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Cited by 1,257Soil Carbon and Nitrogen DynamicsEcology and Vegetation Dynamics StudiesMycorrhizal Fungi and Plant Interactions

PLANT DIVERSITY, SOIL MICROBIAL COMMUNITIES, AND ECOSYSTEM FUNCTION: ARE THERE ANY LINKS?

Open access
Zak, Donald R., Holmes, William E., White, David C., Peacock, Aaron D., Tilman, David·2003·Ecology
DOI 10.1890/02-0433
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Abstract

A current debate in ecology centers on the extent to which ecosystem function depends on biodiversity. Here, we provide evidence from a long-term field manipulation of plant diversity that soil microbial communities, and the key ecosystem processes that they mediate, are significantly altered by plant species richness. After seven years of plant growth, we determined the composition and function of soil microbial communities beneath experimental plant diversity treatments containing 1–16 species. Microbial community biomass, respiration, and fungal abundance significantly increased with greater plant diversity, as did N mineralization rates. However, changes in microbial community biomass, activity, and composition largely resulted from the higher levels of plant production associated with greater diversity, rather than from plant diversity per se. Nonetheless, greater plant production could not explain more rapid N mineralization, indicating that plant diversity affected this microbial process, which controls rates of ecosystem N cycling. Greater N availability probably contributed to the positive relationship between plant diversity and productivity in the N-limited soils of our experiment, suggesting that plant–microbe interactions in soil are an integral component of plant diversity's influence on ecosystem function.

AI snapshot

Written from the paper’s full text.

TL;DR

In a seven-year plant diversity experiment, soil microbial biomass, respiration, fungal abundance, and gross N mineralization increased with plant species richness. Most microbial responses were explained by greater plant production associated with diversity, but faster N mineralization remained linked to plant diversity itself.

Key findings

  • Microbial biomass (total PLFA) increased with plant diversity (ANOVA; F = 5.16, df = 4, 111; P < 0.001), but the effect became nonsignificant when plant biomass was included as a covariate (F = 1.09, df = 1, 110; P = 0.365), while plant biomass was significant (F = 23.13, df = 1, 110; P < 0.0001).
  • Microbial community composition shifted with diversity: bacterial and actinomycetal PLFAs declined and fungal biomarkers increased; the 1-species treatment differed from the 16-species treatment (P < 0.001–0.053), but diversity became nonsignificant with plant biomass as a covariate (P = 0.137–0.980).
  • Microbial respiration increased with plant diversity (F = 11.68, df = 4, 111; P < 0.001), but adjusted means showed no relationship with diversity; plant biomass was significant in ANCOVA (F = 47.49, df = 4, 111; P < 0.001).
  • Gross N mineralization nearly doubled from 1- to 16-species treatments (F = 10.6, df = 4, 111; P < 0.001) and remained significant after adjustment for plant biomass and soil organic matter (least-square means: R² = 0.320, P < 0.001); immobilization of NH₄⁺ (F = 0.67, P = 0.614) and NO₃⁻ (F = 0.85, P = 0.497) showed no diversity effect. Plant N content increased from 4.29 ± 0.456 g N/m² in 1-species to 12.5 ± 0.493 g N/m² in 16-species treatments (F = 25.10, df = 4, 115; P < 0.001).

Methods

  • Long-term field experiment at Cedar Creek Natural History Area, Minnesota: 168 plots (9 × 9 m) seeded in 1994 with 1, 2, 4, 8, or 16 grassland-savanna species drawn from a pool of 18 species; 116 plots sampled in July 2000 with replication n = 39, 24, 12, 12, and 29 for the 1-, 2-, 4-, 8-, and 16-species treatments.
  • Soil cores (2.5 cm diameter, 20 cm deep) from eight random locations per plot were composited; microbial composition and biomass were assessed by phospholipid fatty acid (PLFA) analysis, respiration by CO₂ increase over a two-day incubation, and gross N mineralization/immobilization by ¹⁵N pool dilution.
  • Analyses used one-way ANOVA, ANCOVA with plant biomass as covariate, nonlinear regression on treatment means (n = 5), and two-way ANOVAs testing species richness plus functional group presence; monocultures of the 18 species were also compared.

