Graduate Program

Biological Sciences

Degree Name

Master of Science (MS)

Semester of Degree Completion

Spring 2023

Thesis Director

Scott J. Meiners

Thesis Committee Member

Eric K. Bollinger

Thesis Committee Member

Robert E. Colombo

Abstract

Most oak savannas in the Midwestern United States have been lost to agriculture and habitat degradation. Because of their rarity and ability to support high plant and animal diversity, savannas are often a target for restoration. Oak savanna restoration frequently relies on direct planting of oak seedlings to establish the necessary tree canopy. Returning fire to the system is critical to the herbaceous component of the savanna, but managers risk damaging or killing trees if burning is introduced too soon. I studied growth and physiological responses of three oak species (Quercus alba, Q. macrocarpa, and Q. velutina) to prescribed fire to determine impacts on previously planted trees. This study utilized two restored oak savanna units that were planted in 1995 and 1998, each with burned and unburned areas. I tracked trees ranging from 0.9 to 29.8 cm in diameter to determine the size threshold above which top kill is unlikely, and documented differences in leaf structure and extension growth between burned and unburned portions of each area. There was no mortality observed and no trees larger than 4 cm diameter at breast height (dbh) were top killed by the fire. Fire responses in leaf mass per unit area and chlorophyll content were small and inconsistent across species and units. However, all oak species grew more in burned areas than trees in adjacent unburned areas. Therefore, the addition of low intensity prescribed fire to an oak savanna planting may increase the growth rate of planted trees with minimal risk of mortality.

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