Source: COLORADO STATE UNIVERSITY submitted to
ACTINORHIZAL SHRUBS IN FORESTS AND RANGELANDS OF COLORADO
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0134798
Grant No.
(N/A)
Project No.
COL00660
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Jul 1, 2008
Project End Date
Jun 30, 2011
Grant Year
(N/A)
Project Director
Paschke, M. W.
Recipient Organization
COLORADO STATE UNIVERSITY
(N/A)
FORT COLLINS,CO 80523
Performing Department
FOREST, RANGELAND, & WATERSHED STEWARDSHIP
Non Technical Summary
Actinorhizal shrubs and trees are a group of plants capable of forming symbiotic root nodules with nitrogen fixing bacteria called Frankia. These root nodules allow actinorhizal plants to obtain nearly all of their vital nitrogen requirements without having to take nitrogen from soil like other plants. This ability allows them to flourish in poor soils with low nitrogen. With their Frankia symbionts, actinorhizal shrubs play crucial roles in the recovery and restoration of disturbed ecosystems. Due to their ability to obtain lots of nitrogen in nitrogen-poor ecosystems, actinorhizal shrubs represent a very significant nutritional resource for wildlife. The health and vigor of actinorhizal shrubs is often closely linked to the health and vigor of wildlife populations. Despite this known importance, we know surprisingly little about the symbiosis between these shrubs and their vital Frankia bacteria. Conflicting reports as to whether or not these species are nodulated and the lack of information regarding how much if any nitrogen these plants contribute to ecosystems are glaring holes in our understanding of the basic functioning of these ecosystems. Our objective is to provide unique and crucial information regarding the basic ecology of actinorhizal shrubs in forest and rangeland ecosystems in Colorado. Specifically, we will provide the first estimates of the contributions of nitrogen by actinorhizal shrubs to these ecosystems. Our approach involves a combination of lab, greenhouse and field studies to determine if actinorhizal shrubs are capable of forming root nodules with Frankia bacteria under controlled and field conditions. We will quantify nitrogen fixation by these shrubs in the field and we will use molecular techniques to confirm the presence of Frankia bacteria in root nodules. The ecosystems where these actinorhizal shrubs occur include foothills shrublands, montane forests, subalpine forests, alpine tundra and sagebrush steppe. These ecosystems are a vital part of the culture and economy of Colorado and represent the primary places where Coloradoans work and play. The knowledge derived from the proposed work would allow for better management and restoration of these ecosystems, which would result in improved forest and rangeland health. For example, knowledge of the basic mechanics of nitrogen cycling in these systems would allow managers to make informed decisions regarding promoting or removing actinorhizal shrubs in order to alter vegetation health and development. Information that we obtain regarding nitrogen fixation by various Frankia strains might allow managers to inoculate sites or planted shrubs with appropriate Frankia strains. Additionally, information regarding differences in nitrogen fixation rates between various species, or the same species in various habitats would allow for better management of livestock grazing and the wildlife resources that are a vital part of Colorado's ecosystems and economy.
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1020612107012%
1020790107011%
1020850107011%
1210612107011%
1210790107011%
1210850107011%
1230612107011%
1230790107011%
1230850107011%
Goals / Objectives
The objective of this study is to provide unique and crucial information regarding the basic ecology of actinorhizal shrubs in forest and rangeland habitats in Colorado. Specifically, we will provide the first estimates of the contributions of biologically-fixed nitrogen by actinorhizal shrubs to a variety of forest and rangeland habitats in Colorado. Despite the ecological importance of the actinorhizal symbiosis in Colorado forests and rangelands, there is a paucity of research on the actinorhizal shrub species characteristic of the Interior West. The purpose of our research is to provide a baseline understanding of actinorhizal symbioses in a variety of managed ecosystems of Colorado. This research represents the first attempt to broadly determine rates of N2-fixation for these keystone shrubs. The knowledge derived from this work will allow for better management and restoration of these ecosystems, which would result in improved forest and rangeland health. For example, knowledge of the basic mechanics of nitrogen cycling in these systems will allow managers to make informed decisions regarding promoting or removing actinorhizal shrubs in order to alter successional trajectories of plant communities. Information that we obtain regarding N fixation by various Frankia strains might allow managers to inoculate sites or planted shrubs with appropriate Frankia strains. Additionally, information regarding differences in N2-fixation rates between various species, or the same species in various habitats would allow for better management of livestock grazing and the wildlife resources that are a vital part of Colorado's ecosystems and economy. The knowledge derived from these studies will be transferred to managers and scientists in the form of peer-reviewed publications and presentations at scientific meetings. Additionally, personnel in the Colorado Forest Restoration Institute that are associated with this project will be able to disseminate information to forest managers via the Institutes regular activities. Where appropriate, we will disseminate our finding via Colorado AES publications, such as Technical Bulletins or Technical Reports in order to reach land managers more directly. The project would result in the training of one graduate student (MS), one post-doc, and numerous undergraduate students.
Project Methods
The objective of this work is to provide unique and crucial information regarding the basic ecology of actinorhizal shrubs in forest and rangeland habitats in Colorado. Specifically, we will provide the first estimates of the contributions of biologically-fixed nitrogen by actinorhizal shrubs to a variety of forest and rangeland habitats in Colorado. Hypotheses to be tested include: H1: Actinorhizal shrubs in Colorado forests and rangelands are capable of forming a dinitrogen-fixing symbiosis with Frankia bacteria. H2: Actinorhizal shrubs in Colorado forests and rangelands are capable of contributing biologically-fixed nitrogen to the habitats where they occur. Our approach to testing these hypotheses involves lab, greenhouse and field studies to determine if actinorhizal species such as bitterbrush, mountain mahogany, buffaloberry and Ceanothus are capable of forming root nodules with Frankia bacteria under controlled and field conditions. We will quantify N2-fixation by these shrubs in the field and we will use molecular techniques to confirm the presence of N2-fixing Frankia bacteria in root nodules, and to study their diversity and biogeography in different host plant species and habitats. The proposed work would involve a diverse team of experts with much experience in these techniques. Due to the difficulty of excavating shrubs in the field, hypothesis 1 will be tested in the greenhouse. Various actinorhizal shrub species native to Colorado will be grown in a greenhouse under conditions of low-N availability. The shrubs will be inoculated with soil collected from beneath the same species growing in various habitats in Colorado. These greenhouse experiments will allow us to determine if these species are capable of forming this important symbiosis (H1) and will provide information about soil Frankia (strain types) from various habitats. Nodules that are formed in these studies will be sent to the Molecular Microbial Ecology Lab of Dr. Dittmar Hahn at Texas State University to confirm the presence of Frankia and to identify the Frankia strains present in the various nodules using molecular phylogenetic methods. At the same sites where soil inoculum is collected, we will determine the percentage of N derived by the actinorhizal shrubs from biological N2-fixation (%NDF) (H2). The general approach of Parrotta et al. (1994, 1996) will be employed. Additionally, at these same sites, we will estimate the significance of actinorhizal N inputs (H2) by surveying foliar and soil δ 15N in the surrounding plant community. At each study site, mineral soil from beneath actinorhizal shrubs, non-actinorhizal reference shrubs, and inter-shrub areas will be collected and analyzed for 15N. Foliage from these same shrubs will also be sampled and analyzed for 15N. Analysis of soil and foliage to estimate contributions of actinorhizal species to ecosystem N will follow the general procedures of Rhoades et al. (in press).