Limitations

  • The paper states that the exact mechanisms causing greater rates of N mineralization remain to be determined.
  • The paper states that the results are likely most evident in ecosystems with small existing soil substrate pools; this experiment’s soil contained very little organic matter (4–5 g C/kg) relative to another experiment (130 g C/kg) where plant diversity did not influence soil microbial communities and litter decomposition.
  • Evident from the text: there is no explicit limitations section; microbial composition is inferred from PLFA biomarkers rather than direct taxonomy, and the microbial sampling was from a single date (July 2000) with uneven replication across diversity treatments.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1890/02-0433

Cites

28 of 28 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 11 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    Greater plant production could not explain more rapid N mineralization.

    “Nonetheless, greater plant production could not explain more rapid N mineralization, indicating that plant diversity affected this microbial process, which controls rates of ecosystem N cycling.”
    • Also stated in: § RESULTS AND DISCUSSION · hedged
      “However, when N mineralization was adjusted for differences in plant production, there was still a significant relationship with plant diversity, indicating that greater rates of decomposition were not the only mechanism at work.”
    Quote in the paperSubstantial claim
  • Findingown data

    The balance between gross N mineralization and immobilization was altered by plant diversity such that the net supply of soil N increased with the number of plant species present.

    “In our experiment, the balance between gross N mineralization and immobilization was altered by plant diversity such that the net supply of soil N increased with the number of plant species present.”
    Quote in the paperSubstantial claim
  • Findingown data

    No relationship was observed between plant diversity and abundance of microbial groups when individual PLFAs were adjusted for variation in plant biomass.

    “We also observed no relationship between plant diversity and the abundance of microbial groups when individual PLFAs were adjusted for variation in plant biomass (Fig. 2).”
    Quote in the paperSubstantial claim
  • Findingown data

    Soil microbial communities and the key ecosystem processes they mediate are significantly altered by plant species richness.

    “Here, we provide evidence from a long-term field manipulation of plant diversity that soil microbial communities, and the key ecosystem processes that they mediate, are significantly altered by plant species richness.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Heterotrophic microbial communities inhabiting soil mediate key processes that control ecosystem carbon and nitrogen cycling.
  • Findingown data

    Total plant N content increased significantly from the 1- to 16-species treatments.

    “We observed that total plant N content increased significantly from the 1-to 16-species treatments (F ϭ 25.10, df ϭ 4, 111; P Ͻ 0.001), which is consistent with the general increase in gross N mineralization that we observed across our diversity treatments.”
    Quote in the paperSubstantial claim
  • May combine two claims. 14
  • The quote only partly states this claim. 1
  • Classified as probably not a substantial claim. 3

  • May combine two claims.

    Findingown data

    Microbial community composition changed with greater plant diversity, an effect more attributable to increases in plant production than to greater species richness.

    “Microbial community composition changed with greater plant diversity, an effect that also appears more attributable to increases in plant production than to greater species richness.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Plant diversity had no effect on the microbial assimilation of NH4+ or NO3-.

    “In contrast, plant diversity had no effect on the microbial assimilation of NH 4 ϩ (ANOVA; F ϭ 0.67, df ϭ 4, 115; P ϭ 0.614) or NO 3 Ϫ (ANOVA; F ϭ 0.85, df ϭ 4, 115; P ϭ 0.497), and there was no relationship between plant diversity and these microbial processes (Fig. 5).”
    Quote in the paperSubstantial claim

  • The quote only partly states this claim.

    Findingown data

    Specific respiration increased with plant diversity.

    “Rates of specific respiration, which account for differences in microbial biomass among treatments (i.e., CO 2 produced per unit of microbial biomass), demonstrated that plant diversity significantly and predictably increased the metabolic activity of soil microbial communities (Fig. 3C).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    When N mineralization was adjusted for differences in plant production, there was still a significant relationship with plant diversity, indicating that greater rates of decomposition were not the only mechanism at work.

    “However, when N mineralization was adjusted for differences in plant production, there was still a significant relationship with plant diversity, indicating that greater rates of decomposition were not the only mechanism at work.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The effect of plant diversity on microbial biomass became nonsignificant when plant biomass was included as a covariate, while plant biomass was significant.

    “Nonetheless, the effect of plant diversity on microbial biomass became nonsignificant (ANCOVA; Type III SS; F ϭ 1.09, df ϭ 1, 110; P ϭ 0.365) when we included plant biomass as a covariate (ANCOVA; F ϭ 23.13, df ϭ 1, 110; P Ͻ 0.0001; Fig. 1B).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    Plant diversity altered microbial community composition and function, which, in turn, increased the supply of soil N to plants and contributed to greater productivity in the most species-rich experimental plant communities.

