The assumption that investment in deforesta-
tion avoidance has a high probability of resulting
in zero bene®t (the 0.55 probability that the area
avoided will be zero in Fig. 4b) is prohibitive.
This assumption may be overly severe; if some
gain is assured, then the avoided deforestation
curve in Fig. 5 would not explode to in®nity
until a higher level of required certainty is
reached.