ABSTRACT
The distribution of a species population is a function of its resource requirements for growth and reproduction and of its ability to exploit available environmental resources. The ability of any species population to maintain and reproduce itself in a particular physical environment will depend on the presence of those conditions necessary for, and the absence of those detrimental to, its growth and development. Some species are thermoperiodic in that they require lower night-time or winter temperatures for successful reproduction. Tolerance of the physical conditions discussed differs not only between species but between individuals in a species population. An organism’s tolerance may be wide for some variables but narrow for others. Direct competition is most intense between young individuals of the same species dependent on similar limiting resources of space, light, water and nutrients. Light intensity and duration are more ecologically significant.