    “Although the exact mechanisms causing greater rates of N mineralization remains to be determined, plant diversity altered microbial community composition and function, which, in turn, increased the supply of soil N to plants and contributed to greater productivity in the most species-rich experimental plant communities.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Heterotrophic microbial communities inhabiting soil mediate key processes that control ecosystem carbon and nitrogen cycling.

  • May combine two claims.

    Study design and conductown data

    Soils beneath the experimental plant communities did not differ significantly in C or N concentration, but soil C:N was somewhat higher in the 16-species treatment compared to the others.

    “Soils beneath our experimental plant communities did not differ significantly in C or N concentration, but soil C: N was somewhat higher in the 16-species treatment compared to the others (Table 1).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    Feedbacks between plant and microbial communities control ecosystem productivity, and plant species richness is an important factor influencing this biotic interaction.

    “Feedbacks between plant and microbial communities control ecosystem productivity, and our results demonstrate that plant species richness is an important factor influencing this biotic interaction.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Heterotrophic microbial communities inhabiting soil mediate key processes that control ecosystem carbon and nitrogen cycling.

  • May combine two claims.

    Interpretationown data

    The pattern of gross N mineralization roughly matched the increase in microbial respiration, suggesting that greater microbial activity is one mechanism behind the increase in N mineralization.

    “The pattern of gross N mineralization roughly matched the increase in microbial respiration, suggesting that greater microbial activity is one mechanism behind the increase in N mineralization.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Soil in the experiment contained very little organic matter (4-5 g C/kg) relative to another experiment (130 g C/kg) in which plant diversity did not influence soil microbial communities and litter decomposition.

    “For example, soil in our experiment contained very little organic matter (4-5 g C/kg) relative to another experiment (130 g C/kg) in which plant diversity did not influence soil microbial communities and litter decomposition (Wardle et al. 1999).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Wardle et al. 1999

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data

    Recovery of added isotope averaged 83.4 ± 2.15% in 15NH4+ amended soil, and recovery averaged 81.6 ± 2.40% in samples that received 15NO3-.

    “Recovery of added isotope averaged 83.4 Ϯ 2.15% in 15 NH 4 ϩ amended soil, and recovery averaged 81.6 Ϯ 2.40% in samples that received 15 NO 3 Ϫ .”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    Niche complementarity and the greater microbial supply of growth-limiting soil N are likely mechanisms that fostered higher levels of plant productivity in the most species-rich experimental communities.

    “Niche complementarity and the greater microbial supply of growth-limiting soil N are likely to be mechanisms that fostered higher levels of plant productivity in the most species-rich experimental communities.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Heterotrophic microbial communities inhabiting soil mediate key processes that control ecosystem carbon and nitrogen cycling.

  • May combine two claims.

    Premisecitation

    In the experiment, plant productivity increases with greater species richness, apparently the result of niche complementarity and positive interaction among plant species.

    “In our experiment, plant productivity increases with greater species richness, apparently the result of niche complementarity and positive interaction among plant species (Tilman et al. 2001).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Tilman et al. 2001

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Using treatment means (n=5) in regression analyses provided a more conservative assessment of significance than using data from all plots (n=116).

    “We used treatment means (n ϭ 5) of microbial community biomass, respiration, and rates of gross mineralization and immobilization in our regression analyses, which provided a more conservative assessment of significance than using data from all plots (n ϭ 116).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Greater plant species or functional group richness can foster higher rates of net primary productivity.

    “Some experimental evidence suggests that greater plant species or functional group richness can foster higher rates of net primary productivity (Hector et al. 1999, Tilman et al. 2001), but the mechanisms underlying this response are not well understood, nor are they fully resolved.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Hector et al. 1999

      Not checked in the free run.

    • cites Tilman et al. 2001

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    Many of the responses observed could be explained by greater plant production associated with higher plant diversity, which is likely to result from niche complementarity, positive interactions, and greater resource capture in the most species-rich experimental plant communities.

    “Many of the responses that we observed could be explained by greater plant production (i.e., detritus production) associated with higher levels plant diversity, which are likely to result from niche complementarity, positive interactions, and greater resource capture in the most species-rich experimental plant communities (Tilman et al. 2001).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Tilman et al. 2001

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    Changes in microbial community composition and function cannot be attributed to the occurrence of a particular plant functional group or the presence of a particular plant species.

    “Thus, we cannot attribute changes in microbial community composition and function to the occurrence of a particular plant functional group, nor can we attribute these changes to the presence of a particular plant species.”
    Quote in the paperSubstantial claim
17 of 17

  • The paper relies on this without support.

