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Taylor CR, England LC, Keane JB, Davies JAC, Leake JR, Hartley IP, Smart SM, Janes-Bassett V, Phoenix GK. Elevated CO 2 interacts with nutrient inputs to restructure plant communities in phosphorus-limited grasslands. GLOBAL CHANGE BIOLOGY 2024; 30:e17104. [PMID: 38273555 DOI: 10.1111/gcb.17104] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 12/01/2023] [Accepted: 12/02/2023] [Indexed: 01/27/2024]
Abstract
Globally pervasive increases in atmospheric CO2 and nitrogen (N) deposition could have substantial effects on plant communities, either directly or mediated by their interactions with soil nutrient limitation. While the direct consequences of N enrichment on plant communities are well documented, potential interactions with rising CO2 and globally widespread phosphorus (P) limitation remain poorly understood. We investigated the consequences of simultaneous elevated CO2 (eCO2 ) and N and P additions on grassland biodiversity, community and functional composition in P-limited grasslands. We exposed soil-turf monoliths from limestone and acidic grasslands that have received >25 years of N additions (3.5 and 14 g m-2 year-1 ) and 11 (limestone) or 25 (acidic) years of P additions (3.5 g m-2 year-1 ) to eCO2 (600 ppm) for 3 years. Across both grasslands, eCO2 , N and P additions significantly changed community composition. Limestone communities were more responsive to eCO2 and saw significant functional shifts resulting from eCO2 -nutrient interactions. Here, legume cover tripled in response to combined eCO2 and P additions, and combined eCO2 and N treatments shifted functional dominance from grasses to sedges. We suggest that eCO2 may disproportionately benefit P acquisition by sedges by subsidising the carbon cost of locally intense root exudation at the expense of co-occurring grasses. In contrast, the functional composition of the acidic grassland was insensitive to eCO2 and its interactions with nutrient additions. Greater diversity of P-acquisition strategies in the limestone grassland, combined with a more functionally even and diverse community, may contribute to the stronger responses compared to the acidic grassland. Our work suggests we may see large changes in the composition and biodiversity of P-limited grasslands in response to eCO2 and its interactions with nutrient loading, particularly where these contain a high diversity of P-acquisition strategies or developmentally young soils with sufficient bioavailable mineral P.
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Affiliation(s)
- Christopher R Taylor
- Soil and Ecosystem Ecology, Earth and Environmental Sciences, University of Manchester, Manchester, UK
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, UK
| | - Luke C England
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, UK
| | - J Ben Keane
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, UK
- Department of Environment and Geography, Wentworth Way, University of York, Heslington, York, UK
| | | | - Jonathan R Leake
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, UK
| | - Iain P Hartley
- Geography, Faculty of Environment, Science and Economy, University of Exeter, Exeter, UK
| | | | - Victoria Janes-Bassett
- Geography and Planning, School of Environmental Sciences, University of Liverpool, Liverpool, UK
| | - Gareth K Phoenix
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, UK
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2
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Rojas-Botero S, Teixeira LH, Kollmann J. Low precipitation due to climate change consistently reduces multifunctionality of urban grasslands in mesocosms. PLoS One 2023; 18:e0275044. [PMID: 36735650 PMCID: PMC9897532 DOI: 10.1371/journal.pone.0275044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 01/10/2023] [Indexed: 02/04/2023] Open
Abstract
Urban grasslands are crucial for biodiversity and ecosystem services in cities, while little is known about their multifunctionality under climate change. Thus, we investigated the effects of simulated climate change, i.e., increased [CO2] and temperature, and reduced precipitation, on individual functions and overall multifunctionality in mesocosm grasslands sown with forbs and grasses in four different proportions aiming at mimicking road verge grassland patches. Climate change scenarios RCP2.6 (control) and RCP8.5 (worst-case) were simulated in walk-in climate chambers of an ecotron facility, and watering was manipulated for normal vs. reduced precipitation. We measured eight indicator variables of ecosystem functions based on below- and aboveground characteristics. The young grassland communities responded to higher [CO2] and warmer conditions with increased vegetation cover, height, flower production, and soil respiration. Lower precipitation affected carbon cycling in the ecosystem by reducing biomass production and soil respiration. In turn, the water regulation capacity of the grasslands depended on precipitation interacting with climate change scenario, given the enhanced water efficiency resulting from increased [CO2] under RCP8.5. Multifunctionality was negatively affected by reduced precipitation, especially under RCP2.6. Trade-offs arose among single functions that performed best in either grass- or forb-dominated grasslands. Grasslands with an even ratio of plant functional types coped better with climate change and thus are good options for increasing the benefits of urban green infrastructure. Overall, the study provides experimental evidence of the effects of climate change on the functionality of urban ecosystems. Designing the composition of urban grasslands based on ecological theory may increase their resilience to global change.
