Jerry van Dijk , Bjorn Robroek , Ignacy Kardel & Martin Wassen1 1 2 1
j.vandijk@geo.uu.nl@ Interactive effects of nitrogen enrichment, sulphur pollution and increased drying-rewetting dynamics on fen meadow
vegetation productivity and nutrient dynamics
1Environmental Sciences, Copernicus Institute of Sustainable Development, Utrecht University, PO Box 80115, 3508 TC Utrecht, The Netherlands
2Hydraulic Engineering and Environmental
Recultivation, Warsaw University of Life Sciences
Introduction
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Nitrogen deposition, sulphur pollution and alterations in water availability are among the most important external threats to plant species diversity in fens.
Through their potential to increase plant nutrient availability, all of these environmental problems can increase vegetation productivity, which may have marked effects on plant species diversity.
The specific nutrients that are affected and the mechanisms by which their availability is controlled, however, differ greatly between these three environmental problems, making the net outcome of their combined impact on fen vegetation unpredictable.
Fig. 1. The soil moisture t r e a t m e n t a m p l i f i e d s o i l moisture decreases in dry periods while maintaining the average soil moisture content of the control.
Fig. 2. S-addition significantly i n c r e a s e d N : P r a t i o s o f phytometer species
by reducing P-uptake.
Carex nigra
Fig. 3. S-addition significantly reduced vegetation productivity. Increased soil moisture dynamics significantly increased vegetation productivity up to 20%.
Aim and approach
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Our aim was to assess the interactive effects of nitrogen deposition, sulphur pollution and increased drying- rewetting dynamics on hydrochemistry, fen vegetation biomass and N:P stoichiometry and plant acces to soil P We performed a 3-year field experiment
Nitrogen and sulphur were applied at levels comparable to current atmospheric deposition levels in Western Europe (30 and 32 kg ha yr respectively).
We increased drying-rewetting dynamics with drainage ditches to mimic the effects of climate change.
through root phosphatase activity.
in a rich fen meadow in the Biebrza valley, Poland.
• -1• -1
2006-2007
80 85 90 95 100 105
10-6-2006 10-7-2006 10-8-2006 10-9-2006 10-10-2006 10-11-2006 10-12-2006 10-1-2007 10-2-2007 10-3-2007 10-4-2007 10-5-2007 10-6-20072007-2008
80 85 90 95 100 105
10-6-2007 10-7-2007 10-8-2007 10-9-2007 10-10-2007 10-11-2007 10-12-2007 10-1-2008 10-2-2008 10-3-2008 10-4-2008 10-5-2008 10-6-2008
Moisturecontent (%ofwatersaturation)
2008-2009
80 85 90 95 100 105
10-6 10-7 10-8 10-9 10-10 10-11 10-12 10-1 10-2 10-3 10-4 10-5 10-6
Date
Results
Conclusions
Soil moisture dynamics N:P stoichiometry Vegetation productivity
0 2 4 6 8 10 12
2007 2008 2009
year
C.nigraN:Pratio
-S +S
0 200 400 600 800 1000
2007 2008 2009
year biomass(g•m-2 )
undrained drained 0
200 400 600 800 1000
2007 2008 2009
year biomass(g•m-2 )
-S +S
Interactive effects of N-addition, S-addition and increased drying-rewetting dynamics had no impact on N:P stoichiometry or vegetation productivity.
Current levels of S-deposition have negative effects on fen meadow vegetation productivity and plant access to soil nutrients, indicating toxic effects. We found no eviidence for interference of S-enrichment with soil P-availability.
Even slightly increased drying-rewetting dynamics due to climate change poses a serious new threat to fen meadow plant species diversity by significantly
The fen meadow ecosystem is robust against current levels of N-deposition, confirming critical loads defined for this
increasing vegetation productivity.
