SIMPLE ASPECTS OF FOODWEB COMPLEXITY

Foodweb data [for animals] are examined to obtain a number of indices of the complexity of the webs, such as connectance and mean length of food chains. The index .beta. = E/V (E = number of interactions, V = number of kinds or organism) takes values with mean 1.88 and fractional root mean square deviation 0.27, over a set of 30 foodwebs. These are about equally divided between sink and community webs. Mean chain length is smaller in sink webs than in community webs. The small spread of the .beta. values results from a balance between this and the greater number of chains in the sink webs, when expressed on a scale suggested by a trophic partition of the kinds of organism. Comments are made on a model of foodwebs with an optimal connectance for stability, and on currently available general methods for studying complexity and stability.