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Affiliation(s)
- Sandra Rojas-Botero
- Chair of Restoration Ecology, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
- * E-mail:
| | - Leonardo H. Teixeira
- Chair of Restoration Ecology, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Johannes Kollmann
- Chair of Restoration Ecology, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
- Norwegian Institute of Bioeconomy Research (NIBIO), Ås, Norway
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3
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Chen Y, Zhang Y, Bai E, Piao S, Chen N, Zhao G, Zheng Z, Zhu Y. The stimulatory effect of elevated CO 2 on soil respiration is unaffected by N addition. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 813:151907. [PMID: 34838545 DOI: 10.1016/j.scitotenv.2021.151907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 11/18/2021] [Accepted: 11/19/2021] [Indexed: 06/13/2023]
Abstract
Global atmospheric CO2 keeps rising and brings about significant effects on ecosystem carbon (C) cycling by altering C processes in soils. Soil C responses to elevated CO2 are highly uncertain, and how elevated CO2 interacts with other factors, such as nitrogen (N) availability, to influence soil C flux comprises an important source of this uncertainty, especially for those under-studied ecosystems. By conducting a manipulated CO2 concentration and N availability experiment on typical alpine grassland (4600 m asl), we combined the five-year in-situ measurement of soil respiration (SR) with an incubation experiment of microbial metabolic efficiency in the lab to explore the response of SR to elevated CO2 and N availability. The results showed that elevated CO2 at ambient N conditions and enriched N equally stimulated SR during the experimental period, whereas N supply had no significant effect. Elevated CO2 enhanced soil dissolved organic C and enzyme activity, while had marginal effects on microbial biomass and C use efficiency (CUE). Strengthened microbial activity dominated SR stimulation under elevated CO2. Enriched N boosted enzyme activity and microbial CUE. N availability played divergent roles in mediating SR. The negliable regulation of N supply on elevated CO2 effects on SR was the offset consequences of the negative impacts of enhanced CUE and the positive contribution of heightened enzyme activity. Our findings suggest that rising CO2 would accelerate soil C cycling of the alpine grassland under various N regimes by stimulating microbial activity instead of lowering microbial metabolic efficiency. Such results are crucial for understanding the role of alpine ecosystems in the global C cycle.
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Affiliation(s)
- Yao Chen
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Yangjian Zhang
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China; CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China.
| | - Edith Bai
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Changchun, China
| | - Shilong Piao
- Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing, China
| | - Ning Chen
- Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, China
| | - Guang Zhao
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
| | - Zhoutao Zheng
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
| | - Yixuan Zhu
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
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4
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Multiple constraints cause positive and negative feedbacks limiting grassland soil CO 2 efflux under CO 2 enrichment. Proc Natl Acad Sci U S A 2020; 118:2008284117. [PMID: 33419921 DOI: 10.1073/pnas.2008284117] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Terrestrial ecosystems are increasingly enriched with resources such as atmospheric CO2 that limit ecosystem processes. The consequences for ecosystem carbon cycling depend on the feedbacks from other limiting resources and plant community change, which remain poorly understood for soil CO2 efflux, JCO2, a primary carbon flux from the biosphere to the atmosphere. We applied a unique CO2 enrichment gradient (250 to 500 µL L-1) for eight years to grassland plant communities on soils from different landscape positions. We identified the trajectory of JCO2 responses and feedbacks from other resources, plant diversity [effective species richness, exp(H)], and community change (plant species turnover). We found linear increases in JCO2 on an alluvial sandy loam and a lowland clay soil, and an asymptotic increase on an upland silty clay soil. Structural equation modeling identified CO2 as the dominant limitation on JCO2 on the clay soil. In contrast with theory predicting limitation from a single limiting factor, the linear JCO2 response on the sandy loam was reinforced by positive feedbacks from aboveground net primary productivity and exp(H), while the asymptotic JCO2 response on the silty clay arose from a net negative feedback among exp(H), species turnover, and soil water potential. These findings support a multiple resource limitation view of the effects of global change drivers on grassland ecosystem carbon cycling and highlight a crucial role for positive or negative feedbacks between limiting resources and plant community structure. Incorporating these feedbacks will improve models of terrestrial carbon sequestration and ecosystem services.
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5
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Sage RF. Global change biology: A primer. GLOBAL CHANGE BIOLOGY 2020; 26:3-30. [PMID: 31663217 DOI: 10.1111/gcb.14893] [Citation(s) in RCA: 90] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 09/09/2019] [Indexed: 05/17/2023]
Abstract
Because of human action, the Earth has entered an era where profound changes in the global environment are creating novel conditions that will be discernable far into the future. One consequence may be a large reduction of the Earth's biodiversity, potentially representing a sixth mass extinction. With effective stewardship, the global change drivers that threaten the Earth's biota could be alleviated, but this requires clear understanding of the drivers, their interactions, and how they impact ecological communities. This review identifies 10 anthropogenic global change drivers and discusses how six of the drivers (atmospheric CO2 enrichment, climate change, land transformation, species exploitation, exotic species invasions, eutrophication) impact Earth's biodiversity. Driver impacts on a particular species could be positive or negative. In either case, they initiate secondary responses that cascade along ecological lines of connection and in doing so magnify the initial impact. The unique nature of the threat to the Earth's biodiversity is not simply due to the magnitude of each driver, but due to the speed of change, the novelty of the drivers, and their interactions. Emphasizing one driver, notably climate change, is problematic because the other global change drivers also degrade biodiversity and together threaten the stability of the biosphere. As the main academic journal addressing global change effects on living systems, GCB is well positioned to provide leadership in solving the global change challenge. If humanity cannot meet the challenge, then GCB is positioned to serve as a leading chronicle of the sixth mass extinction to occur on planet Earth.
