Source: AGRICULTURAL RESEARCH SERVICE submitted to
GLOBAL CHANGE IN SEMI-ARID RANGELANDS: ECOSYSTEM RESPONSES AND MANAGEMENT ADAPTATIONS
Sponsoring Institution
Agricultural Research Service/USDA
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0428589
Grant No.
(N/A)
Project No.
3018-11000-006-00D
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Mar 6, 2015
Project End Date
Apr 10, 2016
Grant Year
(N/A)
Project Director
BLUMENTHAL D M
Recipient Organization
AGRICULTURAL RESEARCH SERVICE
(N/A)
CHEYENNE,WY 82001
Performing Department
(N/A)
Non Technical Summary
(N/A)
Animal Health Component
(N/A)
Research Effort Categories
Basic
80%
Applied
20%
Developmental
0%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1020199114010%
1210210107010%
1320320114010%
2130430107025%
1020799114035%
1210110107010%
Goals / Objectives
The semi-arid grasslands of the western Great Plains, mixed-grass prairie and shortgrass steppe, provide a tremendous array of ecosystem services, including livestock forage, a diversity of native plants and animals, resistance to biological invasion, and carbon storage. Global change is expected to dramatically change grasslands and associated ecosystem services, but the nature of its impacts, and the mechanisms underlying those impacts, remain difficult to predict. In water-limited ecosystems, elevated CO2 and warming can have particularly strong and complex effects because, in addition to their direct effects, they alter water availability. Three main objectives will drive our research program over the next five years to understand how these changes might impact the ecosystem services of western rangelands. The first objective is to assess effects of predicted global changes on ecosystem services in a northern mixed-grass prairie. This will be accomplished by determining the effects of temperature, CO2 and precipitation on plant productivity, plant diversity, forage quality, community composition, weed invasion and the ability of native plant communities to recover from disturbance. The biogeochemistry underlying these responses will be studied to improve our understanding of ecosystem responses and to improve algorithms in biogeochemical models like Daycent. We will also evaluate whether and how responses of invasive species differ from those of native species. Our second objective is to develop knowledge and tools that allow rangeland managers to minimize greenhouse gas emissions. We will determine how temperature, CO2 and precipitation influence land-atmosphere exchanges of trace gases and soil carbon (C) storage, and evaluate the relative importance of water, nitrogen (N) and C limitation in regulating C storage. We will use this information plus additional soil C and CO2 flux data from long-term grazing experiments to determine the potential to mitigate greenhouse gas emissions through grazing management, and assess tradeoffs between mitigation and rangeland productivity. The third objective is to develop science-based, region-specific information and technologies for agricultural and natural resource managers that enable climate-smart decision-making and where possible provide assistance to enable land managers to implement those decisions. The work will be conducted as the Northern Plains USDA Climate Change Hub and will be coordinated with NRCS, FS, and other USDA and non-USDA organizations in accordance with guidance found in the USDA Climate Change Hubs Charter, and Terms of Reference.
Project Methods
To address our first objective concerning the responses of rangelands to global changes, we will use a well-replicated Free Air CO2 Enrichment (FACE) and warming experiment to determine how global change influences the northern mixed-grass prairie. We will examine responses of plant production and quality, composition of native plant communities, carbon and nitrogen cycling, and plant invasion. To understand the mechanisms underlying these responses, we will make extensive use of gas exchange, stable isotope, soil water and nitrogen monitoring, and computer simulation methods. We will use additional treatments to learn how seasonality of precipitation influences the northern mixed-grass prairie, and how the magnitude of those effects compares to effects of CO2 and warming. To address our second objective concerning greenhouse gas mitigation tools, we will measure soil respiration and fluxes of nitrous oxide (N2O) and methane (CH4) using static chambers, and net ecosystem CO2 exchange (NEE) using dynamic chambers within plots of the FACE, warming and irrigation manipulative experiment. Results from the static and dynamic chambers will allow us to quantify CO2-enrichment and warming effects on soil trace gas fluxes and ecosystem level CO2 fluxes, and how these fluxes are related to soil moisture and other environmental factors. We will also take advantage of three ongoing NP215 long-term grazing studies to assess the effects of grazing management strategies (stocking rate and season of use) on the size and dynamics of soil C and N pools, and the potential of these strategies to mitigate greenhouse gas emissions in NMP and SGS. We will use natural variation in precipitation to determine the relative influence of above- and below-average years of precipitation on C and N pool changes. The insights provided by these experiments will help scientists and land managers adapt management practices to sustain ecosystem services in the face of global change, and provide critical information for policy makers. To address our third objective, we will utilize collaborative efforts within USDA (ARS, FS, NRCS, RMA, FSA and ERS) as well with other governmental entities (NOAA, USGS, BLM, NWS), land grant university agricultural experiment stations and agricultural extension (in Northern Plains regional states of WY, CO, MT, ND, SD and NE) to synthesize information and data and knowledge to develop technologies (management strategies, management practices) and decision support tools (applications for mobile devices, enhanced models) that can be delivered to land managers via web portals and other technology transfer providers (extension, education, NRCS field offices, eXtension, etc.). An outreach coordinator is needed to manage the 6 state efforts.

