Progress 07/01/08 to 06/30/11
Outputs
OUTPUTS: Hummocks in riparian areas and wetlands are relatively small mounds (< 1 m in diameter and height) that create uneven ground. According to the scientific literature, differential frost heave is the most widely accepted theory of hummock genesis. However, most of the published work on hummocks comes from the physical sciences. Interestingly, no theory of hummock formation in recent review papers includes large ungulate activity as an important factor. But, the management literature in natural resources often suggests that hummocks are an indicator of degraded riparian or wetland conditions caused by large ungulate trailing and trampling (most often attributed to domestic livestock). As a side investigation in a study of hummocked wetlands, we collected slabs of soil from two hummocks and adjacent interspaces for detailed analysis. Slabs were 5-8 cm thick, excavated to a depth of ~30 cm and included an entire hummock and the adjacent interspace. A 5-cm grid was constructed on each slab and soil samples from each cell in the grids were collected for determination of soil texture, bulk density, nitrogen, total carbon, organic- and inorganic-carbon. Soil properties from different regions of the hummocks and interspaces were then compared. Nitrogen and organic C were highest near the soil surface. There were not consistent differences in bulk density between hummocks and interspaces, and soil texture was fairly consistent. Based on these observations, it does not appear that hummocks result from compaction of the interspaces, but may still be related to the activities of large ungulates. We also further investigated the theory that hummocks form as a result of differential frost heave. This theory relies on the coincidence of freezing temperatures and standing water in the interspaces. The objective of this study was to evaluate the temperature regimes in hummocks and interspaces along with presence of water and freezing air temperatures. Four hummocked wetland sites in North-central Colorado were selected for sampling. At each site, four monitoring locations were randomly selected. Each monitoring location was equipped with soil temperature sensors in the interspace, at the base of the hummock and at two thirds of the hummock height. A water sensor was used to determine when there was standing water in the interspace. An air temperature sensor was placed at each site. These sensors were connected to loggers programmed to record hourly data. The temperature for October through December at the top of the hummock was colder and more variable (Mean=1.3 degrees C, SD=4.1) than the hummock base and interspace (Mean=1.9 degrees C, 2.3 degrees C, SD=3.6, 3.4, respectively). Results indicate the coincidence of standing water in the interspace, freezing air temperatures and unfrozen hummocks, suggesting that freeze-thaw processes may be related to hummock formation and maintenance. PARTICIPANTS: In the final 12 months of this project, five individuals have worked on this project. Mae Smith and Jesse Schroeder are M.S. students in Rangeland Ecosystem Science at Colorado State University. Paul Meiman (Department of Forest, Rangeland and Watershed Stewardship), Joe Brummer (Department of Soil and Crop Sciences), and David Cooper (Department of Forest, Rangeland and Watershed Stewardship) are CSU faculty members who are involved. Mae Smith is leading the field component of this project. Meiman, Brummer and Cooper work closely with Smith on the field study. All five worked on developing study methods and their implementation. Meaningful contacts have been made with individuals from the USDA Forest Service, USDI Bureau of Land Management, USDA Natural Resources Conservation Service, USDA Agricultural Research Service, Agriculture Canada, Colorado Division of Wildlife and other agencies. TARGET AUDIENCES: Information from this project has been communicated to individuals in three main groups. The first group includes the audiences at international and local professional meetings. This includes scientists, graduate and undergraduate students, natural resource specialists (agency), consultants (private), livestock producers and land managers. The second group includes stakeholders for the Institute for Livestock and the Environment and is composed of agricultural producers, environmental groups, consultants, agency natural resource managers and agricultural business advisors. The third group includes undergraduate and graduate students enrolled in classes taught by the research team. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Results from this project have been reported in a M.S. Thesis by Mae Lynn Smith and at the 2011 Society for Range Management Annual Meeting held in Billings, MT. Agency natural resource specialists from throughout the western U.S. and from Canada have expressed considerable interest in our project and findings. Some have indicated that their protocols for the evaluation of wetland and riparian conditions will likely be altered. Environmental consultants and livestock producers have also expressed considerable interest. This project has initiated communication between the CSU research team, USDA Agricultural Research Service scientists and land management agency personnel outside Colorado. It is likely that this communication will lead to future collaborations on hummock research and preparation of a review article on hummocks. An improved understanding of factors contributing to hummock development in riparian areas and wetlands will improve the effectiveness of land and natural resource management efforts. Natural resource managers will be better able to maintain or improve ecosystem function and integrity supporting sustainable livestock production, wildlife habitat and other uses. It is difficult to estimate the acres of rangeland impacted by, or the economic importance of this work, but both are likely to be significant. Riparian areas and wetlands occupy a very small portion of the land area, but drive management decisions over extensive areas (entire watersheds).