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Affiliation(s)
- Rowan F Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
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6
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Polley HW, Aspinwall MJ, Collins HP, Gibson AE, Gill RA, Jackson RB, Jin VL, Khasanova AR, Reichmann LG, Fay PA. CO 2 enrichment and soil type additively regulate grassland productivity. THE NEW PHYTOLOGIST 2019; 222:183-192. [PMID: 30367488 DOI: 10.1111/nph.15562] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 10/18/2018] [Indexed: 06/08/2023]
Abstract
Atmospheric CO2 enrichment usually increases the aboveground net primary productivity (ANPP) of grassland vegetation, but the magnitude of the ANPP-CO2 response differs among ecosystems. Soil properties affect ANPP via multiple mechanisms and vary over topographic to geographic gradients, but have received little attention as potential modifiers of the ANPP-CO2 response. We assessed the effects of three soil types, sandy loam, silty clay and clay, on the ANPP response of perennial C3 /C4 grassland communities to a subambient to elevated CO2 gradient over 10 yr in Texas, USA. We predicted an interactive, rather than additive, effect of CO2 and soil type on ANPP. Contrary to prediction, CO2 and soil additively influenced grassland ANPP. Increasing CO2 by 250 μl l-1 increased ANPP by 170 g m-2 across soil types. Increased clay content from 10% to 50% among soils reduced ANPP by 50 g m-2 . CO2 enrichment increased ANPP via a predominant direct effect, accompanied by a smaller indirect effect mediated by a successional shift to increased dominance of the C4 tallgrass Sorghastrum nutans. Our results indicate a large, positive influence of CO2 enrichment on grassland productivity that resulted from the direct physiological benefits of CO2 augmented by species succession, and was expressed similarly across soils of differing physical properties.
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Affiliation(s)
- H Wayne Polley
- Agricultural Research Service, Grassland, Soil and Water Research Laboratory, USDA, 808 East Blackland Road, Temple, TX, 76502, USA
| | - Michael J Aspinwall
- Section of Integrative Biology, The University of Texas at Austin, 1 University Station C0930, Austin, TX, 78712, USA
- Department of Biology, University of North Florida, 1 UNF Drive, Jacksonville, FL, 32224, USA
| | - Harold P Collins
- Agricultural Research Service, Grassland, Soil and Water Research Laboratory, USDA, 808 East Blackland Road, Temple, TX, 76502, USA
| | - Anne E Gibson
- Agricultural Research Service, Grassland, Soil and Water Research Laboratory, USDA, 808 East Blackland Road, Temple, TX, 76502, USA
| | - Richard A Gill
- Department of Biology, Brigham Young University, 4102 LSB, Provo, UT, 84602, USA
| | - Robert B Jackson
- Department of Earth System Science, Woods Institute for the Environment and Precourt Institute for Energy, Stanford University, Y2E2 Building, 379B, Stanford, CA, 94305, USA
| | - Virginia L Jin
- Agricultural Research Service, ARS Agroecosystem Management Research Unit, USDA, University of Nebraska, 251 Filley Hall, Lincoln, NE, 68583, USA
| | - Albina R Khasanova
- Section of Integrative Biology, The University of Texas at Austin, 1 University Station C0930, Austin, TX, 78712, USA
| | - Lara G Reichmann
- Section of Integrative Biology, The University of Texas at Austin, 1 University Station C0930, Austin, TX, 78712, USA
- Data Institute, University of San Francisco, 101 Howard St., San Francisco, CA, 94105, USA
| | - Philip A Fay
- Agricultural Research Service, Grassland, Soil and Water Research Laboratory, USDA, 808 East Blackland Road, Temple, TX, 76502, USA
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7
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Fay PA, Aspinwall MJ, Collins HP, Gibson AE, Gill RH, Jackson RB, Jin VL, Khasanova AR, Reichmann LG, Polley HW. Flowering in grassland predicted by CO 2 and resource effects on species aboveground biomass. GLOBAL CHANGE BIOLOGY 2018; 24:1771-1781. [PMID: 29282824 DOI: 10.1111/gcb.14032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 12/18/2017] [Indexed: 06/07/2023]
Abstract
Continuing enrichment of atmospheric CO2 may change plant community composition, in part by altering the availability of other limiting resources including soil water, nutrients, or light. The combined effects of CO2 enrichment and altered resource availability on species flowering remain poorly understood. We quantified flowering culm and ramet production and biomass allocation to flowering culms/ramets for 10 years in C4 -dominated grassland communities on contrasting soils along a CO2 concentration gradient spanning pre-industrial to expected mid-21st century levels (250-500 μl/L). CO2 enrichment explained up to 77% of the variation in flowering culm count across soils for three of the five species, and was correlated with flowering culm count on at least one soil for four of five species. In contrast, allocation to flowering culms was only weakly correlated with CO2 enrichment for two species. Flowering culm counts were strongly correlated with species aboveground biomass (AGB; R2 = .34-.74), a measure of species abundance. CO2 enrichment also increased soil moisture and decreased light levels within the canopy but did not affect soil inorganic nitrogen availability. Structural equation models fit across the soils suggested species-specific controls on flowering in two general forms: (1) CO2 effects on flowering culm count mediated by canopy light level and relative species AGB (species AGB/total AGB) or by soil moisture effects on flowering culm count; (2) effects of canopy light level or soil inorganic nitrogen on flowering and/or relative species AGB, but with no significant CO2 effect. Understanding the heterogeneity in species responses to CO2 enrichment in plant communities across soils in edaphically variable landscapes is critical to predict CO2 effects on flowering and other plant fitness components, and species potential to adapt to future environmental changes.
