Belowground Biomass Response to Nutrient Enrichment Depends on Light Limitation Across Globally Distributed Grasslands

Journal Article · Fri Nov 29 04:00:00 EST 2019 · Ecosystems

DOI:https://doi.org/10.1007/s10021-019-00350-4· OSTI ID:1608616

Cleland, Elsa ^[1]; Lind, Eric ^[2]; Decrappeo, Nicole ^[3]; DeLorenze, Elizabeth ^[4]; Wilkins, Rachel ^[5]; Adler, Peter ^[6]; Bakker, J D. ^[7]; Brown, Cynthia ^[8]; Davies, Kendi F. ^[9]; Esch, Ellen ^[10]; Firn, Jennifer ^[11]; Gressard, Scott ^[12]; Gruner, Daniel ^[13]; Hagenah, Nicole ^[14]; Harpole, W S. ^[15]; Hautier, Yann ^[16]; Hobbie, Sarah ^[2]; Hofmockel, Kirsten S. ^[17]; Kirkman, Kevin ^[18]; Knops, Johannes ^[19] ; Kopp, Christopher ^[20]; La Pierre, Kimberly ^[21]; Macdougall, Andrew ^[10]; Mcculley, Rebecca ^[22]; Melbourne, Brett ^[23]; Moore, Joslin ^[24]; Prober, Suzanne ^[25]; Riggs, Charlotte ^[26]; Risch, Anita C. ^[27]; Schuetz, Martin ^[27]; Stevens, Carly ^[28]; Wragg, Peter ^[2]; Wright, Justin ^[29]; Borer, Elizabeth ^[2]; Seabloom, Eric ^[2]

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1. University of California, San Diego
2. Minnesota, Univ Of - Minneapol
3. USGS
4. US Geological Survey
5. Cornell University
6. Utah State University
7. University of Washington
8. Colorado State University
9. Department of Ecology and Evolutionary Biology, University of Colorado
10. University of Guelph
11. Queensland University of Technology
12. Dudek Company
13. University of Toronto
14. South African Environmental Observation Network
15. German Centre for Integrative Biodiversity Research
16. Universiteit Utrecht
17. BATTELLE (PACIFIC NW LAB)
18. University of KwaZulu-Natal
19. University of Nebraska - Lincoln
20. University of British Columbia
21. Smithsonian Environmental Research Center
22. University of Kentucky
23. University of Colorado at Boulder
24. Monash University
25. CSIRO
26. US Forest Service
27. Swiss Federal Institute for Forest, Snow and Landscape Research WSL
28. University of Lancaster
29. Duke University

Anthropogenic activities are increasing nutrient inputs to ecosystems worldwide, with consequences for global carbon and nutrient cycles. Recent meta analyses show that above ground primary production is often co-limited by multiple nutrients; however, little is known abouthowroot production responds to changes in nutrient availability. At twenty-nine grassland sites on four continents, we quantified shallow root biomass responses to nitrogen (N), phosphorus (P) and potassium plus micronutrient enrichment and compared below- and above ground responses. We hypothesized that optimal allocation theory would predict context dependence in root biomass responses to nutrient enrichment, given variation among sites in the resources limiting to plant growth (specifically light versus nutrients). Consistent with the predictions of optimal allocation theory, the proportion of total biomass below ground declined with N or P addition, due to increased biomass above ground (for N and P) and decreased biomass below ground (N, particularly in sites with low canopy light penetration). Absolute root biomass increased with N addition where light was abundant at the soil surface, but declined in sites where the grassland canopy intercepted a large proportion of incoming light. These results demonstrate that below ground responses to changes in resource supply can differ strongly from above ground responses, which could significantly modify predictions of future rates of nutrient cycling and carbon sequestration. Our results also highlight how optimal allocation theory developed for individual plants may help predict below ground biomass responses to nutrient enrichment at the ecosystem scale across wide climatic and environmental gradients.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1608616
• Report Number(s): PNNL-SA-142332
• Journal Information: Ecosystems, Journal Name: Ecosystems Journal Issue: 7 Vol. 22
• Country of Publication: United States
• Language: English