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Aboveground herbivory shapes the biomass distribution and flux of soil invertebrates.

Mulder C, Den Hollander HA, Hendriks AJ - PLoS ONE (2008)

Bottom Line: Overall higher biomasses of invertebrates occur in grasslands, and all larger soil organisms differed remarkably.Strong statistical evidence supports a hypothesis explaining from an allometric perspective how the faunal biomass distribution and the energetic flux are affected by livestock, nutrient availability and land use.Our aim is to propose faunal biomass flux and biomass distribution as quantitative descriptors of soil community composition and function, and to illustrate the application of these allometric indicators to soil systems.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology, National Institute for Public Health and the Environment, RIVM-LER, Bilthoven, The Netherlands. Christian.Mulder@rivm.nl

ABSTRACT

Background: Living soil invertebrates provide a universal currency for quality that integrates physical and chemical variables with biogeography as the invertebrates reflect their habitat and most ecological changes occurring therein. The specific goal was the identification of "reference" states for soil sustainability and ecosystem functioning in grazed vs. ungrazed sites.

Methodology/principal findings: Bacterial cells were counted by fluorescent staining and combined direct microscopy and automatic image analysis; invertebrates (nematodes, mites, insects, oligochaetes) were sampled and their body size measured individually to allow allometric scaling. Numerical allometry analyses food webs by a direct comparison of weight averages of components and thus might characterize the detrital soil food webs of our 135 sites regardless of taxonomy. Sharp differences in the frequency distributions are shown. Overall higher biomasses of invertebrates occur in grasslands, and all larger soil organisms differed remarkably.

Conclusions/significance: Strong statistical evidence supports a hypothesis explaining from an allometric perspective how the faunal biomass distribution and the energetic flux are affected by livestock, nutrient availability and land use. Our aim is to propose faunal biomass flux and biomass distribution as quantitative descriptors of soil community composition and function, and to illustrate the application of these allometric indicators to soil systems.

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Related in: MedlinePlus

Distributions of log-transformed faunal biomass (ordinate) along a body size gradient (abscissa) for ungrazed and grazed agroecosystems.After lumping, grazed sites have but a higher biomass contribution of bacterial-feeding nematodes and a lower biomass contribution of hyphal-feeding enchytraeids than ungrazed sites. This structural compensation has at least two main consequences, one for the microbial consumption (microfauna grazing on bacteria, mesofauna browsing fungi) and the other for the soil aggregation and humification by larger arthropods. The peak in the biomass around 0.5 log(M) reflects the activity of gamasid mites (Lysigamasus, Protodinychus, Uropoda etc.) and predatory nematodes such as Aporcelaimellus. Some typical genera are shown: from left to right, Chiloplacus, a bacterial-feeding nematode highly tolerant for grazing pressure and land-use intensity, the predatory mite Alliphis and the microphytophagous Rhysotritia [10].
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pone-0003573-g002: Distributions of log-transformed faunal biomass (ordinate) along a body size gradient (abscissa) for ungrazed and grazed agroecosystems.After lumping, grazed sites have but a higher biomass contribution of bacterial-feeding nematodes and a lower biomass contribution of hyphal-feeding enchytraeids than ungrazed sites. This structural compensation has at least two main consequences, one for the microbial consumption (microfauna grazing on bacteria, mesofauna browsing fungi) and the other for the soil aggregation and humification by larger arthropods. The peak in the biomass around 0.5 log(M) reflects the activity of gamasid mites (Lysigamasus, Protodinychus, Uropoda etc.) and predatory nematodes such as Aporcelaimellus. Some typical genera are shown: from left to right, Chiloplacus, a bacterial-feeding nematode highly tolerant for grazing pressure and land-use intensity, the predatory mite Alliphis and the microphytophagous Rhysotritia [10].

