Three types of power-law distribution of forest fires in Japan

Study on the forest-fire distribution is not only a phenomenological insight of forest ecological dynamics, but also essential for developing forest-fire danger rating method and system. In this paper, three types of power-law characteristics of forest fires are investigated. The first one is the distribution of fire areas. The frequency–area distribution is found obeying good power-law relation that is invariant with time. The second one is the distribution of fire intervals. It is indicated that the frequency–interval distribution of forest fires in Japan is also accord with power law. What is the most interesting is that the frequency–interval distribution is a power law with periodic change, different to that of frequency–size distribution. The third one is the distribution of fire probability against population density. There is positive-exponent power-law relation between fire probability and population density. The results discussed in this paper are expected to promote the forest-fire danger rating method and are helpful to understand the ecological action of forest fires.