Chris Dietrich, INHS entomologist, with Photo Tactic Optimal Insect Extractors that
he invented to help separate insects from samples using light.
Much of what was open woodland and savanna in Illinois has closed in and could now be considered forest. Previous to European settlement, Native Americans used fire as a management tool to maintain an open landscape, especially in the relatively high and dry oak-hickory forests and savannas. Until 1930 or so, many landowners regularly burned their woodlands. However, soon after this time with the advent of Smokey the Bear ("Only you can prevent forest fires") very little burning was done for management. In more recent times, natural areas managers have revived the use of prescribed burning in upland woodlands. Lack of fire in these woodlands may be diminishing the diversity of plant life by promoting conditions that favor a few fire-sensitive, shade-tolerant, mesophytic native plant species such as sugar maple (Acer saccharum), slippery elm (Ulmus rubra), and paw paw (Asimina triloba), as well as numerous exotic plant species such as buckthorn (Rhamnus spp.) and bush honeysuckle (Lonicera spp.). This trend, leading to a lower diversity of plant species, could result in lower diversity of insects and other organisms that are dependent on particular plant species.
Chris Dietrich, INHS entomologist, with Photo Tactic Optimal Insect
Extractors
that
he invented to help separate insects from samples using
light.
In two oak-hickory forests, researchers at the Illinois Natural History Survey are comparing the effects of withholding fire to prescribed burning (in combination with other active management such as selective use of herbicides) on the abundance and diversity of vascular plants, insects, gastropods, soil invertebrates, birds, and lichen communities within these sites. The study areas are Baber Woods Nature Preserve in Edgar County and the Middle Fork Fish and Wildlife Area in Vermilion County. Our extensive studies at Baber Woods show a trend of declining oak reproduction since 1965 with virtually no production in 1998. Management at Baber Woods was initiated in fall 1999. Effects of fire and other management practices will be evaluated by conducting similar studies on nearby control plots. Comprehensive studies were initiated in both restoration sites and the control plots in spring 1998.
Insects
For insects, 100 sweeps are taken with a sweep net along permanent 50-m transects in the experimental and in the nearby control areas. Malaise traps are run for week-long intervals several times per year for each site. Blacklight traps are run at night once or twice a year. Changes in species richness and composition will be monitored by counting morphospecies in these samples.
Birds
Local abundances and community structure of birds are being estimated during the breeding season using the "point-count" method of censusing. Data from the 1999 breeding season indicate that the diversity of birds in Baber Woods is relatively high for central Illinois. Some species will likely benefit and some will be adversely affected by restoration.
Plants
All vascular plants, both woody and herbaceous, have been surveyed and changes in the composition of the plant community will be compared to changes in species composition and abundance of other organisms over time.
A white oak (about 250 years old) in Baber Woods showing
the die-back
of lower
branches caused by crowding from
sugar maples.
Soil Fauna
Researchers are also taking soil samples to study the soil fauna. Soil fauna are complex and play important roles by decomposing dead plant material, recycling limited plant nutrients, and forming soil structure and new soil. Management practices that affect the soil community can therefore impact the plant community. We believe that soil fauna have the potential to serve as informative indicators of ecosystem health and disturbance in natural communities.
Lichens
Lichens were surveyed on the larger trees, oaks in particular. These trees were then mapped for future reference and qualitative and quantitative calculations were made. The lichen community, perhaps due to low light levels, was not extensive at either site, and due to its slow growth and difficulty in identification, will not be studied in detail until several years after a prescribed burn.
Gastropods
Terrestrial gastropods (snails and slugs) number over 100 species in Illinois and occupy many different habitats. How these animals may respond to an increase in herbaceous plants as a result of more light reaching the ground is an interesting question. From all our sites we have found and identified a combined total of 20 species of gastropods.
This study is one of the few to assess the effects of restoration on a wide range of organisms and we hope it will serve as a model for larger-scale, long-term studies of restoration in Illinois. Such studies will provide much needed information for procedures of woodland management that optimize species abundance, diversity, and stability.
Richard L. Larimore, Chris Dietrich, Ed Zaborski, Dave Ketzner, Jeff Brawn, INHS; Bob Szafoni, University of Illinois; and John Ebinger, Eastern Illinois University
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