scholarly journals After a Century, Restored Wetlands May Still Be a Carbon Source

Eos ◽  
2016 ◽  
Vol 97 ◽  
Author(s):  
Terri Cook
Keyword(s):  
Carbon Sequestration ◽  
Carbon Source ◽  
Methane Emissions ◽  
Restored Wetlands

Methane emissions can drastically lower, or even reverse, the benefits of carbon sequestration in restored wetlands, according to new measurements from the Sacramento–San Joaquin Delta.

scholarly journals Multi-year CO<sub>2</sub> budgets in South African semi-arid Karoo ecosystems under different grazing intensities

2020 ◽  
Author(s):  
Oksana Rybchak ◽  
Justin du Toit ◽  
Jean-Pierre Delorme ◽  
Jens-Kristian Jüdt ◽  
Kanisios Mukwashi ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Carbon Source ◽  
South African ◽  
Water Availability ◽  
Carbon Sink ◽  
Grazing Intensity ◽  
Livestock Grazing ◽  
Carbon Uptake ◽  
The Past ◽  
Semi Arid

Abstract. Climatic and land management factors, such as water availability and grazing intensity, play an important role in seasonal and annual variability of the ecosystem–atmosphere exchange of CO2 in semi-arid ecosystems. However, the semi-arid South African ecosystems have been poorly studied. Four years of measurements (November 2015–October 2019) were collected and analysed from two eddy covariance towers near Middelburg in the Karoo, Eastern Cape, South Africa. We studied the impact of grazing intensity on the CO2 exchange by comparing seasonal and interannual CO2 fluxes for two sites with almost identical climatic conditions but different intensity of current and historical livestock grazing. The first site represents lenient grazing (LG) and the vegetation comprises a diverse balance of dwarf shrubs and grasses, while the second site has been degraded through heavy grazing (HG) in the past but then rested for the past 10 years and mainly consists of unpalatable grasses and ephemeral species. Over the observation period, we found that the LG site was a considerable carbon source (82.11 g C m−2), while the HG site was a slight carbon sink (−36.43 g C m−2). The annual carbon budgets ranged from −90 ± 51 g C m−2 yr−1 to 84 ± 43 g C m−2 yr−1 for the LG site and from −92 ± 66 g C m−2 yr−1 to 59 ± 46 g C m−2 yr−1 for the heavily grazed site over the four years of eddy covariance measurements. The significant variation in carbon sequestration rates between the last two years of measurement was explained by water availability (25 % of the precipitation deficit in 2019 compared to the long-term mean precipitation). This indicates that studied ecosystems can quickly switch from a considerable carbon sink to a considerable carbon source ecosystem. Our study shows that the CO2 dynamics in the Karoo are largely driven by water availability and the current and historical effects of livestock grazing intensity on aboveground biomass (AGB). The higher carbon uptake at the HG site indicates that resting period after overgrazing, together with the transition to unpalatable drought-tolerant grass species, creates conditions that are favourable for carbon sequestration in the Karoo ecosystems, but unproductive as Dorper sheep pasture. Furthermore, we observed a slight decrease in carbon uptake peaks at the HG site in response to resuming continuous grazing (July 2017).

Carbon sequestration and methane emissions along a microtopographic gradient in a tropical Andean peatland

2019 ◽  
Vol 654 ◽  
pp. 651-661 ◽  
Author(s):  
Jorge A. Villa ◽  
Gloria M. Mejía ◽  
Daniela Velásquez ◽  
Andrés Botero ◽  
Sharon A. Acosta ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Methane Emissions

Isotopic Insights into Methane Production and Emission in Diverse Amazonian Peatlands

2020 ◽  
Author(s):  
Alison Hoyt ◽  
Hinsby Cadillo-Quiroz ◽  
Xiaomei Xu ◽  
Margaret Torn ◽  
Arturo Bazán Pacaya ◽  
...  
Keyword(s):  
Carbon Source ◽  
Methane Emissions ◽  
Nutrient Inputs ◽  
Tropical Regions ◽  
Hydrogenotrophic Methanogenesis ◽  
Peatland Hydrology ◽  
Methane Budget ◽  
Tropical Peatlands ◽  
Acetoclastic Methanogenesis ◽  
Future Work