Progress 07/01/08 to 06/30/11

Outputs
OUTPUTS: Activities for this project focused on collection, analysis and synthesis of data from a large field survey of the dinitrogen-fixing understory shrub, buffaloberry (Shepherdia canadensis). The field data were collected in 2010 with some follow-up data collection in the spring of 2011. The purpose of these studies was to determine the role of buffaloberry in the ecology of Colorado forests impacted by mountain pine beetle. In the summer of 2010, we established and inventoried 59 study plots in the Colorado State Forest and the Arapahoe Roosevelt and Routt National Forests. These 59 sites were established across a gradient of forests with varying amounts of deforestation by mountain pine beetle and overstory harvesting. At each study site we measured overstory canopy cover as well as understory cover of buffaloberry. We also collected soil samples as well as buffaloberry and reference shrub foliage and analyzed these materials for nitrogen isotopic ratios. These analyses allowed us to estimate the percent of N derived from biological nitrogen fixation by buffaloberry in this ecosystem and provide the first estimate of the contribution of buffaloberry to the N economy of Colorado forests. By sampling sites with various levels of canopy closure we were able to determine the relationship between canopy removal by mountain pine beetles and dinitrogen fixation by buffaloberry. These results have been prepared for dissemination to the user community. The graduate student, Zoe Miller, successfully defended her thesis in 2011. Based on Ms. Miller's thesis, we have prepared a manuscript for publication, which will be submitted upon incorporation of results of follow up studies from 2011. Ms. Miller presented results of this study at the Society for Range Management annual meeting in February, 2011. Preliminary findings were presented at the 2010 annual meeting of the Society for Range Management. PARTICIPANTS: Individuals: Mark W. Paschke, PI/PD; Dan Binkley, coPI Chuck Rhoades, coPI; Dittmar Hahn, collaborator; Jeffrey O. Dawson, collaborator; Brett Wolk, Research Associate; Zoe Miller, MS student; Partner Organizations; USDA Forest Service, Rocky Mountain Research Station; Texas State University; University of Illinois Training or professional development. The project involved the training of one MS student (Zoe Miller), one research associate (Brett Wolk), and one postdoc (Jayne Jonas). TARGET AUDIENCES: Managers of forests and rangelands in the Colorado Rocky Mountains and surrounding states. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Our results demonstrate that buffaloberry can provide a significant source of biological N to forests in north central Colorado. We determined that buffaloberry derives between 70 and 96% of its N from biological fixation in root nodules. Therefore, since buffaloberry is a major understory shrub species in this region, it could provide a significant source of N in these N-limited high elevation forests. We have thus shown that buffaloberry could be an important tool for managers to aid recovery of disturbed lands. Buffaloberry is known to be an important browse species for wildlife and livestock. Our results indicate that its importance to wildlife and livestock is likely related to its N-fixing ability in these N-poor soils. Contrary to our hypothesis, we did not observe changes in the percent N derived from fixation in buffaloberry associated with canopy opening by mountain pine beetle. In other ecosystems, researchers have found increases in N-fixation with increased light availability. It is possible that in Colorado forests potential increases in N-fixation due to increased light availability may be offset by reduced soil moisture associated with increased light. As Colorado forests continue to change in response to mountain pine beetle, managers can expect there to be little impact on N-fixation rates by buffaloberry, and perhaps the species that rely on it.

Publications

  • Miller, Z.M. 2011. An investigation of nitrogen fixation by russet buffaloberry in Colorado conifer forests. M.S. Thesis. Department of Forest and Rangeland Stewardship, Colorado State University, Fort Collins, CO. 84pp.


Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: Activities for this project in 2010 have focused on a large field survey of the dinitrogen-fixing understory shrub, buffaloberry (Shepherdia canadensis) in order to determine its role in the ecology of Colorado forests impacted by mountain pine beetle. In the summer of 2010, we established and inventoried 59 study plots in the Colorado State Forest and the Arapahoe Roosevelt and Routt National Forests. These 59 sites were established across a gradient of forests with varying amounts of deforestation by mountain pine beetle and overstory harvesting. At each study site we measured overstory canopy cover as well as understory cover of buffaloberry. We also collected soil samples as well as buffaloberry and reference shrub foliage and analyzed these materials for nitrogen isotopic ratios. These analyses allowed us to estimate the percent of N derived from biological nitrogen fixation by buffaloberry in this ecosystem and provide the first estimate of the contribution of buffaloberry to the N economy of Colorado forests. By sampling sites with various levels of canopy closure we were able to determine the relationship between canopy removal by mountain pine beetles and dinitrogen fixation by buffaloberry. These results are currently being prepared for dissemination to the user community. The graduate student, Zoe Miller, is preparing her thesis for defense in February 2011. We will submit one or two manuscripts for publication in peer-reviewed journals in 2011. Ms. Miller will present results of this study at the Society for Range Management annual meeting in February, 2011. Preliminary findings were presented at the 2010 annual meeting of the Society for Range Management. PARTICIPANTS: Individuals Mark W. Paschke, PI/PD Dan Binkley, coPI Chuck Rhoades, coPI Dittmar Hahn, collaborator Jeffrey O. Dawson, collaborator Brett Wolk, Research Associate Zoe Miller, MS student Partner Organizations USDA Forest Service, Rocky Mountain Research Station. Texas State University University of Illinois Training or professional development The project currently involves the training of one MS student (Zoe Miller) and one research associate (Brett Wolk). TARGET AUDIENCES: Managers of forests and rangelands in the Colorado Rocky Mountains and surrounding states. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Our results from 2010 studies demonstrate that buffaloberry can provide a significant source of biological N to forests in north central Colorado. We determined that buffaloberry derives between 70 and 96% of its N from biological fixation in root nodules. Therefore, since buffaloberry is a major understory shrub species in this region, it could provide a significant source of N in these N-limited high elevation forests. We have thus shown that buffaloberry could be a important tool for managers to aid recovery of disturbed lands. Buffaloberry is known to be an important browse species for wildlife and livestock. Our results indicate that its importance to wildlife and livestock is likely related to its N-fixing ability in these N-poor soils. Contrary to our hypothesis, we did not observe changes in the percent N derived from fixation in buffaloberry associated with canopy opening by mountain pine beetle. In other ecosystems, researchers have found increases in N-fixation with increased light availability. It is possible that in Colorado forests potential increases in N-fixation due to increased light availability may be offset by reduced soil moisture associated with increased light. As Colorado forests continue to change in response to mountain pine beetle, managers can expect there to be little impact on N-fixation rates by buffaloberry, and perhaps the species that rely on it.

Publications

  • No publications reported this period


Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: Activities for this project, which started in July 2008, have been focused on a field survey of the actinorhizal shrub, buffaloberry (Shepherdia canadensis) in order to determine its role in the recovery of forests impacted by mountain pine bettle. In June 2009, we identified sites in the Colorado State Forest and the Arapahoe Roosevelt and Routt National Forests. In July 2009, a crew of 6 collected data from 60 sites that vary across light and soil gradients as well as in areas affected by mountain pine beetle and overstory harvesting. We took measurements in one 20 m circular plot at each site. In each plot we measured overstory canopy cover as well as understory cover of buffaloberry. We also collected a small amount of buffaloberry and reference shrub foliage to analyze for 15N content and use it to determine N fixation amounts at each site. We also collected a small soil sample to determine 15N content, total nitrogen, and total carbon. Finally, berry production was measured at each site by quantifying un-ripened berries. Collected material has been prepared for analysis at the Mass Spectrometry lab at Colorado State University. In addition, we have propagated buffaloberry shrubs that will serve as material for a detailed greenhouse study of N-fixation by this species as it related to the ecology of mountain forests in Colorado. PARTICIPANTS: Individuals: Mark W. Paschke, PI/PD Dan Binkley, coPI Chuck Rhoades, coPI Dittmar Hahn, collaborator Jeffrey O. Dawson, collaborator Brett Wolk, Research Associate Zoe Miller, MS student Partner Organizations: USDA Forest Service, Rocky Mountain Research Station. Texas State University University of Illinois The project currently involves the training of one MS student (Zoe Miller) and one research associate (Brett Wolk). TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Because the data for this study, which was collected in the summer and fall of 2009, is still being analyzed, there have not been any impacts at this time.

Publications

  • Mirza, B.S., A. Welsh, G. Rasul, J.P. Rieder, M.W. Paschke and D. Hahn. 2009. Variation in Frankia populations of the Elaeagnus host infection group in nodules of six host plant species after inoculation with soil. Microbial Ecology 8:384-393.
  • Welsh, A., B.S. Mirza, J.P. Rieder, M.W. Paschke and D. Hahn. 2009. Diversity of frankiae in root nodules of Morella pensylvanica grown in soils from five continents. Systematic and Applied Microbiology 32:201-210.


Progress 07/01/08 to 12/31/08

Outputs
OUTPUTS: Activities for this project, which started in July 2008, have been focused on identifying suitable study sites and collecting preliminary data on 15N abundance in actinorhizal shrubs. During the fall of 2008, we conducted a survey of six actinorhizal species at four sites in Colorado. At each site, we collected tissue of actinorhizal shrubs and suitable reference species. Collected material has been prepared for analysis at the Mass Spectrometry lab at Colorado State University. In addition, we have collected dormant shoot cuttings of actinorhizal buffaloberry shrubs. These cuttings have been rooted and will serve as material for a detailed greenhouse study of N-fixation by this species. PARTICIPANTS: Individuals Mark W. Paschke, PI/PD Dan Binkley, coPI Chuck Rhoades, coPI Dittmar Hahn, collaborator Jeffrey O. Dawson, collaborator Brett Wolk, Research Associate Zoe Miller, MS student Partner Organizations USDA Forest Service, Rocky Mountain Research Station. Texas State University University of Illinois Training or professional development The project currently involves the training of one MS student (Zoe Miller) and one research associate (Brett Wolk). TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Because this project started in July of 2008, there have not been any impacts at this time.

