.-~cl\ingly im-
At longer timescales. the interaction among climate. ecosystems. and the abiotic components of the environment become increasingly im-portant. These relationships are apparent in the three chapters in part IV. Fountain and Lyons (chapter 16). examining the McMurdo Dry Valleys (MCM) ecosystem in Anta...
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.634.7367 http://pal.lternet.edu/docs/bibliography/Public/221lterc.pdf |
| Summary: | At longer timescales. the interaction among climate. ecosystems. and the abiotic components of the environment become increasingly im-portant. These relationships are apparent in the three chapters in part IV. Fountain and Lyons (chapter 16). examining the McMurdo Dry Valleys (MCM) ecosystem in Antarctic. provide an excellent example of a case where past climatic variations truly dictate current ecosystem status. The relatively large climate variations at MCM haw concentrated nutrients that could not haw been attained without this climate \'ariability, Fountain and Lyons infer climate change from geomorphic ev-idence of past glacier positions and lake level heights as \vell as more recent iso-topic results from ice cores and temperature measurements from boreholes. They focus on evidence from the most recent 60.000 years. Monger (chapter 17) provides an analysis of millennial-scale climate and ecosystem variability at the lornada LTER site in southern New Mexico. Monger notes the difficulty of untangling pre-historic climate/ecosystem interactions. where researchers must rely on indirect proxy indicators in lieu of measured data, Monger analyzes a number of proxy data sources. including paleolake levels. plant remnants preserved in packrat middens. fossil pollens. carbon isotope ratios in paleosols. and erosion rates. Although not-ing the danger of circular reasoning in using proxy data (i.e. ecosystem response used to infer information about climatic change. \vhich is in turn inferred from ecosystem response) Monger uses these data to construct a cogent picture of cli-mate change at the lornada site URN) since the Last Glacial Maximum (LGM) about 18.000-20.000 years B.P, Using remains of beetles. Elias (chapter 18) con-stJ'ucts a temperature history of the Colorado Alpine since the LGM. These late Holocene insect records show a progression from wanner-than-modern to cooler-than-modern summers. and back to warm again. All the authors in this section pro- |
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