Seasonal Species Variation of Sediment Organic Carbon Stocks in Salt Marshes of Tuticorin Area, Southern India

Abstract. Tropical agroforestry has an enormous potential to sequester carbon while simultaneously producing agricultural yields and tree products. The amount of soil organic carbon (SOC) sequestered is however influenced by the type of the agroforestry system established, the soil and climatic conditions and management. In this regional scale study, we utilized a chronosequence approach to investigate how SOC stocks changed when the original forests are converted to agriculture, and then subsequently to four different agroforestry systems (AFSs): homegarden, coffee, coconut and mango. In total we established 224 plots in 56 plot clusters across four climate zones in southern India. Each plot cluster consisted of four plots: a natural forest reference plot, an agriculture reference and two of the same AFS types of two ages (30–60 years and > 60 years). The conversion of forest to agriculture resulted in a large loss the original SOC stock (50–61 %) in the top meter of soil depending on the climate zone. The establishment of homegarden and coffee AFSs on agriculture land caused SOC stocks to rebound to near forest levels, while in mango and coconut AFSs the SOC stock increased only slightly above the agriculture stock. The most important variable regulating SOC stocks and its changes was tree basal area, possibly indicative of organic matter inputs. Furthermore, climatic variables such as temperature and precipitation, and soil variables such as clay fraction and soil pH were likewise all important regulators of SOC and SOC stock changes. Lastly, we found a strong correlation between tree species diversity in homegarden and coffee AFSs and SOC stocks, highlighting possibilities to increase carbon stocks by proper tree species assemblies.

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Bacterial carbon sources in coastal sediments: a cross-system analysis based on stable isotope data of biomarkers

Biogeosciences ◽

10.5194/bg-3-175-2006 ◽

2006 ◽

Vol 3 (2) ◽

pp. 175-185 ◽

Cited By ~ 93

Author(s):

S. Bouillon ◽

H. T. S. Boschker

Keyword(s):

Fatty Acids ◽

Organic Carbon ◽

Salt Marshes ◽

System Analysis ◽

Carbon Sources ◽

Isotopic Fractionation ◽

Coastal Sediments ◽

Large Variability ◽

Coastal Systems ◽

Sediment Organic Carbon

Abstract. Coastal ecosystems are typically highly productive, and the sediments in these systems receive organic matter from a variety of local and imported sources. To assess if general patterns are present in the origin of carbon sources for sedimentary bacteria and their relation to the origin of the sediment organic carbon pool, we compiled both literature and new data on δ13C of bacterial biomarkers (the phospholipid derived fatty acids i+a15:0), along with δ13C data on sediment organic carbon (δ13CTOC) and macrophyte biomass from a variety of typical near-coastal systems. These systems included mangroves, salt marshes (both C3 and C4-dominated sites), seagrass beds, and macroalgae-based systems, as well as unvegetated sediments. First, our δ13Ci+a15:0 data showed large variability over the entire range of δ13CTOC, indicating that in many settings, bacteria may depend on carbon derived from various origins. Secondly, systems where local macrophyte production is the major supplier of organic carbon for in situ decomposition are generally limited to organic carbon-rich, peaty sites (TOC>10 wt%), which are likely to make up only a small part of the global area of vegetated coastal systems. These carbon-rich sediments also provided a field based estimate of isotopic fractionation between bacterial carbon sources and biomarkers (-3.7±2.1), which is similar to the expected value of about -3 associated with the biosynthesis of fatty acids. Thirdly, only in systems with low TOC (below ~1 wt%), we consistently found that bacteria were selectively utilizing an isotopically enriched carbon source, which may be root exudates but more likely is derived from microphytobenthos. In other systems with between ~1 and 10 wt% TOC, bacteria appear to show on average little selectivity and δ13Ci+a15:0 data generally follow the δ13CTOC, even in systems where the TOC is a mixture of algal and macrophyte sources that generally are believed to have a very different degradability.

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Sediment Organic Carbon Accumulation and Erosion-induced CO 2 Emissions in the Delaware Bay Estuarine Salt Marshes

10.1002/essoar.10500786.1 ◽

2019 ◽

Author(s):

Beatrice OHara ◽

Daria Nikitina ◽

Alan Geyer ◽

Daniel Jennings

Keyword(s):

Organic Carbon ◽

Salt Marshes ◽

Delaware Bay ◽

Carbon Accumulation ◽

Sediment Organic Carbon

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On the rebound: soil organic carbon stocks can bounce back to near forest levels when agroforests replace agriculture in southern India

SOIL ◽

10.5194/soil-2-13-2016 ◽

2016 ◽

Vol 2 (1) ◽

pp. 13-23 ◽

Cited By ~ 23

Author(s):

