Source: KANSAS STATE UNIV submitted to
SOIL NUTRIENT AVAILABILITY AND PLANT RESPONSE IN NATIVE AND RESTORED TALLGRASS PRAIRIE
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0182236
Grant No.
(N/A)
Project No.
KS535
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Mar 1, 1999
Project End Date
Mar 1, 2004
Grant Year
(N/A)
Project Director
Blair, J. M.
Recipient Organization
KANSAS STATE UNIV
(N/A)
MANHATTAN,KS 66506
Performing Department
BIOLOGY
Non Technical Summary
This research seeks to understand the factors cotrolling patterns of soil nutrient availability and plant responses in tallgrass prairie. This is crucial for designing more effective strategies for managing both native and restored tallgrass prairie.
Animal Health Component
20%
Research Effort Categories
Basic
80%
Applied
20%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1020199106034%
1020799106033%
1020320106033%
Goals / Objectives
We will quantify spatial and temporal patterns of soil resource availability in tallgrass priaire ecosystems, focusing on soil N pools and fluxes. Specific objectives are: i) to document changes in soil N pools and fluxes, and plant responses, in a large-scale "fire-treatment reversal experiment"; ii) to examine the effects of selected treatments (fire, mowing, nutrient additions) on soil nutrient pools and plant responses; iii) to document changes in soil resource heterogeneity in native and restored tallgrass prairie, and to examine the potential for manipulating soil resource availability and heterogeneity to enhance the recovery of restored grassland ecosystems.
Project Methods
Soil nutrient availability and plant responses will be quantified in new and ongoing field experiments at the Konza Prairie LTER site. These include: i) a "reversal of fire treatments" on selected watresheds (two annually burned and two unburned watersheds) to address the short- and long-term effects of altered fire regimes on soil nutrient pools, N mineralization rates, and plant responses; ii) a long-term plot experiment examining the soil-related mechanisms responsible for tallgrass prairie responses to fire, grazing and nutrient additions; and a prairie restoration project testing the hypotheses that increased soil resource heterogeneity will speed recovery of plant species richness and diversity in restored prairie. This will be done in a new tallgrass prairie restoration project in which soil N, soil depth and water availability are altered in a spatially-explicit manner within replicated restoration plots.

Progress 03/01/99 to 03/01/04

Outputs
Our research focused on two major areas (1) effects of grassland management on soil nutrients, soil biota, and plant responses in native tallgrass prairie, and (2) studies of grassland restoration ecology. We continued a long-term study of the effects of fire, mowing and nutrient additions, initiated at the Konza Prairie research site in 1986. We collected and analyzed new data on root growth dynamics, and we documented soil invertebrate responses, including long-term changes in relative abundance and composition of key macroinvertebrate groups (earthworms, cicadas, and families of Coleoptera)rimental manipulations. Our results demonstrated the importance of changing land-use practices (burning, mowing, fertilization) on belowground communities in grasslands. One important finding was that departures from historical disturbance regimes (i.e., frequent fire and grazing) renders grassland soils more susceptible to increased numbers of exotic earthworm species. We also completed a study of how grazers alter patterns of plant-available resources and alter plant species diversity in grazed grasslands. Grazing increased plant species richness by 25% over an eight-year period. Our results indicated that creation of a mosaic of patches with high and low plant biomass (and hence high and low light availability) and promotion of a dynamic species pool are important mechanisms by which grazers affect species richness in high productivity grasslands. We also continued our studies of grassland restoration ecology. A 12-year chronosequence of restored grasslands established through the Conservation Reserve Program (CRP) was used to (1) compare the structure and function of restored and native tallgrass prairie and (2) evaluate rates of change in ecosystem properties and processes. We found that native C4 grasses dominated vegetation composition after 6 years of grass establishment, and productivity of the restored grasslands was generally higher than native prairie in this region. Root biomass and C:N ratio increased along the chronosequence. Establishment of perennial grasses affected soil physical, chemical, and biological characteristics. Indices of labile soil C (i.e., microbial biomass and potential C mineralization rates) increased over the restoration chronosequence. Lastly, greater conservation of soil N occurred with increasing time in the CRP, as measured by reductions in available nitrate, net N mineralization rates, and net nitrification rates. We also completed, and published results from, an experiment to evaluate the potential for manipulating soil resources as a tool for grassland restoration. Our results showed that the effects of resource availability on productivity and diversity are similar in restored and native grasslands, and that manipulation of a limiting nutrient during grassland establishment can influence patterns of plant diversity in restored grasslands. However, our results also indicate that the importance of resource heterogeneity for restoring diversity and community resemblance to native grasslands may be dampened when a dominant species can successfully establish across a range of resource availability.

