New York, Mar 29 (IANS): Rising levels of nitrogen pollution in the atmosphere can threaten and harm plant diversity, warns a new study.

Nitrogen plays an important role in biological processes and makes up a key element of fertilizer.

However, the results of the study showed that nitrogen pollution could lead to reduction in plant species, which might further cause unintended consequences and affect plant communities adversely.

Plant species diversity acts as an ecological buffer against events such as drought.

"The numerous plant species that live in ecosystems are a bit like rivets on an airplane. You might be able to lose a few without issue, but losing too many can be disastrous. It's hard to determine where that tipping point is," said lead author Samuel Simkin, post-doctoral research associate at the University of Colorado in Boulder, US.

Higher nitrogen levels in the atmosphere can also affect air quality standards and biodiversity conservation efforts.

Air pollution, along with habitat loss, is a major factor implicated in the loss of diversity, the researchers rued.

The findings revealed that regions, especially those with acidic soil were being the most vulnerable.

However, groundcover plant species in forested regions with neutral pH soil were found to be the least vulnerable.

Global emissions of nitrogen to the atmosphere have tripled in the last century due to agriculture and industry, and elevated levels of nitrogen have been shown to cause environmental damage, including decreased plant species richness in experimental plots.

The study, published in the journal Proceedings of the National Academy of Sciences, is the first to analyse ecosystem-specific vulnerabilities to atmospheric nitrogen pollution on a continental scale.

The team examined more than 15,000 forest, woodland, shrubland and grassland sites across US, measuring the threshold at which nitrogen inputs become harmful to plants while also taking other environmental factors such as climate and soil conditions into account.

In all, 24 percent of the sites surveyed were at or above levels that result in plant species losses.