Dr. Panyushkina has been devoting her tree-ring efforts over the last five years to two NSF-supported projects: Pleistocene/Holocene mid-North America climate and Iron Age archaeology of Central Asia.

These efforts resulted in development of a network of subfossil tree rings in the Midwest for the late Pleistocene—Early Holocene transition (from 15,000 to 10,000 years ago) that retains high-resolution chronologies of tree-ring widths, stable isotopes and radiocarbon. This network provides climate proxy and high-resolution radiocarbon data that assesses regional environment response to global climate change. An identified ENSO-like signal in tree-ring variance of developed chronologies provides valuable insights to long-term changes in decadal variability of climate associated with ENSO. In a broader sense, the project results and tree-ring collection contributes to earth science, geology, paleoclimatology, paleoecology, paleobotany and paleolimnology. New dates for geological deposits and high-resolution radiocarbon data place the changes in lake levels of Lake Michigan and Lake Huron within the context of global changes during the Pleistocene deglaciation. The long-term goal of the project is to improve our understanding in atmosphere-ocean-land interaction under changes in climate forcings. Overall, the U.S. Midwest collection has over 600 subfossil tree samples from 24 sites ranging in age from about 4000 years ago to 15,000 years ago, centered at the abrupt climate change associated with the Younger Dryas (YD) Event 10,000 years ago. Almost two dozen collaborators from 16 institutions have been associated with this project, and newly collected wood samples provide a basis for continued work. The prize site is the only know in situ Younger Dryas age forest in N. America, which Dr. Panyushkina intensively analyzed to produce the first annually resolved record of YD environment.

The project on the Iron Age in Central Asia acquired hundreds of tree-ring samples from 1) several dozen archaeological sites associated with Siberian Scythians, Hun-Sarmatians and Turks, and 2) eight upper tree-line sites in the Altai Mountains, South Siberia. This collection provided tree rings for a 2,700-year composite record of larch from ca. 710 BC to AD 2006. The record combines i) two floating tree-ring chronologies from wooden constructions of Pazyryk culture barrows (a 482-year record between 710 and 240 BC) and Hun-Sarmatian kurgans (from AD70 to AD 240) and ii) overlapped chronology from wooden Türk posts and Huns coffins (AD 200-650), and upper tree-line remnant logs and living trees (AD 343-2006). The 2,700-year record has a ca. 300-year gap in the period 240 BC and AD 70 that needs more field collections to be filled. This record suggests absolute dates for the highly debated and controversial chronology of the Pazyryk culture (Siberian Scythians). A 486-year master tree-ring chronology of Pazyryk culture overlaps tree rings of the tribal chief large frozen barrows at elevations of 1600 m and 2400 m asl by establishing a highly replicated chronology of small barrows of ordinary Pazyryks at 1900-2100 m asl elevation. The Pazyryk master chronology synchronizes the 85-year history of thirty two barrows built from BC 320 to BC 240. The crossdated tree rings have provided a new perspective with which to interpret the history of Siberian Scythians evident from the Pazyryk archaeological culture. The developed accurate and precise dates reinforce our understanding of steppe nomadic societies and their interactions with other groups in Eurasia. Climatic extrapolations from the Altai’s tree ring address our understanding of adaptation of ancient nomads to seasonal temperature fluctuations and climate change overall.

The project activities established strong ties with leading archaeologists at the Siberian Branch of Russian Academy of Sciences and State Hermitage Museum (St. Petersburg). Important collaborative contacts were developed with archaeology specialists from Kazakhstan and National Research Institute for Cultural Properties, Nara, Japan. The relationships may form the basis of further work in the area, including workshops and educational opportunities for the local scientists and land administrators in light of the evidence of past climate variability and recent regional climate changes.