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Affiliation(s)
- Philip A Fay
- USDA-ARS, Grassland, Soil, and Water Research Laboratory, Temple, TX, USA
| | | | - Harold P Collins
- USDA-ARS, Grassland, Soil, and Water Research Laboratory, Temple, TX, USA
| | - Anne E Gibson
- USDA-ARS, Grassland, Soil, and Water Research Laboratory, Temple, TX, USA
| | - Richard H Gill
- Department of Biology, Brigham Young University, Provo, UT, USA
| | - Robert B Jackson
- Department of Earth System Science, Stanford University, Stanford, CA, USA
| | - Virginia L Jin
- USDA-ARS Agroecosystem Management Research Unit, University of Nebraska, Lincoln, NE, USA
| | - Albina R Khasanova
- Section of Integrative Biology, The University of Texas at Austin, Austin, TX, USA
| | - Lara G Reichmann
- Section of Integrative Biology, The University of Texas at Austin, Austin, TX, USA
| | - H Wayne Polley
- USDA-ARS, Grassland, Soil, and Water Research Laboratory, Temple, TX, USA
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8
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Sage RF. A portrait of the C4 photosynthetic family on the 50th anniversary of its discovery: species number, evolutionary lineages, and Hall of Fame. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:4039-4056. [PMID: 28110278 DOI: 10.1093/jxb/erx005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Fifty years ago, the C4 photosynthetic pathway was first characterized. In the subsequent five decades, much has been learned about C4 plants, such that it is now possible to place nearly all C4 species into their respective evolutionary lineages. Sixty-one independent lineages of C4 photosynthesis are identified, with additional, ancillary C4 origins possible in 12 of these principal lineages. The lineages produced ~8100 C4 species (5044 grasses, 1322 sedges, and 1777 eudicots). Using midpoints of stem and crown node dates in their respective phylogenies, the oldest and most speciose C4 lineage is the grass lineage Chloridoideae, estimated to be near 30 million years old. Most C4 lineages are estimated to be younger than 15 million years. Older C4 lineages tend to be more speciose, while those younger than 7 million years have <43 species each. To further highlight C4 photosynthesis for a 50th anniversary snapshot, a Hall of Fame comprised of the 40 most significant C4 species is presented. Over the next 50 years, preservation of the Earth's C4 diversity is a concern, largely because of habitat loss due to elevated CO2 effects, invasive species, and expanded agricultural activities. Ironically, some members of the C4 Hall of Fame are leading threats to the natural C4 flora due to their association with human activities on landscapes where most C4 plants occur.
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Affiliation(s)
- Rowan F Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON M5R3C6
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9
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Polley HW, Bailey DW, Nowak RS, Stafford-Smith M. Ecological Consequences of Climate Change on Rangelands. RANGELAND SYSTEMS 2017. [DOI: 10.1007/978-3-319-46709-2_7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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10
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Sage RF. A portrait of the C4 photosynthetic family on the 50th anniversary of its discovery: species number, evolutionary lineages, and Hall of Fame. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:4039-56. [PMID: 27053721 DOI: 10.1093/jxb/erw156] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Fifty years ago, the C4 photosynthetic pathway was first characterized. In the subsequent five decades, much has been learned about C4 plants, such that it is now possible to place nearly all C4 species into their respective evolutionary lineages. Sixty-one independent lineages of C4 photosynthesis are identified, with additional, ancillary C4 origins possible in 12 of these principal lineages. The lineages produced ~8100 C4 species (5044 grasses, 1322 sedges, and 1777 eudicots). Using midpoints of stem and crown node dates in their respective phylogenies, the oldest and most speciose C4 lineage is the grass lineage Chloridoideae, estimated to be near 30 million years old. Most C4 lineages are estimated to be younger than 15 million years. Older C4 lineages tend to be more speciose, while those younger than 7 million years have <43 species each. To further highlight C4 photosynthesis for a 50th anniversary snapshot, a Hall of Fame comprised of the 40 most significant C4 species is presented. Over the next 50 years, preservation of the Earth's C4 diversity is a concern, largely because of habitat loss due to elevated CO2 effects, invasive species, and expanded agricultural activities. Ironically, some members of the C4 Hall of Fame are leading threats to the natural C4 flora due to their association with human activities on landscapes where most C4 plants occur.