Publications

  • No publications reported this period


Progress 01/01/07 to 12/31/07

Outputs
OUTPUTS: We have used a series of controlled greenhouse screening studies where seedlings of reclamation species and common agricultural species are grown in sand culture and exposed to supplemental concentrations of soluble metals. We then determine six measures of toxicity: The 60-day LC50, 60-day EC50-plant, 60-day EC50-shoot, 60-day EC50-root, PT50-shoot, and the PT50-root. In addition, we provide data on tissue metal concentrations of various plant species exposed to varying levels of metals. During 2007, a greenhouse experiment to determine zinc toxicity thresholds for reclamation shrub species was completed. This study involved an undergraduate student who is part of the Hughes Undergraduate Research Scholars Program. Results from this study are being prepared for publication. PARTICIPANTS: Individuals Mark W. Paschke, PI/PD Edward F. Redente, coPI Julie Rieder, post doctoral research associate Paul Swartzinski, MS student Jennifer Shanahan, MS student Jessica Bailey, MS student Johanna Hamburger, undergraduate research associate Collaborators Joe Brummer, Colorado State University, Department of Soil and Crop Sciences Training or professional development During 2007, the project involved the training of one post doc (Rieder), three MS students (Swartzinski, Bailey, Shanahan) and one undergraduate student (Hamburger). TARGET AUDIENCES: The target audience for this work has been government regulators, consultants, and those in the reclamation/restoration industry.

Impacts
Metal toxicity thresholds for plant species that are used in restoration activities in Western North America have not been established. Ecological risk assessments must rely on toxicity thresholds established for agronomic species, which usually differ from those of species used in restoration. As a result, risk assessors have the potential for classifying sites as phytotoxic to perennial, non-agronomic species and calling for intensive remediation activities that may not be necessary. The objective of this study is to provide a better estimate of metal toxicity thresholds for plant species that are commonly used in restoration efforts in the Western United States. In addition, the studies that we are conducting are reporting on the uptake of potentially toxic metals by common rangeland plants. This information is extremely valuable for selecting rangeland restoration species where the future land use will involve grazing by domestic livestock. Results from our studies suggest that restoration species generally have higher metal tolerance than agronomic species reported in the past. Thresholds determined by our studies are more useful for risk assessors than those used in the past, which were based largely on agronomic crops. Our research provides phytotoxicity thresholds for plants commonly used in remediation of hazardous waste sites in the Western U.S. This information is extremely valuable to ecological risk assessors and restoration ecologists involved in the characterization and restoration of metal-contaminated sites by providing information that is critical for making decisions about the degree of contamination and the extent of restoration required. To date, our published findings from this project have been cited 24 times in the literature (Web of Science, 2008). In addition, our results are being used by land mangers in Colorado to determine which plant species to plant on rangelands with naturally high concentrations of soil metals. The uptake information for these rangeland species that we are providing allows these managers to avoid planting species that could result in toxicity to domestic livestock. Additionally, our results are being used by regulators working with rangeland application of municipal biosolids (for example, the city of Fort Collins recycles biosolids on rangeland at the city-owned Meadow Springs Ranch). These biosolids have known metal content and our data allows for the more-informed use of biosolids on rangelands.

Publications

  • Shanahan, J.O., J.E. Brummer, W.C. Leininger and M.W. Paschke. 2007. Manganese and zinc toxicity thresholds for mountain and geyer willow. International Journal of Phytoremediation 9: 437-452.


Progress 01/01/06 to 12/31/06

Outputs
Metal toxicity thresholds for plant species that are used in restoration activities in Western North America have not been established. Ecological risk assessments must rely on toxicity thresholds established for agronomic species, which usually differ from those of species used in restoration. As a result, risk assessors have the potential for classifying sites as phytotoxic to perennial, non-agronomic species and calling for intensive remediation activities that may not be necessary. The objective of this study is to provide a better estimate of metal toxicity thresholds for plant species that are commonly used in restoration efforts in the Western United States. We have used a series of greenhouse screening studies where seedlings of reclamation species and common agricultural species are grown in sand culture and exposed to supplemental concentrations of soluble metals. We then determine six measures of toxicity: The 60-day LC50, 60-day EC50-plant, 60-day EC50-shoot, 60-day EC50-root, PT50-shoot, and the PT50-root. During 2006, an experiment to determine copper toxicity thresholds for reclamation shrub species was completed. Results from this study are being prepared for publication. A study of zinc toxicity thresholds for shrub species has been initiated. Also during 2006, a manuscript describing Zn toxicity in forb species was published in Water Air and Soil Pollution. Results from these studies suggest that restoration species generally have higher metal tolerance than agronomic species reported in the past. Thresholds determined by these studies should be more useful for risk assessors than those currently used, which are based largely on agronomic crops.

Impacts
Our research provides phytotoxicity thresholds for plants commonly used in remediation of hazardous waste sites in the Western U.S. This information will be extremely valuable to ecological risk assessors and restoration ecologists involved in the characterization and restoration of metal-contaminated sites by providing information that is critical for making decisions about the degree of contamination and the extent of restoration required.

Publications

  • Paschke, M.W., L.G. Perry and E.F. Redente. 2006. Zinc toxicity thresholds for reclamation forb species. Water, Air and Soil Pollution 170:317-330.
  • Sullivana, T.S., M.E. Stromberger and M.W. Paschke. 2006. Long-term impacts of infrequent biosolids applications on chemical and microbial properties of a semi-arid rangeland soil. Biol. Fertil. Soils 42:258-266.
  • Sullivana, T.S., M.E. Stromberger and M.W. Paschke. 2006. Parallel shifts in plant and soil microbial communities in response to biosolids in a semi-arid grassland. Soil Biology and Biochemistry 38: 449-459.


Progress 01/01/05 to 12/31/05

Outputs
Metal toxicity thresholds for plant species that are used in restoration activities in Western North America have not been established. As a result, ecological risk assessments must rely on toxicity thresholds established for agronomic species, which usually differ from those of species used in restoration. The reliance on agronomic thresholds means that\risk assessors have the potential for classifying sites as phytotoxic to perennial, non-agronomic species and calling for intensive remediation activities that may not be necessary. The objective of this study is to provide a better estimate of metal toxicity thresholds for grass and forb species that are commonly used in restoration efforts in the Western United States. We have used a series of greenhouse screening studies where seedlings of reclamation species and common agricultural species are grown in sand culture and exposed to supplemental concentrations of soluble metals. We then determine six measures of toxicity: The 60-day LC50, 60-day EC50-plant, 60-day EC50-shoot, 60-day EC50-root, PT50-shoot, and the PT50-root. During 2005, an experiment to determine manganese toxicity thresholds for reclamation shrub species was completed. A study of copper toxicity thresholds for shrub species was initiated and the greenhouse phase of the study was completed in December 2005. Laboratory analysis of plant tissues from an experiment examining Mn toxicity in forbs was completed in early 2005. Also during 2005 a manuscript describing Mn toxicity in forb species was published in Environmental Pollution. A manuscript describing Zn toxicity in forb species has been accepted for publication in Water Air and Soil Pollution. Results from these studies suggest that restoration species generally have higher metal tolerance than agronomic species reported in the past. Thresholds determined by these studies should be more useful for risk assessors than those currently used, which are based largely on agronomic crops.

Impacts
Our research provides phytotoxicity thresholds for plants commonly used in remediation of hazardous waste sites in the Western U.S. This information will be extremely valuable to ecological risk assessors and restoration ecologists involved in the characterization and restoration of metal-contaminated sites by providing information that is critical for making decisions about the degree of contamination and the extent of restoration required.

Publications

  • Paschke, M.W., K. Topper, R.B. Brobst and E.F. Redente. 2005. Long-term effects of biosolids on revegetation of disturbed sagebrush steppe in Northwestern Colorado. Restoration Ecology 13:545-551.
  • Paschke, M.W., A. Valdecantos and E.F. Redente. 2005. Manganese toxicity thresholds for important restoration grass species of the Western United States. Environmental Pollution 135:313-322.
  • Perry, L.G., C. Johnson, E.R. Alford, J.M. Vivanco and M.W. Paschke. 2005. Screening of grassland plants for restoration after spotted knapweed invasion. Restoration Ecology 725-735.
  • Ippolito, J. A., E. F. Redente, and K.A. Barbarick. 2005. Amendment effects on pH and salt content of bauxite residue. Soil Science 170:832-841.


Progress 01/01/04 to 12/31/04

Outputs
Metal toxicity thresholds for plant species that are used in restoration activities in Western North America have not been established. As a result, ecological risk assessments must rely on toxicity thresholds established for agronomic species, which usually differ from those of species used in restoration. As a result, risk assessors have the potential for classifying sites as phytotoxic to perennial, non-agronomic species and calling for intensive remediation activities that may not be necessary. The objective of this study is to provide a better estimate of metal toxicity thresholds for grass and forb species that are commonly used in restoration efforts in the Western United States. We have used a series of greenhouse screening studies where seedlings of reclamation species and common agricultural species are grown in sand culture and exposed to supplemental concentrations of soluble metals. We then determine six measures of toxicity: The 60-day LC50, 60-day EC50-plant, 60-day EC50-shoot, 60-day EC50-root, PT50-shoot, and the PT50-root. During 2004, an experiment to determine manganese toxicity thresholds for reclamation forb species was completed. A study of manganese toxicity thresholds for shrub species was initiated. Laboratory analysis of plant tissues from an experiment examining Cu toxicity in forbs was completed in 2004. Also during 2004 a manuscript describing Mn toxicity in forb species was accepted for publication in Environmental Pollution. A manuscript describing Zn toxicity in forb species was prepared in 2004 and will be submitted to New Phytologist in January 2005. Results from these studies suggest that restoration species generally have higher metal tolerance than agronomic species reported in the past. Thresholds determined by these studies should be more useful for risk assessors than those currently used, which are based largely on agronomic crops.

