1.
Georgia Southern University
The Benefits of Maintaining Mangrove Ecosystems:
The use of Mangroves as Carbon Sinks in terms of Climate Change Mitigation
Kamariah Bankston
Ecosystem Ecology
Dr. Doug Aubrey
April 07, 2015

2. Abstract
Mangrove forests have become a global concern in recent decades, and are gaining more
attention because of the potential they have to alter the amount of carbon in the atmosphere. In
the past fifty years, the size of the intertidal boundary position mangroves occupy, has decreased
by almost half due to deforestation. This has posed a noticeable threat that leads to further
climate change because mangrove forests store and sequester an enormous amount of carbon.
This review paper is aimed at summarizing at previous research articles to demonstrate causes to
maintain and restore mangrove ecosystems. Especially to potentially balance global levels of
atmospheric carbon. Several research articles were also used to support the fact that further
research needs to be conducted so that we may estimate the effects and benefits of mangrove
ecosystems on climate change.
Introduction
With current trends in climate change due to deforestation, it is astounding that important
questions have not been posed. “How fast are mangroves being destroyed by deforestation? How
much carbon is being released into the atmosphere by the doubling effects of tree burning and
the loss of carbon sequestering power?” And lastly, “How much carbon could we potentially
remove from the atmosphere by restoring mangrove forests?”
Tropical mangrove forests ecology has historically been less studied than most other
ecosystems worldwide. The majority of attention that mangroves receive is due to their
adaptation for surroundings, there ecology, and there economically motivated
utilization(Hebbalalu, et al 2014). Mangrove forests occupy the interface between land and sea
on sheltered tropical and subtropical coasts over a broad latitudinal range. Global coverage of

3. mangroves varies but ranges from 1.7–1.8 ∙ 105 km2 of the coastal zone (Lovelock 2008).
Mangroves include both the ecosystem and the plant families that have developed specialized
adaptations to live in this tidal environment that is a mix of saltwater and freshwater. These are
essentially woody plants, that can survive increased salinity, extreme tides, strong winds, high
temperatures, and muddy­anaerobic soils (Maiti, et al 2013). They are responsible for sustaining
productivity in the tropical and subtropical coastal regions and do so by sequestering large
amounts of carbon below and above ground (Lovelock 2008). This paper will address mangrove
dynamics, both physical and biological characteristics, and the effects of anthropogenic
disturbances such as pollution and deforestation.
Mangrove Forests Dynamics
“New studies reveal that the world's coastal mangrove forests are
more beneficial than originally thought. These unique ecosystems are
capable of storing four times more carbon per acre than nearly any other
tropical forest on Earth and may even be able to protect island coasts
from earthquake damage.” ("Mangroves Provide Critical Carbon
Storage" 2011)
We have known for decades that wetland ecosystems have the ability to quickly cycle
carbon. They consists of temperate peatlands, salt marshes and mangrove forests. It has been
recently discovered that in these mangroves, unique ecosystems where saltwater collides with
fresh water, lies the potential to store a huge amount carbon. Research has shown that mangrove
forests are able to store such large amounts of carbon due the deep, organic rich soils where trees
can grow and reproduce at maximum efficiency. The complex root systems of mangrove forests

4. decrease that amount of incoming tidal waters. This allows organic and inorganic material to
settle into the sediment surface layer. The limited oxygen availability slows down the rate of
decay of these organic materials; this further allows for carbon to accumulate in the soil. Studies
support that mangroves contain more carbon in their soil than most tropical forests contain in
their entire ecosystems. When assessing the potential to store such large amounts of carbon, it
becomes evident that the mangrove forest ecosystem may play a very important role in climate
change management. ("Mangroves Provide Critical Carbon Storage" 2011)
Soil Properties and Leaf Traits/ SLA of Mangroves
Soil respiration, or the efflux of carbon from soil, is an important factor of the global
carbon budget and is generally predicted to be strongly correlated with increases in global
temperature; both current and future. Because wetland soils have very high productivity and
stores of organic carbon, they strongly influence global carbon budgets. Large carbon stores in
mangrove soils occur because high amounts of carbon are deposited from allochthonous and
autochthonous sources. Carbon oxidation rates within mangrove soils are low, due to the
extremely anaerobic conditions. Mangrove forests have very complex and dynamic root systems;
they contain aerial root systems (pneumatophores and stilt roots), or above ground, with
abundant arenchyma (air channels in the leaves, stems, etc. Due to high primary productivity
rates of mangrove forests and the highly organized root systems and carbon­rich soils, it is
suggested that mangroves allocate a large portion of their fixed carbon to the growth and
maintenance of root systems.
Soil respiration is directly correlated with Leaf Area Index (LAI). LAI is used to
indicate aboveground biomass, which in turn is used to correlate belowground biomass. The

