Constructing Seasonal Climograph Overlap Envelopes from Holocene Packrat Midden Contents, Dinosaur National Monument, Colorado

Abstract

Five Neotoma spp. (packrat) middens are analyzed from Sand Canyon Alcove, Dinosaur National Monument, Colorado. Plant remains in middens dated at approximately 9870, 9050, 8460, 3000, and 0 14C yr B.P. are used to estimate Holocene seasonal temperature and precipitation values based on modern plant tolerances published by Thompson et al. (1999a, 1999b). Early Holocene vegetation at the alcove shows a transition from a cool/mesic to a warmer, more xeric community between 9050 and 8460 14C yr B.P. Picea pungens, Pinus flexilis, and Juniperus communis exhibit an average minimum elevational displacement of 215 m. Picea pungens and Pinus flexilis are no longer found in the monument.Estimates based on modern plant parameters (Thompson et al., 1999a) suggest that average temperatures at 9870 14C yr B.P. may have been at least 1° to 3°C colder in January and no greater than 3° to 10°C colder in July than modern at this site. Precipitation during this time may have been at least 2 times modern in January and 2 to 3 times modern in July. Discrepancies in estimated temperature and precipitation tolerances between last occurrence and first occurrence taxa in the midden record suggest that midden assemblages may include persisting relict vegetation.

Strengths and Weaknesses of Quantitative Climate Reconstructions Based on Late-Quaternary Biological Proxies

“…Grichuk 1969;Grichuk et al 1984;Markgraf et al 1986;Kershaw & Nix 1988;McKenzie & Busby 1992), plant macrofossils (e.g. Sinka & Atkinson 1989;Mosbrugger & Utescher 1997;Sharpe 2002), chironomids (e.g. Dimitriadis & Cranston 2001), molluscs (e.g.…”

Inferences about winter temperatures and summer rains from the late Quaternary record of C4 perennial grasses and C3 desert shrubs in the northern Chihuahuan Desert

“…Bioclimatic envelopes have been used only sparingly, however, to infer climate from packrat midden records. (Thompson et al, 1999;Arundel, 2002;Sharpe, 2002;Norris et al, in press). Here, we used georeferenced herbarium records and a Geographic Information System (GIS)-based approach to construct bioclimatic climatic envelopes for indicator species.…”

A long‐term vegetation history of the Mojave–Colorado desert ecotone at Joshua Tree National Park

“…For example, the macrofossil assemblages preserved in midden chronologies have been used to investigate past vegetation communities (see regional summaries in Betancourt et al, 1990), to reconstruct plant migrational patterns and pacing (Jackson et al, 2002(Jackson et al, , 2005Lyford et al, 2003;Norris et al, 2006), to infer millennial-scale variability in plant function from morphological and biological traits (Van de Water et al, 1994Hunter et al, 2001), and to quantify past changes in climate and evaluate their effects on shifting plant distributions (Thompson et al, 1999;Arundel, 2002;Sharpe, 2002;Norris et al, 2006;Holmgren et al, 2007).…”