Impacts
Our research provides phytotoxicity thresholds for plants commonly used in remediation of hazardous waste sites in the Western U.S. This information will be extremely valuable to ecological risk assessors and restoration ecologists involved in the characterization and restoration of metal-contaminated sites by providing information that is critical for making decisions about the degree of contamination and the extent of restoration required.

Publications

  • Lair, Kenneth D. and Edward F. Redente. 2004. Influence of auxin and sulfonylurea herbicides on seeded native communities. J. Range Management 57:211-218.
  • Meyer, V.F., E.F. Redente, K.A. Barbarick, R. Brobst, M.W. Paschke and A. Miller. 2004. Plant and soil responses to biosolids application following forest fire. Journal of Environmental Quality 33:873-881.
  • Barbarick, K.A., K. G. Doxtader, E. F. Redente, and R. B. Brobst. 2004. Biosolids effects on microbial activity in shrubland and grassland soils. Soil Science 169:176-187.
  • Dillon, J.H., M.W. Paschke and E.F. Redente. 2004. Comparison of sucrose and dextrose as carbon amendments for soil nitrogen sequestration. Society for Range Management 2004 Annual Meeting. January 2004, Salt Lake City, Utah.
  • Klein, D.A. and M.W. Paschke. 2004. Filamentous fungi: the indeterminate lifestyle and microbial ecology. Microbial Ecology. 47: 224-235.


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

Outputs
Metal toxicity thresholds for plant species that are used in restoration activities in Western North America have not been established. As a result, ecological risk assessments must rely on toxicity thresholds established for agronomic species, which usually differ from those of species used in restoration. As a result, risk assessors have the potential for classifying sites as phytotoxic to perennial, non-agronomic species and calling for intensive remediation activities that may not be necessary. The objective of this study is to provide a better estimate of metal toxicity thresholds for grass and forb species that are commonly used in restoration efforts in the Western United States. We have used a series of greenhouse screening studies where seedlings of reclamation species and common agricultural species are grown in sand culture and exposed to supplemental concentrations of soluble metals. We then determine six measures of toxicity: The 60-day LC50, 60-day EC50-plant, 60-day EC50-shoot, 60-day EC50-root, PT50-shoot, and the PT50-root. During 2003, studies of copper and arsenic toxicity thresholds for reclamation forb species, and a third study of arsenic toxicity thresholds for reclamation grass species were completed. Manuscripts for these three studies are in preparation and will be submitted during 2004. Results suggest that restoration species generally have higher metal tolerance than agronomic species reported in the past. Thresholds determined by these studies should be more useful for risk assessors than those currently used, which are based largely on agronomic crops.

Impacts
Our research provides phytotoxicity thresholds for plants commonly used in remediation of hazardous waste sites in the Western U.S. This information will be extremely valuable to ecological risk assessors and restoration ecologists involved in the characterization and restoration of metal-contaminated sites by providing information that is critical for making decisions about the degree of contamination and the extent of restoration required.

Publications

  • Paschke, M. W., E. F. Redente, and S. L. Brown. 2003. Biology and establishment of mountain shrubs on mining disturbances in the Rocky Mountains, USA. Land Degradation & Development 14:459-480.
  • Ippolito, J.A., K.A. Barbarick, D.M. Heil, J.P. Chandler, and E.F. Redente. 2003. Phosphorus retention mechanisms of a water treatment residual. J. Environ. Qual. 32:1857-1864.
  • Vanderhood, L. A. 2003. Assessment of soil development following a sub-alpine mine reclamation. Ph.D. Thesis. Colorado State University, Fort Collins, CO.


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

Outputs
Metal toxicity thresholds for plant species that are used in restoration activities in Western North America have not been established. As a result, ecological risk assessments must rely on toxicity thresholds established for agronomic species, which usually differ from those of species used in restoration. As a result, risk assessors have the potential for classifying sites as phytotoxic to perennial, non-agronomic species and calling for intensive remediation activities that may not be necessary. The objective of this study is to provide a better estimate of metal toxicity thresholds for grass and forb species that are commonly used in restoration efforts in the Western United States. We have used a series of greenhouse screening studies where seedlings of reclamation species and common agricultural species are grown in sand culture and exposed to supplemental concentrations of soluble metals. We then determine six measures of toxicity: The 60-day LC50, 60-day EC50-plant, 60-day EC50-shoot, 60-day EC50-root, PT50-shoot, and the PT50-root. During 2002, studies of copper, manganese and arsenic toxicity thresholds for reclamation grass species, and a forth study of zinc toxicity thresholds for reclamation forb species were completed. Results from the copper study have been published in the scientific literature. Manuscripts for the manganese, arsenic and zinc / forb studies are in preparation. Results suggest that restoration species generally have higher metal tolerance than agronomic species reported in the past. Thresholds determined by these studies should be more useful for risk assessors than those currently used, which are based largely on agronomic crops.

Impacts
Our research provides phytotoxicity thresholds for plants commonly used in remediation of hazardous waste sites in the Western U.S. This information will be extremely valuable to ecological risk assessors and restoration ecologists involved in the characterization and restoration of metal-contaminated sites by providing information that is critical for making decisions about the degree of contamination and the extent of restoration required.

Publications

  • Redente, E. F., H. Zadeh, and M. W. Paschke. 2002. Phytotoxicity of smelter-impacted soils in southwest Montana, USA. Environmental Toxicology and Chemistry 21:269-274.
  • Ippolito, J.A., K. A. Barbarick, and E. F. Redente. 2002. Combinations of water treatment residuals and biosolids affect two range grasses. Commun. Soil Science Plant Anal. 33:831-844.
  • Winter-Sydnor, M. E. and E. F. Redente. 2002. Reclamation of high-elevation acidic mine waste with organic amendments and topsoil. J. Environmental Quality 31:1528-1537.
  • Paschke, Mark W. and Edward F. Redente. 2002. Copper toxicity thresholds for important reclamation grass species of the western United States. Environmental Toxicology and Chemistry 21:2692-2697.
  • Schuman, Gerald and Edward F. Redente. 2002. Rehabilitation of mined surfaces. p. 147-156 In Grice, A. C. and K. C. Hodgkinson, eds. Global Rangelands, Progress and Prospects. CABI Publishing, New York, NY.


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

Outputs
**Copper toxicity thresholds developed to aid restoration decision makers.** Copper toxicity thresholds for plant species that are used in restoration activities in Western North America have not been established. As a result, ecological risk assessments must rely on toxicity thresholds established for agronomic species, which usually differ from those of species used in restoration. As a result, risk assessors have the potential for classifying sites as phytotoxic to perennial, non-agronomic species and calling for intensive remediation activities that may not be necessary. The objective of this study was to provide a better estimate of Cu toxicity thresholds for five grass species that are commonly used in restoration efforts in the western United States. We used a greenhouse screening study where seedlings of redtop (Agrostis gigantea Roth), slender wheatgrass (Elymus trachycaulus [Link] Gould ex Shinners var Pryor), tufted hairgrass (Deschampsia caespitosa (L.) Beauv.), big bluegrass (Poa secunda J. Presl var Sherman), basin wildrye (Leymus cinereus [Scribn. & Merr.] A. Love var Magnar), and common wheat (Triticum aestivum L.) were grown in sand culture and exposed to supplemental concentrations of soluble Cu ranging from 0 (control) to 300 mg L-1. We determined six measures of toxicity: 1) The 60-day LC50, 2) 60-day EC50-plant, 3) 60-day EC50-shoot, 4) 60-day EC50-root, 5) PT50-shoot, and 6) the PT50-root. Results suggest that these restoration grass species generally have higher Cu tolerance than agronomic species reported in the past. Of the species tested, redtop appeared to be especially tolerant of high levels of substrate and tissue Cu. Values of EC50-plant for restoration grasses were between 283 and 710 mg Cu L-1 compared to 120 mg Cu L-1 for common wheat. Measured PT50-shoot values were between 737 and 10792 mg Cu L-1. Tolerance to Cu for these grasses can be categorized as follows: redtop > big bluegrass > tufted hairgrass > slender wheatgrass > basin wildrye > common wheat. From our data it appears that redtop would be a good species for restoration of Cu contaminated sites. Big bluegrass might also be a useful restoration species on Cu contaminated sites where grazing is to occur, as this species appears to exclude uptake of Cu to shoots relative to the other species tested. Our observation that the agronomic species used in this experiment (common wheat) was the least Cu tolerant species based on EC50-plant is important because it indicates that risk assessments conducted using EC50's for agronomic species may call for remediation efforts that might not be justifiable where restoration grass species are to be used.