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Affiliation(s)
- Rowan F Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON M5R3C6
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11
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Mueller KE, Blumenthal DM, Pendall E, Carrillo Y, Dijkstra FA, Williams DG, Follett RF, Morgan JA. Impacts of warming and elevated CO2 on a semi-arid grassland are non-additive, shift with precipitation, and reverse over time. Ecol Lett 2016; 19:956-66. [PMID: 27339693 DOI: 10.1111/ele.12634] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 04/01/2016] [Accepted: 05/15/2016] [Indexed: 12/28/2022]
Abstract
It is unclear how elevated CO2 (eCO2 ) and the corresponding shifts in temperature and precipitation will interact to impact ecosystems over time. During a 7-year experiment in a semi-arid grassland, the response of plant biomass to eCO2 and warming was largely regulated by interannual precipitation, while the response of plant community composition was more sensitive to experiment duration. The combined effects of eCO2 and warming on aboveground plant biomass were less positive in 'wet' growing seasons, but total plant biomass was consistently stimulated by ~ 25% due to unique, supra-additive responses of roots. Independent of precipitation, the combined effects of eCO2 and warming on C3 graminoids became increasingly positive and supra-additive over time, reversing an initial shift toward C4 grasses. Soil resources also responded dynamically and non-additively to eCO2 and warming, shaping the plant responses. Our results suggest grasslands are poised for drastic changes in function and highlight the need for long-term, factorial experiments.
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Affiliation(s)
- K E Mueller
- Rangeland Resources Research Unit, Agricultural Research Service, United States Department of Agriculture, Fort Collins, CO, 80526, USA
| | - D M Blumenthal
- Rangeland Resources Research Unit, Agricultural Research Service, United States Department of Agriculture, Fort Collins, CO, 80526, USA
| | - E Pendall
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Y Carrillo
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia
| | - F A Dijkstra
- Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - D G Williams
- Department of Botany, University of Wyoming, Laramie, WY, 82071, USA
| | - R F Follett
- Soil Plant and Nutrient Research Unit, Agricultural Research Service, United States Department of Agriculture, Fort Collins, CO, 80526, USA
| | - J A Morgan
- Rangeland Resources Research Unit, Agricultural Research Service, United States Department of Agriculture, Fort Collins, CO, 80526, USA
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12
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Lassaletta L, Aguilera E. Soil carbon sequestration is a climate stabilization wedge: comments on Sommer and Bossio (2014). JOURNAL OF ENVIRONMENTAL MANAGEMENT 2015; 153:48-49. [PMID: 25646676 DOI: 10.1016/j.jenvman.2015.01.038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 01/21/2015] [Indexed: 06/04/2023]
Abstract
Sommer and Bossio (2014) model the potential soil organic carbon (SOC) sequestration in agricultural soils (croplands and grasslands) during the next 87 years, concluding that this process cannot be considered as a climate stabilization wedge. We argue, however, that the amounts of SOC potentially sequestered in both scenarios (pessimistic and optimistic) fulfil the requirements for being considered as wedge because in both cases at least 25 GtC would be sequestered during the next 50 years. We consider that it is precisely in the near future, and meanwhile other solutions are developed, when this stabilization effort is most urgent even if after some decades the sequestration rate is significantly reduced. Indirect effects of SOC sequestration on mitigation could reinforce the potential of this solution. We conclude that the sequestration of organic carbon in agricultural soils as a climate change mitigation tool still deserves important attention for scientists, managers and policy makers.
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Affiliation(s)
- Luis Lassaletta
- PBL Netherlands Environmental Assessment Agency, 3720 A H Bilthoven, The Netherlands.
| | - Eduardo Aguilera
- Universidad Pablo de Olavide, Ctra. de Utrera, km. 1, 41013 Sevilla, Spain.
