University of Minnesota
University of Minnesota
College of Biological Sciences

E120 - Biodiversity II: Effects of Plant Biodiversity on Population and Ecosystem Processes



This experiment (often called the "Big" Biodiversity Experiment; the "small" experiment is no longer maintained) determines effects of plant species numbers and functional traits on community and ecosystem dynamics and functioning. It manipulates the number of plant species in 168 plots, each 9 m x 9 m, by imposing plant species numbers of 1, 2, 4, 8, or 16 perennial grassland species. The species planted in a plot were randomly chosen from a pool of 18 species (4 species, each, of C4 grasses, C3 grasses, legumes, non-legume forbs; 2 species of woody plants). Its high replication (about 35 plots at each level of diversity) and large plots allow observation of responses of herbivorous, parasitoid and predator insects and allow additional treatments to be nested within plots. Planted in 1994, it has been annually sampled since 1996 for plant aboveground biomass and plant species abundances and for insect diversity and species abundances. Root mass, soil nitrate, light interception, biomass of invading plant species, and C and N levels in soils, roots, and aboveground biomass have been determined periodically. In addition, soil microbial processes and abundances of mycorrhizal fungi, soil bacteria and other fungi, N mineralization rates, patterns of N uptake by various species, and invading plant species, have been periodically measured in subprojects in the Biodiversity Experiment.

Key Results


Using two long-term (>12 years) biodiversity experiments, we show that the effects of diversity on biomass productivity increased and became less saturating over time. Our analyses suggest that effects of diversity-dependent ecosystem feedbacks and interspecific complementarity accumulate over time, causing high-diversity species combinations that appeared functionally redundant during early years to become more functionally unique through time. Consequently, simplification of diverse ecosystems will likely have greater negative impacts on ecosystem functioning than has been suggested by short-term experiments. Reich et al. 2012 Science
Results of 11 experiments show that ecologically relevant decreases in grassland plant diversity influenced productivity at least as much as ecologically relevant changes in nitrogen, water, CO2, herbivores, drought, or fire. In particular, a change in plant diversity from four to 16 species caused as large an increase in productivity as addition of 54 kg•ha−1•y−1 of fertilizer N, and was as influential as removing a dominant herbivore, a major natural drought, water addition, and fire suppression. Our results suggest that the loss of biodiversity may have at least as great an impact on ecosystem functioning as other anthropogenic drivers of environmental change, and that use of diverse mixtures of species may be as effective in increasing productivity of some biomass crops as fertilization and may better provide ecosystem services. Tilman et al. 2012 PNAS
Plant biomass production increased with diversity (Fig 1) because of complementary interactions among species and not because of selection (sampling) effects (Figs 2 Tilman et al. 2001b, Pacala and Tilman 2002, Hille Ris Lambers et al. 2004; Fargione et al. in prep.).
Foliar fungal disease incidence decreased at higher diversity because of greater distance between individuals of a species, and resultant lower rates of disease spread (Mitchell et al. 2002).
Greater plant diversity led to greater diversity of herbivorous insects, and this effect continued up the food web to predator and parasitoid insects (Haddad et al. 2001).
Fewer novel plant species invaded higher diversity treatments because of their lower soil NO3 levels, greater neighborhood crowding and competition, and greater chance that functionally similar species would occur in a given neighborhood (Figs 3; Naeem et al. 2000, Kennedy et al. 2002, Fargione et al. 2003, Fargione and Tilman 2005a, 2005b).
Greater plant species numbers led to greater ecosystem stability (lower year-to-year variation in total plant biomass) but to lower species stability (greater year-to-year variation in abundances of individual species), with the stabilizing effect of diversity mainly attributable to statistical averaging effects and overyielding effects (Fig 4; Tilman et al, submitted).
Data gathered this past field season shows that soil total C has now become an increasing function of plant species numbers (Fig 5).
Our results have helped resolve a debate about why plant diversity affects ecosystem functioning. Such resolution was accomplished by a Paris symposium in which we made CDR biodiversity data available so others could test their alternative hypotheses; by a paper by 12 ecologists with divergent views that explored areas of agreement and articulated areas in need of 10 further testing (Loreau et al. 2001); and by our analyses of alternative hypotheses using results of the CDR biodiversity experiment (Tilman et al. 2001b).