Impacts
Our research provides phytotoxicity thresholds for plants commonly used in the remediation of hazardous waste sites in the western U.S. This information will be extremely valuable to ecological risk assessors and restoration ecologists involved in the characterization and restoration of metal contaminated sites by providing information that is critical for making decisions about degree of contamination and extent of restoration required.

Publications

  • Meyer, V. F., E. F. Redente, K. A. Barbarick, and R. Brobst. 2001. Biosolids application affect runoff water quality following forest fire. J. Environ. Quality 30:1528-1532.
  • Newman Gregory J. and Edward F. Redente. 2001. Long-term plant community development as influenced by revegetation techniques. J. Range Management 54:717-724.
  • Bilodeau, Rebecca. 2001. A simulation model of seedling competition between Bromus tectorum, Pseudoroegneria spicata, and Artemisia tridentata. MS Thesis, Colorado State University, Fort Collins, CO 62 pp.
  • Grantham, William P., Edward F. Redente, Calvin F. Bagley, and Mark W. Paschke. 2001. Tracked vehicle impacts to vegetation structure and soil erodibility. J. Range Management 54: 711-716.
  • Zadeh, Holley. 2001. Successional patterns and rates of recovery of disturbed sites in Rocky Mountain National Park, Colorado. MS Thesis, Colorado State University, Fort Collins, CO 80 pp.


Progress 01/01/00 to 12/31/00

Outputs
Increased concentrations of heavy metals in soils can lead to toxic effects in plants. Potentially toxic quantities of heavy metals in soils largely result from anthropogenic sources. These include mining and smelting activities, textile and microelectronics industries, pyrometallurgical industries, fossil fuel combustion, agriculture sources (fertilizers, manures and pesticides), corrosion of metals and, waste disposal such as land application of sewage sludge. Metal toxicity thresholds for plants can be used to estimate a plant's ability to establish and survive on a contaminated site. Unfortunately, there is a paucity of data on toxicity thresholds for native plant species. Most work on metal effects on native plant species has focused on relative toxicity of species or ecotypes for selection and use in phytoremediation efforts. The vast majority of plant metal toxicity thresholds have been determined for agricultural species. As a result, ecological risk assessments and natural resource damage assessments under CERCLA (Comprehensive Environmental Response, Compensation, and Liability Act) must rely on toxicity thresholds established for agronomic species. These crop plants may have very different physiological characteristics and sensitivity levels than species used in the reclamation of sites contaminated with metals and may therefore be inappropriate for these ecological assessments. In this study, we have described Zn, Cu, and Mn toxicity thresholds for five grass species that are commonly used in reclamation activities in Western North America. Until now, this information has been unavailable and, as a result, ecological risk assessments have relied on toxicity thresholds established for agronomic species. We used a greenhouse screening study where seedlings of redtop (Agrostis alba Roth), slender wheatgrass (Elymus trachycaulus [1] Gould ex Shinners var Pryor), tufted hairgrass (Deschampsia caespitosa (L.) Beauv.), big bluegrass (Poa ampla J. Presl var Sherman), and Great Basin wildrye (Leymus cinereus [Scribn. & Merr.] A. Love var Magnar) were grown in sand culture and exposed to concentrations of soluble Zn,Cu, or Mn. We determined six commonly-used measures of toxicity in this study: 1) The 50-day LC50 (the concentration of metal that kills 50% of the seedlings by 50 days), 2) The 50-day EC50-plant (the concentration of metal that reduces seedling biomass by 50% after 50 days), 3) The 50-day EC50-shoot (the concentration of metal that reduces shoot biomass by 50% after 50 days) 4) The 50-day EC50-root (the concentration of metal that reduces root biomass by 50% after 50 days), 5) The PT50-shoot (the shoot metal concentration corresponding to a 50% seedling biomass reduction) and 6) The PT50-root (the root metal concentration corresponding to a 50% seedling biomass reduction).

Impacts
Our research provides the first measure of phytotoxicity thresholds for plants commonly used in the remediation of hazardous waste sites in the western U.S. This information will be extremely valuable to ecological risk assessors and restoration ecologists involved in the characterization and restoration of metal contaminated sites by providing information that is critical for making decisions about degree of contamination and extent of restoration required.

Publications

  • Arthur, D. 2000. Restoration at the Rocky Mountain Arsenal National Wildlife Refuge. Ph.D. Dissertation. Colorado State University. Fort Collins, CO.
  • Meyer, V. 2000. The effect of biosolids application on erosion control and ecosystem recovery following the Buffalo Creek fire. M.S. Thesis. Colorado State University. Fort Collins, CO.
  • Paschke, M.W., Redente, E.F., Levy, D.B. 2000. Zinc toxicity thresholds for important reclamation grass species of the Western United States. Environmental Toxicology and Chemistry 19:2751-2756.
  • Pierce, B. 2000. Microbial responses to biosolids treatment of rangeland. Ph.D. Dissertation. Colorado State University. Fort Collins, CO.
  • Sydnor, R.S. and Redente, E.F. 2000. Long-term plant community development on topsoil treatments overlying a phytotoxic growth medium. J. Environmental Quality 29:1778-1786
  • Stevenson, B., McLendon, T., and Redente, E.F. 2000. Effects of soil fumigation and seeding regimes on secondary succession in a semiarid shrubland. Arid Soil Research and Rehabilitation 14:87-99.
  • Winter, M. 2000. Reclamation of waste rock at the Summitville Mine Superfund site using organic matter and topsoil treatments. M.S. Thesis. Colorado State University. Fort Collins, CO.


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

Outputs
Increased concentrations of Zn in soils can lead to toxic effects in plants. Potentially toxic quantities of Zn in soils largely result from anthropogenic sources. These include mining and smelting activities, fossil fuel combustion, pesticides, and waste disposal such as land application of sewage sludge. Metal toxicity thresholds for plants can be used to estimate a plant's ability to establish and survive on a contaminated site. Unfortunately, there is a paucity of data on toxicity thresholds for native plant species. The vast majority of plant metal toxicity thresholds have been determined for agricultural species. As a result, ecological risk assessments and natural resource damage assessments under CERCLA (Comprehensive Environmental Response, Compensation, and Liability Act) must rely on toxicity thresholds established for agronomic species. These crop plants may have very different physiological characteristics and sensitivity levels than species used in the reclamation of sites contaminated with metals and may therefore be inappropriate for these ecological assessments. In this study, we describe Zn toxicity thresholds for five grass species that are commonly used in reclamation activities in Western North America. Until now, this information has been unavailable and, as a result, ecological risk assessments have relied on toxicity thresholds established for agronomic species. We used a greenhouse screening study where seedlings of redtop (Agrostis alba Roth), slender wheatgrass (Elymus trachycaulus [1] Gould ex Shinners var Pryor), tufted hairgrass (Deschampsia caespitosa (L.) Beauv.), big bluegrass (Poa ampla J. Presl var Sherman), and Great Basin wildrye (Leymus cinereus [Scribn. & Merr.] A. Love var Magnar) were grown in sand culture and exposed to concentrations of soluble Zn ranging from 0.6 (control) to 500 mg L-1. We determined six commonly-used measures of toxicity in this study: 1) The 50-day LC50 (the concentration of metal that kills 50% of the seedlings by 50 days), 2) The 50-day EC50-plant (the concentration of metal that reduces seedling biomass by 50% after 50 days), 3) The 50-day EC50-shoot (the concentration of metal that reduces shoot biomass by 50% after 50 days) 4) The 50-day EC50-root (the concentration of metal that reduces root biomass by 50% after 50 days), 5) The PT50-shoot (the shoot metal concentration corresponding to a 50% seedling biomass reduction) and 6) The PT50-root (the root metal concentration corresponding to a 50% seedling biomass reduction). Results suggest that these grass species have higher Zn phytotoxicity thresholds (PT50s) than agronomic species reported in the past. Roots appeared to be more susceptible to the toxic effects of zinc (as indicated by reduced growth) than shoots. This observation suggests that measures of EC50- shoot alone may be misleading for these species where growth reduction is primarily manifested in roots. Values of EC50-plant for these reclamation grasses were between 84 and 222 mg L-1. Measured PT50-shoot values were between 2449 and 5026 mg L-1. These thresholds should be more useful for risk assessors than those based on agronomic crops that are currently used.

Impacts
Our research provides the first measure of phytotoxicity thresholds for plants commonly used in the remediation of hazardous waste sites in the western U.S. This information will be extremely valuable to ecological risk assessors and restoration ecologists involved in the characterization and restoration of metal contaminated sites by providing information that is critical for making decisions about degree of contamination and extent of restoration required.

