America Bulletin 60, (1949). 969–997.Google Scholar
Grimm, E.C. CONNISS: a FORTRAN 77 programme for stratigraphically constrained cluster analysis by the method of incremental sum of squares. Computers and Geoscience 13, (1987). 13–35.Google Scholar
Hall, M. Repairing mountains: restoration, ecology and wilderness in twentieth-century Utah. Environmental History 6, (2001). 574–600.Google Scholar
Harden, T., Macklin, M.G., and Baker, V.R. Holocene flood histories in south-western USA. Earth Surface Processes and Landforms 35, (2010). 707–716.CrossRefGoogle Scholar
Herzschuh, U. Reliability of pollen ratios for environmental reconstructions on the Tibetan Plateau. Journal of Biogeography 34, (2007). 1265–1273.CrossRefGoogle Scholar
Higuera, P.E., Whitlock, C., and Gage, J.A. Linking tree-ring and sediment-charcoal records to reconstruct fire occurrence and area burned in subalpine forests of Yellowstone National Park, USA. The Holocene 21, (2011). http://dx.doi.org/10.1177/0959683610374882Google Scholar
Higuera, P.E., Peters, M.E., Brubaker, L.B., and Gavin, D.G. Understanding the origin and analysis of sediment-charcoal records with a simulation model. Quaternary Science Reviews 26, (2007). 1790–1809.Google Scholar
Higuera, P.E., Brubaker, L.B., Anderson, P.M., Hu, F.S., and Brown, T.A. Vegetation mediated the impacts of postglacial climatic change on fire regimes in the south-central Brooks Range, Alaska. Ecological Monographs 79, (2009). 201–219.Google Scholar
Higuera, P.E., Gavin, D.G., Bartlein, P.J., and Hallett, D.J. Peak detection in sediment-charcoal records: impacts of alternative data analysis methods on fire-history interpretations. International Journal of Wildland Fire 19, (2010). 996–1014.Google Scholar
Kapp, R.O., Davis, O.K., and King, J.E. Pollen and Spores. 2nd ed. (2000). American Association of Stratigraphic Palynologists, New York.Google Scholar
Knight, T.A., Meko, D.M., and Baisan, C.H. A bimillennial-length tree-ring reconstruction of precipitation for the Tavaputs Plateau, northeastern Utah. Quaternary Research (2010). http://dx.doi.org/10.1016/j.yqres.2009.08.002Google Scholar
Long, C.J., Whitlock, C., Bartlein, P.J., and Millspaugh, S.H. A 9000-year fire history from the Oregon Coast Range, based on a high-resolution charcoal study. Canadian Journal of Forest Research 28, (1998). 774–787.Google Scholar
Lundeen, Z., (2012). Paleoecological and Isotopic Records of Climate Change and Variability, Bear River Range, Southeast Idaho. Ph.D. Dissertation, University of Utah, .Google Scholar
Lynch, J.A., Hollis, J.L., and Hu, F.S. Climatic and landscape controls of the boreal fire regime: Holocene records from Alaska. Journal of Ecology 92, (2004). 477–489.Google Scholar
Madsen, D.B., Elias, S.A., Weng, C., Jackson, S.T., Thompson, R.S., and Rhode, D. The Paleoecology of Red Valley Bog, Markagunt Plateau, Utah. Utah Geological Survey Technical Report. (2002). Google Scholar
Maher, L.J. Pollen analyses of surface materials from the southern San Juan Mountains, Colorado. GSA Bulletin 74, (1963). 1485–1504.Google Scholar
Mantua, N.J., Hare, S.R., Zhang, Y., Wallace, J.M., and Francis, R.C. A Pacific interdecadal oscillation with impacts on salmon production. Bulletin of the American Meteorological Society 78, (1997). 1069–1079.2.0.CO;2>CrossRefGoogle Scholar
Marlon, J., Bartlein, P.J., and Whitlock, C. Fire–fuel–climate linkages in the northwestern USA during the Holocene. The Holocene 16, (2006). 1059–1071.Google Scholar
Marlon, J.R., Bartlein, P.J., Carcaillet, C., Gavin, D.G., Harrison, S.P., Higuera, P.E., Joos, F., Power, M.J., and Prentice, I.C. Climate and human influences on global biomass burning over the past two millennia. Nature Geoscience (2008). http://dx.doi.org/10.1038/ngeo313Google Scholar
McCabe, G.J., and Dettinger, M.D. Decadal variations in the strength of ENSO teleconnections with precipitation in the western United States. International Journal of Climatology 19, (1999). 1399–1410.Google Scholar
Mensing, S.A., Benson, L.V., Kashgarian, M., and Lund, S. A Holocene pollen record of persistent droughts from Pyramid Lake, Nevada, USA. Quaternary Research 62, (2004). 29–38.Google Scholar