Progress 03/06/15 to 04/10/16

Outputs
Progress Report Objectives (from AD-416): The semi-arid grasslands of the western Great Plains, mixed-grass prairie and shortgrass steppe, provide a tremendous array of ecosystem services, including livestock forage, a diversity of native plants and animals, resistance to biological invasion, and carbon storage. Global change is expected to dramatically change grasslands and associated ecosystem services, but the nature of its impacts, and the mechanisms underlying those impacts, remain difficult to predict. In water-limited ecosystems, elevated CO2 and warming can have particularly strong and complex effects because, in addition to their direct effects, they alter water availability. Three main objectives will drive our research program over the next five years to understand how these changes might impact the ecosystem services of western rangelands. The first objective is to assess effects of predicted global changes on ecosystem services in a northern mixed-grass prairie. This will be accomplished by determining the effects of temperature, CO2 and precipitation on plant productivity, plant diversity, forage quality, community composition, weed invasion and the ability of native plant communities to recover from disturbance. The biogeochemistry underlying these responses will be studied to improve our understanding of ecosystem responses and to improve algorithms in biogeochemical models like Daycent. We will also evaluate whether and how responses of invasive species differ from those of native species. Our second objective is to develop knowledge and tools that allow rangeland managers to minimize greenhouse gas emissions. We will determine how temperature, CO2 and precipitation influence land-atmosphere exchanges of trace gases and soil carbon (C) storage, and evaluate the relative importance of water, nitrogen (N) and C limitation in regulating C storage. We will use this information plus additional soil C and CO2 flux data from long-term grazing experiments to determine the potential to mitigate greenhouse gas emissions through grazing management, and assess tradeoffs between mitigation and rangeland productivity. The third objective is to develop science-based, region-specific information and technologies for agricultural and natural resource managers that enable climate-smart decision-making and where possible provide assistance to enable land managers to implement those decisions. The work will be conducted as the Northern Plains USDA Climate Change Hub and will be coordinated with NRCS, FS, and other USDA and non-USDA organizations in accordance with guidance found in the USDA Climate Change Hubs Charter, and Terms of Reference. Approach (from AD-416): To address our first objective concerning the responses of rangelands to global changes, we will use a well-replicated Free Air CO2 Enrichment (FACE) and warming experiment to determine how global change influences the northern mixed-grass prairie. We will examine responses of plant production and quality, composition of native plant communities, carbon and nitrogen cycling, and plant invasion. To understand the mechanisms underlying these responses, we will make extensive use of gas exchange, stable isotope, soil water and nitrogen monitoring, and computer simulation methods. We will use additional treatments to learn how seasonality of precipitation influences the northern mixed-grass prairie, and how the magnitude of those effects compares to effects of CO2 and warming. To address our second objective concerning greenhouse gas mitigation tools, we will measure soil respiration and fluxes of nitrous oxide (N2O) and methane (CH4) using static chambers, and net ecosystem CO2 exchange (NEE) using dynamic chambers within plots of the FACE, warming and irrigation manipulative experiment. Results from the static and dynamic chambers will allow us to quantify CO2-enrichment and warming effects on soil trace gas fluxes and ecosystem level CO2 fluxes, and how these fluxes are related to soil moisture and other environmental factors. We will also take advantage of three ongoing NP215 long-term grazing studies to assess the effects of grazing management strategies (stocking rate and season of use) on the size and dynamics of soil C and N pools, and the potential of these strategies to mitigate greenhouse gas emissions in NMP and SGS. We will use natural variation in precipitation to determine the relative influence of above- and below-average years of precipitation on C and N pool changes. The insights provided by these experiments will help scientists and land managers adapt management practices to