Publications

  • Levy, David B., Redente, E.F., and Uphoff, G.D. 1999. Phytotoxicity assessment of native grasses growing in Pb-Zn tailings Tri-State Mining District, USA. Soil Science 164:363-375.
  • Ippolito, J.A., Barbarick, K.A., and Redente, E.F. 1999. Co-application effects of water treatment residuals and biosolids on two range grasses. J. Environmental Quality 28:1644-1650


Progress 01/01/98 to 12/31/98

Outputs
**Changing soil nitrogen levels speeds restoration on degraded rangeland** Results from our previous work strongly suggest that N cycling is an important control mechanism during secondary succession, and that, when appropriately manipulated, N availability can be an important management tool. We have demonstrated that the reduction of N availability can greatly accelerate the rate of recovery of abandoned croplands towards a more desirable plant community composed of native perennial plant species. However, to utilize this information for management, we need to develop a practical understanding of the long-term consequences of N manipulation in plant communities. Therefore, the overall objective of our research is to determine if N-stress related changes in plant community structure and function have long term consequences following removal of the N-related stressor. Supporting objectives include answering the questions: 1) will changes in plant community composition resulting from N manipulation be long-lasting, or will the systems rapidly revert to pre-treatment conditions once the N-stressor is removed? and, 2) will the below- ground system show a marked decline in terms of structural and functional attributes once N manipulations are ended, resulting in concomitant plant community changes? In finding the answers to these questions we hope to develop general guiding principles for the restoration of degraded rangelands based on the manipulation of soil N-availability. Results of our previous studies have indicate that available nitrogen (N) controls the rate and course of recovery of abandoned croplands in the shortgrass steppe of Colorado. The addition of N slowed the rate of plant community succession at all of the previously cultivated sites in the study. Whereas, reducing N availability increased the rate of succession and recovery of the sites towards productive rangelands. Changes in N availability were coupled with distinct changes in soil microbial community composition and function during succession. Experimental manipulations of N availability (additions of N and sucrose) ceased in 1997. During the first growing season of the current project (1998) we have observed that the changes to plant community composition caused by reduced N availability (sucrose addition) at the early- and mid-successional sites have continued. These low N plots have continued on their accelerated course toward later seral conditions despite the halting of sucrose additions. In contrast, sucrose treated plots at the late-seral and uncultivated sites appear to be more similar to untreated control plots than they were 1996, the last year of treatment. Similar results have been observed for N amended plots, with past treatment effects being more evident at the early- and mid-seral sites.

Impacts
(N/A)

Publications

  • BOWERMAN, A.G., and REDENTE, E.F. 1998. Biointrusion of protective barriers at hazardous waste sites. J. Envir. Qual. 27:625-632.
  • HORN, B.E., and REDENTE, E.F. 1998. Soil nitrogen and plant cover of an old-field on the shortgrass steppe in southeastern Colorado. Arid Soil Res. and Rehab. 12:193-206.
  • KLEIN, D.A., PASCHKE, M.W., and REDENTE, E.F. 1998. Assessment of fungal-bacterial development in a successional shortgrass steppe by direct integration of chloroform-fumigation extraction and microscopically derived data. Soil Biol. Biochem. 30:573-581.
  • LAIR, K.D. 1998. Influence of herbicides and environmental factors on revegetation success in the Conservation Reserve Program in Southeastern Colorado. Ph.D. Thesis. Colorado State University, Fort Collins, CO
  • PIERCE, B.L., REDENTE, E.F., BARBARICKK. A., BROBST, R.B., and HEGEMAN, P. 1998. Plant biomass and elemental changes in shrubland forages following biosolids application. J. Envir. Qual. 27:789- 794.


Progress 01/01/97 to 12/31/97

Outputs
**Rate of secondary succession increased thereby decreasing time required to restore degraded rangelands throughout Colorado** Role of nitrogen (N) availability in plant and soil community dynamics during rangeland recovery is assessed along a chronosequence of abandoned cropland in N. central Colo. Purpose of research is to investigate a promising method for increasing rate of secondary succession following disturbance, thereby decreasing time necessary to restore degraded rangelands. Results to date indicated that changes in N avail. are coupled with distinct changes in plant and soil community composition during succession. Early-seral communities are dominated by exotic annual plants and high levels of active soil bacteria. Later-seral communities are characterized by native perennial plants and higher proportion of less active soil fungi. At all stages of succession, reduction of N avail. from addition of sucrose resulted in decrease in relative biomass of annual plant species and increase in perennial species. Increase of N avail. from N additions resulted in increase in relative biomass of annual plant species and decrease in perennial species. A significant portion of annual species we are reducing, or increasing, by N addition are undesirable introduced species that are often the target of weed control programs. During course of succession, and in response to N manipulations, we have observed concomitant changes in rates of litter decomposition and N mineralization. N reduction resulted in significant declines in litter decomposition rates at all study sites. During same time, N additions stimulated rates of nitrification while reducing overall rates on N-mineralization. We observed changes in belowground microbial community related to successional status and N manipulations. Increased fungal hyphal lengths occurred at late-seral sites in comparison with early- and mid-seral sites, indicating succession allowed increased development of this component of the system. Significant increase in total fungal biomass also occurred with decreased N availability, which was reflected in total microbial biomass value. Bacteria, in comparison, did not show consistent responses to changes in N avail. Reducing soil N avail. caused plant and soil communities to take on later-seral characteristics, whereas increasing soil N avail. caused plant and soil communities to take on earlier-seral characteristics. Results suggest N manipulation has potential to be a powerful tool to rapidly alter rate and course of secondary succession on abandoned cropland. Understanding mechanistic role of N in ecosystem recovery is important not only for mgmt. of deteriorated rangeland, but also for understanding long-term consequences of N enrichment associated with deposition of nitrogen oxide pollutants from fossil fuel combustion.

Impacts
(N/A)

Publications

  • REDENTE, E. F., MCLENDON, T., AND AGNEW W. 1997. Influence of topsoil depth on plant community dynamics of a seeded site in northwest Colorado. Arid Soil Res. and Rehab. 11:139-149.
  • REDENTE, E. F. AND RICHARDS, J. L. 1997. Effects of lime and fertilizer amendments on plant growth in smelter impacted soils in Montana. Arid Soil Res. and Rehab. 11:353-366.
  • BANAR, ALETHEA K. 1997. The distribution of species in a mixed grass prairie remnant: a test of the core-satellite hypothesis. M.S. Thesis, Colo. State Univ., Fort Collins, CO. 74 p.
  • KLEIN, D. A., PASCHKE, M. W., AND REDENTE, E. F. 1997. Integration of fumigation extraction and microscopically derived data to assess fungal-bacterial structure in soil. Annual Meeting of the American Society of Microbiology, Miami Beach, FL May 1997.
  • REICH, R. M., C. D. BONHAM, AND K. L. METZGER. 1997. Modeling small-scale spatial interaction of shortgrass prairie species. Ecological Modeling 101:163-174.
  • REICH, R. M., K. L. METZGER, AND C. D. BONHAM. 1997. Application of permutation procedures for comparing multi-species point patterns of grassland plants. Grassland Sci. 43 (3):189-195.
  • FLIPPIN-DUDLEY, SYNDI J. 1997. Vegetation measurements for estimating flow resistance. Ph.D. Dissertation. Colorado State University, Ft. Collins.


Progress 01/01/96 to 12/30/96

Outputs
Results to date indicate that changes in nitrogen (N) availability are coupled with distinct changes in plant and soil community composition during succession. At all stages of succession, a reduction of N availability from addition of sucrose has resulted in a decrease in relative biomass of annual plant species and an increase in perennial species. An increase in N availability has resulted in an increase in relative biomass of annuals and a decrease in perennials. A significant portion of the annual species that we are reducing by N reduction or increasing by N addition, are undesirable introduced species that are often the target of weed control programs. In addition to changing species composition, an increase in N availability has resulted in greater allocation to shoots, whereas, a reduction in N availability has resulted in an increased allocation to roots. We have also observed concomitant changes in rates of litter decomposition and N mineralization with changes in N availability. We have also observed changes in the belowground microbial community related to successional status and N manipulations. Total fungal/total bacterial ratio increased with succession. Reducing soil N availability caused soil communities to take on later seral characteristics, whereas, increasing soil N availability caused soil communities to take on earlier-seral characteristics. We have thus hastened successional processes with soil N reduction and hindered successional development with N enrichments.