Publications
- Smith, M.L. 2011. Characteristics of hummocks and hummocked wetlands in Colorado, M.S. Thesis, Colorado State University
- Smith, M.L., Meiman, P.J. and Brummer, J.E. 2011. Characteristics of hummocked and non-hummocked riparian areas and wetlands in Colorado. IX International Rangeland Congress, 5 April 2011, Rosario, Santa Fe, Argentina.
- Meiman, P.J., Smith, M.L. and Brummer, J.E. 2011., Fine-scale observations of hummocks and adjacent interspaces, Society for Range Management International Meeting, February 8, 2011, Billings, MT.
- Smith, M.L., Meiman, P.J. and Brummer, J.E. 2011., Evaluation of freeze-thaw dynamics in hummocked wetlands, Society for Range Management International Meeting, February 8, 2011, Billings, MT.
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: Hummocks in riparian areas and wetlands are sometimes interpreted as an indication of degradation caused by domestic livestock. Livestock and land managers are sometimes forced to reduce animal numbers, change the season or duration of livestock grazing, or to discontinue domestic livestock grazing in areas where hummocks exist. Significant changes in land use management have been, and continue to be implemented based on assumptions about hummocks and domestic livestock. But it remains unknown whether or not hummocks are caused exclusively by livestock. Even if livestock grazing management is related to hummock formation, observational evidence suggests that removal of livestock may not lead to their disappearance. The existing scientific literature on hummock formation is limited, but does suggest that hummocks may form as a result of processes unrelated to large ungulate activity. Riparian areas and wetlands are crucial to ecosystem function, natural resource conservation and land use management, so interpretation of their condition is important. The interpretation of hummocks in Colorado riparian areas and wetlands has tremendous potential to influence natural resource conservation specialists and livestock producers in the state, so an improved understanding of conditions related to hummock development is essential. A field study was conducted in 2010 to improve our understanding of hummock development by characterizing the soil temperature regimes of hummocks and interspaces. We also collected data on air temperature and ice formation in interspaces between hummocks. Four hummocked wetlands in Colorado were instrumented with temperature probes and water/ice sensors connected to data loggers programmed to record hourly readings from October 2009 through May 2010. At each site, 4 hummocks and adjacent interspaces were instrumented. Soil temperature probes were located near the soil surface on hummocks and in interspaces and at the bases of hummocks. Water/ice sensors were placed in interspaces. Preliminary analyses suggest that there were 68, 80, 109 and 101 air freeze-thaw cycles in one winter at the 4 sites, respectively. This is 2-3x the number of cycles observed to initiate soil mound formation in lab experiments. There was also much evidence of differential freezing suggesting this may an important factor in hummock development. All sites experienced the coincidence of water in the interspace, freezing air temperatures and unfrozen hummock bases, supporting the theory that pressure exerted on unfrozen soil in a mound by ice formation in depressions with standing water may lead to hummock development. Further, the hummock top was significantly colder than the base and interspace at all sites. Water moves toward colder regions even in subzero temperatures. These differentials appear sufficient for hummock development, and similar differentials may have led to hummock genesis. PARTICIPANTS: In the past 6 months, five individuals have worked on this project. Mae Smith and Jesse Schroeder are M.S. students in Rangeland Ecosystem Science at Colorado State University. Paul Meiman (Department of Forest, Rangeland and Watershed Stewardship), Joe Brummer (Department of Soil and Crop Sciences), and David Cooper (Department of Forest, Rangeland and Watershed Stewardship) are CSU faculty members who are involved. Mae Smith is leading the field component of this project. Meiman, Brummer and Cooper work closely with Smith on the field study. All five worked on developing study methods and their implementation. Meaningful contacts have been made with individuals from the USDA Forest Service, USDI Bureau of Land Management, USDA Natural Resources Conservation Service, USDA Agricultural Research Service, Agriculture Canada, Colorado Division of Wildlife and other agencies. TARGET AUDIENCES: Information from this project has been communicated to individuals in three main groups. The first group includes the audiences at international and local professional meetings. This includes scientists, graduate and undergraduate students, natural resource specialists (agency), consultants (private), livestock producers and land managers. The second group includes stakeholders for the Institute for Livestock and the Environment and is composed of agricultural producers, environmental groups, consultants, agency natural resource managers and agricultural business advisors. The third group includes undergraduate and graduate students enrolled in classes taught by the research team. