Experimental addition of nitrogen to a whole forest ecosystem at Gårdsjön, Sweden (NITREX): Nitrate leaching during 26 years of treatment

Chronic high deposition of nitrogen (N) to forest ecosystems can lead to increased leaching of inorganic N to surface waters, enhancing acidification and eutrophication. For 26 years nitrogen has been added as ammonium nitrate (NH4NO3) at 40kgN ha-1 yr-1 to a whole forested catchment ecosystem at Gårdsjön, Sweden, to experimentally simulate the transition from a N-limited to N-rich state.

Over the first 10 years of treatment there was an increasing amount of nitrate (NO3-) and to a lesser extent ammonium (NH4+) lost in runoff, but then N leaching stabilised, and for the subsequent 16 years the fraction of N added lost in runoff remained at 9%. NO3- concentrations in runoff were low in the summer during the first years of treatment, but now are high throughout the year. High frequency sampling showed that peaks in NO3- concentrations generally occurred with high discharge, and were enhanced if high discharge coincided with occasions of N addition.

Approximately 50% of the added N has gone to the soil. The added N is equivalent to 140 years of ambient N deposition. At current ambient levels of N deposition there thus appears to be no immediate risk of N saturation at this coniferous forest ecosystem, and by inference to other such N-limited forests in Scandinavia.

Subscribe to our newsletter

Last updated: 2021-06-24

IVL Swedish Environmental Research Institute

About IVL

IVL Swedish Environmental Research Institute has a wide environmental profile. We combine applied research and development with close collaboration between industry and the public sphere. Our consultancy is evidence-based, and our research is characterized by interdisciplinary science and system thinking.


Ikon med telefon

+46 (0)10-788 65 00

Social media

Ikon med LikedIn
Ikon med twitter
Ikon med facebook

© 2015 IVL Svenska Miljöinstitutet AB | About Cookies | How we process personal data

Ikon med kryss
To top