Hostname: page-component-cd9895bd7-dzt6s Total loading time: 0 Render date: 2024-12-23T01:10:46.518Z Has data issue: false hasContentIssue false
  • English
  • Français

Macrofossil Analysis of wood rat (Neotoma) Middens as a Key to the Quaternary Vegetational History of Arid America

Published online by Cambridge University Press:  20 January 2017

Philip V. Wells
Philip V. Wells*
Affiliation:
Departments of Botany and of Systematics and Ecology, University of Kansas, Lawrence, Kansas 66045, USA
Get access Rights & Permissions [Opens in a new window]

Abstract

Wood rat (Neotoma) deposits preserved in dry rock shelters have radiocarbon ages extending from close to the present to >40,000 BP, thus providing elaborate samples of changing vegetation during the climatic shifts of the late Pleistocene and Holocene. The established record extends geographically from Oregon and Wyoming (at 45°N) south to Baja California, Sonora, and to Tehuacan (at 18°N) in southern Mexico. Several hundred ancient middens have been uncovered, and over 130 have been radiocarbon-dated.

There are about 20 extant species of Neotoma with a combined range extending from the Yukon and New England to Nicaragua and Florida. Hence, a wider application for the method seems likely, wherever dry caves favor preservation. The acquisitive rats accumulate an incredibly detailed inventory of the local flora and fauna within a small home range, measured at about 100 m or less in radius. The biomass spectrum of a modern wood rat deposit was compared with associated pollen spectra and source vegetation. The most dominant arborescent species, as determined by a quantitative study of the local vegetation, were proportionately represented in the midden, but not in the pollen rain. Less dominant species were variable in proportionality.

A novel approach to the comparative ecological physiology of long-dead plants has been demonstrated with macrofossils from ancient wood rat deposits. The ratio of the stable isotopes of carbon (13C/12C) is more altered from the atmospheric proportion during CO2 fixation by C3 plants than it is by the different (PEP) carboxylating enzyme of heliophile or xerophytic, C4 or CAM plants. Mass spectrometry of the carbon of macrofossils enables the distinction to be made in the past.

The desiccated, allelochemic urine, or amberat, indurates and preserves the middens by cementing the loose debris of macrofossils into a tough, coherent mass of surprising strength and rigidity, that adheres tenaciously to rock surfaces. Water softens the most indurated middens by dissolving the crystallized urine, causing them to dislodge and to fall apart; it also removes the osmotic and allelochemic deterrent to decay by fungi, or to consumption by termites, crickets, or other decomposing herbivores. A secure position in a dry rock shelter is therefore essential to preservation of the macrofossils for time periods on the order of 104 years. Attrition with time is seen in the frequency distribution of radiocarbon dates obtained on 132 Neotoma middens. The distribution is skewed toward the end of the Wisconsin glacial and the Holocene, and there is a decline in frequency with age. Cave erosion, including destructive rockfalls and new crevices that admit seepage and cause deterioration and dislodgement of the middens, is probably the main factor in the progressive attrition with increasing age.

Type
Research Article
Information
Quaternary Research , Volume 6 , Issue 2 , June 1976 , pp. 223 - 248
Copyright
University of Washington

