Master of Science (MS)
Semester of Degree Completion
John E. Ebinger
The sampling transects at Indiana Dunes were established to show the pre-burn condition of the vetetation and to monitor the long term effects of burning. However, one year of monitoring showed changes in vetetation that further substantiate the need for the burning program.
Miller Woods (Transect A) has burned frequently in recent years. The one year without fire showed little change in the herbaceous layer. The few notable herbaceous changes might indicate a transition to a more mesic community, but should be viewed skeptically because of the wet season in 1982.
Nearly half of the small shrub species at Miller Woods are low blueberries (Vaccinium angustifolium and Vaccinium vacillans). Blueberries decrease rapidly in the absence of fire. In one year without fire the blueberries decreased 60,000 stems/ha at Transect A. This dramatic decrease of the dominant meant an over-all decrease of small shrubs even though there was an increase of other species.
Inland Marsh (Transect B) was chosen for its undisturbed condition. There was little change in herbaceous vegetation. An increase of cattails (Thypha latifolia) and purple loosestrife (Lythrum salivaria) would be expected in a marsh without burning. Significant increases were not shown along the transect in one year, probably because deep water along the transect limits the species. Buttonbush (Cephalanthus occidentalis), the only woody species did increase by about 25% density.
Inland Savanna (Transect C), of the transects sampled showed the least change. The slight herbaceous changes reflect the increasingly mesic conditions caused by the extending canopy. The slight decline of small shrubs further demonstrates the loss of light to the understory. The shrub species which did increase are commonly found in mesic woods, not sand savannas.
Dune Acres (Transect D) was once so open a savanna that it is variously called Lois Howe prairie, Lupine Lane Prairie, and Dune Acres Prairie. This area shows the greatest effects of fire suppression. There was an increase of woodland and wetland herbaceous species that might have been caused by the wet season, but which was probably caused by increasing shade. There was a corresponding decrease of prairie and dry-savanna species caused not only by the wet season, but also by the increased canopy and duff.
Small shrubs increased 43,000 stems/ha showing the rapid transition of the area. This overall increase encompassed a decline in such prariie or savanna species as low blueberries and black oak (Quercus velutina).
The areas vary in their current need for fire. Miller Woods shows no immdeiate need for fire. Inland Marsh shows no herbaceous imbalance due to fire suppression. Inland Savanna has sufficient canopy that without burning soon it will begin to change rapidly. Dune Acres is now in danger of loosing floristic diversity. If fire does not soon remove shrubs and duff, it could become a dense community of shrubs with few surviving herbaceous species. The savanna species would be greatly reduced and the prairie flora lost.
Kerr, Kathryn Ann, "Vegetation Changes in Four Study Areas at Indiana Dunes National Lakeshore" (1984). Masters Theses. 2785.