sustain ecosystem services in the face of global change, and provide critical information for policy makers. To address our third objective, we will utilize collaborative efforts within USDA (ARS, FS, NRCS, RMA, FSA and ERS) as well with other governmental entities (NOAA, USGS, BLM, NWS), land grant university agricultural experiment stations and agricultural extension (in Northern Plains regional states of WY, CO, MT, ND, SD and NE) to synthesize information and data and knowledge to develop technologies (management strategies, management practices) and decision support tools (applications for mobile devices, enhanced models) that can be delivered to land managers via web portals and other technology transfer providers (extension, education, NRCS field offices, eXtension, etc.). An outreach coordinator is needed to manage the 6 state efforts. All milestones from project 3018-11000-005-00D (completed in April 2015) were fully met. The subsequent bridging project 3018-11000-006-00D did not contain additional milestones. Project 3018-11000-005-00D ended in April 2015 and was replaced by bridging project 3018-11000-006-00D. Bridging project 3018-11000-006-00D ended in April 2016. Ongoing objectives from bridging project 3018-11000- 006-00D were incorporated into the other research project within the Rangeland Resources Research Unit (3018-21610-001-00D). Research under Project 3018-11000-005-00D and bridging project 3018-11000-006-00D was guided by two objectives: (1) Assess effects of predicted global changes on ecosystem services in northern mixed-grass prairie, and (2) Develop knowledge and tools that allow rangeland managers to minimize greenhouse gas emissions. Both objectives were centered on the Prairie Heating and CO2 Enrichment (PHACE) experiment in which atmospheric carbon dioxide (CO2) concentration, temperature and soil water were all manipulated to further our understanding of how semi-arid rangelands respond to multiple global change factors. The second objective included measurements of soil carbon within a separate, long-term grazing experiment. A core group of scientists from ARS, the University of Wyoming, Colorado State University, The University of Western Sydney, Australia, and the Biometeorology Institute in Florence, Italy, plus several graduate students and post docs collaborated on this unique project. A post-doc hired in 2013 to replace one of the two lead scientists who retired continues to be central to publishing the now complete datasets from the PHACE experiment. The experimental plots were divided into two halves, with one side comprised of a native northern mixed-grass prairie, and the other side seeded under different disturbance regimes with various native and invasive plant species. This plot arrangement allowed us to evaluate both the basic responses of this rangeland to climate change, and also to investigate how global changes interact with disturbance and plant invasion. To date the PHACE experiment has led to 34 publications, and many results with broad implications for rangeland ecosystems. One central finding is that effects of elevated CO2 and warmer temperatures depend to a large extent on the combined effects of these two factors on soil-plant water relations. Due to higher than expected water savings from elevated CO2, the combination of warming and elevated CO2 is not likely to reduce either the productivity or stability of forage production in the near term (<100 years). Furthermore, growing seasons may be lengthened not only by warming, as expected, but also by elevated CO2, which can delay drought-induced senescence. We have also learned how a number of other plant and soil attributes, particularly the cycling of soil/plant nitrogen and carbon may determine the ultimate interactions of this rangeland ecosystem with a changing climate. For example, the combination of elevated CO2 and warming caused this rangeland ecosystem to become a net carbon source, largely due to CO2-induced increases in ecosystem respiration. This in turn suggests that elevated atmospheric CO2 in some semiarid rangelands will lead to further increases atmospheric CO2, contributing to more positive feedbacks between terrestrial ecosystems global change. While elevated CO2 and warming may not reduce plant productivity, they are likely to change the abundance of key native and invasive species. For example, C4 grasses initially responded positively to the combination of CO2 and warming, but this result reversed over time, with C3 grasses increasing dramatically at the expense of C4 grasses. Such changes are likely to lead to greater forage availability in the spring and