Ecology is “the scientific study of how organisms interact with their environments.” (Campbell, et all, 2007). Ecology includes four hierarchical levels: organismal ecology, population ecology, community ecology, and ecosystem ecology. Population ecology and ecosystem ecology will be explored throughout this paper. In addition, the population growth and human activities and their impact on the environment will be discussed. This includes the concept of regulation of population growth through community interactions and the effects of human activities on ecosystems and the biosphere.
Dynamics of population
The inherent tendency of the animal population is to increase in number each day, week, month and year. This increase in number is not infinite since the carrying capacity of the environment always imposes a restriction upon it. After reaching the carrying capacity level, the population density tends to fluctuate and it depends on the co-actions between individuals of the same population or between populations of different species. The co-action between the same population is known as intraspecific interaction and the population between different species is known as interspecific.
An individual interacts with individuals of other species in different methods. When interaction results in a benefit for one or both of the species and harm to neither, the results are termed positive interactions. Several degrees of such interactions can be recognized. These interactions can be commensalism, proto-cooperation, and mutualism. Commensalism, wherein one species gain and the second are neither helped nor harmed; proto-cooperation, wherein both gain though each is also able to survive separately; and mutualism, wherein both gain but neither can survive without the other. Negative interactions occur when one of the species is harmed by the relationship. Various levels of negative interactions have also been recognized:...