Impacts
Our research contributed new knowledge regarding the influence of management practices (fire, mowing, fertilization) on soil processes and soil biota in native prairie, and explored the potential for manipulating soil resources to improve prairie restorations. Understanding the relationships between management, soil resources and plant responses will lead to more effective management of native and restored prairies.

Publications

  • Baer, S.G., S.L. Collins, J.M. Blair, A. Fiedler and A.K. Knapp. 2004. Soil heterogeneity effects on tallgrass prairie community heterogeneity: an application of ecological theory to restoration ecology. Restoration Ecology. In Press.
  • Bohlen, P.J., R.W. Parmelee and J.M. Blair. 2004. Integrating the effects of earthworms on nutrient cycling across spatial and temporal scales. Pages 161-180 In Earthworm Ecology, 2nd Ed. (C.A. Edwards, ed.). CRC Press, St. Lucie Press, Boca Raton, Florida.
  • Silletti, A.M., A.K. Knapp and J.M. Blair. 2004. Competition and coexistence in grassland co-dominants: responses to neighbor removal and resource availability. Canadian Journal of Botany 82:450-460.
  • Baer, S.G., J.M. Blair, S.L. Collins, A.K. Knapp and A.K. Fiedler. 2004. Plant community responses to resource availability and heterogeneity during restoration. Oecologia 139:617-629.


Progress 01/01/03 to 12/31/03

Outputs
In 2003, we continued and expanded our research efforts in two areas: 1) effects of grassland management on soil nutrients, soil biota, and plant responses in native tallgrass prairie, and 2) studies of grassland restoration ecology. We continued a long-term study of the effects of fire, mowing and nutrient additions (the "Belowground Plot Experiment"), initiated at the Konza Prairie research site in 1986. We published a manuscript summarizing the long-term changes in soil macroinvertebrate communities in this experiment. This manuscript documented long-term changes in relative abundance and composition of key macroinvertebrate groups (earthworms, cicadas, and families of Coleoptera) as a result of our experimental manipulations. The results demonstrated the importance of changing land-use practices (burning, mowing, fertilization) on belowground communities in grasslands. One important finding was that departures from historical disturbance regimes (i.e., frequent fire and grazing) may render soils more susceptible to increased numbers of exotic earthworm species. We also completed analyses of data from a study to assess how large ungulates alter patterns of plant-available resources in grazed grasslands, and whether or not changes in patterns of resource availability are linked to increased plant species diversity in the presence of grazers. Grazing increased plant species richness by 25% over an eight-year period. Neither heterogeneity nor absolute levels of soil water or available nitrogen were related to patterns of species richness in grazed and ungrazed sites. However, high spatial heterogeneity in light and higher rates of species turnover were both strongly related to increases in plant species richness in grazed areas. Our results indicated that creation of a mosaic of patches with high and low plant biomass (and hence high and low light availability) and promotion of a dynamic species pool are important mechanisms by which grazers affect species richness in high productivity grasslands. We also continued our studies of grassland restoration ecology. We published results from an experiment that evaluated the potential for manipulating soil resources as a tool for grassland restoration. The results showed that the effects of resource availability on productivity and diversity are similar in restored and native grasslands, and that manipulation of a limiting nutrient during grassland establishment can influence patterns of plant diversity in restored grasslands. We also completed and submitted a second manuscript (in review), which examines whether general patterns of community assembly, developed for systems recovering naturally from disturbance and undisturbed communities, are applicable to restored communities. Our results suggest that the importance of resource heterogeneity for restoring diversity and community resemblance to native grasslands may be dampened when a dominant species can successfully establish across a range of resource availability. This article contributes to the growing body of theory regarding the relationships among resource availability, resource heterogeneity and plant community composition.

Impacts
Our research addresses how management practices (fire, mowing, fertilization) affect soils and soil biota in native prairie, and explores the potential for manipulating soil resources to improve prairie restorations. Understanding the relationships between management, soil resources and plant responses will lead to more effective management of native and restored prairies.

Publications

  • Baer, S. G., J. M. Blair, A. K. Knapp, and S. L. Collins. 2003. Soil resources regulate productivity and diversity in newly established tallgrass prairie. Ecology. 84:724-735.
  • Bakker, C., J. M. Blair, and A. K. Knapp. 2003. A comparative assessment of potential mechanisms influencing plant species richness in grazed grasslands. Oecologia. In Press.
  • Callaham, M. A., Jr., J. M. Blair, T. C. Todd, D. J. Kitchen, and M. R. Whiles. 2003. Effects of fire, mowing and fertilization effects on density and biomass of macroinvertebrates in North American tallgrass prairie soils. Soil Biology & Biochemistry. 35:1079-1093.