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13
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Fay PA, Newingham BA, Polley HW, Morgan JA, LeCain DR, Nowak RS, Smith SD. Dominant plant taxa predict plant productivity responses to CO2 enrichment across precipitation and soil gradients. AOB PLANTS 2015; 7:plv027. [PMID: 25829380 PMCID: PMC4429605 DOI: 10.1093/aobpla/plv027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 03/13/2015] [Indexed: 05/27/2023]
Abstract
The Earth's atmosphere will continue to be enriched with carbon dioxide (CO2) over the coming century. Carbon dioxide enrichment often reduces leaf transpiration, which in water-limited ecosystems may increase soil water content, change species abundances and increase the productivity of plant communities. The effect of increased soil water on community productivity and community change may be greater in ecosystems with lower precipitation, or on coarser-textured soils, but responses are likely absent in deserts. We tested correlations among yearly increases in soil water content, community change and community plant productivity responses to CO2 enrichment in experiments in a mesic grassland with fine- to coarse-textured soils, a semi-arid grassland and a xeric shrubland. We found no correlation between CO2-caused changes in soil water content and changes in biomass of dominant plant taxa or total community aboveground biomass in either grassland type or on any soil in the mesic grassland (P > 0.60). Instead, increases in dominant taxa biomass explained up to 85 % of the increases in total community biomass under CO2 enrichment. The effect of community change on community productivity was stronger in the semi-arid grassland than in the mesic grassland, where community biomass change on one soil was not correlated with the change in either the soil water content or the dominant taxa. No sustained increases in soil water content or community productivity and no change in dominant plant taxa occurred in the xeric shrubland. Thus, community change was a crucial driver of community productivity responses to CO2 enrichment in the grasslands, but effects of soil water change on productivity were not evident in yearly responses to CO2 enrichment. Future research is necessary to isolate and clarify the mechanisms controlling the temporal and spatial variations in the linkages among soil water, community change and plant productivity responses to CO2 enrichment.
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Affiliation(s)
- Philip A Fay
- Grassland, Soil, and Water Laboratory, USDA-ARS, 808 E Blackland Rd., Temple, TX 76502, USA
| | - Beth A Newingham
- College of Natural Resources, University of Idaho, PO Box 441133, Moscow, ID 83844, USA Present address: Great Basin Rangelands Research, USDA-ARS, 920 Valley Rd., Reno, NV 89512, USA
| | - H Wayne Polley
- Grassland, Soil, and Water Laboratory, USDA-ARS, 808 E Blackland Rd., Temple, TX 76502, USA
| | - Jack A Morgan
- Rangeland Resources Research Unit, USDA-ARS, 1701 Centre Avenue, Fort Collins, CO 80526, USA
| | - Daniel R LeCain
- Rangeland Resources Research Unit, USDA-ARS, 1701 Centre Avenue, Fort Collins, CO 80526, USA
| | - Robert S Nowak
- Department of Natural Resources and Environmental Science/MS 186, University of Nevada Reno, 1664 North Virginia, Reno, NV 89557, USA
| | - Stanley D Smith
- School of Life Sciences, University of Nevada, Las Vegas, 4505 S. Maryland Parkway, Las Vegas, NV 89154, USA
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Polley HW, Derner JD, Jackson RB, Gill RA, Procter AC, Fay PA. Plant community change mediates the response of foliar δ(15)N to CO 2 enrichment in mesic grasslands. Oecologia 2015; 178:591-601. [PMID: 25604918 DOI: 10.1007/s00442-015-3221-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 01/03/2015] [Indexed: 11/28/2022]
Abstract
Rising atmospheric CO2 concentration may change the isotopic signature of plant N by altering plant and microbial processes involved in the N cycle. CO2 may increase leaf δ(15)N by increasing plant community productivity, C input to soil, and, ultimately, microbial mineralization of old, (15)N-enriched organic matter. We predicted that CO2 would increase aboveground productivity (ANPP; g biomass m(-2)) and foliar δ(15)N values of two grassland communities in Texas, USA: (1) a pasture dominated by a C4 exotic grass, and (2) assemblages of tallgrass prairie species, the latter grown on clay, sandy loam, and silty clay soils. Grasslands were exposed in separate experiments to a pre-industrial to elevated CO2 gradient for 4 years. CO2 stimulated ANPP of pasture and of prairie assemblages on each of the three soils, but increased leaf δ(15)N only for prairie plants on a silty clay. δ(15)N increased linearly as mineral-associated soil C declined on the silty clay. Mineral-associated C declined as ANPP increased. Structural equation modeling indicted that CO2 increased ANPP partly by favoring a tallgrass (Sorghastrum nutans) over a mid-grass species (Bouteloua curtipendula). CO2 may have increased foliar δ(15)N on the silty clay by reducing fractionation during N uptake and assimilation. However, we interpret the soil-specific, δ(15)N-CO2 response as resulting from increased ANPP that stimulated mineralization from recalcitrant organic matter. By contrast, CO2 favored a forb species (Solanum dimidiatum) with higher δ(15)N than the dominant grass (Bothriochloa ischaemum) in pasture. CO2 enrichment changed grassland δ(15)N by shifting species relative abundances.
