Pristine forests in South America have an unexpected nitrogen cycle that is driven largely by air pollution, acid rain and artificial nitrogen fertilisation, shows a study from the US Geological Survey and New Jersey-based Princeton University. Prior to this study, most scientists believed that nitrogen cycle consisted of forms that came from simple inorganic compounds, such as nitrate. Organic forms associated with carbon were not given much importance. The study is very significant. It shows that in some forests excess nitrogen is encouraging growth of species that prefer large amounts of inorganic nitrogen. Secondly, a few forest areas which are getting saturated with nitrogen, may, in future, fail to serve as a buffer against pollution (www.scitechdaily.com, March 30, 2002).