Progress 01/01/02 to 12/31/02

Outputs
In 2002, we focused our research efforts on (1) long-term studies of how grassland management affects soil nutrients, soil biota, and plant responses in native tallgrass prairie, and (2) studies of grassland restoration ecology. We continued treatments in a long-term study of the effects of fire, mowing and nutrient additions (the "Belowground Plot Experiment"), initiated at the Konza Prairie research site in 1986. In 2002, we published a study of the responses of belowground insect herbivores (cicadas) to these management combinations, and related these responses in insect herbivores to changes in plant community composition and plant resource quality. We also prepared and submitted a second manuscript (accepted pending successful revision) summarizing the long-term changes in soil macroinvertebrate communities in this experiment. In 2002, we also continued our studies of grassland restoration ecology. We published research results from a detailed analysis of a 12-year chronosequence of grasslands restored through the Conservation Reserve Program (CRP), focusing on how various aspects of ecosystem structure and function recover during the restoration processes. Among our key findings were that root biomass and the C:N ratio of roots increased throughout the 12 year chronosequence, and C and N storage in roots of restored grasslands approached that reported for tallgrass prairie that has never been cultivated. Establishment of perennial vegetation also affected soil physical, chemical, and biological characteristics. After 12 years in the CRP, total soil C in the surface 5 cm of restored grasslands was 26% greater than in recently restored fields, though still lower than in native prairie. Indices of labile C pools (i.e., microbial biomass and soil respiration) also increased over the restoration chronosequence. Although complete restoration of ecosystem structure and function was not the primary intention of the CRP, this study demonstrates that establishment of the matrix vegetation (i.e., native C4 grasses) drives ecosystem processes in the trajectory of the original system. We also published results from an experiment designed to evaluate the potential for manipulating soil resources as a tool for grassland restoration. Our results indicated that manipulation of available N and soil rooting depth can affect both productivity and species composition of newly-restored grasslands, and that manipulation of soil resources can be used to minimizing recruitment of weedy plant species without negatively impacting overall plant diversity or the growth of native prairie plants. In total, our results demonstrated that the effects of resource availability on productivity and diversity are similar in restored and mature grasslands, and that manipulation of a limiting nutrient during grassland establishment can influence floristic composition, with consequences for long-term patterns of diversity in restored ecosystems. Finally, we have continued to document how changes in vegetative cover from grasslands to woodlands can alter local productivity and biogeochemistry in the Flints Hills region.

Impacts
Our research addresses how management practices (fire, mowing, fertilization) affect soils and soil biota in native prairie, and explores the potential for manipulating soil resources to improve prairie restorations. Understanding the relationships between management, soil resources and plant responses will lead to more effective management of native and restored prairies.

Publications

  • Baer, S.G., J.M. Blair, A.K. Knapp and S.L. Collins. 2002. Soil resources regulate productivity and diversity in newly established tallgrass prairie. Ecology. In Press.
  • Baer, S.G., D.J. Kitchen, J.M. Blair and C.W. Rice. 2002. Changes in ecosystem structure and function in a chronosequence of grasslands restored through the Conservation Reserve Program. Ecological Applications. In Press.
  • Callaham, M.A., Jr., M.R. Whiles and J.M. Blair. 2002. Annual fire, mowing and fertilization effects on two cicadas (Homoptera:Cicadidae) in tallgrass prairie. American Midland Naturalist 148:90-101.