Future Research


This experiment, now in its 17th year, is still highly productive, resulting in 43 peer reviewed papers during the current grant. We propose continuing our annual sampling of primary productivity and plant species abundances, and periodic sampling of soil properties, heterotroph communities, and other parameters. Among the questions that we will address in future research are: 

(1) Why did the impact of plant diversity on primary productivity increase so much from 1996 to 2005 and then slow during the past 5 years? Might productivity in low diversity plots slowly increase, and eventually catch up with that of high diversity plots? 
(2) What are the long-term prospects for high diversity plantings to serve as C sinks, and what role might herbivory play, since many herbivores preferentially feed on legumes? Can high diversity plant mixtures accrue more soil C and N than occurs in nearby native grassland ecosystems? 
(3) What are the quantitative dependences of various ecosystem services on plant species composition and diversity? We will explicitly quantify such services as improved ground water quality, provisioning of predatory and parasitoid insects of importance for the control of agricultural pests, provisioning of pollinators of agricultural relevance, reductions in the diversity and prevalence of agriculturally important pathogens, and the ability of high diversity buffer strips to capture sediment in surface runoff and remove excess nutrients and other agrichemicals. We also estimate the economic values of these and other ecosystem services. 
(4) Finally, we note that the CDR Biodiversity Experiment, the oldest and best replicated large-plot biodiversity experiment in the world, has become an important resource for many non-CDR researchers who visit CDR to sample the experiment to address their own novel questions (Zak et al. 2003, Haddad et al. 2009, 2011; P Vanderkoornhuyse, Universite de Rennes). We actively encourage and continually seek such outside collaborations and independent research initiatives.

Methods for e120


Datasets for e120: Biodiversity II: Effects of Plant Biodiversity on Population and Ecosystem Processes

Dataset IDTitleRange of Years (# years with data)
acqe120Developing seedheads treated with fungicide and insecticide2005-2005 (1 year)
invre120Invasion strip root biomass2002-2002 (1 year)
invne120Invasion strip soil nitrogen2002-2002 (1 year)
acve120Local plant diversity and soybean biological control 2011 Aphid and Enemy Surveys2011-2011 (1 year)
acxe120Local plant diversity and soybean biological control 2011 Harvest Measures2011-2011 (1 year)
acwe120Local plant diversity and soybean biological control 2012 Aphid Surveys2012-2012 (1 year)
adce120Local plant diversity and soybean biological control 2012 Enemy Surveys2012-2012 (1 year)
aage120Main Plots All Arthropod Insect Sweepnet Sampling 1996-20061996-2006 (10 years)
lpe120Percent light penetration1996-2000 (5 years)
nbe120Plant aboveground biomass carbon and nitrogen1996-2006 (7 years)
ple120Plant aboveground biomass data2001-2014 (14 years)
pce120Plant species percent cover data1996-2007 (6 years)
aafe120Plant traits2008-2008 (1 year)
rbe120Root biomass data1997-2010 (9 years)
nre120Root carbon/nitrogen data1997-2006 (6 years)
care120Soil carbon1994-2006 (7 years)
nohe120Soil nitrate and ammonium1996-2007 (8 years)
ne120Soil nitrogen1994-2006 (7 years)

Selected Recent Publications

Davies, T. J., Urban, M. C., Rayfield, B., Cadotte, M. W. and Peres-Neto, P. R. (2016), Deconstructing the relationships between phylogenetic diversity and ecology: a case study on ecosystem functioning. Ecology 97(9): 2212. doi:10.1002/ecy.1507 2016 [Full Text] e120

Essarioui, A., Kistler, H. C. & Kinkel, L. L. Nutrient use preferences among soil Streptomyces suggest greater resource competition in monoculture than polyculture plant communities. Plant Soil (2016). doi:10.1007/s11104-016-2968-0 2016 [Full Text] e120

O`Connor, Mary I.; Gonzalez, Andrew; Byrnes, Jarrett E. K.; Cardinale, Bradley J.; Duffy,J. Emmett; Gamfeldt, Lars; Griffin, John N.; Hooper, David; Hungate, Bruce A.; Paquette, Alain; Thompson, Patrick L.; Dee, Laura E.; Dolan, Kristin L. A general biodiversity-function relationship is mediated by trophic level. Oikos, 2016, doi/10.1111/oik.03652 2016 e120 e123 e141

