Once carbon is in the soil some of it is respired by microbes and returns to the atmosphere as carbon dioxide. Some of the carbon that plants capture gets added to soils either via internal transport in the plant or when plant parts, such as leaves and roots, die and become incorporated into the soil. This carbon dioxide is the byproduct of the plants breaking down sugars (i.e.
This process is called “fixation” or “uptake” of carbon dioxide.Ĭarbon is also lost back to the atmosphere when plants respire (exhale) carbon dioxide, the same way people exhale carbon dioxide. As part of the growth process, plants capture carbon dioxide from the air and convert it to plant parts such as leaves, stems, or roots. Their soils are largely anaerobic (without oxygen) so carbon that gets incorporated into the soils decomposes very slowly and can persist for hundreds or even thousands of years ( carbon storage).Ĭoastal wetlands tend to be very productive ecosystems-meaning that the plants grow a lot each year.Their plants usually grow a lot each year, and in the process, capture (or sequester) large amounts of carbon dioxide (CO2).2014 Marine PolicyĬoastal wetland ecosystems (salt marshes, mangroves, and seagrass beds) can store large quantities carbon for two main reasons: This diagram is adapted from a figure in Sutton-Grier et al. (3) A small amount of carbon is lost back to the atmosphere through respiration, while the rest is stored in the leaves, branches, and roots of the plants. This oxygen-poor environment causes very slow breakdown of the plant materials, resulting in significant carbon storage. (2) Dead leaves, branches, and roots containing carbon are buried in the soil, which is frequently, if not always, covered with tidal waters. This diagram illustrates the mechanisms by which carbon moves into and out of coastal wetlands: (1) Carbon dioxide in the atmosphere is taken in by trees and plants during the process of photosynthesis. Unfortunately, coastal habitats around the world are being lost at a rapid rate, largely due to coastal development for housing, ports, and commercial facilities. Carbon stored in the habitats can also be released, contibuting to increased levels of greenhouse gases in the atmosphere. When these habitats are damaged or destroyed, it is not only their carbon sequestration capacity that is lost. Most coastal blue carbon is stored in the soil, not in above-ground plant materials as with tropical forests.Ĭoastal habitats are important for capturing carbon-but their destruction poses a great risk. They also store three to five times more carbon per equivalent area than tropical forests.
Julie is shown here in West Falmouth, Massachusetts.Ĭurrent studies suggest that mangroves and coastal wetlands annually sequester carbon at a rate ten times greater than mature tropical forests. This research is part of an ongoing project in collaboration with several partners to determine how much carbon is stored in eelgrass beds in the North Atlantic region.
MIT Sea Grant coastal ecologist Julie Simpson takes samples from a sediment core taken inside an eelgrass bed. Carbon storage - the long-term confinement of carbon in plant materials or sediment, measured as a total weight of carbon stored.Carbon sequestration - the process of capturing carbon dioxide from the atmosphere, measured as a rate of carbon uptake per year.Salt marshes, mangroves, and seagrass beds play two important roles: Using more scientific lingo, coastal blue carbon is the carbon captured by living coastal and marine organisms and stored in coastal ecosystems. These types of habitat are known as carbon sinks and contain large stores of carbon accumulated over hundreds to thousands of years. Salt marshes, mangroves, and seagrass beds absorb large quantities of the greenhouse gas carbon dioxide from the atmosphere and store it, thus decreasing the effects of global warming. Healthy coastal habitat is not only important for seafood and recreation, it also plays an important role in reducing climate change. Recording this data over time in a variety of marshes around Chesapeake Bay may yield new insights about whether the increase in marsh elevations can keep pace with rising sea level in the estuary. Scientists are testing how fast soil is building up in this marsh on Maryland's Eastern Shore.
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