A 1,461-year growing season precipitation reconstruction for the Carolina coastal plain.

摘要

A recollection and dating of ancient cypress trees and subfossil logs was performed at Black River, North Carolina, and the separate Black River, South Carolina. The new updated and expanded chronologies date from AD 365 to 2010 and 549 to 2010, respectively. Baldcypress ring-width chronologies are dominated by high inter-annual to decadal variability and do not tend to capture century scale fluctuations in tree-ring growth that could be associated with centennial scale change in climate. The tree-ring chronologies were standardized with a technique designed to preserve low frequency variance known as regional curve standardization. The two chronologies were averaged into a single baldcypress growth history for the coastal plain of North and South Carolina. The averaged coastal Carolina and Black River, NC chronologies were used for reconstructions of growing season precipitation and provides estimates of centennial scale dryness during the Medieval Climate Anomaly and early Colonial Era and wetter than average conditions during the 8 th, 16th and 17th centuries, the latter possibly associated with the Little Ice Age. A long-term trend of improved tree growth and greater reconstructed growing season precipitation is observed from approximately 1750 to 2010, even though the instrumental precipitation data available from 1895–2005 do not exhibit significant linear trend. It is possible that the recent trend in tree growth is a function of anthropogenic disturbance to our baldcypress collection sites (including logging, land clearing of the drainage basin, atmospheric deposition of nutrients, carbon dioxide fertilization), or even the standardization procedures used for chronology development. However, the Medieval Climate Anomaly, Little Ice Age, and the trend toward greater wetness in the 20th century have been detected in hydrological proxies elsewhere in North America. These centennial scale changes in southeastern USA precipitation need to be tested with additional climate proxies and historical documentary evidence.