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Root responses to elevated CO2, warming and irrigation in a semi-arid grassland: Integrating biomass, length and life span in a 5-year field experiment

Journal Article · · Journal of Ecology
 [1];  [2];  [3];  [4];  [2];  [2]
  1. Cleveland State Univ., Cleveland, OH (United States); DOE/OSTI
  2. US Dept. of Agriculture (USDA), Fort Collins, CO (United States)
  3. University of Minnesota, Saint Paul, MN (United States)
  4. Univ. of Western Sydney, NSW (Australia)
+ Show Author Affiliations
Plant roots mediate the impacts of environmental change on ecosystems, yet knowledge of root responses to environmental change is limited because few experiments evaluate multiple environmental factors and their interactions. Inferences about root functions are also limited because root length dynamics are rarely measured. Using a 5-year experiment in a mixed-grass prairie, we report the responses of root biomass, length and life span to elevated carbon dioxide (CO2), warming, elevated CO2 and warming combined, and irrigation. Root biomass was quantified using soil cores and root length dynamics were assessed using minirhizotrons. By comparing root dynamics with published results for soil resources and above-ground productivity, we provide mechanistic insights into how climate change might impact grassland ecosystems. In the upper soil layer, 0–15 cm depth, both irrigation and elevated CO2 alone increased total root length by twofold, but irrigation decreased root biomass and elevated CO2 had only small positive effects on root biomass. The large positive effects of irrigation and elevated CO2 alone on total root length were due to increases in both root length production and root life span. The increased total root length and life span under irrigation and elevated CO2 coincided with apparent shifts from water limitation of plant growth to nitrogen limitation. Warming alone had minimal effects on root biomass, length and life span in this shallow soil layer. Warming and elevated CO2 combined increased root biomass and total root length by c. 25%, but total root length in this treatment was lower than expected if the effects of CO2 and warming alone were additive. Treatment effects on total root length and root life span varied with soil depth and root diameter. Synthesis. Sub-additive effects of CO2 and warming suggest studies of elevated CO2 alone might overestimate the future capacity of grassland root systems to acquire resources. In this mixed-grass prairie, elevated CO2 with warming stimulated total root length and root life span in deeper soils, likely enhancing plant access to more stable pools of growth-limiting resources, including water and phosphorus. Therefore, these root responses help explain previous observations of higher, and more stable, above-ground productivity in these projected climate conditions.
Research Organization:
University of Wyoming, Laramie, WY (United States)
Sponsoring Organization:
USDOE; USDOE Office of Science (SC)
Grant/Contract Number:
SC0006973
OSTI ID:
1610913
Alternate ID(s):
OSTI ID: 1437082
Journal Information:
Journal of Ecology, Journal Name: Journal of Ecology Journal Issue: 6 Vol. 106; ISSN 0022-0477
Publisher:
WileyCopyright Statement
Country of Publication:
United States
Language:
English

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Cited By (4)

Data from: Root responses to elevated CO2, warming, and irrigation in a semi-arid grassland: integrating biomass, length, and life span in a 5‐year field experiment dataset January 2019
Temporal Coupling of Subsurface and Surface Soil CO 2 Fluxes: Insights From a Nonsteady State Model and Cross-Wavelet Coherence Analysis journal April 2018
Distinct fine‐root responses to precipitation changes in herbaceous and woody plants: a meta‐analysis journal November 2019
N : P stoichiometry and habitat effects on Mediterranean savanna seasonal root dynamics journal January 2019

Similar Records

Long-term exposure to elevated CO2 enhances plant community stability by suppressing dominant plant species in a mixed-grass prairie
Journal Article · Sun Oct 12 20:00:00 EDT 2014 · Proceedings of the National Academy of Sciences of the United States of America · OSTI ID:1348417

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
Environmental Sciences & Ecology
Plant Sciences