Paleoclimatic Reconstruction Based on Leaf Morphology: Calibration from Living Forests

I have just finished working on a project comparing modern leaf morphology and wood anatomy with climate parameters from approximately 15 sites in Eastern North America. This involves sampling leaves and wood from modern forests, statistical tests of the resultant data and predictive equation formation. The manuscripts are being submitted for this project currently. We have discovered that leaves from areas with wet soils (those areas prone to fossil preservation) tend to show lower temperatures than the actual. (See Kowalski and Dilcher, 2003). In addition, we have calculated a new mean annual precipitation regression that is more precise and accurate than those previously published.

To the right is a view of Dilcher's Woods, one of our collection sites, located in Gainesville, Florida. Below right, some of the variety of morphologic characters leaves show.

I have been working on South American models for climate reconstruction indicates that mean annual temperature (MAT) – leaf morphology correlation equations based on Northern Hemisphere or Australian data do not accurately predict the MAT of South American sites (See Kowalski, 2002). I have revised a correlation equation for use in the South American tropics.

Temperature and Elevation of the Cenozoic of South America

I have been working on a macrofossil flora from the Nabón Basin, located in Southern Ecuador. I am interested in the vegetation of the area as well what that vegetation can tell us about the climate and uplift history of the Northern Andes during the mid to late Miocene. There are approximately 78 species present in the flora, and the fossils are found in stratigraphically distinct

layers that span about 2 million years. Climate-leaf morphology correlation is a useful tool in determining paleoclimate, and can be performed on six separate localities in the basin. This allows me to look at the change in the climate of this region at a relatively fine scale. Temperature estimation can be used to determine elevation, and elevation estimates at each locality allow calculation of an uplift rate for the area surrounding the basin.

Miocene Flora of Ecuador

I am trying to determine the systematics of the species most commonly found throughout the Nabón Basin, Ecuador. Thus far the most common species belong to the families Fabaceae, Cecropiaceae, and Lauraceae. Also found are Proteaceae, Sapindaceae, Rosaceae and Clusiaceae. To the right are several examples of the fossils found in the Nabon Basin.

Paleocene Flora of the Crazy Mountains Basin, Montana

This summer, I will be starting a project in the Crazy Mountains Basin of central Montana. This project is in collaboration with vertebrate paleontologists and isotope geologists and will look at the biotic and isotope stratigraphy of the basin, look for early ancestors to many of the modern groups of mammals, and determine the flora and climate of the Paleocene of western North America.