Fig. 3. Two stages (see Fig. 1) in the modeling of a rare fungus using Bayesian belief networks as developed from the influence diagram shown in Fig. 2. (a) beta-level model after peer review, (b) gamma-level model after incorporating known site field data (Table 1). See text for discussion of the initial alpha-level model. No delta-level model is available as further field validation studies had not been conducted.