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Affiliation(s)
- H Wayne Polley
- Grassland, Soil and Water Research Laboratory, USDA-Agricultural Research Service, Temple, TX, 76502, USA,
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Procter AC, Ellis JC, Fay PA, Polley HW, Jackson RB. Fungal Community Responses to Past and Future Atmospheric CO2 Differ by Soil Type. Appl Environ Microbiol 2014; 80:7364-77. [PMID: 25239904 PMCID: PMC4249185 DOI: 10.1128/aem.02083-14] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 09/16/2014] [Indexed: 11/20/2022] Open
Abstract
Soils sequester and release substantial atmospheric carbon, but the contribution of fungal communities to soil carbon balance under rising CO2 is not well understood. Soil properties likely mediate these fungal responses but are rarely explored in CO2 experiments. We studied soil fungal communities in a grassland ecosystem exposed to a preindustrial-to-future CO2 gradient (250 to 500 ppm) in a black clay soil and a sandy loam soil. Sanger sequencing and pyrosequencing of the rRNA gene cluster revealed that fungal community composition and its response to CO2 differed significantly between soils. Fungal species richness and relative abundance of Chytridiomycota (chytrids) increased linearly with CO2 in the black clay (P < 0.04, R(2) > 0.7), whereas the relative abundance of Glomeromycota (arbuscular mycorrhizal fungi) increased linearly with elevated CO2 in the sandy loam (P = 0.02, R(2) = 0.63). Across both soils, decomposition rate was positively correlated with chytrid relative abundance (r = 0.57) and, in the black clay soil, fungal species richness. Decomposition rate was more strongly correlated with microbial biomass (r = 0.88) than with fungal variables. Increased labile carbon availability with elevated CO2 may explain the greater fungal species richness and Chytridiomycota abundance in the black clay soil, whereas increased phosphorus limitation may explain the increase in Glomeromycota at elevated CO2 in the sandy loam. Our results demonstrate that soil type plays a key role in soil fungal responses to rising atmospheric CO2.
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Affiliation(s)
- Andrew C Procter
- Department of Biology, Duke University, Durham, North Carolina, USA
| | | | - Philip A Fay
- Grassland, Soil and Water Research Laboratory, U.S. Department of Agriculture, Agricultural Research Service, Temple, Texas, USA
| | - H Wayne Polley
- Grassland, Soil and Water Research Laboratory, U.S. Department of Agriculture, Agricultural Research Service, Temple, Texas, USA
| | - Robert B Jackson
- Department of Biology, Duke University, Durham, North Carolina, USA Nicholas School of the Environment, Duke University, Durham, North Carolina, USA School of Earth Sciences, Stanford University, Stanford, California, USA
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Polley HW, Derner JD, Jackson RB, Wilsey BJ, Fay PA. Impacts of climate change drivers on C4 grassland productivity: scaling driver effects through the plant community. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:3415-3424. [PMID: 24501178 DOI: 10.1093/jxb/eru009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Climate change drivers affect plant community productivity via three pathways: (i) direct effects of drivers on plants; (ii) the response of species abundances to drivers (community response); and (iii) the feedback effect of community change on productivity (community effect). The contribution of each pathway to driver-productivity relationships depends on functional traits of dominant species. We used data from three experiments in Texas, USA, to assess the role of community dynamics in the aboveground net primary productivity (ANPP) response of C4 grasslands to two climate drivers applied singly: atmospheric CO2 enrichment and augmented summer precipitation. The ANPP-driver response differed among experiments because community responses and effects differed. ANPP increased by 80-120g m(-2) per 100 μl l(-1) rise in CO2 in separate experiments with pasture and tallgrass prairie assemblages. Augmenting ambient precipitation by 128mm during one summer month each year increased ANPP more in native than in exotic communities in a third experiment. The community effect accounted for 21-38% of the ANPP CO2 response in the prairie experiment but little of the response in the pasture experiment. The community response to CO2 was linked to species traits associated with greater soil water from reduced transpiration (e.g. greater height). Community effects on the ANPP CO2 response and the greater ANPP response of native than exotic communities to augmented precipitation depended on species differences in transpiration efficiency. These results indicate that feedbacks from community change influenced ANPP-driver responses. However, the species traits that regulated community effects on ANPP differed from the traits that determined how communities responded to drivers.
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Affiliation(s)
- H Wayne Polley
- USDA-Agricultural Research Service, Grassland, Soil & Water Research Laboratory, Temple, Texas, 76502, USA
| | - Justin D Derner
- USDA-Agricultural Research Service, High Plains Grasslands Research Station, Cheyenne, Wyoming, 82009, USA
| | - Robert B Jackson
- Nicholas School of the Environment, Duke University, Durham, North Carolina 27708, USA Biology Department, Duke University, Durham, North Carolina 27708, USA
| | - Brian J Wilsey
- Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, Iowa 50011, USA
| | - Philip A Fay
- USDA-Agricultural Research Service, Grassland, Soil & Water Research Laboratory, Temple, Texas, 76502, USA
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Newton PCD, Lieffering M, Parsons AJ, Brock SC, Theobald PW, Hunt CL, Luo D, Hovenden MJ. Selective grazing modifies previously anticipated responses of plant community composition to elevated CO(2) in a temperate grassland. GLOBAL CHANGE BIOLOGY 2014; 20:158-169. [PMID: 23828718 DOI: 10.1111/gcb.12301] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 06/05/2013] [Indexed: 06/02/2023]
Abstract
Our limited understanding of terrestrial ecosystem responses to elevated CO2 is a major constraint on predicting the impacts of climate change. A change in botanical composition has been identified as a key factor in the CO2 response with profound implications for ecosystem services such as plant production and soil carbon storage. In temperate grasslands, there is a strong consensus that elevated CO2 will result in a greater physiological stimulus to growth in legumes and to a lesser extent forbs, compared with C3 grasses, and the presumption this will lead in turn to a greater proportion of these functional groups in the plant community. However, this view is based on data mainly collected in experiments of three or less years in duration and not in experiments where defoliation has been by grazing animals. Grazing is, however, the most common management of grasslands and known in itself to influence botanical composition. In a long-term Free Air Carbon Dioxide Enrichment (FACE) experiment in a temperate grassland managed with grazing animals (sheep), we found the response to elevated CO2 in plant community composition in the first 5 years was consistent with the expectation of increased proportions of legumes and forbs. However, in the longer term, these differences diminished so that the proportions of grasses, legumes and forbs were the same under both ambient and elevated CO2 . Analysis of vegetation before and after each grazing event showed there was a sustained disproportionately greater removal ('apparent selection') of legumes and forbs by the grazing animals. This bias in removal was greater under elevated CO2 than ambient CO2 . This is consistent with sustained faster growth rates of legumes and forbs under elevated CO2 being countered by selective defoliation, and so leading to little difference in community composition.