&lt;p&gt;Tropical peatlands have the potential to be significant sources of methane (CH&lt;sub&gt;4&lt;/sub&gt;) to the atmosphere but their contribution to the global methane budget remains uncertain. Although much prior work has focused in Southeast Asia, other tropical regions, such as the Congo and the Amazon, have a much wider diversity of peatlands with more variable CH&lt;sub&gt;4&lt;/sub&gt; emissions. Our work aims to better understand CH&lt;sub&gt;4&lt;/sub&gt; production and emissions in these diverse peatlands, and how they are controlled by hydrology, geochemistry and vegetation. Using stable isotope and radiocarbon measurements, we assess the production pathway for methanogenesis and its carbon source at sites across the Pastaza-Mara&amp;#241;on basin in Peru. As the largest peatland complex in the Amazon, this region is home to many peatland types, from palm swamps to open peatlands to pole forests. We find clear links between site geochemistry, hydrology, and CH&lt;sub&gt;4 &lt;/sub&gt;production. In rain-fed ombrotrophic sites (pH 3-4), we observe low emissions and highly depleted &amp;#948;&lt;sup&gt;13&lt;/sup&gt;CH&lt;sub&gt;4&lt;/sub&gt; values (as low as -100&amp;#8240;). The lack of external nutrients and acidic conditions likely limit methanogenesis, and hydrogenotrophic methanogenesis dominates. In more minerotrophic sites (pH 5-6), more enriched methane (-75 to -60&amp;#8240;) suggests a contribution from acetoclastic methanogenesis. Emissions rates are also higher, likely fueled by external nutrient inputs from seasonal flooding. Across sites, modern, vegetation-derived inputs are the dominant carbon source for methanogenesis, with a limited contribution from old peat carbon in some ombrotrophic sites. The strong relationships we observe between peatland hydrology, vegetation, geochemistry and methane emissions will enable future work to upscale methane emissions across the region.&lt;/p&gt;

Variability of nitrogen-cycle microbial communities determined by the age of restored wetlands

2020 ◽  
Author(s):  
Kuno Kasak ◽  
Tyler Anthony ◽  
Alex Valach ◽  
Kyle Hemes ◽  
Keit Kill ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Microbial Communities ◽  
Nitrogen Cycling ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Chemical Parameters ◽  
Restored Wetlands ◽  
Soil Microbial Community Structure ◽  
C And N ◽  
Soil Chemical Parameters

&lt;p&gt;&lt;span&gt;Restoring degraded peat soils to wetlands can be an attractive and efficient measure with many benefits including carbon sequestration, water quality improvement, food and habitat for wildlife, flood control, and opportunities for recreation. Agricultural lands which are restored to wetlands will start rebuild soils and reverse land subsidence. Using eddy covariance towers in four wetlands that were restored in 1997, 2010, 2013 and 2016 in the Sacramento-San Joaquin Delta in California, we saw high carbon sequestration potentials and peat accumulation. Since soil restoration takes place gradually, it is important to specify the critical turning-points in the process of improving soil microbial community structure and nitrogen cycling. In August 2018, soil samples from four wetlands with different restoration ages in the Delta were collected for chemical and microbial analyses. The bacterial and archaeal 16S rRNA genes and functional genes involved in nitrogen cycling (&lt;em&gt;nirS&lt;/em&gt;, &lt;em&gt;nirK&lt;/em&gt;, &lt;em&gt;nosZ-I&lt;/em&gt;, &lt;em&gt;nosZ-II&lt;/em&gt;, bacterial and archaeal &lt;em&gt;amoA&lt;/em&gt;, &lt;em&gt;nifH&lt;/em&gt;, &lt;em&gt;nrfA&lt;/em&gt;, and ANAMMOX-specific genes) in soils were determined using a quantitative PCR method. Soil chemical parameters such as C%, N%, Al, Mn, Fe and two different organic and inorganic P pools were analysed as well. Preliminary results indicate significant dissimilarities in the abundance of soil bacterial and archaeal communities, as well as &lt;em&gt;nirS&lt;/em&gt;, &lt;em&gt;nirK&lt;/em&gt;, &lt;em&gt;nosZ&lt;/em&gt;, &lt;em&gt;nifH&lt;/em&gt;, &lt;em&gt;nrfA&lt;/em&gt; and archaeal &lt;em&gt;amoA&lt;/em&gt; gene-possessing microbial communities in different wetlands. Data analysis showed several statistically significant relationships between target gene parameters and soil chemical parameters that were different when comparing the sites with the restoration age. It is clear, that the complexity of the relationships increases as the wetland gets older. For example, in younger wetlands the availability of C and N plays a crucial role in gene abundances while in the oldest wetland, the most important chemical parameters were different phosphorus forms. This might indicate that more than 20 years of C and N accumulation has led to the availability of phosphorus for N transformation now to be the main limiting factor. Another important finding was that the design criteria can also determine how the wetland acts in terms of nitrogen gas emissions. For example, one of the wetlands was designed with more varied bathymetry that includes many open channels and a fluctuating water table. We saw that the &lt;em&gt;nifH&lt;/em&gt; gene-possessing microbes that are responsible for molecular N fixing are highly abundant in open water areas while at the same time this wetland has also the highest abundance of &lt;em&gt;nir&lt;/em&gt; genes that control N&lt;sub&gt;2&lt;/sub&gt;O production by denitrifiers. Our study demonstrates that the design of the wetland can have a significant impact on N-transforming processes, but most importantly at some age, restored wetlands become more similar to natural wetlands.&lt;/span&gt;&lt;/p&gt;