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Bender, M.M., (1968). Mass spectrometric studies of Carbon 13 variations in corn and other grasses. Radiocarbon 10 468–472.Google Scholar
Björkman, O., Berry, J., (1973). High efficiency photosynthesis. Scientific American 229 80–93.CrossRefGoogle Scholar
Bonaccorso, F.J., Brown, J.H., (1972). House construction of the desert wood rat, Neotoma lepida lepida. Journal of Mammalogy 53 283–288.Google Scholar
Byers, D.S., (1967) “The Prehistory of the Tehuacan Valley,” Vol. I, Environment and Subsistence University of Texas Press Austin .Google Scholar
Cameron, G.N., Rainey, D.G., (1972). Habitat utilization by Neotoma lepida in the Mohave Desert. Journal of Mammalogy 53 251–266.CrossRefGoogle Scholar
Fergusson, G.J., Libby, W.F., (1962). UCLA radiocarbon dates. I. Radiocarbon 4 109–114.Google Scholar
Fergusson, G.J., Libby, W.F., (1964). UCLA radiocarbon dates. III. Radiocarbon 6 318–339.Google Scholar
Finley, R.B., (1958). The wood rats of Colorado: distribution and ecology. University of Kansas Publications, Museum of Natural History 10 213–552.Google Scholar
Gehlbach, F.R., (1967). Vegetation of the Guadalupe Escarpment, New Mexico-Texas. Ecology 48 404–419.Google Scholar
Hall, E.R., Genoways, H.H., (1970). Taxonomy of the Neotoma albigula group of wood rats in central Mexico. Journal of Mammalogy 51 504–516.Google Scholar
Hall, E.R., Kelson, K.R., (1959). The Mammals of North America. Ronald Press New York 2 volumes.Google Scholar
Hatch, M.D., Osmond, C.B., Slatyer, R.A., (1971). Photosynthesis and Photorespiration. Wiley New York .Google Scholar
King, J.E., Van Devender, T., (1976). Pollen analysis of fossil packrat middens from the Sonoran Desert. Quaternary Research .Google Scholar
Leskinen, P.H., (1970). Late Pleistocene Vegetation Change in the Christman Tree Pass Area, Newberry, Mountains, Nevada. M.S. thesis Department of Geography, University of Arizona Tucson .Google Scholar
Linsdale, M.J., Tevis, L.P. Jr., (1951). The Dusky-footed Wood Rat. University of California Press Berkeley/Los Angeles .Google Scholar
Long, A., Hansen, R.M., Martin, P.S., (1974). Extinction of the Shasta ground sloth. Geological Society of America Bulletin 85 1843–1848.Google Scholar
Long, A., Martin, P.S., (1974). Death of American ground sloths. Science 186 638–640.Google Scholar
Madsen, D.B., (1973). Late Quaternary Paleoecology in the Southeastern Great Basin. Ph.D. dissertation University of Missouri Columbia .Google Scholar
Mehringer, P.J., (1969). Isotopes' radiocarbon measurements. VII. Radiocarbon 11 53–105.Google Scholar
Mehringer, P.J., Ferguson, C.W., (1969). Pluvial Occurrence of Bristlecone Pine (Pinus aristata) in a Mohave Desert Mountain Range. Department of Geochronology Interim Research Report 14 University of Arizona 1–16.Google Scholar
Oosting, H.J., (1942). An ecological analysis of the plant communities of Piedmont, North Carolina. American Midland Naturalist 28 1–126.CrossRefGoogle Scholar
Orr, P.C., (1957). On the occurrence and nature of “amberat”. Observations, Western Speleological Institute 2 1–3.Google Scholar
Phillips, A.M., Van Devender, T.R., (1974). Pleistocene packrat middens from the lower Grand Canyon of Arizona. Journal, Arizona Academy of Science 9 117–119.CrossRefGoogle Scholar
Rainey, D.G., (1956). Eastern wood rat, Neotoma floridana: life history and ecology. University of Kansas Publications, Museum of Natural History 8 535–646.Google Scholar
Rice, E.L., (1974). Allelopathy. Academic Press New York .Google Scholar
Stebbins, G.L., (1975). The role of polyploid complexes in the evolution of North American grasslands. Taxon 24 91–106.Google Scholar
Stones, R.C., Hayward, C.L., (1968). Natural history of the desert wood rat, Neotoma lepida. American Midland Naturalist 80 458–476.Google Scholar
Troughton, J.H., Wells, P.V., Mooney, H.A., (1974). Photosynthetic mechanisms and paleoecology from carbon isotope ratios in ancient specimens of C4 and CAM plants. Science 185 610–612.Google Scholar
Van Devender, T.R., (1973). Late Pleistocene Plants and Animals of the Sonoran Desert: A Survey of Ancient Packrat Middens in South-western Arizona. Ph.D. dissertation University of Arizona Tucson .Google Scholar
Van Devender, T.R., King, J.E., (1971). Late Pleistocene vegetational records in western Arizona. Journal, Arizona Academy of Science 6 240–244.CrossRefGoogle Scholar
Vorhies, C.T., Taylor, W.P., (1940). Life history and ecology of the white-throated wood-rat, Neotoma albigula Hartley, in relation to grazing in Arizona. University of Arizona, College of Agriculture Technical Bulletin 86 455–529.Google Scholar
Wells, P.V., (1961). An investigation of vegetational and climatic change in the Mohave Desert by means of plant remains preserved in subfossil packrat middens. Unpublished research proposal to the National Science Foundation, September 14, 1961.Google Scholar
Wells, P.V., (1966). Late Pleistocene vegetation and degree of pluvial climatic change in the Chihuahuan Desert. Science 153 970–975.Google Scholar
Wells, P.V., (1969). Preuves paléontologiques d'une végétation tardi-Pleistocène (datée par le 14C) dans les régions aujourd'hui désertiques d'Amérique du Nord. Revue de Géographie Physique et de Géologie Dynamique 11 335–340.Google Scholar
Wells, P.V., (1970a). Postglacial vegetational history of the Great Plains. Science 167 1574–1582.Google Scholar
Wells, P.V., (1970b). Historical factors controlling vegetational patterns and floristic distributions in the Central Plains region of North America. Dort, W., Jones, J.K. Pleistocene and Recent Environments of the Central Great Plains University of Kansas Press Lawrence 211–221.Google Scholar
Wells, P.V., (1976). Postglacial origin of the Chihuahuan Desert less than 11,500 years ago. Wauer, R.H., Riskind, D.H. Symposium on the Biological Resources of the Chihuahuan Desert Region U.S. Govt. Printing Office Washington, D.C .Google Scholar
Wells, P.V., Berger, R., (1967). Late Pleistocene history of coniferous woodland in the Mohave Desert. Science 155 1640–1647.CrossRefGoogle ScholarPubMed
Wells, P.V., Jorgensen, C.D., (1964). Pleistocene wood rat middens and climatic change in Mohave Desert: A record of juniper woodlands. Science 143 1171–1174.CrossRefGoogle Scholar
Whittaker, R.H., Feeny, P.P., (1971). Allelochemics: chemical interactions between species. Science 171 757–770.Google Scholar