Term ecosystem refers to community of biotic and abiotic elements as well as processes that are influencing on behavior and life of certain unit in defined natural habitats. Every ecosystem has its characteristic biotic and abiotic elements. Entry of new elements to certain ecosystem has often very negative effects, and more often than not causes extinction of some species that used to be important parts of this ecosystem. Therefore it is really vital to try to reduce the input of new species as much as possible, because once these new species are introduced to certain ecosystem they tend to change it, often by endangering originla species.
Humans shouldn't be really messing with nature's selection, especially in ecosystems with many different species because nature is the one that knows best. The secret of the nature selection is in forcing species to constant adaptation where only the strongest survive. However unlike the humans, the nature knows where exactly does certain animal and plant species belong. Human intervention to a certain ecosystem often results in only negative effects because we still have to learn so much different things to be able to compete with mother nature.
Process of natural selection usually lasts very long, therefore giving species enough time to completely adapt to new conditions. This is the main reason why natural selection is always better than the selection caused by human intervention. Convention on biological diversity that was ratified by 175 countries has important role in preservation of environment and current ecosystems. This Convention through its articles defines protection of ecosystem, natural habitats and preservation of diversity of species in their natural surroundings. This Convention defines ecosystem as "dynamic complexity of plants, animals, communities of microorganisms and their lifeless environment in interaction as one functional community".
Term ecosystem was for the first time used in publication of British ecologist Arthur Tansley in 1935, and the term itself was coined by his fellow colleague Roy Clapham, five years before. The recent research, where the team of more than 1000 scientists worked on evaluation of Earth's ecosystems has special place in studying the ecosystem. Results of this comprehensive research were anything but positive, and scientists concluded that people have violated ecosystems in last 50 years more than ever before in the entire history of the Earth.