A STOCHASTIC ECOLOGICAL MODEL

By including under the name 'niches' all the beneficial and adverse fa ctors or attributes for an ecological system that contribute or affect the biomasses of the species in that system, the contributory functio ns of these factors, together with their distributions in spatial regi on, have been proposed. From the random nature of these functions, ter med as 'random causes' for the ecosystem, the stochastic evolution equ ations for the biodensities of the spreading species have been deduced . These equations are found to be very general in nature and also desc ribe the nonlocal contributions of the biodensities. They can produce stochastic partial differential equations for the biodensities of the species for various ecological systems. Finally, it has been discussed how the experimental values of the population growth and spread over a region with the niche distribution therein, can determine the ecolog ical niche-contribution functions to the species of the system. The st ationary or equilibrium transition probabilities for the general ecolo gical systems are also given.