Biogeography of the Pleistocene

Deevey, Edward S.

doi:10.1130/0016-7606(1949)60[1315:botp]2.0.co;2

Cited by 161 publications

(77 citation statements)

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“…The conventional wisdom, which we here dispute, is that tundra and boreal forest extended well south of the ice sheets and that the deciduous forest of the East retreated to the coastal plain, to Florida, and westward into Texas and Mexico (Davis, 1984;Delcourt, 1984, 1993;Deevey, 1949;Jacobson et al, 1987;Royal1 et al, 1991, Watts, 1970, 1979, 1980a. Our contention, which we will attempt to document, is that the boreal zone was narrow and that southward movement of the deciduous forest was minimal.…”

Section: Introductionmentioning

confidence: 62%

“…The data supporting this scenario were substantial by the 1950s. In the 1940s to 1960s, very little paleontologial data existed for North America, but several workers nevertheless drew maps of LGM vegetation (e.g., Deevey, 1949) showing tundra and boreal forest in a wide belt extending to central Georgia, with ice covering the peaks of the Appalachians and the deciduous forest relegated to refugia in Florida and Mexico (e.g., Figures 1 and 2). Since the temperate climate of Europe is due to the Gulf Stream, which was probably deflected during glacial episodes, there is good reason a priori for suspecting that the European and North American situations need not have been analogous.…”

Section: Our Contention Is That the Dominant Reconstructions Of Lgm Vmentioning

confidence: 99%

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The Pleistocene biogeography of eastern North America: A nonmigration scenario for deciduous forest

Loehle¹,

Iltis²

1998

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8ECFIVEDThe current reconstruction of the vegetation of eastern North America at the last glacial maximum postulates a very wide zone of tundra and boreal forest south of the ice. This reconstruction requires that the deciduous forest retreated far to the south. We believe that this reconstruction is seriously in error. Geologic evidence for glacial activity or tundra is absent from the southern Appalachians. Positive evidence for boreal forest is based on pollen identifications for Picea, Betula, and Pinus, when in reality southern members of these genera have pollen that cannot be distinguished from that of northern members. Further, pollen of typical southern species such as oaks and hickories occurs throughout profiles that past authors had labeled boreal. Pollen evidence for a far southern deciduous forest refuge is lacking. Data on endemics are particularly challenging for the scenario in which deciduous forest migrated to the south and back. The southern Appalachian region is rife with endemics that are often extreme-habitat specialists unable to migrate. The previously glaciated zone is almost completely lacking in endemics. Outlier populations, range boundaries, and absence of certain hybrids all argue against a large boreal zone. Our new reconstruction postulates a cold zone no more than 75-100 miles wide south of the ice in the East. South of this cold zone, the drop in temperature may have shifted species abundances but was not sufficient to remove species growing there today. This new reconstruction has implications for the existence of refugia, for estimates of species climatic tolerances, for testing general circulation models of climate, and for estimates of plant migration rates.

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Section: Introductionmentioning

confidence: 62%

Section: Our Contention Is That the Dominant Reconstructions Of Lgm Vmentioning

confidence: 99%

The Pleistocene biogeography of eastern North America: A nonmigration scenario for deciduous forest

Loehle¹,

Iltis²

1998

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“…Populations genetically similar or ancestral to holbrooki could have been continuously distributed along the southeastern coastal regions in the Pleistocene. Climatic shifts (Deevey, 1949) may have resulted in a retreat of these spadefoots into Florida and Mexico, or southern Texas. With a return to more favorable climates during the Pleistocene, the ancestral holbrooki complex would then have extended its range northward.…”

Section: Scaphiopus H Holbrookimentioning

confidence: 99%

RELATIONSHIPS OF ALLOPATRIC POPULATIONS OF SPADEFOOTS (GENUS SCAPHIOPUS )

