Reclamation of coastal salt marshes promoted carbon loss from previously-sequestered soil carbon pool

Bu, Naishun; Qu, Jianhua; Li, Gang; Zhao, Bin; Zhang, Rong-Juan; Fang, Changming

doi:10.1016/j.ecoleng.2015.04.051

Cited by 69 publications

(33 citation statements)

References 30 publications

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“…CO 2 emissions were on the low end of the range of CO 2 emissions estimated from (Coverdale et al, 2014) for marsh edge erosion which we would expect to have an α close to 1. CO 2 emissions estimated from stock change reported in Bu et al (2015) where marsh sediments were covered with fill (reclaimed), and which would be expected to be anoxic, were similar to the model values where α would approach zero.…”

Section: Discussionsupporting

confidence: 49%

Modeled CO2 Emissions from Coastal Wetland Transitions to Other Land Uses: Tidal Marshes, Mangrove Forests, and Seagrass Beds

2017

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The sediments of coastal wetlands contain large stores of carbon which are vulnerable to oxidation once disturbed, resulting in high levels of CO 2 emissions that may be avoided if coastal ecosystems are conserved or restored. We used a simple model to estimate CO 2 emissions from mangrove forests, seagrass beds, and tidal marshes based on known decomposition rates for organic matter in these ecosystems under either oxic or anoxic conditions combined with assumptions of the proportion of sediment carbon being deposited in either oxic or anoxic environments following a disturbance of the habitat. Our model found that over 40 years after disturbance the cumulative CO 2 emitted from tidal marshes, mangrove forests, and seagrass beds were ∼70-80% of the initial carbon stocks in the top meter of the sediment. Comparison of our estimates of CO 2 emissions with empirical studies suggests that (1) assuming 50% of organic material moves to an oxic environment after disturbance gives rise to estimates that are similar to CO 2 emissions reported for tidal marshes; (2) field measurements of CO 2 emissions in disturbed mangrove forests were generally higher than our modeled emissions that assumed 50% of organic matter was deposited in oxic conditions, suggesting higher proportions of organic matter may be exposed to oxic conditions after disturbance in mangrove ecosystems; and (3) the generally low observed rates of CO 2 emissions from disturbed seagrasses compared to our estimates, assuming removal of 50% of the organic matter to oxic environments, suggests that lower proportions may be exposed to oxic conditions in seagrass ecosystems. There are significant gaps in our knowledge of the fate of wetland sediment carbon in the marine environment after disturbance. Greater knowledge of the distribution, form, decomposition, and emission rates of wetland sediment carbon after disturbance would help to improve models.

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Section: Discussionsupporting

confidence: 49%

Modeled CO2 Emissions from Coastal Wetland Transitions to Other Land Uses: Tidal Marshes, Mangrove Forests, and Seagrass Beds

2017

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“…It has been an important regional practice to offset the negative impact of fast population growth and urbanization progress on farmland shortage [1][2][3]. However, the newly reclaimed coastal mudflat areas generally have brackish shallow groundwater table and high content of salt in the soils, which impede the growth of plants [4].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Potential Use of Bundled Crop Straws as Subsurface Drainage Material in the Newly Reclaimed Coastal Land in Eastern China

Zhang

Feng

et al. 2018

Water

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Initial land reclamation of the saline soils often requires higher drainage intensity for quick leaching of salts from the soil profile; however, drainage pipes placed at closer spacing may result in higher cost. Seeking an inexpensive degradable organic subsurface drainage material may satisfy such needs of initial drainage, low investment and a heathy soil environment. Crop straws are porous organic materials that have certain strength and endurance. In this research, we explored the potential of using bundled maize stalks and rice straws as subsurface drainage material in place of plastic pipes. Through an experimental study in large lysimeters that were filled with saline coastal soil and planted with maize, we examined the drainage performance of the two organic materials by comparing with the conventional plastic drainage pipes; soil moisture distribution, soil salinity changed with depth, and the crop information were monitored in the lysimeters during the maize growing period. The results showed that maize stalk drainage and the rice straw drainage were significantly (p < 0.05) more efficient in removing salt and water from the crop root zone than the plastic drainage pipes; they excelled in drainage rate, leaching fraction, and lowering water table; and their efficient drainage processes lowered salt stress in the crop root zone and resulted in a slightly higher level of biomass. The experimental results suggest that crop straws may be used as a good organic substitute for the plastic drainage pipes in the initial stage land reclamation of the saline coastal soils.