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Preliminary results from this project have been reported at international and local professional meetings and the 2010 Society for Range Management and Weed Science Society of America Annual Meeting held in Denver, CO. Agency natural resource specialists from throughout the western U.S. and from Canada have expressed considerable interest in our project and findings. Some have indicated that their protocols for the evaluation of wetland and riparian conditions may need to be altered. Environmental consultants and livestock producers have also expressed considerable interest. This project has initiated communication between the CSU research team, USDA Agricultural Research Service scientists and land management agency personnel outside Colorado. It is likely that this communication will lead to future collaborations on hummock research and preparation of a review article on hummocks. An improved understanding of factors contributing to hummock development in riparian areas and wetlands will improve the effectiveness of land and natural resource management efforts. Natural resource managers will be better able to maintain or improve ecosystem function and integrity supporting sustainable livestock production, wildlife habitat and other uses. It is difficult to estimate the acres of rangeland impacted by, or the economic importance of this work, but both are likely to be significant. Riparian areas and wetlands occupy a very small portion of the land area, but drive management decisions over extensive areas (entire watersheds).
Publications
- Smith, M.L., Meiman, P.J. and Brummer, J.E. 2010. Characteristics of Hummocked and Non-Hummocked Riparian Areas and Wetlands in Colorado. Society for Range Management and Weed Science Society of America Annual Meeting, 7-11 February 2010, Denver, CO.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: Hummocks in riparian areas and wetlands are sometimes interpreted as an indication of degradation caused by domestic livestock. Livestock and land managers are sometimes forced to reduce animal numbers, change the season or duration of livestock grazing, or to discontinue domestic livestock grazing in areas where hummocks exist. Interestingly, hummocks may persist for many years after exclusion of domestic livestock. Significant changes in land use management have been, and continue to be implemented based on assumptions about hummocks and domestic livestock. But it remains unknown whether or not hummocks are caused exclusively by livestock. Even if livestock grazing management is related to hummock formation, observational evidence suggests that removal of livestock may not lead to their disappearance. The existing scientific literature on hummock formation is limited, but does suggest that hummocks may form as a result of processes unrelated to large ungulate activity. Riparian areas and wetlands are crucial to ecosystem function, natural resource conservation and land use management, so interpretation of their condition is important. The interpretation of hummocks in riparian areas and wetlands of Colorado has tremendous potential to influence natural resource conservation specialists and livestock producers in the state, so an improved understanding of conditions leading to hummock formation is essential. A field study was initiated in 2009 to identify and describe the edaphic, climatic, topographic and vegetative characteristics of riparian wetlands that do, and do not support hummocks and to describe how hummock size and shape vary at hummocked sites. Twenty-five natural resource professionals throughout Colorado provided ten sites each that were a mix of hummocked and non-hummocked in proportion to their local abundance. Forty hummocked and 40 non-hummocked sites were randomly selected for sampling and 73 (35 hummocked and 38 non-hummocked) sites were suitable. Hummock density was determined at hummocked sites in 5- by 2-meter belts. The height, major and perpendicular diameters, and side steepness were determined for two hummocks in each belt. Vegetation at each site was described using the Daubenmire method for canopy cover. One composite soil sample was collected at each site and site characteristics were recorded (elevation, topographical position, slope, aspect, etc.). Livestock grazing histories for the sites were provided by natural resource professionals. Preliminary analyses suggest that the mean elevation