Increasing effects of chronic nutrient enrichment on plant diversity loss and ecosystem productivity over time

Authors: SEABLOOM, ERIC - University Of Minnesota; ADLER, PETER - Utah State University; ALBERTI, JUAN - (NCE, CECR)networks Of Centres Of Exellence Of Canada, Centres Of Excellence For Commercilization A; BIEDERMAN, LORI - Iowa State University; BUCKLEY, YVONNE - Trinity College; CADOTTE, MARC - University Of Toronto; COLLINS, SCOTT - University Of New Mexico; DEE, LAURA - University Of Colorado; Fay, Philip; FIRN, JENNIFER - University Of Minnesota; HAGENAH, NICOLE - University Of Pretoria; HARPOLE, W - Helmholtz Centre For Environmental Research; HAUTIER, YANN - Utrecht University; HECTOR, ANDY - University Of Oxford; HOBBIE, SARAH - University Of Minnesota; ISBELL, FOREST - University Of Minnesota; KNOPS, JOHANNES - University Of Nebraska; KOMATSU, KIMBERLY - Smithsonian Environmental Research Center; LAUNGANI, RAMESH - Doane University; MACDOUGALL, ANDREW - University Of Guelph; MCCULLEY, REBECCA - University Of Kentucky; MOORE, JOSLIN - Monash University; MORGAN, JOHN - La Trobe University; OHLERT, TIMOTHY - University Of New Mexico; PROBER, SUZANNE - Commonwealth Scientific And Industrial Research Organisation (CSIRO); RISCH, ANITA - Swiss Federal Research Institute Wsl; SCHUETZ, MARTIN - Swiss Federal Research Institute Wsl; STEVENS, CARLY - Lancaster University; BORER, ELIZABETH - University Of Minnesota

Submitted to: Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2020
Publication Date: 2/3/2021
Citation: Seabloom, E.W., Adler, P.B., Alberti, J., Biederman, L., Buckley, Y.M., Cadotte, M.W., Collins, S.L., Dee, L., Fay, P.A., Firn, J., Hagenah, N., Harpole, W.S., Hautier, Y., Hector, A., Hobbie, S.E., Isbell, F., Knops, J.M., Komatsu, K.J., Laungani, R., Macdougall, A., Mcculley, R.L., Moore, J.L., Morgan, J.W., Ohlert, T., Prober, S.M., Risch, A.C., Schuetz, M., Stevens, C.J., Borer, E.T. 2021. Increasing effects of chronic nutrient enrichment on plant diversity loss and ecosystem productivity over time. Ecology. 102(2):e03218. https://doi.org/10.1002/ecy.3218.
DOI: https://doi.org/10.1002/ecy.3218

Interpretive Summary: Human activities are enriching many of Earth’s ecosystems with biologically limiting mineral nutrients such as nitrogen (N), phosphorus (P), and potassium (K). In grassland ecosystems, this enrichment is generally considered to increase production but at the expense of reduced plant diversity. Losses in plant diversity may have many negative consequences, including suppressing initial gains in productivity, loss of biodiversity of animals that depend on the lost plant species, and reduced resilience to climate variability. However, the time frame over which these effects accumulate is poorly understood. Examination of the long-term effects of experimental fertilization with N, P, and K at 47 grasslands sites in twelve countries, revealed that increases in productivity and losses of plant diversity were widespread and increased in magnitude through time. These results suggest that the impacts of enrichment of ecosystems with limiting nutrients unfold over longer time frames than is commonly appreciated, and that deleterious impacts will continue to accrue in the absence of policy and management actions to mitigate these effects. Long term experiments are required to detect these effects, because short-term experiments will underestimate the long-term effects of human-caused nutrient enrichment on global grassland ecosystems.

Technical Abstract: Global changes act on multiple, interlinked components of ecosystems, creating the potential for feedbacks that may either increase or dampen their effects over time. For example, human activities are enriching many of Earth’s ecosystems with biologically limiting mineral nutrients such as nitrogen (N), phosphorus (P), and potassium (K). In grassland ecosystems, this enrichment generally reduces plant diversity and increases productivity. The widely demonstrated positive effect of diversity on productivity suggests the potential for a negative feedback through time, whereby nutrient-induced declines in diversity reduce the initial gains in productivity arising from nutrient enrichment. In addition, plant productivity and diversity can be inhibited by accumulations of dead biomass (i.e., litter), and nutrient enrichment has the potential to either speed or slow decomposition, potentially increasing or decreasing accumulation of dead plant biomass. We examined the effects of experimental nutrient addition at 47 grasslands sites in twelve countries. Nutrient enrichment increased aboveground, live biomass and reduced plant diversity at nearly all sites, and these effects became stronger through time. This work suggests that short-term experiments underestimate the long-term effects of human-caused nutrient enrichment on global, grassland ecosystems.