Tropical wetlands: seasonal hydrologic pulsing, carbon sequestration, and methane emissions

2009 ◽  
Vol 18 (5) ◽  
pp. 573-586 ◽  
Author(s):  
William J. Mitsch ◽  
Amanda Nahlik ◽  
Piotr Wolski ◽  
Blanca Bernal ◽  
Li Zhang ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Methane Emissions ◽  
Tropical Wetlands

Tidal and nontidal marsh restoration: a trade‐off between carbon sequestration, methane emissions, and soil accretion

2021 ◽  
Author(s):  
Ariane Arias‐Ortiz ◽  
Patty Y. Oikawa ◽  
Joseph Carlin ◽  
Pere Masqué ◽  
Julie Shahan ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Methane Emissions ◽  
Trade Off ◽  
Marsh Restoration

scholarly journals Organic Fertilizer Regulates Soil Carbon, Nitrogen Balance and Greenhouse Gas Emissions in Tobacco Production System

2021 ◽  
Vol 25 (06) ◽  
pp. 1339-1345
Author(s):  
Taibo Liang
Keyword(s):  
Carbon Sequestration ◽  
Carbon Source ◽  
Greenhouse Gas ◽  
Emission Reduction ◽  
Ammonia Volatilization ◽  
Organic Fertilizer ◽  
Chemical Fertilizer ◽  
Fertilizer Treatment ◽  
Soil Ecosystem ◽  
Tobacco Plants

The impact of organic fertilizers on the carbon source/sink balance of tobacco soil ecosystem remains controversial. A two-year field experiment was conducted to investigate the effects of different fertilization treatments(no fertilizer,chemical fertilizer, chemical fertilizer and organic fertilizer) on greenhouse gas (GHG) emissionsincludingsoil carbon dioxide (CO2), nitrous oxide (N2O), ammonia volatilization and comprehensive greenhouse effects. The results showed that tobacco soil ecosystem can be carbon source orsink, depending mainly on the carbon sequestration of the plant. Comparing with chemical fertilizer, the combined application of chemical fertilizer and organic fertilizer increased the CO2emission flux and C emission from soil, and significantly increased the carbon sequestration of tobacco plants. The carbon sequestration function of organic fertilizer was closely related to the carbon accumulation of tobacco plants. Comparedwith the chemical fertilizer, soil ammonia volatilization and N2O emission flux were increased by adding organic fertilizer. Both the soil N emission and the biological nitrogen fixation were increased by organic fertilizer. The greenhouse gas emission intensity(GHGI)of organic fertilizer treatment decreased by 14.60%, a remarkable emission reduction, whilethe tobacco yield of organic fertilizer treatment increased 19.12%. Therefore, increasing organic fertilizer in tobacco planting fields is an important way to promote tobacco yield, carbon sequestration and emission reduction.© 2021 Friends Science Publishers

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