Doctoral Dissertation Research: High-Resolution Climate and Land-Use Records from Cave Stalagmites and County Gazetters for China Over the Last 2,000 Years

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A major concern of contemporary scientists is distinguishing global environmental changes associated with natural variations in climate from those that resulting from human activities. Land-use and land-cover changes are among the most important changes instigated by humans, but studies of these changes generally have been limited to the last 10 to 30 years, a very short period compared with the history of human activity. An urgent need therefore exists for high-resolution climate data over the last few thousand years and for information on land-use and land-cover changes over the same time period. This doctoral dissertation research project will explore the degree to which cave stalagmites can provide both high-resolution climate and land-use data for the areas near and above caves, thereby allowing a more accurate assessment of the role of humans in environmental change. Working in Guizhou Province of south central China, a region dominated by karst features, including many caves with speleothems. The doctoral candidate will study stalagmites from areas that still have natural vegetation cover and that have not been affected directly by human activities, particularly agriculture. Stalagmite annual layer thickness, gray-scale, stable isotope, and UV laser-induced luminescence proxy measures of climate will be taken and compared with meteorological records drawn from county gazetteers, which provide meteorological information for periods of more than 2,000 years. These comparisons will be used to determine which variables best reflect variations in rainfall and temperature. Appropriate proxy measures then will be compared with gazetteer data dealing with extreme climate events, such as floods and droughts, hail, freezing of rivers and lakes, and snow. Preliminary studies of one stalagmite have identified variations in summer rainfall and shown evidence of major floods back to ca. AD 1430. Investigations also will be made of stalagmites from caves in agricultural areas, particularly locations for which there have been significant changes in land use at a known times in the past, as determined from satellite images, aerial photographs, historical maps, and interviews with local residents. This part of the project will aim at identifying whether information about land use and land cover above the caves can be determined from speleothem records, thereby lengthening the periods over which land uses can be inferred back in time beyond reliable historical records. In addition to providing valuable information about relationships among climate, land-use, and natural vegetative processes over long periods for southern China, the project will make significant methodological contributions by assessing the degree to which cave deposits can be used to provide high-resolution climate and land-use and land-cover data. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.