Impacts
(N/A)

Publications

  • KLEIN, D. A., McLENDON, T., PASCHKE, M. W. AND REDENTE, E. F. 1996. N availability and fungal-bacterial responses in successional semiarid steppe soils. Arid Soil Res. And Rehab. 10:321-332.
  • PASCHKE, M. W., McLENDON, T., KLEIN, D. A., AND REDENTE, E. F. 1996. Effects on N availability on plant and soil communities during secondary succession on a shortgrass steppe. Bulletin of the Ecological Soc. of America. 77:342.
  • HORN, BLAINE E. 1996. Influence of soil nitrogen availability on an old-field plant community. Ph.D. Diss., Colo. State Univ., Fort Collins, 117 p.
  • REDENTE, E.F. AND BAKER, D.A. 1996. Direct Revegetation of mine tailing: a case study in Colorado. 7th Billings Symp., Planning, Rehab. and Treatment of Disturbed Lands. Montana State Univ. Reclamation Research Unit Publ #9603. Bozeman, MT.
  • XIAO, X, WANG, Y, OJIMA, DS, AND BONHAM, CD. 1996. Temporal variation in aboveground biomass of Aneurolepidium chinense (leymus chinense) steppe from popul. to commun. levels in the Xilin river basin, Inner Mong., China. Vegetatio123:1-12.


Progress 01/01/95 to 12/30/95

Outputs
Succession is the process by which ecosystems recover from disturbance. Soil nitrogen (N) availability is an important mechanism controlling the rate of succession. Increased N availability slows the recovery rate and decreased N availability increases the rate. Therefore, the recovery rate of previously cultivated rangelands should be increased by controlling available soil N. In the fall of 1993, this study was initiated in a shortgrass steppe community to test these concepts. Four sites were selected that represent a successional chronosequence (from 4 to 38 years) following abandonment of cultivation. Each site was treated with fertilizer to raise the level of soil N and sucrose, to lower the level of soil N. Following two growing seasons of applying nitrogen or sucrose, all four sites have shown significant changes in species composition with changes in N availability. When N availability is high, the presence of lichens are significantly reduced, late-seral species decrease, and early-seral species increase. When N availability is reduced, the presence of lichens is unchanged, late-seral species increase in importance, and early-seral species decline. Data for soil microbial activity, litter decomposition, soil N pools, and plant tissue N are currently being analyzed from samples collected in 1995. The results from this work provide evidence of the importance of soil N availability as a mechanism controlling the rate of succession and therefore the recovery of disturbed rangelands.

Impacts
(N/A)

Publications

  • HARRIS-PIERCE, R.L., REDENTE, E.F. and BARBARICK, K.A. 1995. Sewage sludge appl. effects on runoff water quality in a semiarid grassland. J.Envir. Qual. 24:112-115.
  • HOFFMANN, L.A., REDENTE, E.F. and McEWEN. 1995. Effects of selective seed predation by rodents on shortgrass establishment. Ecol. Appl. 5:200-208.
  • KLEIN, D.A., McLENDON, T., PASCHKE, M.W. and REDENTE, E.F. 1995. Saprophytic fungal-bacterial biomass variations in successional communities of a semi-arid steppe ecosystem. Biol. Fertil. Soils 19:253-256.
  • RICHARD, C.E. and REDENTE, E.F. 1995. Nitrogen and phosphorus effects on blue grama and buffalograss interactions. J.Range Mgmt. 48:417-422.
  • ANGLETON, G. and BONHAM, C.D.. 1995. Least squares regression vs. geometric mean regression for ecotoxicology studies. Appl. Math. & Comp. 72:21-32.
  • BRADY, W., MITCHELL, J., BONHAM, C.D. and COOK, J. 1995. Assessing the power of the point-line transect to monitor changes in plant basal cover. J Range Mgmt. 48:187-190.
  • BONHAM, C.D, REICH, R., and LEADER, K. 1995. Spatial cross-correlation of Bouteloua gracilis with site factors. Grassland Sci. 41:196-201.
  • RYAN, M. 1995. Application of ecological risk assessment problem formulation to livestock grazing. MS Thesis, Colo State Univ, Ft Collins, 41p.
  • LEADER, G. 1995. Macroinvertebrates as bioindicators of water quality on elk su.


Progress 01/01/94 to 12/30/94

Outputs
One of the specific objectives of this project is to determine the effects of biosolids (sewage sludge) application on rangeland ecosystem structure and function. This study was initiated because of the increasing interest in land application of biosolids as the technology of choice because it provides a method to recycle a useful by-product and uses natural ecosystem processes to reduce environmental degradation. This study is being conducted at two sites in Colorado. The first site is a shortgrass prairie, and the second is a sagebrush shrubland. Both sites were treated with biosolids at application rates that ranged from 0 to as high as 40 Mg/ha. Plant and soil measurements were made between 1992 and 1994 to determine the effect of surface applying biosolids on plant community structure and production, concentration of heavy metals in plant tissue, and accumulation of essential nutrients and heavy metals in soils. The results from these studies indicate that biosolids can be surface applied to rangelands in an environmentally acceptable way without causing changes in community structure or increasing levels of heavy metals in plants and soils that would be potentially toxic.

Impacts
(N/A)

Publications

  • EHRLICH, J. 1994. Plant community development, nitrogen pools, and decomposition rates along a disturbance gradient in Rocky Mountain National Park. M.S. Thesis. Colorado State University. 76 p. 1994. M.S. Thesis.
  • HARRIS-PIERCE, R. 1994. The effect of sewage sludge application on native rangeland soils and vegetation. M.S. Thesis. Colorado State Univ., Fort Collins, CO. 137 p. 1994. M.S. Thesis.
  • PIERCE, R. 1994. The effect of biosolids application on a semiarid rangeland site in Colorado. M.S. Thesis. Colorado State Univ., Fort Collins. 129 p.
  • ZAKELY, R.T. 1994. Plant community disturbance evaluation, Grand Teton National Park: Successional responses to natural and induced vegetation recovery. M.S. Thesis. Colorado State Univ., Fort Collins. 83 p.
  • XIAO, X. 1994. Climate and soil texture controls of grassland ecosystem properties in Inner Mongolia from patch to regional scales. Ph.D. Thesis. Colorado State Univ., Ft. Collins. 153 p.
  • REMINGTON, K.K., C.D. BONHAM, AND R.M. REICH. 1994. Modeling the distribution Agropyron cristatum biomass in a grazed pasture using the Weibull distribution. J. Japanese Society of Grassland Sci. 40:190-197.


Progress 01/01/93 to 12/30/93

Outputs
In May of 1993 a new project was initiated to determine the role of nitrogen availability as a primary control mechanism in shrub establishment within grasslands and to determine the competitive relationships between mid- and late-seral grasses and shrubs in relation to nitrogen availability. The research is being conducted to improve our understanding of the developmental dynamics of shrublands on western rangelands. Understanding the complex dynamics of replacement of grassland communities by shrubs becomes increasingly important as more stress is placed on these systems by the multiple demands of our society, increases in nitrogen levels from atmospheric and agricultural depositions, and by possible global climatic changes. This research is focusing on the mechanisms controlling the successional responses which will hold the greatest potential for increasing our understanding of the response patterns being produced. Research is being conducted in the field where mid- and late-seral grasses and shrubs are growing together under an induced available nitrogen gradient.

Impacts
(N/A)

Publications

  • MCLENDON, T. AND REDENTE, E.F. 1993. Vegetation Restoration Research, Rocky Mountain National Park: Anthropic Disturbance, Patterns of Secondary Succession, and Alternative Sources of Fill Material. NPS No.1268-1-9002. 45p.
  • MCLENDON, T., REDENTE, E.F., AND STEVENSON, B.A. 1993. Effects of Soil Fumigation and Initial Species Composition on a Semiarid Secondary Succession. 78th Ann. ESA Mtg. Madison, WI. 74:355.
  • PIERCE B.L., REDENTE, E.F., AND BARBARICK, K.A. 1993. The Effect of Biosolids Application on Native Rangeland Soils and Vegetation at Wolcott, Colorado. EPA Ann. Rpt. 83p.
  • REICH, R.M., BONHAM, C.D., AND K.K. REMINGTON. 1993. Double Sampling Revisited. J. Range Mange. 46:88-90.
  • COTTS, N.R. AND REDENTE, E.F. 1993. Evaluation of Revegetation Techniques for , Grand Teton National Park. NPS No.PX1200-8-0932. 54p. n
  • HARRIS, R.L., REDENTE, E.F., AND BARBARICK, K.A. 1993. The Effect of Sewage a Sludge Application on Native Rangeland Soils and Vegetation at Meadows Springs Ranch. City of Fort Collins, CO. 84p.
  • HUBBARD, D.C. 1993. Application of Climate-Soil Water Balance Model on Reclaimed Mine Spoil in the Piceance Basin. M.S. Thesis. Colo. State Univ. 90p.
  • MCLENDON, T. AND REDENTE, E.F. 1993. Vegetation Restoration Management Plan Rocky Mountain National Park. NPS No.1268-1-9002. 27p.


