UWP - Geography - Joy Wolf

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Wisconsin Oak Savanna Fire History

Fires swept through Wisconsin oak savanna systems and played an
important role in maintaining the community structure and diversity.

Benefits of oak savanna fires: Create sun space Enrich the soil Remove invasive species	...larger oaks survive the fires.
*Bur oak (Quercus macrocarpa) has thick corky bark that is resistant to fire.*

Fire history records are limited in Midwestern ecosystems, yet are essential toward

1. understanding oak dynamics

2. developing / implementing management programs for restoration and preservation.

3. developing a policy of prescribed burns in remnant patches

In this research, we determined the fire history for the past 200 years
using dendrochronology. Dendrochronology is the study of patterns
in tree rings to determine ecosystem dynamics, disturbance regimes,
land use changes, and climatic fluctuations.

My students involved in this research learn about fire and
vegetation dynamics in the oak savanna, the lab techniques for
dendrochronology, and the human element in ecosystem processes.
We examined land use records, aerial photos, vegetation maps,
and climate data to correlate with fire dates and the tree ring record.

Here's what we're doing!

The study site is within a landscape of fragmented oak savanna and oak woodland. Photo: Pete Schwalbe	In October 2000, the area was cut for development.
	I acquired the cross-sections in Feb 2001
The University provided a space for the wood to dry slowly .	Many students helped in sanding the wood.
Inspecting the rings for marker years & fires.	Cross sections allowed us to follow the wood for false rings.
Skeleton plots show marker years & fire dates (2 plots from different radii)	FHX2 Fire Frequency output
Fire seasonality: most fires occurred during the dormant season. nThe age structure was bimodal n half germinated between 1804-1815 n half germinated between 1847-1862	The marker and fire years were correlated with with local climate data.
After fire years were dated, land use history was used to explain the fire frequency.	Land managers can use this data to restore an adjacent oak savanna.