reduced forage availability in the summer. Experimental work on the invasive perennial forb Dalmatian toadflax (Linaria dalmatica) demonstrated that elevated CO2 and warming led to a 13-fold increase in its invasion of northern mixed-grass prairie. Other invasive species also thrived under future climatic conditions, including the invasive annual grass cheatgrass (Bromus tectorum), which produces four times as much seed with warming as it does without, irrespective of CO2 enrichment. In a rare experimental test of how climate change influences biological control, we found that elevated CO2 increased seed consumption of the invasive perennial forb diffuse knapweed (Centaurea diffusa) by a biological control weevil. Unfortunately, these effects were not strong enough to eliminate a net increase in knapweed seed production with elevated CO2. Together, the findings from the PHACE experiment provide a picture of the northern mixed-grass rangeland ecosystem of the future, and a basis for adaptive management strategies. Although forage production may be largely unaffected by the combination of warming and elevated CO2, the timing of forage availability may shift, influencing forage availability for livestock as well as wildlife, competition from invasive weeds may increase, and the ecosystem may become a net carbon source. Many of these patterns are likely to apply not just to northern mixed-grass prairie, but to semiarid rangelands around the world. Experimental treatments in the PHACE experiment ended in July 2013. Efforts since then to process samples and compile datasets are now complete. Publications still in progress will address effects of elevated CO2 and warming on 1) root architecture and chemistry of key rangeland species; 2) microbial carbon use efficiency and effects on nitrogen availability; 3) rhizosphere nitrogen fixation; 4) root crown biomass and chemistry; 5) soil nematodes; and 6) mycorrhizae. We are also continuing efforts to use leaf traits to predict responses to global changes, both within the PHACE experiment and through synthesis of literature from prior global change experiments. In our greenhouse gas mitigation research, all soils harvested (most recently in 2013) have been analyzed for soil carbon and nitrogen content, as well as for stable isotopes of carbon, to determine the long-term effects of livestock grazing on soil C sequestration and storage. Continued collaborative efforts with the Bureau of Land Management, included the completion of a greenhouse study quantifying variation in drought tolerance among grass accessions and cultivars from across the western U.S. Funding associated with the USDA Climate Hubs (received in 2014) led to the addition of a 3rd objective to this project: Develop science-based, region-specific information and technologies for agricultural and natural resource managers that enable climate-smart decision-making and where possible provide assistance to enable land managers to implement those decisions. The work is being conducted as the USDA Northern Plains Regional Climate Hub with coordination through collaborative efforts with the Natural Resources Conservation Service (NRCS) and Forest Service (FS) via guidance found in the USDA Climate Hubs Charter, and Terms of Reference. Efforts in 2014 centered on engagement with Extension programs in the six regional states (Montana, Wyoming, Colorado, North Dakota, South Dakota and Nebraska) regarding disseminating information to, and receiving feedback from, agricultural producers on tools and management practices for enhanced decision making with increased weather variability and extreme events (e. g., drought). Progress in developing the USDA Northern Plains Regional Climate Hub in 2016 includes the successful recruitment of a Fellow that will modify the Forest Service Adaptation Workbook (A Climate Change Tool for Forest Management and Conservation) for semiarid rangelands of western Great Plains. Recruitment of a Director is ongoing at this time. Efforts with Cooperative Extension involved the completion of a white paper addressing gaps in knowledge and program delivery for producers, and the announcement of three mini-grants emphasizing multi-state efforts in 1) scenario planning for resilient beef systems, 2) climate curriculum emphasizing a primer for weather extremes, and 3) connecting agricultural producers to early adopters of adaptation strategies for weather and extreme events. 212 2 A 2008 212 3 A 2008 212 3 B 2008 212 4 C 2008 All accomplishments for FY16 have been reported in project 3018-21610-001- 00D. All publications for FY16 have been reported in project 3018-21610-001- 00D.