Progress 07/01/92 to 06/30/93

Outputs
Experiments were conducted at a Colorado shortgrass steppe site to test whether small mammal foraging acts as a trophic constraint on native grass establishment. Five native grasses that vary from large to small seed size were seeded at three densities in replicated plots within and outside rodent exclosures. Vegetation data (seedling frequency, percent cover, and aboveground biomass) were collected to assess establishment. Capture-recapture studies revealed that heteromyid granivores, Dipodomys ordii and Perognathus hispidus comprised approximately 40% of the local rodent community. Seed foraging was positively related to seed size and to seeding density, particularly where large-seeded grass species were present. Spatial heterogeneity is characteristic of most ecosystems. The objective is to identify and characterize forage production in relation to scales of vegetation patterns as affected by elk grazing and the occurrence of tree canopy. Data from a previous study was analyzed using Moran's I values to determine pattern scales for vegetation and soil characteristics of an ungrazed site. Analyses revealed that blue grama biomass was significantly autocorrelated in a negative manner, spatially, with soil pH and percent clay in the top 15 cm of soil.

Impacts
(N/A)

Publications

  • BENKOBI, L. 1992. Actual and simulated soil loss as a function of various amounts and types of surface cover. Ph.D. Thesis, Colo. State Univ., Fort Collins. 108 pp.
  • COTTRELL, T. R. AND BONMAN, C. D. 1992. Characteristics of sites occupied by subspecies of Artemisia tridentata in the Piceance Basin, Colorado. Great Basin Nat. 52:174-178.
  • HOFFMANN, L. 1992. Small mammal granivory and herbivory: trophic constraints on the establishment of native grasses. Ph.D. Thesis, Colo. State Univ., Fort Collins. 107 pp.
  • MCLENDON, T. AND REDENTE, E. 1992. Effects of nitrogen limitation on secondary succession dynamics on a semiarid sagebrush site. Oecologia 91:312- 317.
  • REDENTE, E., FRIEDLANDER, J. E., AND MCLENDON, T. 1992. Response of early and late successional species to nutrient gradients. Plant and Soil 140:127- 135.
  • REMINGTON, K. K., BONHAM, C. D., AND REICH, R. M. 1992. Blue grama- buffalograss responses to grazing: a Weibull distribution. J. Range Mange. 45:272-276.


Progress 07/01/91 to 06/30/92

Outputs
Research was initiated to determine whether small mammal granivory and herbivoryconstrains the establishment of seeded native grasses in revegetation. Indications are that rodent granivory is primarily by Heteromyid rodents, particularly kangaroo rats (Dipodomys ordii). Large seeds are preferred over smaller seeds. Buchloe dactyloides and Bouteloua curtipendula are preferred, Bouteloua gracilis is minimally disturbed. Panicum virgatum is most severely grazed by cottontail rabbits (Syvilagus audubonii). Small mammals constrain but do not eliminate grass establishment. Plant establishment was measured on CRP lands for monitoring purposes. An efficient method to measure spatial patterns was tested utilizing Stipa comata and Agropyron smithii. Data analysis included the Blocked-Quadrat-Variance (BQV), Paired-Quadrat-Variance (PQV), and Two Term Local Quadrat Variance (TTLQV) methods. In another study of pattern analyses, the three-parameter Weibull distribution was evaluated as an alternative to normal distribution in modelling the frequency distributions of p height and biomass as a function of grazing intensity (light and heavy) over the growing season on shortgrass steppe. Weibull gave better results than did the normal distribution.

Impacts
(N/A)

Publications

  • BONHAM, C.D., T.R. COTTRELL, AND J.E. MITCHELL. 1991. Inferences for Life History Strategies of Artemisia Tridentata Subspecies. J. Veg. Sci. 2:339-.
  • REEVES, F. B. AND REDENTE, E. F. 1991. The Importance of Mutualism in Succession. IN: Skujins, J. (Ed.). Semiarid Lands and Deserts: Soil Resource and Reclamation. Marcel Dekker, Inc. New York, NY, pp. 423-442.
  • MCLENDON, T. AND REDENTE, E. F. 1990. Secondary Succession Patterns Following Soil Disturbance in a Sagebrush Steppe Community. Oecologia 85:293-300.
  • COTTS, N.R., REDENTE, E. F., AND SCHILLER, R. 1991. Restoration Methods for Abandoned Roads at Lower Elevations in Grand Teton National Park. Arid Soil Research and Rehabilitation. 5:235-249.
  • COTTS, N. R. AND REDENTE, E. F. 1991. Restoration Techniques for Road Disturbances in Grand Teton National Park. Proc. of the 1991 Nat'l Mtg. of the Am. Soc. for Surface Mining and Reclamation. Princeton, WV.
  • BONHAM, C.D. 1991. The State of Range Management on Public Lands. Rangelands. 13:239-240.
  • REMINGTON, K.K. 1991. M.S. Thesis. Bouteloua gracilis and Buchloe Dactyloides Response to Grazing: A Weibull Distribution. Colo. State Univ., Fort Collins. 27 pp.


Progress 01/01/90 to 12/30/90

Outputs
Research is focusing on the effects of herbivory and granivory by small mammals on the establishment of native grass species in semiarid grasslands. Small mammal activities can influence plant community composition as rodents select large-seeded over small-seeded species. This may be related to higher energetic and nutritional values as a result of larger caryopses or more numerous caryopses within a bur. Evaluation of reseeding efforts on Conservation Reserve Program (CRP) lands includes estimation of plant biomass produced by the several species planted. As seeds germinate and become established, it is known that various spatial patterns develop. A Normal and Weibull disstribution were compared to estimate average seeded crested wheatgrass forage production. The Normal Distribution was found to fit all cases of data for plant height and weight. It appears that as plants develop into mature stands of grasses, plant biomass follow a Weibull Distribution. Spatial patterns of forage production in blue grama-buffalograss communities were measured in conjunction with grazing. These patterns were observed as developed with respect to grazing intensities of light and heavy. Patterns and estimates of available forage were described by the parameters of the Gamma Distribution, which allows an interpretation as to level of homogeneity in height and biomass of individual plant species.

Impacts
(N/A)

Publications

  • BONHAM, C.D., MACK, S.E., and TRLICA, M.J. 1990. Leaf conductance and transpiration of winterfat associated with 2 species of wheatgrass on disturbed sites. J. Range Manage. 43:501-505.
  • BONHAM, C.D., and MACK, S.E. 1990. Root distribution of EUROTIA LANATA in association with two species of AGROPYRON on disturbed soils. Bot. Gaz. (Dec).
  • CARPENTER, A.T., MOORE, J.C., and REDENTE, E.F. 1990. Plant community dynamics in a semiarid ecosystem in relation to nutrient addition following a major disturbance. Plant and Soil 126:91-90.
  • COTTS, N.R. 1990. Evaluation of restoration techniques for Grand Teton National Park. M.S. Thesis. Colo. State Univ., Fort Collins, CO 97 pp.
  • McLENDON, T., and REDENTE, E.F. 1990. Nitrogen and phosphorus effects on secondary succession dynamics on a semiarid sagebrush site. EcoL. Soc. America Ann. Meet. 71:248.
  • RICHARD, C.E. 1990. Nitrogen and phosphorus effects on blue grama and buffalograss interactions. M.S. Thesis. Colo. State Univ., Fort Collins, CO. 78 pp.
  • RICHARD, C.E., and REDENTE, E.F. 1990. Competition between blue grama and buffalograss for nitrogen and phosphorus. Abst. Soc. for Range Manage. Ann. Meet., Reno, NV.
  • STARK, J.M., and REDENTE, E.F. 1990. Copper fertilization to prevent molybden.


Progress 01/01/89 to 12/30/89

Outputs
Establishment and competitive requirements between blue grama (Bouteloua gracilis) and buffalograss (Buchloe dactyloides) were studied under field conditions. Seedlings from both species have similar morphologies until stolons are developed by buffalograss. Competitive effects are minimal between species and do not significantly affect seedling development. Buffalograss seedlings produced up to one-meter size plants in a single year. Nutrient-rich versus nutrient-poor greenhouse studies between these two species indicated blue grama had greater biomass than buffalograss with low P and equal biomass with high P. High nutrient availability intensifies competition between the species. Seventy-five stands with different compositions of blue grama and buffalograss were sampled in 1987 in another study. Multiple regression and principal component analysis techniques were used to investigate the relationship between blue grama and buffalograss composition and soil characteristics. Results showed that lime and clay content in soil and aspect of slope were variables highly correlated with composition of the two species. Blue grama is often more abundant on sandy soil, while buffalograss is found on clay soil. However, blue grama was also found on clay soils when lime content was high. The essential factor underlying sand, clay, and lime content of soil is interpreted as an environmental stress of drought, or low water potential. Relative crowding coefficients were calculated for blue grama & buffalograss.

Impacts
(N/A)

Publications

  • BAI, T. 1989. Association of Bouteloua gracilis and Buchloe dactyloides. Ph.D. Dissertation, Range Science Dept., Colorado State University. 51 pp.
  • RICHARD, C.E. and REDENTE, E.F. 1990. Competition between blue grama and buffalograss for N and P. SRM Abstract. Reno, NV.