Properties of food webs

On the assumption that systems of interacting species, when perturbed from equilib- rium, should return to equilibrium quickly, one can predict four properties of food webs: (1) food chains should be short, (2) species feeding on more than one trophic level (omnivores) should be rare, (3) those species that do feed on more than one trophic level should do so by feeding on species in adjacent trophic levels, and (4) host-parasitoid systems are likely to be exceptions to (1)-(3) when interaction coefficients permit greater trophic complexity. By generating random, model food webs (with many features identical to webs described from a variety of marine, freshwater, and terrestrial systems), it is possible to generate expected values for the number of trophic levels and the degree of omnivory within webs. When compared with these random webs, real world webs are shown to have fewer trophic levels, less omnivory, and very few omnivores feeding on nonadjacent trophic levels. Insect webs are shown to have a greater degree of omnivory than other webs. The confirmation of all these predictions from stability analyses suggests that system stability places necessary, though not sufficient, limitations on the possible shapes of food webs.

[1]  J. Lawton,et al.  On feeding on more than one trophic level , 1978, Nature.

[2]  J. Lawton,et al.  Number of trophic levels in ecological communities , 1977, Nature.

[3]  R. Paine,et al.  Species Introduction in a Tropical Lake , 1973, Science.

[4]  R. Kowalski.  FURTHER ELABORATION OF THE WINTER MOTH POPULATION MODELS , 1977 .

[5]  Thomas L. Vincent,et al.  Return time and vulnerability for a food chain model , 1979 .

[6]  C. Jeffries.  Qualitative Stability and Digraphs in Model Ecosystems , 1974 .

[7]  D. L. DEANGELIS,et al.  Energy flow and the number of trophic levels in ecological communities , 1978, Nature.

[8]  A. Kohn.  The Ecology of Conus in Hawaii , 1959 .

[9]  J. Teal.  Energy Flow in the Salt Marsh Ecosystem of Georgia , 1962 .

[10]  William A. Niering,et al.  Terrestrial Ecology of Kapingamarangi Atoll, Caroline Islands , 1963 .

[11]  D. Force.  Ecology of Insect Host-Parasitoid Communities , 1974, Science.

[12]  L. Tilly,et al.  The Structure and Dynamics of Cone Spring , 1968 .

[13]  Joel E. Cohen,et al.  Food Webs and Niche Spaces , 1980 .

[14]  P. Saunders.  Population dynamics and the length of food chains , 1978, Nature.

[15]  T. Reynoldson,et al.  The Food of Four Species of Lake-Dwelling Triclads , 1963 .

[16]  O. W. Richards.  Studies on the Ecology of English Heaths: III. Animal Communities of the Felling and Burn Successions at Oxshott Heath, Surrey , 1926 .

[17]  R. Paine.  Food Web Complexity and Species Diversity , 1966, The American Naturalist.

[18]  J. D. Thomas.  The food and growth of brown trout (Salmo trutta L.) and its feeding relationships with the salmon parr (Salmo salar L.) and the eel (Anguilla anguilla L.) in the River Teify, West Wales. , 1962 .

[19]  J. E. Cohen,et al.  Food webs and niche space. , 1979, Monographs in population biology.

[20]  G. Wayne Mninshall,et al.  Role of Allochthonous Detritus in the Trophic Structure of a Woodland Springbrook Community , 1967 .

[21]  J. H. Stone.  The Chaetognatha Community of the Agulhas Current: Its Structure and Related Properties , 1969 .

[22]  P. Hartley.  Food and Feeding Relationships in a Community of Fresh-Water Fishes , 1948 .

[23]  R. May.  Qualitative Stability in Model Ecosystems , 1973 .

[24]  N. Hairston.  The Local Distribution and Ecology of the Plethodontid Salamanders of the Southern Appalachians , 1949 .

[25]  I. Valiela.  An Experimental Study of the Mortality Factors of Larval Musca autumnalis DeGeer , 1969 .

[26]  J. Harrison.  The distribution of feeding habits among animals in a tropical rain forest. , 1962 .

[27]  R. B. Root.  Organization of a Plant-Arthropod Association in Simple and Diverse Habitats: The Fauna of Collards (Brassica Oleracea) , 1973 .

[28]  S. Pimm,et al.  The structure of food webs. , 1979, Theoretical population biology.

[29]  R. Grigg,et al.  Ecological studies during Project Sealab II. A sand-bottom community at depth of 61 meters and the fauna attracted to "Sealab II" are investigated. , 1967, Science.

[30]  R. D. Bird.  Biotic Communities of the Aspen Parkland of Central Canada , 1930 .