5. highly variable relationship between LAI and soil respiration observed over our could reflect
wide variation in the allocation of resources to fine roots , or variation in the heterotrophic
component of respiration. Both soil respiration and the heterotrophic component of respiration
may be strongly influenced by nutrient availability and redox of soils. (Lovelock 2008).
Natural Disasters
Due to the location of mangroves on the coast and their role of as natural barriers and
bioshields, most mangrove forest are vulnerable to human induced and naturally occurring
disasters that involve air temperature, velocity, and wind direction. For example, tree species that
mangrove consists of are strong, healthy and highly tolerant to the conditions of subtropical and
tropical environments; however they are extremely sensitive to cold temperatures. Frosts and
freezes associated with severe cold weather events act as disturbances that devitalize, damage, or
kill mangrove tree species in subtropical areas.
Hydro­meteorological disasters have recently gained more attention, especially in coastal
regions of developing nations. These hydro­meteorological events include avalanche, cyclone,
drought, epidemic/ pandemic, flood/ tsunami, insect infestation, landslide, tornado, volcano, and
wild fire; they range from tropical to arctic environments. These events have a direct affect on
the livelihoods of people living in these areas; especially due to the fact that their technology is
not as developed. Therefore, their resilience to restore the environment and their way of life to
pre­disaster conditions is highly unlikely ( Kesavan, et al 2006).
“ For the planet Earth at crossroads, the imminent threat, however,
is from a vicious spiral among environmental degradation, poverty

6. and climate change­related natural disasters interacting in a
mutually reinforcing manner.’’(Kesavan, et al 2006)
Effects of Anthropogenic Disturbances
Mangroves have been subject to various anthropogenic and environmental disturbances.
Several of the effects include deforestation, the response to sea­level rise, pollution, and natural
disasters.These common disturbances may vary in their duration, frequency, size, and intensity
(Liu, et al 2014).
Deforestation
“Deforestation of mangroves is of global concern given their
importance for carbon storage, biogeochemical cycling and the
provision of other ecosystem services, but the links between rates of
loss and potential drivers or risk factors are rarely evaluated.
”("Making Predictions Of Mangrove Deforestation: A Comparison
Of Two Methods In Kenya." 2013)
Anthropogenic deforestation is commonly driven by population, suitability for land use
change, and accessibility. Deforestation based on anthropogenic causes can be best predicted by
population density, soil type and proximity to roads ("Making Predictions Of Mangrove
Deforestation: A Comparison Of Two Methods In Kenya." 2013). The second largest cause of
carbon dioxide emissions is deforestation and the degradation of ecosystems, after the emissions
from the burning of fossil fuels. Approximately one third of wetlands have been lost in the past
fifty years; wetlands have one of the highest deforestation rates. The result of deforestation

7. and/or disturbance of wetland ecosystems is large emissions of carbon dioxide to the atmosphere
(Adame, et al 2015).
Pollution
Mangrove forests are essential in regard to biomass production and maintenance of the
natural balance in tropical coastal areas. Mangroves, like most other ecosystems, fall subject to
pollution from anthropogenic causes, or human activities. The main example is oil pollution; one
of the leading causes in the decline of mangroves (Semboung, et al 2014). Mangroves naturally
play the role of a sink for anthropogenic and industrial pollutants.
Mangrove ecosystems consists of several aspects due to carbon and nutrients cycles,
sediment characteristics, and tidal conditions. These aspects which affect speciation, and the
availability of biological contaminants. Metals can enter mangrove ecosystem through rivers,
marine water intrusion or through atmospheric deposition; for example agriculture runoff. A
mangrove not only acts as a pollutant sink but they can also oxidize metals that are present in the
sediment via exudation through aerial roots. In economic terms, mangrove wetlands are
commonly used as a low cost waste disposal sites. There has recently been a rise in pressure on
mangrove patches due to anthropogenic industrial causes (Maiti, et al 2013).
Results
Benefits of Maintaining Mangroves
Mangroves consistently provide a various amount of ecosystem services and products,
but more importantly they have the ability to store a massive amount of carbon in their below
ground mass. For example, a study was recently conducted on the island of Guadeloupe by
Global ReLeaf. The findings suggest that ancient mangrove forests absorb majority of the force