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“…For example, Bu et al . () reported the loss of 21% of initial OC in the top metre after embankment, whereas Bai et al . () and Deng et al .…”

Section: Discussionmentioning

confidence: 98%

“…An example of such an ecosystem service is OC storage. Several studies have shown that the embankment and drainage of OC‐rich coastal sediments leads to a loss of previously stored OC (Bai et al ., ; Bu et al ., ; Deng et al ., ). In a study summarizing available data on this process, Pendleton et al .…”

Section: Introductionmentioning

confidence: 99%

“…An example of such an ecosystem service is OC storage. Several studies have shown that the embankment and drainage of OC-rich coastal sediments leads to a loss of previously stored OC (Bai et al, 2013;Bu et al, 2015;Deng et al, 2016). In a study summarizing available data on this process, Pendleton et al (2012) calculated that the conversion and degradation of vegetated coastal ecosystems might result in an average annual emission of ca.…”

Section: Introductionmentioning

confidence: 99%

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Soil organic carbon stocks in a tidal marsh landscape are dominated by human marsh embankment and subsequent marsh progradation

Broek

Baert

Temmerman

et al. 2018

European J Soil Science

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Summary Tidal marshes are coastal and estuarine ecosystems that store large amounts of sedimentary organic carbon (OC). Despite the valuable ecosystem services they deliver, tidal marshes have been converted to other land‐use types over the past centuries. Although previous studies have reported large decreases in soil organic carbon (SOC) stocks after tidal marsh embankment, knowledge on the magnitude and rate of OC losses is still limited. Here, we studied the effect of stepwise embankments of brackish and salt marshes and subsequent marsh progradation on SOC stocks in the Scheldt estuary (the Netherlands). We collected samples from soil profiles along tidal marsh–reclaimed tidal marsh chronosequences and determined total OC stocks and the stable carbon signature of the OC. Our results showed that large losses of previously sequestered SOC occur on a decadal timescale with the embankment of brackish (−8.7 ± 0.7 kg OC m−2) and salt marshes (−6.7 ± 0.8 kg OC m−2). The (incomplete) replacement of tidal marsh OC by agricultural OC is substantially faster in topsoils (ca. a century) compared with subsoils (multiple centuries). Simulations with a coupled land use–SOC model showed that large rates of marsh progradation following embankment construction resulted in a substantial increase in landscape‐scale SOC storage, whereas large SOC losses occurred in landscapes dominated by embanked tidal marshes. The findings of our study might help to assess how these management practices affect regional SOC stocks. Highlights We studied how OC stocks in tidal marsh sediments are affected by embankment construction OC stocks of both brackish and salt marsh sediments were reduced by ca. 60% with embankment Gains in landscape‐scale SOC storage occurred with marsh progradation after embankment If no marsh progradation occurs, embankments always lead to SOC loss at the landscape scale

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Reclamation of coastal salt marshes promoted carbon loss from previously-sequestered soil carbon pool

Cited by 69 publications

References 30 publications

Modeled CO2 Emissions from Coastal Wetland Transitions to Other Land Uses: Tidal Marshes, Mangrove Forests, and Seagrass Beds

Modeled CO2 Emissions from Coastal Wetland Transitions to Other Land Uses: Tidal Marshes, Mangrove Forests, and Seagrass Beds

Experimental Study on the Potential Use of Bundled Crop Straws as Subsurface Drainage Material in the Newly Reclaimed Coastal Land in Eastern China

Soil organic carbon stocks in a tidal marsh landscape are dominated by human marsh embankment and subsequent marsh progradation

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