Poudel, R., Jumpponen, A., Schlatter, D. C., Paulitz, T. C., Gardener, B. B., Kinkel, L. L. and Garrett, K. A. (2016). Microbiome Networks: A Systems Framework for Identifying Candidate Microbial Assemblages for Disease Management. Phytopathology 106(10): 1083-1096. 2016 [Full Text] e120

Yguel, B., Jactel, H., Pearse, I. S., Moen, D., Winter, M., Hortal, J., Helmus, M. R., Kuhn, I., Pavoine, S., Purschke, O., Weiher, E., Violle, C., Ozinga, W., Brandle, M., Bartish, I. and Prinzing, A. (2016). "The Evolutionary Legacy of Diversification Predicts Ecosystem Function." Am Nat 188(4): 398-410. 2016 e120

Cardinale, Bradley J.; Venail, Patrick; Gross, Kevin; Oakley, Todd H.; Narwani, Anita; Allan, Eric; Flombaum, Pedro; Joshi, Jasmin; Reich, Peter B.; Tilman, David; van Ruijven, Jasper; Further re-analyses looking for effects of phylogenetic diversity on community biomass and stability. Functional Ecology 2015 29, 12, 1607-1610 DOI 10.1111/1365-2435.12540 2015 [Full Text] e120 e141

Chen, Xiao-Yong; Wang, Xiao-Yan; Jiao, Jing; Schmid, Bernhard. Complementarity effects do not necessarily result in significant transgressive over-performance in mixtures. Biological Invasions, 2014; 2015, 17(2), 529 - 535 DOI 10.1007/s10530-014-0755-5 2015 [Full Text] e120

Clark, Adam Thomas; Hao Ye, Forest Isbell, Ethan R. Deyle, Jane M. Cowles, David Tilman, and George Sugihara. 2015 Spatial convergent cross mapping to detect causal relationships from short time series. Ecology 96:1174?1181. 2015 [Full Text] e120

Cowles, Jane M. Mechanisms of Coexistence: Implications for Biodiversity-Ecosystem Functioning Relationships in a Changing World. Ph. D. Thesis. University of Minnesota. Retrieved from the University of Minnesota Digital Conservancy, 2015 [Full Text] e120 e249

Daniel C. Schlatter, Matthew G. Bakker, James M. Bradeen, and Linda L. Kinkel 2015. Plant community richness and microbial interactions structure bacterial communities in soil. Ecology 96:134?142. 2015 [Full Text] e120

Guiz, Jordan; Hillebrand, Helmut; Borer, Elizabeth T.; Abbas, Maike; Ebeling, Anne; Weigelt, Alexandra; Oelmann, Yvonne; Fornara, Dario; Wilcke, Wolfgang; Temperton, Vicky M.; Weisser, Wolfgang W.; Long-term effects of plant diversity and composition on plant stoichiometry.Oikos, 2015, DOI: 10.1111/oik.02504 2015 e120

Hautier, Y.; Tilman, D.; Isbell, F.; Seabloom, E. W.; Borer, E. T.; Reich, P. B.; Anthropogenic environmental changes affect ecosystem stability via biodiversity. Science, 2015, 348, 6232, 336-340 DOI:10.1126/science.aaa1788 2015 [Full Text] e001 e002 e003 e012 e098 e120 e141 e245 e247 e248

Isbell, Forest; Craven, Dylan; Connolly, John; Loreau, Michel; Schmid, Bernhard; Beierkuhnlein, Carl; Bezemer, T.Martijn; Bonin, Catherine; Bruelheide, Helge; de Luca, Enrica; Ebeling, Anne; Griffin, John N.; Guo, Qinfeng; Hautier, Yann; Hector, Andy; Jentsch, Anke; Kreyling, J?rgen; Lanta, Vojtech; Manning, Pete; Meyer, Sebastian T.; Mori, Akira S.; Naeem, Shahid; Niklaus, Pascal A.; Polley, H.Wayne; Reich, Peter B.; Roscher, Christiane; Seabloom, Eric W.; Smith, Melinda D.; Thakur, Madhav P.; Tilman, David; Tracy, Benjamin F.; van der Putten, Wim H.; van Ruijven, Jasper; Weigelt, Alexandra; Weisser, Wolfgang W.; Wilsey, Brian; Eisenhauer, Nico. Biodiversity increases the resistance of ecosystem productivity to climate extremes. Nature 2015 526, 574-577 2015 [Full Text] e120 e141