Mock, C.J. Climate controls and spatial variations of precipitation in the western United States. Journal of Climate 9, (1996). 1111–1125.Google Scholar
Mock, C.J., and Brunelle-Daines, A. A modern analogue of western United States summer paleoclimate at 6000 years before present. The Holocene 9, (1999). 541–545.Google Scholar
Morris, J.L., (2011). Historic and Holocene forest disturbance in south central Utah. Ph.D. Dissertation, University of Utah, .Google Scholar
Morris, J.L., and Brunelle, A. Pollen records of historic spruce beetle (Dendroctonus rufipennis) disturbance from the subalpine ranges of southern Utah, USA. The Holocene (2012). http://dx.doi.org/10.1177/0959683612437870CrossRefGoogle Scholar
Morris, J.L., Brunelle, A., and Munson, A.S. Pollen evidence of historical forest disturbance on the Wasatch Plateau, Utah. Western North American Naturalist 70, (2010). 175–188.CrossRefGoogle Scholar
Moy, C.M., Selzer, G.O., Rodbell, D.T., and Anderson, D.M. Variability of El Niño/Southern Oscillation activity at millennial timescales during the Holocene epoch. Nature 420, (2002). 162–165.Google Scholar
Mulvey, W.E., Currey, D.R., and Lindsay, L.M.W. Southernmost occurrence of later Pleistocene glaciation in Utah: Brian Head-Sidney Peaks area, Markagunt Plateau. Encyclia 61, (1984). 97–101.Google Scholar
Notaro, M., and Zarrin, A. Sensitivity of the North American monsoon to antecedent Rocky Mountain snowpack. Geophysical Research Letters 38, (2011). http://dx.doi.org/10.1029/2011GL048803CrossRefGoogle Scholar
Ohlson, M., Brown, K.J., Birks, H.J.B., Grytnes, J.A., Hörnberg, G., Niklasson, M., Seppä, H., and Bradshaw, R.H.W. Invasion of Norway spruce diversifies the fire regime in European forests. Journal of Ecology 99, (2011). 395–403.Google Scholar
Peet, R.K. Forest vegetation of the Colorado Front Range: composition and dynamics. Vegetatio 45, (1981). 3–75.Google Scholar
Power, M.J., 84 co authors, Changes in fire regime since the Last Glacial Maximum: an assessment based on a global synthesis and analysis of charcoal data. Climate Dynamics 30, (2008). 887–907.Google Scholar
Power, M.J., Marlon, J.R., Bartlein, P.J., and Harrison, S. Fire history and the global charcoal database: a new tool for hypothesis testing and data exploration. Palaeogeography, Palaeoclimatology, Palaeoecology 291, (2010). 52–59.Google Scholar
Power, M.J., Mayle, F.E., Bartlein, P.J., Marlon, J.R., Anderson, R.S., Behling, H., Brown, K.J., Carcaillet, C., Colomboroli, D., Gavin, D.G., Hallett, D.J., Horn, S.P., Kennedy, L.M., Lane, C.S., Long, C.J., Moreno, P.I., Paitre, C., Robinson, G., Taylor, Z., and Walsh, M.K. Climatic control of the biomass-burning decline in the Americas after A.D. The Holocene 1500, (2012). http://dx.doi.org/10.1177/0959683612450196Google Scholar
Raffa, K.F., Aukema, B.H., Bentz, B.J., Carroll, A.L., Hicke, J.A., Turner, M.G., and Romme, W.H. Cross-scale drivers of natural disturbances prone to anthropogenic amplification: the dynamics of bark beetle eruptions. Bioscience 58, (2008). 501–517.Google Scholar
Reimer, P.J., Baillie, M.G.L., Bard, E., Bayliss, A., Beck, J.W., Bertrand, C., Blackwell, P.G., Buck, C.E., Burr, G., Cutler, K.B., Damon, P.E., Edwards, R.L., Fairbanks, R.G., Friedrich, M., Guilderson, T.P., Hughen, K.A., Kromer, B., McCormac, F.G., Manning, S., Bronk Ramsey, C., Reimer, R.W., Remmele, S., Southon, J.R., Stuiver, M., Talamo, S., Taylor, F.W., van der Plicht, J., and Weyhenmeyer, C.E. Intcal09 and Marine09 radiocarbon age calibration curves, 0–50,000 years cal BP. Radiocarbon 51, (2009). 1111–1150.Google Scholar
Reinemann, S.A., Porinchu, D.F., Bloom, A.M., Mark, B.G., and Box, J.E. A multi-proxy paleolimnological reconstruction of Holocene climate conditions in the Great Basin, USA. Quaternary Research 72, (2009). 347–358.Google Scholar
Renssen, H., Seppä, H., Crosta, X., Goosse, H., and Roche, D.M. Global characterization of the Holocene Thermal Maximum. Quaternary Science Reviews 48, (2012). 7–19.Google Scholar
Ritchie, J.C. Current trends in studies of long-term plant community dynamics. New Phytologist 130, (1995). 469–494.Google Scholar