Mentions: Figure 2 shows a striking multimodality in the biomass spectra for both the “grazed” and “ungrazed” meta-categories. Most fluctuations occurred within the microfauna (nematodes) and mesofauna (mites, collembolans, and enchytraeids). Soil faunal taxa exhibited a variety of relationships between biomass and binned body size within the investigated agroecosystems (Table 2). Faunal biomass–size slopes (FBS) ranged from a1 = 0.02–0.64 (arable fields), a1 = 0.07–0.53 (organic grasslands), a1 = 0.25–0.52 (semi-intensive farms), a1 = 0.26–0.45 (conventional farms), a1 = 0.29–0.69 (intensive farms), and a1 = 0.41–0.92 (forested sites). Intercepts of faunal biomass relationships ranged from b1 = 3.56–4.33 (arable fields), b1 = 3.60–4.41 (forested sites), b1 = 3.62–4.31 (intensive farms), b1 = 3.75–4.34 (organic grasslands), b1 = 3.81–4.43 (semi-intensive farms), and b1 = 3.90–4.53 (conventional farms). The most pronounced increase in the FBS occurred in forests, despite their lowest intercepts (Table 2). Our coefficients tend to decrease with the width of the body-size range covered by the linear regressions. Size bins seem to influence the resulting power functions, as previously reported by Siemann et al. [28]. Our faunal spectra tend to show a fluctuating increase in biomass with body size up to a peak near the largest weight-bins comparable to those of Duplisea and Drgas [29]. The latter implies that the micro– and mesofaunal biomass clump in grazed grasslands (104.16 = 14,484 µg) is about two-fold that in ungrazed sites (103.90 = 7,951 µg): less disturbance like grazing, trampling, manuring and tillage leads to lower intercepts of the biomass–body-size distribution (Pearson's Correlation equal to 0.227, p = 0.0059). On the other hand, soil nutrients seem to enhance the slope of the faunal biomass–body-size distribution (Table 2). That is, in P-enriched, intensively-managed soils, the biomass totals of the occurring larger soil animals tend to be greater relative to the biomass totals of the smaller animals than in infertile forests. In other words, the lack of nutrients in forests kills off or diminishes the relative abundance of large compared to small animals.


Aboveground herbivory shapes the biomass distribution and flux of soil invertebrates.

Mulder C, Den Hollander HA, Hendriks AJ - PLoS ONE (2008)

Distributions of log-transformed faunal biomass (ordinate) along a body size gradient (abscissa) for ungrazed and grazed agroecosystems.After lumping, grazed sites have but a higher biomass contribution of bacterial-feeding nematodes and a lower biomass contribution of hyphal-feeding enchytraeids than ungrazed sites. This structural compensation has at least two main consequences, one for the microbial consumption (microfauna grazing on bacteria, mesofauna browsing fungi) and the other for the soil aggregation and humification by larger arthropods. The peak in the biomass around 0.5 log(M) reflects the activity of gamasid mites (Lysigamasus, Protodinychus, Uropoda etc.) and predatory nematodes such as Aporcelaimellus. Some typical genera are shown: from left to right, Chiloplacus, a bacterial-feeding nematode highly tolerant for grazing pressure and land-use intensity, the predatory mite Alliphis and the microphytophagous Rhysotritia [10].
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2570614&req=5