Leblanc, N., Kinkel, L. L., and Kistler, H. C. 2015. Soil fungal communities respond to grassland community richness and soil edaphics. Microbial Ecology 70:188-195. 2015 [Full Text] e120

Lefcheck, J. S., J. E. K. Byrnes, F. Isbell, L. Gamfeldt, J. N. Griffin, N. Eisenhauer, M. J. S. Hensel, A. Hector, B. J. Cardinale, and J. E. Duffy. Biodiversity enhances ecosystem multifunctionality across taxa, trophic levels, and habitats. Nature Communications, 2015, 6:6936 DOI: 10.1038/ncomms7936 2015 [Full Text] e060 e120 e141

Lind, Eric M.; Vincent, John B.; Weiblen, George D.; Cavender-Bares, Jeannine Marie; Borer, Elizabeth T. ; Trophic phylogenetics: evolutionary influences on body size, feeding, and species associations in grassland arthropods. Ecology, 2015, 96, 4, 998 - 1009 ( 2015 [Full Text] e120

Schlatter, Daniel C.; Bakker, Matthew G.; Bradeen, James M.; Kinkel, Linda L. 2015. Plant community richness and microbial interactions structure bacterial communities in soil. Ecology 96:134 to 142. 2015 [Full Text] e120

Smith, M. D.; La Pierre, K. J.; Collins, S. L.; Knapp, A. K.; Gross, K. L.; Barrett, J. E.; Frey, S. D.; Gough, L.; Miller, R. J.; Morris, J. T.; Rustad, L. E.; Yarie, J. Global environmental change and the nature of aboveground net primary productivity responses: insights from long-term experiments. Oecologia, 2015, 177, 4, 935-947, Germany 2015 [Full Text] e120 e141

Song, Z.; Schlatter, D.; Kennedy, P.; Kinkel, L. L.; Kistler, H. C.; Nguyen, N. Bates, S. T. (2015) Effort versus Reward: Preparing Samples for Fungal Community Characterization in High-Throughput Sequencing Surveys of Soils. PLoS ONE 10(5): e0127234. doi:10.1371/journal.pone.0127234 2015 [Full Text] e120

Venail, P., Gross, K., Oakley, T. H., Narwani, A., Allan, E., Flombaum, P., Isbell, F., Joshi, J., Reich, P. B., Tilman, D., van Ruijven, J., Cardinale, B. J. (2015), Species richness, but not phylogenetic diversity, influences community biomass production and temporal stability in a re-examination of 16 grassland biodiversity studies. Functional Ecology, 29: 615?626. doi: 10.1111/1365-2435.12432 2015 [Full Text] e120 e141

Wragg, Peter D., Human impacts on how savanna plants interact through fire, resources, and microclimate. Ph.D. Dissertation, University of Minnesota. 2015 2015 [Full Text] e120 e249 e252

Beckman, Noelle G.; Dybzinski, Ray; Tilman, G. David; Neighborhoods have little effect on fungal attack or insect predation of developing seeds in a grassland biodiversity experiment; Oecologia, 2014; 174(2):521-532. 2014 [Full Text] e120

Burrows, R. L.; Glomalin Production and Infectivity of Arbuscular-Mycorrhizal Fungi in Response to Grassland Plant Diversity, American Journal of Plant Sciences, Vol. 5 No. 1, 2014, pp. 103-111. doi: 10.4236/ajps.2014.51013. 2014 [Full Text] e120

Forsythe, Jennifer Ann; A field study of specificity in the arbuscular mycorrhizal symbiosis, Masters Thesis University of British Columbia 2014 [Full Text] e120

Gross, Kevin; Cardinale, Bradley J.; Fox, Jeremy W.; Gonzalez, Andrew; Loreau, Michel; Polley, H. Wayne; Reich, Peter B.; Ruijven, Jasper van; Species Richness and the Temporal Stability of Biomass Production: A New Analysis of Recent Biodiversity Experiments.; Am.Nat., 2014, 183, 1, 1-12, The University of Chicago Press for The American Society of Naturalists 2014 [Full Text] e120; e141

Tilman, David; Isbell, Forest ; Cowles, Jane M.; Biodiversity and ecosystem functioning; Annual Review of Ecology, Evolution, and Systematics. 2014; 45: 471-493. DOI: 10.1146/annurev-ecolsys-120213-091917 2014 [Full Text] e120