Impacts
(N/A)

Publications


    Progress 10/01/14 to 09/30/15

    Outputs
    Progress Report Objectives (from AD-416): The semi-arid grasslands of the western Great Plains, mixed-grass prairie and shortgrass steppe, provide a tremendous array of ecosystem services, including livestock forage, a diversity of native plants and animals, resistance to biological invasion, and carbon storage. Global change is expected to dramatically change grasslands and associated ecosystem services, but the nature of its impacts, and the mechanisms underlying those impacts, remain difficult to predict. In water-limited ecosystems, elevated CO2 and warming can have particularly strong and complex effects because, in addition to their direct effects, they alter water availability. Three main objectives will drive our research program over the next five years to understand how these changes might impact the ecosystem services of western rangelands. The first objective is to assess effects of predicted global changes on ecosystem services in a northern mixed-grass prairie. This will be accomplished by determining the effects of temperature, CO2 and precipitation on plant productivity, plant diversity, forage quality, community composition, weed invasion and the ability of native plant communities to recover from disturbance. The biogeochemistry underlying these responses will be studied to improve our understanding of ecosystem responses and to improve algorithms in biogeochemical models like Daycent. We will also evaluate whether and how responses of invasive species differ from those of native species. Our second objective is to develop knowledge and tools that allow rangeland managers to minimize greenhouse gas emissions. We will determine how temperature, CO2 and precipitation influence land-atmosphere exchanges of trace gases and soil carbon (C) storage, and evaluate the relative importance of water, nitrogen (N) and C limitation in regulating C storage. We will use this information plus additional soil C and CO2 flux data from long-term grazing experiments to determine the potential to mitigate greenhouse gas emissions through grazing management, and assess tradeoffs between mitigation and rangeland productivity. The third objective is to develop science-based, region-specific information and technologies for agricultural and natural resource managers that enable climate-smart decision-making and where possible provide assistance to enable land managers to implement those decisions. The work will be conducted as the Northern Plains USDA Climate Change Hub and will be coordinated with NRCS, FS, and other USDA and non-USDA organizations in accordance with guidance found in the USDA Climate Change Hubs Charter, and Terms of Reference. Approach (from AD-416): To address our first objective concerning the responses of rangelands to global changes, we will use a well-replicated Free Air CO2 Enrichment (FACE) and warming experiment to determine how global change influences the northern mixed-grass prairie. We will examine responses of plant production and quality, composition of native plant communities, carbon and nitrogen cycling, and plant invasion. To understand the mechanisms underlying these responses, we will make extensive use of gas exchange, stable isotope, soil water and nitrogen monitoring, and computer simulation methods. We will use additional treatments to learn how seasonality of precipitation influences the northern mixed-grass prairie, and how the magnitude of those effects compares to effects of CO2 and warming. To address our second objective concerning greenhouse gas mitigation tools, we will measure soil respiration and fluxes of nitrous oxide (N2O) and methane (CH4) using static chambers, and net ecosystem CO2 exchange (NEE) using dynamic chambers within plots of the FACE, warming and irrigation manipulative experiment. Results from the static and dynamic chambers will allow us to quantify CO2-enrichment and warming effects on soil trace gas fluxes and ecosystem level CO2 fluxes, and how these fluxes are related to soil moisture and other environmental factors. We will also take advantage of three ongoing NP215 long-term grazing studies to assess the effects of grazing management strategies (stocking rate and season of use) on the size and dynamics of soil C and N pools, and the potential of these strategies to mitigate greenhouse gas emissions in NMP and SGS. We will use natural variation in precipitation to determine the relative influence of above- and below-average years of precipitation on C and N pool changes. The insights provided by these experiments will help scientists and land managers adapt management practices to sustain ecosystem services in the face of global change, and provide critical information for policy makers. To address our third objective, we will utilize collaborative efforts within USDA (ARS, FS, NRCS, RMA, FSA and ERS) as well with other governmental entities (NOAA, USGS, BLM, NWS), land grant university agricultural experiment stations and agricultural extension (in Northern Plains regional states of WY, CO, MT, ND, SD and NE) to synthesize information and data and knowledge to develop technologies (management strategies, management practices) and decision support tools (applications for mobile devices, enhanced models) that can be delivered to land managers via web portals and other technology transfer providers (extension, education, NRCS field offices, eXtension, etc.). An outreach coordinator is needed to manage the 6 state efforts. Please refer to project 3018-11000-005-00D (Acc # 419473).

    Impacts
    (N/A)

    Publications