pone-0003573-g002: Distributions of log-transformed faunal biomass (ordinate) along a body size gradient (abscissa) for ungrazed and grazed agroecosystems.After lumping, grazed sites have but a higher biomass contribution of bacterial-feeding nematodes and a lower biomass contribution of hyphal-feeding enchytraeids than ungrazed sites. This structural compensation has at least two main consequences, one for the microbial consumption (microfauna grazing on bacteria, mesofauna browsing fungi) and the other for the soil aggregation and humification by larger arthropods. The peak in the biomass around 0.5 log(M) reflects the activity of gamasid mites (Lysigamasus, Protodinychus, Uropoda etc.) and predatory nematodes such as Aporcelaimellus. Some typical genera are shown: from left to right, Chiloplacus, a bacterial-feeding nematode highly tolerant for grazing pressure and land-use intensity, the predatory mite Alliphis and the microphytophagous Rhysotritia [10].
Mentions: Figure 2 shows a striking multimodality in the biomass spectra for both the “grazed” and “ungrazed” meta-categories. Most fluctuations occurred within the microfauna (nematodes) and mesofauna (mites, collembolans, and enchytraeids). Soil faunal taxa exhibited a variety of relationships between biomass and binned body size within the investigated agroecosystems (Table 2). Faunal biomass–size slopes (FBS) ranged from a1 = 0.02–0.64 (arable fields), a1 = 0.07–0.53 (organic grasslands), a1 = 0.25–0.52 (semi-intensive farms), a1 = 0.26–0.45 (conventional farms), a1 = 0.29–0.69 (intensive farms), and a1 = 0.41–0.92 (forested sites). Intercepts of faunal biomass relationships ranged from b1 = 3.56–4.33 (arable fields), b1 = 3.60–4.41 (forested sites), b1 = 3.62–4.31 (intensive farms), b1 = 3.75–4.34 (organic grasslands), b1 = 3.81–4.43 (semi-intensive farms), and b1 = 3.90–4.53 (conventional farms). The most pronounced increase in the FBS occurred in forests, despite their lowest intercepts (Table 2). Our coefficients tend to decrease with the width of the body-size range covered by the linear regressions. Size bins seem to influence the resulting power functions, as previously reported by Siemann et al. [28]. Our faunal spectra tend to show a fluctuating increase in biomass with body size up to a peak near the largest weight-bins comparable to those of Duplisea and Drgas [29]. The latter implies that the micro– and mesofaunal biomass clump in grazed grasslands (104.16 = 14,484 µg) is about two-fold that in ungrazed sites (103.90 = 7,951 µg): less disturbance like grazing, trampling, manuring and tillage leads to lower intercepts of the biomass–body-size distribution (Pearson's Correlation equal to 0.227, p = 0.0059). On the other hand, soil nutrients seem to enhance the slope of the faunal biomass–body-size distribution (Table 2). That is, in P-enriched, intensively-managed soils, the biomass totals of the occurring larger soil animals tend to be greater relative to the biomass totals of the smaller animals than in infertile forests. In other words, the lack of nutrients in forests kills off or diminishes the relative abundance of large compared to small animals.

Bottom Line: Overall higher biomasses of invertebrates occur in grasslands, and all larger soil organisms differed remarkably.Strong statistical evidence supports a hypothesis explaining from an allometric perspective how the faunal biomass distribution and the energetic flux are affected by livestock, nutrient availability and land use.Our aim is to propose faunal biomass flux and biomass distribution as quantitative descriptors of soil community composition and function, and to illustrate the application of these allometric indicators to soil systems.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology, National Institute for Public Health and the Environment, RIVM-LER, Bilthoven, The Netherlands. Christian.Mulder@rivm.nl

ABSTRACT

Background: Living soil invertebrates provide a universal currency for quality that integrates physical and chemical variables with biogeography as the invertebrates reflect their habitat and most ecological changes occurring therein. The specific goal was the identification of "reference" states for soil sustainability and ecosystem functioning in grazed vs. ungrazed sites.

Methodology/principal findings: Bacterial cells were counted by fluorescent staining and combined direct microscopy and automatic image analysis; invertebrates (nematodes, mites, insects, oligochaetes) were sampled and their body size measured individually to allow allometric scaling. Numerical allometry analyses food webs by a direct comparison of weight averages of components and thus might characterize the detrital soil food webs of our 135 sites regardless of taxonomy. Sharp differences in the frequency distributions are shown. Overall higher biomasses of invertebrates occur in grasslands, and all larger soil organisms differed remarkably.

Conclusions/significance: Strong statistical evidence supports a hypothesis explaining from an allometric perspective how the faunal biomass distribution and the energetic flux are affected by livestock, nutrient availability and land use. Our aim is to propose faunal biomass flux and biomass distribution as quantitative descriptors of soil community composition and function, and to illustrate the application of these allometric indicators to soil systems.

Show MeSH
Related in: MedlinePlus