Nitrogen leaching after a winter warm spell in temperate ecosystems is driven by plant responses

Juergen Kreyling1, Jan Schuerings1, Andrey Malyshev1, Lukas Vogt1, Christiane Werner1, Anke Jentsch1
1 University of Bayreuth

O 2.9 in Environmental controls on fluxes and processes in ecosystems

17.07.2014, 12:00-12:20, H18

Leaching of nitrogen (N) from ecosystems poses serious environmental problems. N-leaching is commonly related to severe atmospheric N deposition. Extreme events such as winter warm spells, however, can also disrupt biogeochmical cycles and will become more frequent with climate change. Here, we used a mesocosm/ lysimeter approach to investigate N leaching in response to a 12-day winter warming pulse at two field sites with contrasting winter climate and in seven different temperate plant communities (n = 140 lysimeters). The extreme winter warm spell resulted in significant N-leaching after the warm spell (up to 80 mg l-1). This leaching, however, was affected by the climatic setting with stronger leaching under colder ambient conditions. The difference between the sites can be explained by the plants becoming photosynthetically activated by the warm spell, followed by frost damage at the cold site due to missing insulation by snow cover, resulting in reduced N uptake by the plants. N leaching furthermore differed among contrasting plant communities with almost no leaching from grassland communities and strongest leaching from shrubland communities. Leaching from shrubland communities even surpassed leaching from bare ground controls. We conclude that winter warm spells can strongly affect the biogeochemistry of temperate ecosystems with plant performance and plant community composition controlling the amount of N leaching.

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last modified 2014-03-28