As mentioned above, the limit to development is set by Shannon's diversity index pertaining to the material transfers or flows. MacArthur applied Shannon's diversity index to the material flows in an ecosystem to arrive at a measure for the diversity of flows, H:
where k is a scalar constant, and T is the TST, or the sum over all combinations of Tj.
Hcan, like the AMI, be multiplied by TST to scale the diversity of flows to the system in question. TST x H is called the development capacity, or limit for development, C:
The development capacity is limited by two factors, namely TST and the number of compartments. The limits to TST are the same as in the case of ascendency. If a certain amount of TST is split between too many compartments, then some compartments will end up with a very small throughput. These are, in turn, prone to extinction should the system undergo disturbances. This process is believed to reduce the number of compartments and thus the number of flows. More stable systems are thus believed to show a higher C compared to systems undergoing frequent perturbations.
The initial complexity, H, consists of two elements. One is the AMI, describing the information gained by reducing the uncertainty in flow probability. It is an index of the organized part of the system. The other is the residual uncertainty, or Hc (also called conditional diversity). Thus, H = AMI + Hc.
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