Research in the Crosstimbers of the Tallgrass Prairie Preserve, Osage County, Oklahoma

1. In March 2003, a severe tornado (F4 on the Fujita scale) struck a crosstimbers stand, causing substantial damage and mortality. Blackjack oak proved much more susceptible to damage than post oak, but had a much stronger resprouting response. The bird community was strongly affected by tornado damage. Ongoing research will evaluate the long-term effects of the tornado on a permanently marked plot. Crosstimbers dominate the dry, sandstone-derived ridges of the Tallgrass Prairie Preserve. They are more species-poor than other forests of the preserve, and grade imperceptibly into savannahs and prairies. Tornado path Sandstone outcrops crosstimbers Sandstone Tallgrass Prairie The bird community savannas Acidity, sand Limestone or bottomland Map of a crosstimbers stand (units are meters) showing highly clumped spatial distribution of both species mesic forest Shortgrass prairie / limestone outcrops Epicormic sprouting on oaks Forest cover Research focus: Response to a tornado Quercus marilandica Quercus stellata Fires seem to have the largest effects on the prairie/forest border Number of basal sprouts Number of basal sprouts DBH (cm) DBH (cm) The plant virus biodiversity and ecology (PVBE) group is attempting to inventory the plant viruses of the Tallgrass Prairie Preserve, with a special interest in the crosstimbers. So far, approximately half of crosstimber specimens are positive for RNA viruses, although the majority display no obvious viral symptoms. Recent clearing of old-growth oaks on the border of the preserve has provided an opportunity for expanding the fire history study backwards in time, and over a larger spatial extent. Poisson regressions demonstrate the relation between number of basal sprouts and Diameter for Q. marilandica and Q. stellata. Both have similar numbers of sprouts when undamaged, but blackjack oak (marilandica) responds more dramatically to destruction. Research in the crosstimbers is of international interest, as there are other ancient oak woodlands in the temperate northern hemisphere. This Quercus robur specimen is part of a complex of ancient oak woodlands in Östergötland Province, Sweden. There are many ecological similarities between these woodlands and the crosstimbers. Fumiko Shirakura1, Matt Allen1, José Ramón Arévalo1,2, Mary Carmen Cobo1,3, Peter Earls1, Daniel McGlinn1, Kiyoshi Sasaki1, Vaskar Thapa1, and Michael W. Palmer1 1Oklahoma State University, 2University of La Laguna, 3Jaén University Research focus: Gradient Analysis Research focus: Spatial patterns The crosstimbers are forests dominated by Quercus stellata (post oak) and Quercus marilandica (blackjack oak), and are prevalent throughout much of Oklahoma. Research conducted by LIBRA at the Tallgrass Prairie Preserve (managed by The Nature Conservancy) aims to resolve how these enigmatic ecosystems function. Research in the Crosstimbers of the Tallgrass Prairie Preserve, Osage County, Oklahoma Research focus: codominance Throughout their ranges, post and blackjack oak share dominance. Thus, they can provide a useful model system for the study of coexistence. Blackjack oak Post oak Research focus: Plant Viruses of the Crosstimbers Research focus: fire history Although the effects of fire on grasslands are well-studied, the historic fire regime is largely unknown. Fire scars on trees at the edges of crosstimbers represent an opportunity for understanding fire history of both forests and grasslands. Contrary to popular thought, oaks effectively record fire events Fire history is closely tied in with human history, thus its study requires a transdisciplinary approach Preliminary research on the fire history of the tornado site demonstrates the feasibility of research in fire ecology Acknowledgements David W. Stahle, Richard Guyette, Donald A. Falk, Michael Stambaugh Stephen W. Hallgren, Ronald Tyrl, Tom Wohlgemuth, Jerad Linneman, Shyam Thomas, Robert Hamilton, Miwa Hara, Michael C. Marler, Per Milberg and the Quercus group of Linköping University, many volunteers Support by The Nature Conservancy, OSU Botany Department, Payne County Audubon Society, Oklahoma Department of Wildlife Conservation, Oklahoma State Regents for Higher Education, National Science Foundation Several hundred tree disks have been collected and are currently being cross-dated and evaluated for fire history. Fire history of the tornado site: summary There were 47 fire events over 51 years (a higher fire frequency than any documented in the literature). All known fires were recorded by the trees. Most fires occurred in dormant season since 1973, although a few were in the early and late growing season. Fire years did not correspond with drought years dLaboratory for Innovative Biodiversity Research and Analysis Support for the fire history project is provided by the National Science Foundation’s Small Grants for Exploratory Research