Nitrogen Pollution - Plant Growth In Tropical Regions Up By 20 Percent

A study being performed by UC Irvine ecologists have found that the abundance of nitrogen in tropical forests have boosted the plant growth in certain regions by an average of 20%! This contradicts comments previously made that the forests would not respond to the nitrogen pollution.

Faster plant growth means the tropics will take in more carbon dioxide than previously thought, though the long-term effects are unclear. Over the next century, nitrogen pollution in the atmosphere is expected to rise, with the biggest increases in the developing equatorial regions such as India, South America, Africa and Southeast Asia.

The use of nitrogen fertilizer to boost crop growth has effected ecosystems further afield. Run off water and evaporation mixed with the burning of forests has put more nitrogen into the air.

Surprisingly, tropical forests that seasonally where dry, located in mountainous regions or had regrown from slash-and-burn agriculture has also responded to added nitrogen. Although these tropical forests that typically come to mind are not the normal forests that come to mind, although, they collectively account for more than half of the world’s tropical forests.

Scientists believed added nitrogen would have little effect in the tropics because plants there typically have ample nitrogen. If one necessary plant nutrient is in short supply – in this case phosphorus, which is normally found in these regions – plant growth will be poor, even if other nutrients such as nitrogen are abundant.

It is difficult to predict the long-term effects of nitrogen on global climate change. One element of discussion will be the degree to which humans change natural ecosystems, for example the process of cutting down or burning the tropical forests. Climate change may also determine how these areas grow back, whether as forests, grasslands or deserts. It also is unknown how nitrogen will affect the fate of carbon once plants die and begin to decompose.

David LeBauer, graduate student researcher of Earth system science at UCI and lead author of the study, has stated;

“What is clear is that we need to consider how nitrogen pollution interacts with carbon dioxide pollution, our study is a step toward understanding the far-reaching effects of nitrogen pollution and how it may change our climate.”

Comments

[gaston monescu]

interesting. the issue gets clearer and more opaque at the same time...