GSA Connects 2021 in Portland, Oregon

Paper No. 112-2
Presentation Time: 1:45 PM


NANAVATI, William, PhD, Geography, Portland State University, 1721 SW Broadway, Portland, OR 97201 and MUELLER, Pietra, Springfield, IL 62704

Although Dr. Eric Grimm left us too soon, his work and mentorship live on through his enduring influence on Quaternary paleoecology and paleoclimatology. Eric was a champion of multiproxy, interdisciplinary research that examined environmental history across spatial and temporal scales. Eric’s willingness to collaborate with and educate young scientists, made him an incredible role model for many Quaternary researchers, and serves his legacy well. Here, we present important lessons we learned working with Eric and demonstrate how they helped inform the research and interpretation of a 1900-year-long lake sediment core from Sweeton Pond, Ozark County, Missouri. The multiproxy study from Sweeton Pond provides a high-resolution environmental history from modern oak-hickory (Quercus-Carya) forest in the central U.S. Ozark Highlands. Eric’s interest in interdisciplinary research is highlighted in this study, as pollen and charcoal data from Sweeton Pond were compared to dendroecological, historical, and archaeological data to assess the long-term role of climate, fire, and land use in shaping the local vegetation history. This study suggests that between ~80 and 1360 CE, the landscape surrounding Sweeton Pond was characterized by open oak-hickory forest and frequent, low-severity fires, contemporaneous with warm, dry conditions. At ~1360, mesic, fire-sensitive species expanded near Sweeton Pond during a period of low fire frequency, concomitant with cool, wet conditions. Despite climate conditions that were seemingly less favorable for fire, increased Osage American Indian land use in the Ozark Highlands by the 15th century, was accompanied by more fires and increased abundance of fire-dependent shortleaf pine (Pinus echinata) near Sweeton Pond. The expansion of both fire-sensitive and fire-dependent taxa coincident with Osage occupation of the area suggests that American Indian land use increased landscape heterogeneity. Large increases in disturbance pollen types (e.g. Ambrosia-type) at the expense of shortleaf pine pollen indicate extensive Euro-American settlement in the nineteenth century. Euro-American settlement brought with it extensive agriculture and logging near Sweeton Pond, which gave rise to fuel fragmentation and the reduction of fire activity. After 1920, fire was actively suppressed.