期刊
JOURNAL OF QUATERNARY SCIENCE
卷 22, 期 2, 页码 141-161出版社
WILEY
DOI: 10.1002/jqs.1023
关键词
Chihuahuan Desert; bioclimatic envelopes; Pleistocene; Holocene; North American monsoon
Late Quaternary histories of two North American desert biomes-C-4 grasslands and C-3 shrublands-are poorly known despite their sensitivity and potential value in reconstructing summer rains and winter temperatures. Plant macrofossil assemblages from packrat midden series in the northern Chihuahuan Desert show that C-4 grasses and annuals typical of desert grassland persisted near their present northern limits throughout the last glacial-interglacial cycle. By contrast, key C-3 desert shrubs appeared somewhat abruptly after 5000 cal. yr BP. Bioclimatic envelopes for select C-4 and C-3 species are mapped to interpret the glacial-interglacial persistence of desert grassland and the mid-to-late Holocene expansion of desert shrublands. The envelopes suggest relatively warm Pleistocene temperatures with moist summers allowed for persistence of C-4 grasses, whereas winters were probably too cold (or too wet) for C-3 desert shrubs. Contrary to climate model results, core processes associated with the North American Monsoon and moisture transport to the northern Chihuahuan Desert remained intact throughout the last glacial-interglacial cycle. Mid-latitude effects, however, truncated midsummer (July-August) moisture transport north of 35 degrees N. The sudden expansion of desert shrublands after 5000 cal. yr BP may be a threshold response to warmer winters associated with increasing boreal winter insolation, and enhanced El Nino-Southern Oscillation variability. Published in 2006 by John Wiley & Sons, Ltd.
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