Elevated levels of nitrogen fuel plant growth by about 20 per cent, claims a research team from the University of California, Irvine (UCI). This dislodges the popular belief that forest will remain immune to nitrogen pollution.
Plants growing at a faster rate will absorb more carbon dioxide than previously thought, says David Lebauer of UCI who led the research. Lebauer and his colleagues believe that nitrogen pollution will be on the rise especially in the tropical regions. Nitrogen pollution is supposed to hit India, South America, Africa and Southeast Asia. One of the main sources of nitrogen in the environment is nitrogen fertilizer. After being added to farmland, nitrogen through run-off water vaporizes into the atmosphere. Among other sources, industrial burning and forest cleaning also contribute to rising levels of atmospheric nitrogen.
Leafing through 100 other studies, the researchers tried to grasp how nitrogen affected the growth rates of various ecosystems. They considered tropical forests, grasslands, wetlands, and tundra. Except deserts, nitrogen influenced the growth rates in all ecosystems.
To their surprise, the researchers found that dry tropical forests and forest regrown after slash-and-burn agriculture also showed response to increased nitrogen levels. Despite not being typical tropical forests, such forests cover almost half of the world’s tropical forests. The findings of the study have been reported in the February issue of the journal Ecology. Forecasting the effects of nitrogen on global climate is a daunting task. But, human activities like cutting and burning of forests will play a decisive role in increasing the levels of atmospheric nitrogen. Yet, there are some questions remain unanswered. One of them is that how nitrogen will shape the fate of carbon once plants die and decay.
Despite the prevailing uncertainties of future scenarios, the nitrogen pollution study offers a new window into pollution phenomena that will have significant roles in changing global climate.