H. C. Hombegowda ◽

O. van Straaten ◽

M. Köhler ◽

D. Hölscher

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Tree Species ◽

Regional Scale ◽

Clay Fraction ◽

Carbon Stocks ◽

Southern India ◽

Home Garden ◽

Soc Stock ◽

Soc Stocks

Abstract. Tropical agroforestry has an enormous potential to sequester carbon while simultaneously producing agricultural yields and tree products. The amount of soil organic carbon (SOC) sequestered is influenced by the type of the agroforestry system established, the soil and climatic conditions, and management. In this regional-scale study, we utilized a chronosequence approach to investigate how SOC stocks changed when the original forests are converted to agriculture, and then subsequently to four different agroforestry systems (AFSs): home garden, coffee, coconut and mango. In total we established 224 plots in 56 plot clusters across 4 climate zones in southern India. Each plot cluster consisted of four plots: a natural forest reference, an agriculture reference and two of the same AFS types of two ages (30–60 years and > 60 years). The conversion of forest to agriculture resulted in a large loss the original SOC stock (50–61 %) in the top meter of soil depending on the climate zone. The establishment of home garden and coffee AFSs on agriculture land caused SOC stocks to rebound to near forest levels, while in mango and coconut AFSs the SOC stock increased only slightly above the agriculture SOC stock. The most important variable regulating SOC stocks and its changes was tree basal area, possibly indicative of organic matter inputs. Furthermore, climatic variables such as temperature and precipitation, and soil variables such as clay fraction and soil pH were likewise all important regulators of SOC and SOC stock changes. Lastly, we found a strong correlation between tree species diversity in home garden and coffee AFSs and SOC stocks, highlighting possibilities to increase carbon stocks by proper tree species assemblies.

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Comparison of Three Methods for the Quantification of Sediment Organic Carbon in Salt Marshes of the Rubicon Estuary, Tasmania, Australia

International Journal of Biology ◽

10.5539/ijb.v5n4p1 ◽

2013 ◽

Vol 5 (4) ◽

Cited By ~ 4

Author(s):

Kim M. Beasy ◽

Joanna C. Ellison

Keyword(s):

Organic Carbon ◽

Salt Marshes ◽

Sediment Organic Carbon

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Bacterial carbon sources in coastal sediments: a review based on stable isotope data of biomarkers

Biogeosciences Discussions ◽

10.5194/bgd-2-1617-2005 ◽

2005 ◽

Vol 2 (5) ◽

pp. 1617-1644 ◽

Cited By ~ 2

Author(s):

S. Bouillon ◽

H. T. S. Boschker

Keyword(s):

Organic Carbon ◽

Salt Marshes ◽

Carbon Sources ◽

Isotopic Fractionation ◽

Lipid Synthesis ◽

Coastal Sediments ◽

Large Variability ◽

Coastal Systems ◽

Sediment Organic Carbon ◽

Bacterial Lipid

Abstract. Coastal ecosystems are typically highly productive, and recieve organic matter from a variety of local and imported sources. To assess if general patterns are present in the origin of carbon sources for sedimentary bacteria and their relation to the origin of the sediment organic carbon pool, we compiled both literature and new data on δ13C of bacterial biomarker PLFA (the phospholipid derived fatty acids i+a15:0) along with δ13C data on sediment organic carbon δ13CTOC and macrophyte biomass. Such data were collected from a variety of typical near-coastal systems, including mangroves, salt marshes (both C3 and C4-dominated sites), seagrass beds, and macroalgae-based systems, as well as unvegetated sediments. First, our δ13Ci+a15:0 data showed a large variability over the entire range of δ13CTOC, indicating that in many settings, bacteria may depend on carbon derived from various origins. Secondly, systems where local macrophyte production is the major supplier of organic carbon for in situ decomposition are generally limited to organic carbon-rich, peaty sites (TOC>10 wt%) which are likely to make up only a small part of the global area of vegetated coastal systems. These carbon-rich sediments also provided a field based estimate of isotopic fractionation in bacterial lipid synthesis (-3.7±2.1), that is similar to the expected value. Thirdly, only in systems with low TOC (below ~1 wt%), we consistently found that bacteria were on average selectively utilizing an isotopically enriched carbon source, which may be root exudates but more likely is derived from microphytobenthos. In other systems with between ~1 and 10 wt% TOC, bacteria appear to show on average little selectivity and δ13Ci+a15:0 data generally follow the δ13CTOC, even in systems where the TOC is a mixture of algal and macrophyte sources that generally are believed to have a very different degradability.

Download Full-text