    Heterotrophic microbial communities inhabiting soil mediate key processes that control ecosystem carbon and nitrogen cycling.

    “Heterotrophic microbial communities inhabiting soil mediate key processes that control ecosystem carbon (C) and nitrogen (N) cycling, and they potentially represent a mechanistic link between plant diversity and ecosystem function.”

  • The paper relies on this without support.

    Plant species differ in their biochemical composition.

    “Because plant species differ in their biochemical composition, changes in plant diversity could alter the production, as well as the range, of organic compounds in detritus that limit, and thus control, the composition and function of heterotrophic microbial communities.”

  • The paper relies on this without support.

    The effect of plant species richness on heterotrophic microbial communities would be most apparent in soil containing relatively low initial quantities of growth-limiting organic substrates (organic matter).

    “We reasoned that the effect of plant species richness on heterotrophic microbial communities would be most apparent in soil containing relatively low initial quantities of growth-limiting organic substrates (i.e., organic matter).”
3 of 3

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • The underlying relationships between plant diversity and soil carbon storage, soil microbial biomass and activity, and root biomass have been reported in several independent experimental settings, providing some evidence that the proposed links are of general significance.

    “Although we cannot rule out that the proposed mechanisms are particularly pronounced at the field site of The Jena Experiment, the underlying relationships between plant diversity and soil carbon storage 17,24 , soil microbial biomass and activity 37,45,46 , and root biomass 24,47 have been reported in several independent experimental settings providing some evidence that the proposed links are of”

    From Plant diversity increases soil microbial activity and soil carbon storage (2015) · cites this paper as [37]

  • Fine root carbon is a measure of carbon input and basal respiration is a measure of microbial metabolic activity, and both were included as variables potentially mediating plant community effects.

    “As variables potentially mediating plant community effects we included fine root carbon as measure of carbon input 31,32 and basal respiration as measure of microbial metabolic activity 20,34,37 .”

    From Plant diversity increases soil microbial activity and soil carbon storage (2015) · cites this paper as [37]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Plant N ANOVA has conflicting degrees of freedom

    Minor

    The results and Fig. 6 give different residual degrees of freedom for the same plant N comparison, while reporting the same F statistic.

  • Immobilization ANOVA degrees of freedom conflict with sample count

    Minor

    A one-way ANOVA across five treatments using the stated 116 sampled plots would have 111 residual degrees of freedom, not 115. Both immobilization tests report 115.

2 of 2

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Related

Authors
Zak, D. R., Holmes, W. E., White, D. C., Peacock, A. D., & Tilman, D.
Affiliations
  • University of Michigan (US)
  • University of Tennessee at Knoxville (US)
  • University of Minnesota (US)
Corresponding author
Zak, Donald R.
ORCID
Venue
Ecology
Publisher
Wiley
Published
2003-08
Volume
84
Issue
8
Pages
2042-2050
ISSN
0012-9658 (ISSN-L)
DOI
10.1890/02-0433
OpenAlex
W2097385742
Semantic Scholar
85563ba6cdfe3994601a05877c729295936b99d8
Cited by
1,257
References
28
Citations by year
2026: 31 · 2025: 47 · 2024: 42 · 2023: 65 · 2022: 75 · 2021: 93 · 2020: 72 · 2019: 98 · 2018: 70 · 2017: 71 · 2016: 72 · 2015: 78 · 2014: 74 · 2013: 70 · 2012: 49
FWCI
24.34
Type
journal article
Language
en
Open access
Licence
doi.wiley.com/10.1002/tdm_license_1.1 (tdm, 4414 d)
Locations
  • Ecology (publishedVersion)
  • Deep Blue (University of Michigan) (submittedVersion)
Funders
  • National Science Foundation
  • U.S. Department of Energy
  • U.S. Department of Agriculture
  • U.S. Forest Service
  • Biological and Environmental Research
Topics
  • Life Sciences › Agricultural and Biological Sciences › Soil Science › Soil Carbon and Nitrogen Dynamics
  • Physical Sciences › Environmental Science › Nature and Landscape Conservation › Ecology and Vegetation Dynamics Studies
  • Life Sciences › Agricultural and Biological Sciences › Plant Science › Mycorrhizal Fungi and Plant Interactions
Keywords
plant diversity, soil microbial communities, plant species richness, ecosystem functioning, nitrogen mineralization, plant production, nitrogen cycling, plant-microbe interactions, soil microbial biomass, soil respiration, fungal abundance, nitrogen limitation, biodiversity-productivity relationship

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