Newsletter Signup

To be added to the SIOSA email list to receive the quarterly SIOSA newsletter and information on events, email admin@siosa.org.

Upcoming Events

For Lands Sake! and Winterset Library One Earth Book Club:

Tuesday, Nov. 28: “Listen to the Land” — Larry Stone

Tuesday, Jan. 23: “Sylven T. Runkel: Citizen of the Natural World” — Stone and Stravers

Meet at 7:00 PM at Winterset Library

 

Next SIOSA board meeting

Thursday, November 2, 1:00 PM at Decatur County Conservation Board office west of Leon.

Oak Savannas

What is an Oak Savanna?

An oak savanna is a unique habitat that expresses characteristics of both grasslands and woodlands and functions as a transition zone between the two distinct landscapes. Savannas are best characterized by their structure of open grown trees with thick herbaceous ground cover. The dominant tree in most Midwest savannas is the bur oak; white oak, red oak or hickory trees are also commonly found in the oak savanna ecosystem.

The open canopy-like growth of the trees allows sufficient sunlight to reach the ground level thereby encouraging the growth of a diverse array of grasses, flowering plants, and sedges on the ground. This thick and diverse plant growth creates an inviting habitat for wildlife and helps the underlying soil become more productive. As stated, it is common to find the oak savanna as a transitional area between open grasslands and forests; here in the Midwest savannas are key components of the tall grass prairie, providing islands of trees in a sea of grass.

Fritz James Prairie Restoration

Fritz James Prairie Restoration

New:  Video of Fritz James Restoration in Madison County. Click Here

_____________________________________________________________________________________________________________

Quick Facts: Properly maintained Oak Savanna can…

  • attract wildlife
  • increase hunting opportunities
  • promote growth of beautiful wildflowers and fungi
  • provide scenic walking areas
  • improve water’s ability to infiltrate in soil
  • improve the soil’s ability to store and move water
  • reduce fuel loads in canopy under stories

_____________________________________________________________________

Why should we care about the Oak Savanna?

For hundreds of years the landscape of Iowa was maintained and transformed by fire. Native Americans burned the prairies and savannas of Iowa to attract buffalo, protect themselves from wildfires, as a weapon, and to improve mast production in the woodlands. Settlement quickly changed how the land in Iowa was managed.

The development of row-crop agriculture and intensive grazing practically stopped the wide use of fire as a land management tool. We quickly lost the culture of fire in our state. Along with the loss of fire came the encroachment of woody vegetation onto the prairies and into the oak savannas.

Oak Savannas are one of the most altered plant communities in the Midwest and among the most threatened in the world. With the lack of fire and grazing, savannas quickly become overgrown with trees, brush and invasive species. This in turn shades the herbaceous ground layer, effectively eliminating the benefits of the savanna structure.Today efforts are being made to bring fire back to the landscape to recapture these lost habitats. The land in Southern Iowa is proving to have a long memory and we are seeing many native communities rebound.

  • Click Here for an article about Oak Savannas by the Iowa Natural Heritage Foundation.

 


 

What can we do?

Working in collaboration with landowners and other partners, such as the County Conservation Board and the U.S. Fish and Wildlife Service, SIOSA has the resources and capacity to restore overgrown woodlands back to a savanna ecosystem. Many have already taken advantage of this opportunity to restore their land back to its natural form. There are two basic methods being used to restore savannas in southern Iowa.

Prescribed fire helps remove old duff and litter and releases native vegetation while suppressing woody plants. Before land can be burned, a burn plan must be developed with the landowner. Personnel and equipment need to be available on the burn site for precautionary reasons during a burn. Afterwards, the land should be monitored for some time until pre-burn temperatures have been reached within the soil. Where the trees and brush have encroached too much for fire to be effective, thinning the brush may be the best method to open the canopy. In most cases the combination of methods quickly transforms a closed woodland back to savanna.

_______________________________________________________________________________________________________________

Oak Savanna Restoration

 

High quality oak savannas can be found scattered across the landscape of southern Iowa and northern Missouri.  These extremely rare ecosystems are somewhere in the middle of the continuum between the tallgrass prairie and deciduous forests..  Fires started by both lightning and Native Americans allowed these areas to develop a thick vegetative mat composed of sedges, forbs, and grasses dotted with giant, fire-tolerant oak trees.  Due to the westward movement of pioneers, fire was suppressed from these landscapes allowing for invasive vegetation to encroach.  However, with patience and hard work, these pristine sites can be returned to their original state.

Since fire has been absent from the majority of these sites for such a long period of time, restoration typically starts with removing undesirable, woody vegetation from the understory.  This step can be done through prescribed burning or by mechanical removal.  Prescribed fire works by producing heat which kills the invasive woody vegetation while desirable, fire-tolerant vegetation will remain unharmed.  This method is the most “natural” technique but may take several years of burning to accomplish your goal.  The alternative, mechanical clearing, is typically accomplished by using a tractor/skidloader mounted forestry mower or by a specialized brush saw.  When this method is used in restoration efforts, undesirable woody vegetation is cut and all cut stumps MUST be treated with chemical to reduce resprouting.  Although mechanical clearing is often times more costly and labor intensive than burning alone, results can be seen in days rather than years.

Forestry Mower

Once the undesirable, woody vegetation has been eliminated from the understory, larger diameter trees can be selectively cut to reduce canopy cover on the restoration site.  During this step, all invasive trees such as ironwood, locust, etc. should be cut or girdled, treated with chemical, and “bucked up” so that all debris lays as close to the ground as possible.  After the invasive trees have been eradicated, remaining trees should be selectively cut to accomplish the desired canopy cover.  This process often times varies between project sites based on the wishes of the landowner or contracting agency.  In some instances the desired canopy cover is accomplished all in one cutting, while other times the canopy is opened through several cuttings spanning 2-3 years.

Finally and most importantly, a prescribed burn plan for your restoration site must be developed to keep invasive vegetation from encroaching, return nutrients to the soil, and allow the dormant native seed to once again flourish.  Burning typically is recommended to be done every 1-3 years and often times a “patchy” burn accomplished.  This patchwork of burned and non burned areas assures some habitat will be left for both vertebrate and nonvertebrates inhabitants of these rare oak savanna ecosystems.

Mark Erke – Owner, Midwest Land Restoration, LLC