Analysis of size and complexity of randomly constructed food webs by information theoretic metrics

This chapter studies random, steady state food webs of varying size and complexity (up to 2,000 species and 1.3 million connections) which were generated with and without ecologically realistic constraints. This chapter analyses trends in network metrics, such as ascendancy, developmental capacity, and throughput as functions of size and complexity while holding constant the total annual gross primary production. It shows that total system biomass declined as the number of nodes representing biodiversity increased, or as the connectivity of the network increased. Total consumer biomass was...

This chapter studies random, steady state food webs of varying size and complexity (up to 2,000 species and 1.3 million connections) which were generated with and without ecologically realistic constraints. This chapter analyses trends in network metrics, such as ascendancy, developmental capacity, and throughput as functions of size and complexity while holding constant the total annual gross primary production. It shows that total system biomass declined as the number of nodes representing biodiversity increased, or as the connectivity of the network increased. Total consumer biomass was not affected by the number of nodes or connections, and was not correlated with primary producer biomass. Therefore, loss of total biomass was more associated with decreased NPP and a decrease in the efficiency of primary production than a loss of consumer biomass. The ratio of tertiary consumer to detritivore biomass, an indicator of the direction of energy flow, was positively correlated to taxonomic diversity, but negatively correlated with the number of connections. The ratio of ascendancy to capacity was negatively correlated with network size, and complexity was within the range of those of real aquatic ecosystems of similar size. The trends indicate that more energy is dissipated as the density of network connections increases.