Paleoenvironmental Change in Central Texas: The Palynological Evidence

Analysis of pollen spectra from Boriack and Weakly bogs provides a 16,000 year sequence for central Texas. Fluctuations between grass and arboreal pollen indicate that numerous shifts between forest, woodland, and open plant communities occurred during this span. Open communities were present at the Last Glacial Maximum, and between 12,000-13,000 BP, 9000-10,000 BP, and 8000-2500 BP. A two-phased mid-Holocene dry interval occurred with extremes recorded at 6500 BP and 5000 BP. Examination of arboreal and grass pollen frequencies verifies that the structure of Pleistotene plant communities is not the same as Holocene communities; modern analogs may not exist for these Pleistocene communities. Comparisons between shifts in the fossil pollen assemblages and climatic simulations indicate that orbital parameters as well as glacial meltwater routing may have had important effects on past plant communities.