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Affiliation(s)
- Paul C D Newton
- AgResearch, Private Bag 11008, Palmerston North, New Zealand
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The response of aboveground net primary productivity of desert vegetation to rainfall pulse in the temperate desert region of northwest China. PLoS One 2013; 8:e73003. [PMID: 24019888 PMCID: PMC3760839 DOI: 10.1371/journal.pone.0073003] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 07/15/2013] [Indexed: 11/19/2022] Open
Abstract
Rainfall events can be characterized as "pulses", which are discrete and variable episodes that can significantly influence the structure and function of desert ecosystems, including shifts in aboveground net primary productivity (ANPP). To determine the threshold and hierarchical response of rainfall event size on the Normalized Difference Vegetation Index (NDVI, a proxy for ANPP) and the difference across a desert area in northwestern China with two habitats - dune and desert - we selected 17 independent summer rainfall events from 2005 to 2012, and obtained a corresponding NDVI dataset extracted from MODIS images. Based on the threshold-delay model and statistical analysis, the results showed that the response of NDVI to rainfall pulses began at about a 5 mm event size. Furthermore, when the rainfall event size was more than 30 mm, NDVI rapidly increased 3- to 6-fold compared with the response to events of less than 30 mm, suggesting that 30 mm was the threshold for a large NDVI response. These results revealed the importance of the 5 mm and 30 mm rainfall events for plant survival and growth in desert regions. There was an 8- to 16-day lag time between the rainfall event and the NDVI response, and the response duration varied with rainfall event size, reaching a maximum of 32 days. Due to differences in soil physical and mineralogical properties, and to biodiversity structure and the root systems' abilities to exploit moisture, dune and desert areas differed in precipitation responses: dune habitats were characterized by a single, late summer productivity peak; in contrast, deserts showed a multi-peak pattern throughout the growing season.
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Xu X, Sherry RA, Niu S, Li D, Luo Y. Net primary productivity and rain-use efficiency as affected by warming, altered precipitation, and clipping in a mixed-grass prairie. GLOBAL CHANGE BIOLOGY 2013; 19:2753-64. [PMID: 23649795 DOI: 10.1111/gcb.12248] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 04/20/2013] [Accepted: 04/27/2013] [Indexed: 05/14/2023]
Abstract
Grassland productivity in response to climate change and land use is a global concern. In order to explore the effects of climate change and land use on net primary productivity (NPP), NPP partitioning [fBNPP , defined as the fraction of belowground NPP (BNPP) to NPP], and rain-use efficiency (RUE) of NPP, we conducted a field experiment with warming (+3 °C), altered precipitation (double and half), and annual clipping in a mixed-grass prairie in Oklahoma, USA since July, 2009. Across the years, warming significantly increased BNPP, fBNPP , and RUEBNPP by an average of 11.6%, 2.8%, and 6.6%, respectively. This indicates that BNPP was more sensitive to warming than aboveground NPP (ANPP) since warming did not change ANPP and RUEANPP much. Double precipitation stimulated ANPP, BNPP, and NPP but suppressed RUEANPP , RUEBNPP , and RUENPP while half precipitation decreased ANPP, BNPP, and NPP but increased RUEANPP , RUEBNPP , and RUENPP . Clipping interacted with altered precipitation in impacting RUEANPP , RUEBNPP , and RUENPP , suggesting land use could confound the effects of precipitation changes on ecosystem processes. Soil moisture was found to be a main factor in regulating variation in ANPP, BNPP, and NPP while soil temperature was the dominant factor influencing fBNPP . These findings suggest that BNPP is critical point to future research. Additionally, results from single-factor manipulative experiments should be treated with caution due to the non-additive interactive effects of warming with altered precipitation and land use (clipping).
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Affiliation(s)
- Xia Xu
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019, USA.
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