1. Belowground Biomass Response to Nutrient Enrichment Depends on Light Limitation Across Globally Distributed Grasslands
- Author
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Cleland, Elsa E., Lind, Eric M., DeCrappeo, Nicole M., DeLorenze, Elizabeth, Wilkins, Rachel Abbott, Adler, Peter B., Bakker, Jonathan D., Brown, Cynthia S., Davies, Kendi F., Esch, Ellen, Firn, Jennifer, Gressard, Scott, Gruner, Daniel S., Hagenah, Nicole, Harpole, W. Stanley, Hautier, Yann, Hobbie, Sarah E., Hofmockel, Kirsten S., Kirkman, Kevin, Knops, Johannes, Kopp, Christopher W., La Pierre, Kimberly J., MacDougall, Andrew, McCulley, Rebecca L., Melbourne, Brett A., Moore, Joslin L., Prober, Suzanne M., Riggs, Charlotte, Risch, Anita C., Schuetz, Martin, Stevens, Carly, Wragg, Peter D., Wright, Justin, Borer, Elizabeth T., Seabloom, Eric W., Sub Ecology and Biodiversity, Ecology and Biodiversity, Sub Ecology and Biodiversity, and Ecology and Biodiversity
- Subjects
0106 biological sciences ,Canopy ,roots ,Nutrient cycle ,010504 meteorology & atmospheric sciences ,Life on Land ,Evolution ,optimal allocation ,Context (language use) ,Carbon sequestration ,010603 evolutionary biology ,01 natural sciences ,Grassland ,nitrogen ,Nutrient ,Behavior and Systematics ,belowground biomass ,Taverne ,Environmental Chemistry ,Ecosystem ,phosphorus ,Ecology, Evolution, Behavior and Systematics ,0105 earth and related environmental sciences ,Biomass (ecology) ,geography ,geography.geographical_feature_category ,Ecology ,food and beverages ,Biological Sciences ,Nutrient Network ,Agronomy ,fertilization ,Environmental science ,Environmental Sciences - Abstract
Anthropogenic activities are increasing nutrient inputs to ecosystems worldwide, with consequences for global carbon and nutrient cycles. Recent meta-analyses show that aboveground primary production is often co-limited by multiple nutrients; however, little is known about how root 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 aboveground 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 belowground declined with N or P addition, due to increased biomass aboveground (for N and P) and decreased biomass belowground (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 belowground responses to changes in resource supply can differ strongly from aboveground 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 belowground biomass responses to nutrient enrichment at the ecosystem scale across wide climatic and environmental gradients.
- Published
- 2019