of hummocked sites (2,757 m) was greater than non-hummocked sites (2,335 m) (P<0.001). Hummock size and shape were more variable than expected and there were no differences between grazed and ungrazed sites. The lowest elevation sites had the highest hummock density. Hummock density was lower, but height was greater in riverine compared to most slope wetlands. Hummocks at low elevations tended to be more oblong than at higher elevations. Soils, vegetation and other site characteristic data are currently being analyzed. PARTICIPANTS: In the past 6 months, six individuals have worked on this project. Andrew Don Carlos is a Ph.D. student in Human Dimensions of Natural Resources, and Mae Smith is a M.S. student in Rangeland Ecosystem Science at Colorado State University. Paul Meiman (Department of Forest, Rangeland and Watershed Stewardship), Joe Brummer (Department of Soil and Crop Sciences), Alan Bright (Department of Human Dimensions of Natural Resources) and David Cooper (Department of Forest, Rangeland and Watershed Stewardship) are CSU faculty members who are involved. Andrew Don Carlos led the development of an interview protocol, conducted interviews, developed and is administering a web-based survey regarding the interpretation of hummocks relative to the condition of riparian areas and wetlands. Mae Smith is leading the field component of this project. Meiman and Bright work with Don Carlos on the interviews and survey. Meiman, Brummer and Cooper work closely with Smith on the field study. All six worked on developing study methods and their implementation. Meaningful contacts have been made with individuals from the USDA Forest Service, USDI Bureau of Land Management, USDA Natural Resources Conservation Service, USDA Agricultural Research Service, Agriculture Canada, Colorado Division of Wildlife and other agencies. TARGET AUDIENCES: Information from this project has been communicated to individuals in three main groups. The first group includes the audiences at international and local professional meetings. This includes scientists, graduate and undergraduate students, natural resource specialists (agency), consultants (private), livestock producers and land managers. The second group includes stakeholders for the Institute for Livestock and the Environment and is composed of agricultural producers, environmental groups, consultants, agency natural resource managers and agricultural business advisors. The third group includes undergraduate and graduate students enrolled in classes taught by the research team. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Preliminary results from this project have been reported at international and local professional meetings and the 2009 Stakeholder Summit for the Institute for Livestock and the Environment. Agency natural resource specialists from throughout the western U.S. and from Canada have expressed considerable interest in our project and findings. Some have indicated that their protocols for the evaluation of wetland and riparian conditions may need to be altered. Environmental consultants and livestock producers have also expressed considerable interest. This project has also initiated communication between the CSU research team, USDA Agricultural Research Service scientists and land management agency personnel outside Colorado. It is likely that this communication will lead to future collaborations on hummock research and preparation of a review article on hummocks. An improved understanding of factors leading to hummock presence in riparian areas and wetlands will improve the effectiveness of land and natural resource management efforts. Natural resource managers will be better able to maintain or improve ecosystem function and integrity supporting sustainable livestock production, wildlife habitat and other uses. It is difficult to estimate the acres of rangeland impacted by, or the economic importance of this work, but both are likely to be significant. Riparian areas and wetlands occupy a very small portion of the land area, but drive management decisions over extensive areas (entire watersheds).
Publications
- Don Carlos, A.W., Bright, A.D., Meiman, P.J., Brummer, J.E. and Cooper, D.J. 2009. Interpretation of Hummocks Relative to the Condition of Wetlands in Colorado. Society for Range Management Annual Meeting, February 8-13, Albuquerque, NM.
- Don Carlos, A.W., Bright, A.D., Meiman, P.J., Brummer, J.E. and Cooper, D.J. 2009. Interpretation of Hummocks Relative to the Condition of Wetlands in Colorado. Institute for Livestock and the Environment 2nd Annual Stakeholder Summit, 19 November, 2009, Fort Collins, CO.
- Smith, M.L., Meiman, P.J. and Brummer, J.E. 2009. Characteristics of Hummocked and Non-Hummocked Riparian Areas and Wetlands in Colorado. Institute for Livestock and the Environment 2nd Annual Stakeholder Summit, 19 November, 2009, Fort Collins, CO.