Progress 01/01/01 to 12/31/01

Outputs
In 2001, we continued ongoing studies aimed at understanding the effects of selected management practices on soil nutrient pools, soil biota, and plant responses in native tallgrass prairie. Specifically, we continued treatments in a long-term study of the effects of fire, mowing and nutrient additions (the "Belowground Plot Experiment"), initiated at the Konza Prairie research site in 1986. We continued to collect and analyze new data on root growth dynamics using a minirhizotron root imaging system. In 2001, we published a summary of how these treatments can alter the composition of the earthworm community, and affect the relative abundance of native and exotic earthworm species in prairie soils. We also continued our studies of prairie restoration ecology. A 12-year chronosequence of restored grasslands established through the Conservation Reserve Program (CRP) was used to (1) compare the structure and function of the restored ecosystems to native tallgrass prairie and (2) evaluate rates of change in ecosystem properties and processes over the restoration chronosequence. We found that native C4 grasses dominated vegetation composition after 6 years of grass establishment, and productivity of the restored grasslands was generally higher than native prairie in this region. Root biomass and the C:N ratio of roots increased along the chronosequence. Establishment of perennial grasses affected soil physical, chemical, and biological characteristics. Indices of labile soil C (i.e., microbial biomass and potential C mineralization rates) increased over the restoration chronosequence. Lastly, greater conservation of soil N occurred with increasing time in the CRP, as measured by reductions in available nitrate, net N mineralization rates, and net nitrification rates. Although complete restoration of ecosystem structure and function was not the primary intention of the CRP, this study demonstrates that establishment of the matrix vegetation (i.e., native C4 grasses) drives ecosystem processes in the trajectory of the original system. We also completed a third growing season in our studies of how resource availability and heterogeneity affects the recovery of native plant species in newly restored prairie. Results to date have shown that experimental manipulation of available N and soil rooting depth can affect both productivity and species composition of newly-restored grasslands, indicating that manipulation of soil resources is a useful tool for minimizing recruitment of weedy plant species without negatively impacting overall plant diversity or the growth of native prairie plants. Results from this study are being prepared for publication. Finally, we also completed, and have begun publishing results from, studies of how changes in vegetative cover from grasslands to woodlands can alter local productivity and biogeochemistry in the Flints Hills region of Kansas.

Impacts
This research examines soil nutrient availability and plant responses in native and restored tallgrass prairie. We are evaluating the effects of management practices (fire, mowing, fertilization) in native prairie, and the potential for manipulating soil resources to improve prairie restorations. Understanding the relationships between management, soil resources and plant responses will lead to more effective management of native and restored prairies.

Publications

  • Callaham, M.A., Jr., J.M. Blair and P.F. Hendrix. 2001. Different behavioral patterns of the earthworms Octolasion tyrtaeum and Diplocardia spp. in tallgrass prairie soils: potential influences on plant growth. Biology and Fertility of Soils 34:49-56.
  • Norris, M.D., J.M. Blair and L.C. Johnson. 2001. Land cover change in eastern Kansas: litter dynamics of closed-canopy eastern redcedar forests in tallgrass prairie. Canadian Journal of Botany 79:214-222.
  • Norris, M.D., J.M. Blair, L.C. Johnson and R.B. McKane. 2001. Developing allometric equations to assess shifts in biomass, productivity, and nutrient stores following Juniperus virginiana forest establishment in tallgrass prairie. Canadian Journal of Forest Research 31:1940-1946.


Progress 01/01/00 to 12/30/00

Outputs
In 2000, we continued with several long-term studies designed to elucidate the effects of selected management practices on soil nutrient pools, soil biota, and plant responses in native tallgrass prairie. An analysis of 14 years of data on grassland ecosystem responses to fire, aboveground biomass removal and N or P fertilization is nearing completion. We have been examining effects of these management practices on plant productivity, species composition, and soil properties, and plan to synthesize these results in a monograph. We have continued to obtain data on belowground plant responses (biomass, root depth distributions and plant tissue chemistry) in conjunction with this project. We made substantial progress in analyzing minirhizotron data for determining patterns of root growth, and presented these results at a national meeting in 2000. Our results to date indicate greater root length densities and greater absolute rates of root turnover in annually burned prairie. However, relative root turnover (expressed as a proportion of total root length) was greater in unburned prairie. This is consistent with higher root tissue quality (lower C:N ratios)in unburned prairie, as suggested more rapid turnover of root tissue N in the absence of burning. We also continued our studies of restored prairies. In 2000, we completed a study of CRP fields representing a chronosequence of restoration. Our results indicated little increase in total soil C and N pools, even 10 years after replanting with native grasses. However, there were significant increases in more labile soil pools, including active (mineralizable) soil C and microbial biomass C and N, and decreases in inorganic N availability. We completed a third growing season in our studies of how resource availability affects the recovery of native plant species in restored prairie. Results to date have shown that C amendments added at the initiation of the experiment were effective at stimulating microbial immobilization of soil N and maintaining lower N availability in the second and third growing season. The effects of reduced N availability in the initial three years of restoration have included reduced biomass and productivity of non-native plants, but not native prairie species. These results suggest that manipulation of soil resources may be a useful tool for minimizing recruitment of weedy plant species in the early phases of a prairie restoration, without negatively impacting overall plant diversity or the growth of native prairie plants.

