FIRST PASSAGE FLOWS IN ECOLOGICAL NETWORKS - MEASUREMENT BY INPUT-OUTPUT FLOW-ANALYSIS

This paper explains the rationale behind measuring first passage flows of conservative substances in ecological networks by a simple modific ation of input-output flow analysis (Higashi et al., 1993a, Ecol. Mode l., 66: 1-42). Pilette and Kincaid (1992, Ecol. Model., 64: 1-10) pose d this ''first flow-through'' problem and described a different method to solve it. This method, however, does not account for their intende d ''all non-duplicated routes and transfers'' from one compartment to another, and consequently underestimates indirect transfers. In additi on, it incorrectly treats storages as equivalent to flows. We correct their version, according to the discrete time input-output flow-storag e analysis of Higashi et al. (1993b, Ecol. Model., 66: 43-64), and der ive a correct evaluation of direct transfers. This, however, turns out to be equivalent to simple flow ratios obtained from standard, contin uous time input-output flow analysis.