ABSTRACT
The impact of human activities on the biosphere has accelerated rapidly consequent upon an exponential rate of population growth combined with scientific and technical developments. In comparison to many other forms of life the human population is relatively small. As predators humans are without equal; neither lack of food nor the presence of a powerful enough predator has been able to set a limit to their numbers. Human activities have effected very considerable changes in the numbers and relative proportion of species populations by either direct or indirect habitat modification. Humans have become increasingly powerful agents of species dispersal and distribution. Prolific seed production combined with a wide range of tolerance of environmental conditions has aided and accelerated their widespread dispersal and distribution by human activity. The main factors involved are ecosystem modification and loss, species over- exploitation, and species invasions.