Wasserman

1958

Evolution

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“…By analogy with European mountains, it has been assumed (e.g., Deevey, 1949;Delcourt and Delcourt, 1984) that the southern Appalachians, particularly the Great Smoky Mountains, should have been covered by permanent ice caps and should have generated glaciers. Mountain glaciers produce obvious signs like Ushaped valleys, striations, and moraines.…”

Section: Geologic Anomaliesmentioning

confidence: 99%

“…The Pleistocene Last Glacial Maximum (LGM) period of 18 000 years ago has been widely interpreted as a time of bitter cold in eastern North America when tundra and boreal forest extended hundreds of miles south of the ice sheets and the temperate forest of the East retreated to the southern coastal plain, to Florida, and westward into Texas and Mexico (Davis, 1983(Davis, , 1984Davis and Shaw, 2001;Deevey, 1949;Delcourt, 1984, 1993;Jacobson et al, 1987;Maher et al, 1998;Maxwell and Davis, 1972;Overpeck et al, 1992;Prentice et al, 1991;Ritchie, 1987;Royall et al, 1991;Schoonmaker and Foster, 1991;Tallis, 1991;Watts, 1970Watts, , 1971Watts, , 1973Watts, , 1979Watts, , 1980aWatts and Stuvier, 1980;Webb et al, 1988Webb et al, , 1993Whitehead, 1973;Wilkins et al, 1991). This reconstruction, which may be called the standard model, is commonly presented in textbooks (e.g., Bradley, 1999;Delcourt and Delcourt, 1993;Pielou, 1991;Ritchie, 1987;Tallis, 1991).…”

Section: Introductionmentioning

confidence: 99%

Predicting Pleistocene climate from vegetation in North America

Loehle

2007

Clim. Past

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Abstract. Climates at the Last Glacial Maximum have been inferred from fossil pollen assemblages, but these inferred climates are colder for eastern North America than those produced by climate simulations. It has been suggested that low CO 2 levels could account for this discrepancy. In this study biogeographic evidence is used to test the CO 2 effect model. The recolonization of glaciated zones in eastern North America following the last ice age produced distinct biogeographic patterns. It has been assumed that a wide zone south of the ice was tundra or boreal parkland (Boreal-Parkland Zone or BPZ), which would have been recolonized from southern refugia as the ice melted, but the patterns in this zone differ from those in the glaciated zone, which creates a major biogeographic anomaly. In the glacial zone, there are few endemics but in the BPZ there are many across multiple taxa. In the glacial zone, there are the expected gradients of genetic diversity with distance from the ice-free zone, but no evidence of this is found in the BPZ. Many races and related species exist in the BPZ which would have merged or hybridized if confined to the same refugia. Evidence for distinct southern refugia for most temperate species is lacking. Extinctions of temperate flora were rare. The interpretation of spruce as a boreal climate indicator may be mistaken over much of the region if the spruce was actually an extinct temperate species. All of these anomalies call into question the concept that climates in the zone south of the ice were extremely cold or that temperate species had to migrate far to the south. An alternate hypothesis is that low CO 2 levels gave an advantage to pine and spruce, which are the dominant trees in the BPZ, and to herbaceous species over trees, which also fits the observed pattern. Thus climate reconstruction from pollen data is probably biased and needs to incorporate CO 2 effects. Most temperate species could have survived across their current ranges at lower abundance by retreating to moist microsites. These would be microrefugia not easily detected by pollen records, especially if most species became rare. These results mean that climate reconstructions based on terrestrial plant indicators will not be valid for periods with markedly different CO 2 levels.

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Biogeography of the Pleistocene

Cited by 161 publications

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The Pleistocene biogeography of eastern North America: A nonmigration scenario for deciduous forest

The Pleistocene biogeography of eastern North America: A nonmigration scenario for deciduous forest

RELATIONSHIPS OF ALLOPATRIC POPULATIONS OF SPADEFOOTS (GENUS SCAPHIOPUS )

Predicting Pleistocene climate from vegetation in North America

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