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Key biogeochemical factors affecting soil carbon storage in Posidonia meadows.
- Source :
- Biogeosciences; 8/1/2016, Vol. 13 Issue 15, p4581-4594, 14p
- Publication Year :
- 2016
-
Abstract
- Biotic and abiotic factors influence the accumulation of organic carbon (C<subscript>org</subscript>) in seagrass ecosystems. We surveyed Posidonia sinuosa meadows growing in different water depths to assess the variability in the sources, stocks and accumulation rates of C<subscript>org</subscript>. We show that over the last 500 years, P. sinuosa meadows closer to the upper limit of distribution (at 2-4m depth) accumulated 3- to 4-fold higher C<subscript>org</subscript> stocks (averaging 6.3 kg C<subscript>org</subscript> m<superscript>-2</superscript>) at 3- to 4-fold higher rates (12.8 g C<subscript>org</subscript> m<superscript>-2</superscript> yr<superscript>-1</superscript>) compared to meadows closer to the deep limits of distribution (at 6-8m depth; 1.8 kg C<subscript>org</subscript> m<superscript>-2</superscript> and 3.6 g C<subscript>org</subscript> m<superscript>-2</superscript> yr<superscript>-1</superscript>). In shallower meadows, C<subscript>org</subscript> stocks were mostly derived from seagrass detritus (88% in average) compared to meadows closer to the deep limit of distribution (45% on average). In addition, soil accumulation rates and fine-grained sediment content (< 0.125 mm) in shallower meadows (2.0 mm yr<superscript>-1</superscript> and 9 %, respectively) were approximately 2-fold higher than in deeper meadows (1.2 mm yr<superscript>-1</superscript> and 5 %, respectively). The C<subscript>org</subscript> stocks and accumulation rates accumulated over the last 500 years in bare sediments (0.6 kg C<subscript>org</subscript> m<superscript>-2</superscript> and 1.2 g C<subscript>org</subscript> m<superscript>-2</superscript> yr<superscript>-1</superscript>) were 3- to 11-fold lower than in P. sinuosa meadows, while fine-grained sediment content (1 %) and seagrass detritus contribution to the C<subscript>org</subscript> pool (20 %) were 8- and 3-fold lower than in Posidonia meadows, respectively. The patterns found support the hypothesis that C<subscript>org</subscript> storage in seagrass soils is influenced by interactions of biological (e.g., meadow productivity, cover and density), chemical (e.g., recalcitrance of C<subscript>org</subscript> stocks) and physical (e.g., hydrodynamic energy and soil accumulation rates) factors within the meadow. We conclude that there is a need to improve global estimates of seagrass carbon storage accounting for biogeochemical factors driving variability within habitats. [ABSTRACT FROM AUTHOR]
- Subjects :
- POSIDONIA
CARBON in soils
BIOGEOCHEMISTRY
CARBON sequestration
SEAGRASSES
WATER depth
Subjects
Details
- Language :
- English
- ISSN :
- 17264170
- Volume :
- 13
- Issue :
- 15
- Database :
- Complementary Index
- Journal :
- Biogeosciences
- Publication Type :
- Academic Journal
- Accession number :
- 117501061
- Full Text :
- https://doi.org/10.5194/bg-13-4581-2016