Rodionov, S.N. A sequential algorithm for testing climate regime shifts. Geophysical Research Letters 31, (2004). L09204 http://dx.doi.org/10.1029/2004GL019448Google Scholar
Ropelewski, C.F., and Halpert, M.S. North American precipitation and temperature patterns associated with the El Niño/Southern Oscillation (ENSO). Monthly Weather Reviews 114, (1986). 2352–2362.2.0.CO;2>CrossRefGoogle Scholar
Scheffer, M., Carpenter, S., Foley, J.A., Folkes, C., and Walker, B. Catastrophic shifts in ecosystems. Nature 413, (2001). 591–596.Google Scholar
Schoennagel, T., Veblen, T.T., Romme, W.H., Sibold, J.S., and Cooke, E.R. ENSO and PDO variability affect drought-induced fire occurrence in Rocky Mountain subalpine forests. Ecological Applications 15, (2005). 2000–2014.Google Scholar
Seppä, H., Alenius, T., Muukkonen, P., Giesecke, T., Miller, P.A., and Ojala, A.E.K. Calibrated pollen accumulation rates as a basis for quantitative tree biomass reconstructions. The Holocene 19, (2009). 209–220.Google Scholar
Shafer, D.S., (1989). The timing of late Quaternary monsoon precipitation maxima in the southwest United States. Ph.D. Dissertation, University of Arizona, .Google Scholar
Shuman, B., Henderson, A.K., Colman, S.M., Stone, J.R., Fritz, S.C., Stevens, L.R., Power, M.J., and Whitlock, C. Holocene lake-level trends in the Rocky Mountains, U.S.A. Quaternary Science Reviews 28, (2009). 1861–1879.Google Scholar
Thompson, R.S., Anderson, K.H., and Bartlein, P.J. Atlas of relations between climatic parameters and distributions of important trees and shrubs in North America. USGS Professional Papers 1650a,b. (1999). Google Scholar
Weng, C., and Jackson, S.T. Late Glacial and Holocene vegetation history and paleoclimate of the Kaibab Plateau, Arizona. Palaeogeography, Palaeoclimatology, Palaeoecology 153, (1999). 179–201.Google Scholar
Westerling, A.L., Hidalgo, H.G., Cayan, D.R., and Swetnam, T.W. Warming and earlier spring increase western US fire activity. Science 313, (2006). 940–943.Google Scholar
Whitlock, C., and Larsen, C.P.S. Charcoal as a fire proxy. Smol, J.P., and Birks, H.J.B. Tracking Environmental Change Using Lake Sediments, Vol. 3, Terrestrial, Algal, and Siliceous Indicators. (2001). Kluwer Academic Publishers, Dordrecht. 75–97.Google Scholar
Whitlock, C., and Millspaugh, S.H. Testing the assumptions of fire-history studies: an examination of modern charcoal accumulation in Yellowstone National Park, USA. The Holocene 6, (1996). 7–15.Google Scholar
Whitlock, C., Bartlein, P.J., Marlon, J., Brunelle, A., and Long, C. Holocene fire reconstructions from the northwestern U.S.: an examination at multiple timescales. Fifth Symposium on Fire and Forest Meteorology. American Meteorological Society (2003). Google Scholar
Whitlock, C., Higuera, P.E., McWerthy, D.B., and Briles, C.E. Paleoecological perspectives on fire ecology: revisiting the fire-regime concept. The Open Ecology Journal 3, (2010). 6–23.Google Scholar
Williams, A.P., Allen, C.D., Millar, C.I., Swetnam, T.W., Michaelsen, J., Still, C.J., and Leavitt, S.W. Forest responses to increasing aridity and warmth in the southwestern United States. Proceedings of the North American Academy of Sciences 107, (2010). 211289–221294.Google Scholar
Willis, K.J., and Birks, H.J.B. What is natural? The need for long-term perspective in biodiversity conservation. Science 314, (2006). 1261–1265.Google Scholar
Wilson, M.T., and Thomas, H.E. Hydrology and hydrogeology of Navajo Lake, Kane County, Utah: U.S. Geological Survey Professional Paper 417-C. (1964). (26 pp.)Google Scholar
Wise, E. Spatiotemporal variability of the precipitation dipole transition zone in the western United States. Geophysical Research Letters 37, (2010). http://dx.doi.org/10.1029/2009GL042193Google Scholar
Zhao, Y., and Harrison, S.P. Mid-Holocene monsoons: a multi-model analysis of the inter-hemispheric differences in the responses to orbital forcing and ocean feedbacks. Climate Dynamics (2011). http://dx.doi.org/10.1007/s00382-011-1193-zGoogle Scholar
Zhao, Y., Liu, H., Li, F., Huang, X., Sun, J., Zhao, W., Herzschuh, U., and Yu, T. Application and limitations of the Artemisia/Chenopodiaceae pollen ratio in arid and semi-arid China. The Holocene (2012). http://dx.doi.org/10.1177/0959683612449762Google Scholar