Carbon Isotopic Records From Stalagmites And The Signification Of Paleo-ecological Environment In The Area Of Guangxi-guizhou, China

摘要

High resolution carbon isotopic records in millennial, centennial and decadal timescales from three stalagmites from three different caves under a similar monsoon climate in Guangxi-Guizhou, China, provided detailed information on the paleo-ecological environmental conditions in the past 15,000 years. The results indicate that during the glacial period, or cold-dry period, such as Heinrich event H1 and Younger Dryas event karst development was poor as was pedogenesis, C3 vegetation didn't grow well, resulting in C4 plants dominating and with heavy δ~(13)C values in stalagmites. In a warm-humid stage, C3 vegetation grew well and predominated with negative δ~(13)C values. The δ~(13)C records from stalagmites could be indicative of sensitive vegetation changes and reflective of climate changes in precipitation, temperature, etc. The δ~(13)C records may also be used to distinguish different effects from nature or human activity. Particularly since the late Holocene, human activities have increased disturbances to environment, even more than natural factors. Forest vegetation was destroyed, C4 plants became dominant, and rock desertification was aggravated because of severe water and soil loss, all resulting in sharply increasing δ~(13)C values of stalagmites that are heavier than pre-middle Holocene δ~(13)C values.