Read the full story from U.S. EPA.
Can there be too much of a good thing?
That’s the case with nitrogen, an essential element for plant growth that, in overabundance, can also be potentially damaging. Nitrogen moves from the air to the land, soil, and water via a process called nitrogen deposition. Atmospheric nitrogen deposition has increased ten-fold or more since pre-industrial levels due to increased emissions from the burning of fossil fuels, fertilizer use, and other human activities.
Once nitrogen is emitted into the atmosphere, it can travel vast distances and deposit in the environment, making it a national as well as local problem. Elevated nitrogen deposition can increase leaf biomass in the canopy, shading ground-dwelling plants from the sun. Additionally, physical and chemical reactions that occur when nitrogen compounds are deposited can lead to more acidic soils. Both effects restrict plant growth and increase competition for limited resources, resulting in a loss of local biodiversity…
That’s why EPA researcher Chris Clark and a team of scientists from EPA, U.S. Geological Survey, the U.S. Forest Service, the University of Colorado, and multiple other universities are exploring the effects of nitrogen deposition on herbaceous plants (those with non-woody stems such as grass) in a first-of-its-kind study focused on multiple ecosystems across the nation. The new research expands the focus to not only grasslands, but into habitats that have not received much attention, including the forest understory.
The study, recently published in Proceedings of the National Academy of Sciences, assesses how nitrogen deposition affects herbaceous plants at over 15,000 forest, woodland, shrubland, and grassland sites throughout the United States. The research addresses how physical, chemical, and climatic factors such as soil acidity, temperature, and precipitation can affect an area’s vulnerability to nitrogen deposition.