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The dual importance of competition and predation as regulatory forces in terrestrial ecosystems: evidence from decomposer food-webs

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Abstract

The relative importance of predation and competition (resource limitation) in influencing the components of a below-ground food-web consisting of three trophic levels (bacteria and fungi; bacterial-feeding and fungal-feeding nematodes; and top predatory nematodes) was estimated using microbial biomass and nematode frequency data collected throughout a 1-year period in two agro-ecosystems. The study suggested that bacterial and fungal biomass were likely to be regulated by grazing and competition respectively, and that these differences were likely to be attributed to the biological (probably morphological) differences between bacteria and fungi, in contrast to the predictions of the hypothesis of Hairston et al. (1960). Top predatory nematodes were sometimes strongly related to the microbial but not microbial-feeding trophic levels, indicating that microbial biomass may directly influence top predator numbers, and that the intermediate level may simply serve as a conduit by which resources pass from the bottom to top trophic levels. This study also suggests that the detritus food-web acts as two distinct (bacterial-and fungal-based) compartments.

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References

  • Hairston NG, Smith FE, Slobodkin LB (1960) Community structure, population control and competition. Am Nat 94:421–425

    Google Scholar 

  • Ingham RE, Trofymow JA, Ingham ER, Coleman DC (1985) Interactions of bacteria, fungi and their nematode grazers: effects on nutrient cycling and plant growth. Ecol Monogr 55:119–140

    Google Scholar 

  • Ingham ER, Coleman DC, Moore JC (1989) An analysis of food-web structure and function in a shortgrass prairie, a mountain meadow and a lodgepole pine forest. Biol Fertil Soils 8:29–37

    Google Scholar 

  • Lawton JH (1989) Food webs. In: Cherrett JM (ed) Ecological concepts. Blackwell Scientific Publications, Oxford, pp 43–78

    Google Scholar 

  • Kareiva P, Sahakian R (1990) Tritrophic effects of a simple architectural mutation in pea plants. Nature 345:433–434

    Google Scholar 

  • McNaughton SJ, Oesterheld M, Frank DA, Williams KJ (1989) Ecosystem level patterns of primary productivity and herbivory in terrestrial habitats. Nature 341:142–144

    Google Scholar 

  • Menge BA, Sutherland JP (1976) Species diversity gradients: synthesis of the roles of predation, competition and spatial heterogeniety. Am Nat 110:351–369

    Google Scholar 

  • Menge BA, Lubchenco J, Gaines SD, Ashkenas LR (1986) A test of the Menge-Sutherland model of community organisation in a tropical rocky intertidal food-web. Oecologia 71:75–89

    Google Scholar 

  • Moore JC, Hunt HW (1988) Resource compartmentation and the stability of real ecosystems. Nature 333:261–263

    Google Scholar 

  • Murdoch WW (1966) “Community structure, population control, and competition” — a critique. Am Nat 100:219–226

    Google Scholar 

  • Pimm SL (1982) Food webs. Chapman and Hall, London

    Google Scholar 

  • Pimm SL, Lawton JH, Cohen JE (1991) Food web patterns and their consequences. Nature 350:669–674

    Google Scholar 

  • Polis GA (1991) Complex trophic interactions in deserts: an empirical critique of food-web theory. Am Nat 138:123–155

    Google Scholar 

  • Power ME (1992) Top-down and bottom-up forces in food webs: do plants have primacy? Ecology 73:733–746

    Google Scholar 

  • Schnürer J, Clarholm M, Boström S, Rosswall T (1986) Effects of moisture on soil microorganisms and nematodes: a field experiment. Microb Ecol 12:217–230

    Google Scholar 

  • Schoener TW (1989) Food webs from the small to the large. Ecology 70:1559–1589

    Google Scholar 

  • Swift MJ, Heal OW, Anderson JM (1979) Decomposition in terrestrial ecosystems. University of California Press, Berkeley

    Google Scholar 

  • Wardle DA (1991) Free lunch? Nature 352:482

    Google Scholar 

  • Wardle DA (1992) A comparative assessment of factors which influence microbial biomass carbon and nitrogen levels in soils. Biol Rev 67:321–358

    Google Scholar 

  • Wardle DA (1993) Changes in the microbial biomass and metabolic quotient during leaf litter succession in some New Zealand forest and scrubland ecosystems. Funct Ecol (in press)

  • Wardle DA, Parkinson D (1990) Response of the soil microbial biomass to glucose, and selective inhibitors, across a soil moisture gradient. Soil Biol Biochem 22:824–834

    Google Scholar 

  • Wardle DA, Nicholson KS, Yeates GW (1993) Effect of weed management strategies on some soil associated arthropods in maize and asparagus ecosystems. Pedobiologia (in press)

  • West AW (1986) Improvements to the selective respiratory inhibition technique to measure eukaryote: prokaryote ratios in soils. J Microbiol Methods 5:177–189

    Google Scholar 

  • White TRC (1978) The importance of a relative shortage of food in animal ecology. Oecologia 33:71–86

    Google Scholar 

  • Yeates GW (1971) Feeding types and feeding groups in plant and soil nematodes. Pedobiologia 11:173–179

    Google Scholar 

  • Yeates GW (1987) How plants affect nematodes. Adv Ecol Res 17:61–113

    Google Scholar 

  • Yeates GW, Freckman DW, Bongers T (1992) A guide to nematode feeding habits for soil ecologists. J Nematol (in press)

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Wardle, D.A., Yeates, G.W. The dual importance of competition and predation as regulatory forces in terrestrial ecosystems: evidence from decomposer food-webs. Oecologia 93, 303–306 (1993). https://doi.org/10.1007/BF00317685

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  • DOI: https://doi.org/10.1007/BF00317685

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