Soil Characteristics and Microbes Influencing Establishment of Prairie Species

M. Jernegan, V. Hustad, M. Tonsor, R. Jadhav, G. Ahrens and J. Coons
Eastern Illinois University, Department of Biological Sciences

Abstract

Illinois is known as the Prairie State, however prairie that once covered 22 million acres of the state now occupies a mere 0.01% of the original. Restoration of tallgrass prairies often is impeded by failure to establish diverse native prairie species because of soil characteristics including both physical and microbial factors. In Coles County (IL) attempts to establish prairie species in one area between a bike trail and a road have failed, yet prairie remnants and restored prairie exists at other nearby sites. Hence the objective of this study was to determine if soil characteristics or microbes affect emergence of prairie species from soils collected at these three sites (remnant prairie, restored prairie, and attempted restoration site). Soil was collected from each site, and analyzed to determine texture, pH, moisture, organic matter and nutrients. Half of the soil was autoclaved and the other half was not. Three common prairie species (Chamaechrista fasciculata, Dalea purpurea, and Monarda fistulosa) were planted in each type of soil in trays. Weekly observations were made for emergence, leaf number and height of planted species. Plants from seed bank also were counted weekly. After four weeks, mass and leaf area were measured. Soil had more clay, lower organic matter and higher pH at the restoration site than at remnant or restored prairies. The remnant prairie had higher moisture, phosphates and sulfates than the other sites. Plants in autoclaved soil tended to have greater emergence and faster plant development than those in non-autoclaved soil. Grass and forb emergence in autoclaved soil was reduced relative to not autoclaved soil. Plants grown in soil from the remnant prairie developed more rapidly than those in soil from the other two sites. Hence, problems with establishment at the restoration site may relate to soil characteristics.

Introduction
 

The original tallgrass prairie remaining in Illinois is scattered in small remnants along railroad tracks, in cemeteries and in restored areas. Prairies began to diminish when European settlers started to build railroads and houses, stopped using fire, and began to farm the fertile soil (Miller, 1997; Sampson and Knopf, 1996). In the 20th century, ecologists realized that tallgrass prairies in the Midwest were diminishing, and restoration of these historic grasslands began (Allison, 2002; Curtis and Greene, 1949). Soil conditions are essential to prairie vigor. Microorganisms including both beneficial ones (mycorrhizal fungi and nitrogen fixing bacteria) and harmful plant pathogens (fungi and bacteria) are found in soil (McClain, 1997). In Coles County (IL), attempts to establish prairie species in one area between a bike trail and a road have failed, yet prairie remnants and restored prairies exist at other nearby sites. The purpose of this study was to determine if soil characteristics or microbes affect emergence of prairie species from soils collected at these three sites. Information gained will aid with prairie restoration efforts.

Methods

• The remnant prairie is along an old railroad that is now a bike trial, the restored prairie was an agricultural field restored to a prairie, and the attempted restoration site is near a bike path & highway.

• Fifteen soil cores (15-35 cm deep and 2 cm wide) plus 3 shovelfuls of soil were collected from each site.

• Percent soil moisture, soil nutrients, and organic matter were determined using protocol from “The Science Source”, Waldoboro, Maine, Chemical Composition of Soil #2000.

• Soil texture was determined by shaking 5 ml soil, 30 ml distilled water, and 3 drops dispersing solution (Lamotte Chetertown, Maryland). After 1 week, heights of sand, silt and clay were measured to calculate percentages of each. Then a soil triangle was used to determine texture.

• pH was measured with a soil water-slurry mixture using a Corning pH meter Model 7.

• For plant development studies, half of the soil was autoclaved for 3 hours and half was not.

• For each site and autoclave treatment, three trays (10 X 20 X 6 cm) were planted with 20 seeds each of Chamaechrista fasciculata, Dalea purpurea, and Monarda fistulosa.

• Trays were placed in growth room with light intensity of 78.3 ± 9 µmol/m2/sec at 25.0 ± 2.1ºC.

• Plant species emerging from the seed bank were recorded as either grasses or forbs.

• After 4 weeks, emergence, height, leaf number, leaf area, and fresh and dry masses were measured.

• Data were analyzed using two-way analysis of variance followed by mean separations using Duncan’s multiple range test at 5% level where appropriate.

Results

• Soils of remnant & restored prairies were lower in clay & higher in organic matter than soil of the attempted restoration site.

• Moisture was highest in the remnant prairie.

• pH was highest at the attempted restoration site.

• Soil nutrients at these sites exhibit no consistent patterns.

Significance

• Overall growth for Dalea purpurea and Monarda fistulosa was greater when planted in soil from the remnant prairie than other sites.

• Growth for Chamaechrista fasciculata was not affected by site.

• Plants in autoclaved soil grew significantly better or similar to those in not autoclaved soil.

References

1. Allison, S.K. 2002. When is a restoration successful? Results from a 45-year-old tallgrass prairie restoration. Ecological Restoration 20 :10-17.
2. Curtis, J.T. and H.C. Greene. 1949. A study of relic Wisconsin prairies by the species-presence method. Ecology 30:80-92.
3. McClain, W.E. 1997. Prairie Establishment and Landscaping. Technical Publication #2. Division of Natural Heritage. Illinois Department of Natural Resources. Springfield, IL.
4. Miller. R.M. 1997. Prairie underground: The Tallgrass Restoration Handbook for Prairies, Savannas, and Woodlands. Packard, S. and C.E. Mutel (eds.), Island Press, Washington D.C. p.23-27.
5. Sampson, F.B. and F.L. Knopf. 1996. Prairie Conservation: Preserving North America’s Most Endangered Ecosystems. Island Press. Washington D.C. p. 41.

Acknowledgements

• Larry Thorsen and Douglas-Hart Nature Center for site selection.

• Troy Link for assistance with project.