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Progress 07/01/08 to 12/31/08
Outputs
OUTPUTS: The presence of hummocks in riparian areas and wetlands is sometimes interpreted as an indication of wetland or riparian degradation caused by domestic livestock. Recent conversations with natural resource specialists in Colorado suggest that this interpretation may exist locally. Livestock and land managers are sometimes forced to reduce animal numbers, change the season or duration of livestock grazing, or to discontinue domestic livestock grazing in areas where hummocks exist. Interestingly, hummocks may persist for many years after exclusion of domestic livestock. Significant changes in land use management have been, and continue to be implemented based on assumptions about hummocks and domestic livestock. But it remains unknown how common such assumptions are and what they are based upon. Even if livestock grazing management is related to hummock formation, observational evidence suggests that removal of livestock may not lead to their disappearance. The existing scientific literature on hummock formation is limited, but does suggest that hummocks may form as a result of processes unrelated to large ungulate activity. Riparian areas and wetlands are crucial to ecosystem function, natural resource conservation and land use management, so interpretation of their condition is important. The interpretation of hummocks in riparian areas and wetlands of Colorado has tremendous potential to influence natural resource conservation specialists and livestock producers in the state, so a characterization of how hummocks are treated relative to the condition of these areas is critical. Of equal importance is the basis for those interpretations. A two-stage approach is being used to collect qualitative and quantitative data related to the interpretation of hummock presence in Colorado riparian areas and wetlands. Stage one involves 25-50 semi-structured interviews with employees of federal, state, and local agencies, and stakeholder groups. Interviews have been structured to examine beliefs about a) the origin of hummocks, b) their positive and/or negative impacts, and c) the need for action to address the presence of hummocks. The interview protocol includes follow-up questions to establish the basis for participant interpretations. Interview data will be transcribed and subject to content analysis. Text transcripts will be coded into relevant content categories based on issues of interest outlined above and other emergent data trends. Interview results will be used to assist in development of a quantitative survey. Stage two will involve the administration of a survey to Colorado natural resource managers, scientists, and stakeholders. To date, the interview protocol has been developed and approved by the Institutional Review Board. A list of potential interviewees from 6 agencies in Colorado, and representing 6 professional disciplines has been developed and 12 of the 25-50 interviews have been completed. PARTICIPANTS: In the past 6 months, five individuals have worked on this project. Andrew Don Carlos is a Ph.D. student in Human Dimensions of Natural Resources at Colorado State University. Paul Meiman (Department of Forest, Rangeland and Watershed Stewardship), Joe Brummer (Department of Soil and Crop Sciences), Alan Bright (Department of Human Dimensions of Natural Resources) and David Cooper (Department of Forest, Rangeland and Watershed Stewardship) are CSU faculty members who are involved. Andrew Don Carlos led the development of the interview protocol and is conducting the interviews. Meiman and Bright worked fairly closely with Don Carlos on interview development and Brummer and Cooper provided valuable input as well. All five worked on developing study methods and identifying potential interviewees. Meaningful contacts have been made with individuals from the USDA Forest Service, USDI Bureau of Land Management, USDA Natural Resources Conservation Service, Colorado Division of Wildlife and other agencies. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
This project started just over 6 months ago, so the interviews are not yet completed, have not been thoroughly analyzed and the survey has not yet been administered. Despite this, outcomes and impacts are emerging. The work conducted so far will be critical to later components of this project and will influence future projects. For this project, the information obtained through the interviews will be instrumental in the development of the survey to quantify how Colorado natural resource managers, scientists, and private and nonprofit stakeholders interpret the presence of hummocks in riparian areas and wetlands. Feedback from the interviews completed so far indicates the need to modify interview questions for use on the survey to ensure that relevant information is being collected. For example, interview questions may be placing too much emphasis on hummocks causing interviewees to temper their responses regarding these features. Instead of asking whether or not hummocks are used to determine riparian area and wetland condition, it may be more appropriate to ask how important hummock presence or absence is to condition assessments in these areas. Also, interviewees have provided many references of individuals for subsequent interviews. Following the interviews, some interviewees have stated that they may need to expand their consideration of hummocks (e.g. consider a broader range of potential positive and negative effects, characteristics of sites where they occur or multiple methods of formation). Interviewees also expressed interest in development of evaluative standards for hummocks in wetlands/riparian areas and suggested a need exists for greater collaboration between stakeholders (eg: agencies, producers, scientists) to share knowledge, experience and responsibility for improved understanding of hummocks.
Publications
- No publications reported this period
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