Details

Autor(en) / Beteiligte

• Poszwa, Anne
• Ferry, Bruno
• Dambrine, Etienne
• Pollier, Benoît
• Wickman, Tonie
• Loubet, Michel
• Bishop, Kevin

Titel

Variations of bioavailable Sr concentration and 87Sr/86Sr ratio in boreal forest ecosystems

Ist Teil von

• Biogeochemistry, 2004-01, Vol.67 (1), p.1

Ort / Verlag

Dordrecht: Springer Nature B.V

Erscheinungsjahr

2004

Quelle

SpringerNature Journals

Beschreibungen/Notizen

• The mean depth of Sr and water uptake in mixed Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) stands was investigated, using natural variations of ^sup 87^Sr/^sup 86^Sr and ^sup 18^O/^sup 16^O in soils in relation to depth. Three spruce-pine pairs were studied on a podzol and a peat site in Northern Sweden. Tree leaf and wood, as well as soils, soil solutions and roots below each tree were analysed for Sr and Ca concentrations and ^sup 87^Sr/^sup 86^Sr ratio. The ^sup 18^O/^sup 16^O ratio was also determined in xylem sap and soil solutions in relation to depth. Soil solution ^sup 18^O/^sup 16^O decreased in relation to depth. Comparing with xylem sap ^sup 18^O/^sup 16^O data indicated a deeper uptake of soil water by pine than spruce on the podzol site and a superficial uptake by both species on the peat. The ^sup 87^Sr/^sup 86^Sr ratio of bioavailable Sr generally increased in soils in relation to depth. Contrastingly, the ^sup 87^Sr/^sup 86^Sr ratio in spruce wood was generally higher than in pine wood suggesting a deeper uptake of Sr by spruce. But the ^sup 87^Sr/^sup 86^Sr ratio and concentrations of bioavailable Sr were systematically higher below spruce than below pine. In order to explain these unexpected results, we built a simple flux model to investigate the possible effects of interspecific variations in Sr cycling, soil mineral weathering and depth of Sr uptake on soil and tree ^sup 87^Sr/^sup 86^Sr ratio. At the study sites, spruce cycled in litterfall up to 12 times more strontium than pine. The use of the model showed that this difference in Sr cycling could alone explain higher isotopic signatures of trees and topsoils below spruce. Besides, high isotopic signatures of roots in the A/E horizons below spruce led us to hypothesise a species-specific weathering process. Finally, the comparison between the ^sup 87^Sr/^sup 86^Sr ratios in wood and root or soil solutions below each species suggested that the average depth of Sr and water uptake were close, but irregular variations of the Sr isotopic ratio with depth reduce the accuracy of the results. Tree species strongly influence Sr isotopic ratios in boreal forest soils through differences in Sr cycling, and possibly through specific mineral weathering.[PUBLICATION ABSTRACT]