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Physiological responses to nitrogen and sulphur addition and raised temperature in Sphagnum balticum
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
2009 (English)In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 161, no 3, 481-490 p.Article in journal (Refereed) PublishedText
Abstract [en]

Sphagnum, the main genus which forms boreal peat, is strongly affected by N and S deposition and raised temperature, but the physiological mechanisms behind the responses are largely unknown. We measured maximum photosynthetic rate (NP(max)), maximum efficiency of photosystem II [variable fluorescence (F (v))/maximum fluorescence yield (F (m))] and concentrations of N, C, chlorophyll and carotenoids as responses to N and S addition and increased temperature in Sphagnum balticum (a widespread species in the northern peatlands) in a 12-year factorial experiment. NP(max) did not differ between control (0.2 g N m(-2) year(-1)) and high N (3.0 g N m(-2) year(-1)), but was higher in the mid N treatment (1.5 g N m(-2) year(-1)). N, C, carotenoids and chlorophyll concentration increased in shoot apices after N addition. F (v)/F (m) did not differ between N treatments. Increased temperature (+3.6A degrees C) had a small negative effect on N concentration, but had no significant effect on NP(max) or F (v)/F (m). Addition of 2 g S m(-2) year(-1) showed a weak negative effect on NP(max) and F (v)/F (m). Our results suggest a unimodal response of NP(max) to N addition and tissue N concentration in S. balticum, with an optimum N concentration for photosynthetic rate of similar to 13 mg N g(-1). In conclusion, high S deposition may reduce photosynthetic capacity in Sphagnum, but the negative effects may be relaxed under high N availability. We suggest that previously reported negative effects on Sphagnum productivity under high N deposition are not related to negative effects on the photosynthetic apparatus, but differences in optimum N concentration among Sphagnum species may affect their competitive ability under different N deposition regimes.

Place, publisher, year, edition, pages
New York: Springer-Verlag New York, 2009. Vol. 161, no 3, 481-490 p.
Keyword [en]
Chlorophyll fluorescence, Nutrient deposition, Peatlands, Photosynthesis, Photosynthetic nitrogen-use efficiency
National Category
Ecology Environmental Sciences
URN: urn:nbn:se:umu:diva-115978DOI: 10.1007/s00442-009-1406-xISI: 000269010300004PubMedID: 19593588OAI: diva2:907188
Available from: 2016-02-26 Created: 2016-02-08 Last updated: 2016-02-26Bibliographically approved

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Granath, GustafWiedermann, Magdalena M
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