Impacts
This research examines soil nutrient availability and plant responses in native and restored tallgrass prairie. We are evaluating the effects of management practices (fire, mowing, fertilization) in native prairie, and the potential for manipulating soil resources to improve prairie restorations. Understanding the relationships between management, soil resources and plant responses will lead to more effective management of native and restored prairies.

Publications

  • Blair, J.M., S.L. Collins and A.K. Knapp. 2000. Ecosystems as functional units in nature. Natural Resources & Environment 14:150-155.
  • Baer, S.G., C.W. Rice and J.M. Blair. 2000. Assessment of surface soil quality in field planted to native grasses with short- and long-term enrollment in the CRP. Journal of Soil and Water Conservation 55:142-146.
  • Fay, P.A., J.D. Carlisle, A.K. Knapp, J.M. Blair and S.L. Collins. 2000. Altering rainfall timing and quantity in a mesic grassland ecosystem: Design and performance of rainfall manipulation shelters. Ecosystems 3:308-319.


Progress 01/01/99 to 12/31/99

Outputs
Our research in 1999 has continued to examine the influence of selected management practices on soil nutrient pools, soil biota, and plant responses in native tallgrass prairie. As part of an ongoing, long-term study, we completed analysis of 13 years of data on aboveground plant productivity (ANPP) in response to annual fire, aboveground biomass removal and N fertilization. We also obtained data on belowground plant responses (biomass, root depth distributions and plant tissue chemistry), soil nutrient availability (N availability, net N mineralization and net nitrification), and soil invertebrate populations in these experimental plots. Results of this study demonstrate enhanced ANPP and total root biomass in response to annual burning, in spite of lower soil N availability. We've also used this experiment to document the effects of management on the relative abundance of selected groups of soil invertebrates, including native and exotic earthworm species in tallgrass prairie. We found invasive European species were most abundant in areas of high litter accumulation (unburned and not mowed) and in fertilized plots, while native taxa were proportionally more abundant in prairie that was burned, mowed and unfertilized. These results suggest that management practices that alter litter accumulation and nutrient status are important in affecting the success of invasive exotic earthworm taxa in tallgrass prairie. Sampling for other soil invertebrate groups (macro- and microarthropods) was also completed this year, and the analyses of these samples are underway. We have also continued our studies of the role of soil resource heterogeneity on plant productivity and species composition in newly restored prairie. Results to date suggest the C amendments added at the initiation of the experiment were effective at stimulating microbial immobilization of soil N and maintaining lower N availability in the second growing season. The effects of reduced N availability in the initial two years of restoration have included reduced biomass and productivity of non-native plants, but not native prairie species, and reduced diversity of non-native volunteer species, but no reduction in overall plant diversity. These results suggest that manipulation of soil resources may be a useful tool for minimizing recruitment of weedy plant species in the early phases of a prairie restoration, without negatively impacting overall plant diversity or the growth of native prairie plants.

Impacts
This research examines soil nutrient availability and plant responses in native and restored tallgrass prairie. We are evaluating the effects of management practices (fire, mowing, fertilization) in native prairie, and the potential for manipulating soil resources to improve prairie restorations. Understanding the relationships between management, soil resources and plant responses will lead to more effective management of native and restored prairies.

Publications

  • Baer, S.G., J.M. Blair and A.K. Knapp. 1999. Manipulation of soil resource heterogeneity in a tallgrass prairie restoration. Proceedings of the North American Prairie Conference 16:78-87.
  • Callaham, M.A. Jr. and J.M. Blair. 1999. Influence of differing land management on the invasion of North American tallgrass prairie soils by European earthworms. Pedobiologia 43:1-6.
  • Harmon, M.E., K.J. Naddlehoffer and J.M. Blair. 1999. Measuring decomposition, nutrient turnover and stores in plant litter. pp. 202-240 In Standard Soil Methods for Long Term Ecological Research (G.P. Robertson, D.C. Coleman , C.S. Bledsoe and P. Sollins, eds.) Oxford University Press, New York.
  • Robertson, G.P., D. Wedin, P.M. Groffman, J.M. Blair, E. Holland, K.J. Nadelhoffer and D. Harris. 1999. Soil carbon and nitrogen availability: Nitrogen mineralization, nitrification, soil respiration potentials. pp. 258-271 In Standard Soil Methods for Long Term Ecological Research (G.P. Robertson, D.C. Coleman , C.S. Bledsoe and P. Sollins, eds.) Oxford University Press, New York.