8. from waves caused by earthquakes, thus protecting fragile coastlines from extreme damage.
Mangrove vegetation is also directly harvested to be utilized as food supplements and to produce
timber products.
Mangrove as a Carbon Sink
“While, comparing the carbon storage capacity (both above and
below ground) of mangroves ecosystem with other ecosystems,
mangroves has superiority and could be act as effective carbon sink.
(Maiti and Chowdhury 2013)”
Carbon emissions are the leading driver of climate change and global warming. From
1992 to 2008 there was an increase of 36% in global carbon dioxide emission and continues to
increase. Researchers have found that mangrove deforestation contributes to approximately ten
percent of global carbon emissions. Mangroves act as an effective carbon sink and sequester
approximately one hundred tons of carbon dioxide per hectare; that is more than any other
non­mangrove forest types. Mangroves are most carbon­rich forests in the tropics and recognized
for their high carbon assimilation and flux rates. Mangrove sediment acts as a carbon reservoir
due to its soft and muddy texture, that extends up to a depth of 3 ­ 4 m. When comparing other
ecosystems with mangrove ecosystems the above and below ground carbon storage capacity of
mangroves is by far superior. This is accounted for by rapidly decomposing litter in warm moist
soils. This in turn contributes to the carbon flux of the soil and results in an increase the total
organic carbon content of the soil. As stated in ​Effects of anthropogenic pollution on mangrove
biodiversity: a review, ​“​Organic rich soils ranged from 0.5 m to more than 3 m in depth and
accounted for 49% ­ 98% of carbon storage. Mangrove deforestation generates emission of 0.02 ­

9. 0.12 Pg carbon/year, as much as around 10% of emissions globally despite accounting for about
0.7% of tropical forest area. ”(Maiti and Chowdhury 2013)
Goods and Services Provided by Mangroves
Mangrove forests are known to provide a range of goods and services to people and other
organisms. These include protection from floods and other natural disasters, plant and animal
products, sediment (nutrient­rich) trapping, and nutrient uptake. Furthermore, some ecosystem
services, such as providing food and habitat for plants and animals, are essential for preserving
ecosystem integrity and biodiversity of that region. The quality and availability of the goods and
services provided vary based on their location in one of the three hydrogeomorphic zones (Ewel,
et al 1998).
Discussion and Conclusions
Mangrove forests ecosystems may hold the key to climate mitigation in terms of carbon
storage. In “Biomass and Carbon Stocks of Sofala Bay Mangrove Forests”, authors Almeida
Sitoe, Luis Mandlate, and Bernard Guedes state “Mangroves could be key ecosystems in
strategies addressing the mitigation of climate changes through carbon storage. However, little is
known regarding the carbon stocks of these ecosystems, particularly below­ground” (Sitoe, et al
2014). New research has shed light on the importance of mangrove forest ecosystems. It is
believed that despite being abundant globally, the immense benefits provided by mangrove forest
ecosystems are not properly documented; there is a lack of a direct, easily observed relationship
between a mangrove forest and the benefits it provided. Mangrove forests ecosystems will
continue to be exploited until there is widespread documentation (Ewel, et al 1998). The
overlapping range of operations of mangrove ecosystems provides cause to prioritize protecting

10. and conserving these habitats. In addition to these causes, chemical pollution, toxin
accumulation and biotransformation of toxic metals should be further researched to determine
whether it plays a significant role in the reduction of mangrove biodiversity. Furthermore, the
distribution of both spatial and temporal carbon profiles should be analyzed because it is
essential to determine the carbon sequestration potential of mangrove ecosystems, especially in
regard to economically developing countries (Maiti and Chowdhury 2013).
Future Applications
In some areas of the world, mangrove restoration projects have increased as the benefits
of restoring them become more widely known. For example, American Forests' Global ReLeaf
program has been working to restore the fragile mangrove ecosystems of southeastern China
since 2009 ("Mangroves Provide Critical Carbon Storage" 2011). Research has shown that
immature mangrove plantations accumulated large quantities of soil organic carbon, but not as
much soil organic carbon as the natural mangrove forests. These results indicate that similar rates
of carbon decay occur in both artificial and natural mangroves.
“Carbon sequestration must be viewed as a long­term process in
order to see meaningful impacts of conservation tillage, residue
management, manure and fertilizer use, crop rotations, etc. Farmers,
crop advisors, and others who deal with carbon conservation
benefits as well as carbon sequestration need to recognize that
carbon sequestration is a reversible process. They must adopt a
management strategy that improves soil carbon status as à long­ to
improve soil quality as well as the environment.” (Haris, et al 2013)

11. Deforestation of mangroves is a local and global concern. Their
importance for carbon storage, biogeochemical cycling and the provision of other
ecosystem services have been evaluated, however the links between rates of loss
and the associated carbon emissions are rarely evaluated.

12. References
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