Balvanera, Patricia; Siddique, Ilyas; Dee, Laura; Paquette, Alain; Isbell, Forest; Gonzalez, Andrew; Byrnes, Jarrett; O?Connor, Mary I.; Hungate, Bruce A.; Griffin, John N.; 2013; Linking Biodiversity and Ecosystem Services: Current Uncertainties and the Necessary Next Steps; Bioscience; doi:10.1093/biosci/bit003 2013 [Full Text] e120

Blinnikov, Mikhail S.; Bagent, Chelsey M.; Reyerson, Paul E.; Phytolith assemblages and opal concentrations from modern soils differentiate temperate grasslands of controlled composition on experimental plots at Cedar Creek, Minnesota; Quaternary International 287 (2013) 101e113; doi:10.1016/j.quaint.2011.12.023 2013 [Full Text] e120

Cardinale, Bradley J.; Gross, Kevin; Fritschie, Keith; Flombaum, Pedro; Fox, Jeremy W.; Rixen, Christian; van Ruijven, Jasper; Reich, Peter B.; Scherer-Lorenzen, Michael; Wilsey, Brian J.; Biodiversity simultaneously enhances the production and stability of community biomass, but the effects are independent. Ecology 94:1697?1707. 2013 [Full Text] e120 e141

Isbell, F.; Tilman, D.; Polasky, S.; Binder, S.; Hawthorne, P.; Low biodiversity state persists two decades after cessation of nutrient enrichment; Ecology Letters (2013) 16: 454?460 DOI: 10.1111/ele.12066 2013 [Full Text] e001 e002 e120 e141

Isbell, Forest; Reich, Peter B.; Tilman, David; Hobbie, Sarah E.; Polasky, Stephen; Binder, Seth. Nutrient enrichment, biodiversity loss, and consequent declines in ecosystem productivity. Proceedings of the National Academy of Sciences of the United States of America. 2013 110 (29):11911-11916. 2013 [Full Text] e001 e002. e120 e141

Joern, Anthony, and Angela N. Laws. "Ecological mechanisms underlying arthropod species diversity in grasslands." Annual review of entomology 58 (2013): 19-36. 2013 [Full Text] e120

Kosmala, Margaret Candace; 2013; Effects of human actions on four ecological systems, with a focus on trophic relationships; PhD Thesis University of Minnesota; Digital Conservancy Permanent URL 2013 [Full Text] e120

Mueller, Kevin E.; Tilman, David; Fornara, Dario A.; Hobbie, Sarah E.; Root depth distribution and the diversity?productivity relationship in a long-term grassland experiment; Ecology; Volume 94, Issue 4 (April 2013) pp. 787-793 2013 [Full Text] e120

Pasari, Jae R; Levi,Taal; Zavaleta,Erika S; Tilman,David; Several scales of biodiversity affect ecosystem multifunctionality; PNAS; 2013; 110 (25) 10219-10222; published ahead of print June 3, 2013; doi:10.1073/pnas.1220333110 2013 [Full Text] e120

de Mazancourt, Claire; Isbell, Forest; Larocque, Allen; Berendse, Frank; De Luca, Enrica; Grace, James B.; Haegeman, Bart; Wayne Polley, H.; Roscher,C hristiane; Predicting ecosystem stability from community composition and biodiversity; Ecol.Lett.; 2013, 16, 5, 617-625 2013 [Full Text] e120

Bakker, M. B.; Tu, Z. J.; Bradeen, J. M.; and Kinkel, L. L.; Implications of Pyrosequencing Error Correction for Biological Data Interpretation. Public Library of Science (PLoS ONE) 7(8): e44357. doi:10.1371/journal.pone.0044357. 2012 [Full Text] e120

Hawthorne, Peter Loken; Deterministic and stochastic forces in community ecology: integrating competing paradigms in theory and observation.; PhD Thesis University of Minnesota; Digital Conservancy Permanent URL 2012 [Full Text] e120

Tilman, D.; Reich, P. B.; Isbell, F.; Biodiversity impacts ecosystem productivity as much as resources, disturbance, or herbivory; Proceedings of the National Academy of Sciences; 2012; 109, 26, 10394-10397 2012 [Full Text] e001 e002 e003 e004 e012 e062 e098 e120 e141 e172