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Carbon Cycling and Storage in Mangrove Forests
Abstract and Figures
Mangroves are ecologically and economically important forests of the tropics. They are highly productive ecosystems with rates of primary production equal to those of tropical humid evergreen forests and coral reefs. Although mangroves occupy only 0.5% of the global coastal area, they contribute 10-15% (24 Tg C y(-1)) to coastal sediment carbon storage and export 10-11% of the particulate terrestrial carbon to the ocean. Their disproportionate contribution to carbon sequestration is now perceived as a means for conservation and restoration and a way to help ameliorate greenhouse gas emissions. Of immediate concern are potential carbon losses to deforestation (90-970 Tg C y(-1)) that are greater than these ecosystems' rates of carbon storage. Large reservoirs of dissolved inorganic carbon in deep soils, pumped via subsurface pathways to adjacent waterways, are a large loss of carbon, at a potential rate up to 40% of annual primary production. Patterns of carbon allocation and rates of carbon flux in mangrove forests are nearly identical to those of other tropical forests.
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... Among individual studies, Ouyang et al. (2018) investigated the sources of soil 308 respiration for Avicennia marina (grey mangrove) seedlings and found that roots contributed to 31.8% ± 9.7% of soil respiration, while their contribution may be higher for mature mangroves 310 (Troxler et al. 2015). Alongi (2014) estimated that heterotrophic respiration from mangroves 311 could reach 1,101 g C m -2 yr -1 . Nonetheless, this estimate includes CO2 emissions from adjacent 312 waterways and subsurface CO2 production that may lead to the production of dissolved 313 inorganic carbon from dissolved CO2. ...
... Nonetheless, this estimate includes CO2 emissions from adjacent 312 waterways and subsurface CO2 production that may lead to the production of dissolved 313 inorganic carbon from dissolved CO2. Therefore, heterotrophic respiration from mangrove soils 314 should be lower than the estimate of 257.1 g C m -2 yr -1 by Alongi (2014), and far lower than 315 the rate of heterotrophic respiration in humid forests (Luyssaert et al., 2007;Malhi, 2012). 316 ...
... After removing the top 0.5 cm of soil prior to repeated measurement 543 of CO2 fluxes, soil respiration rate was found to be greatly improved, suggesting a significant 544 impact of biofilm on CO2 fluxes from soil (Lovelock, 2008). Other studies in temperate, (Alongi, 2014), indicated that the 576 gross primary production of benthic algae could account for more than 10% of mangrove 577 ecosystems, of which half is probably respired. However, since benthic metabolisms are highly 578 variable at diurnal, seasonal and annual scales, incorporating biofilm into the carbon budget of 579 coastal vegetated wetlands is challenging. ...
Increasing awareness of the significance of coastal wetlands in global carbon budgets combined with recently developed approaches such as in-situ gas analyzers connected to flux chambers, has led to the wide interests in quantifying greenhouse gas exchange in these ecosystems, for which less attention was paid to than terrestrial ecosystems. Considering the high net primary production and large carbon stocks of coastal wetlands, recent researches have pointed out their conservation as an opportunity to mitigate climate change. CO2 emissions are especially low in mangrove ecosystems (257 g C m-2 yr-1), while CO2 emissions from saltmarshes (564 g C m-2 yr-1) are relatively similar to those from terrestrial ecosystems (592 g C m-2 yr-1). Contrasting trends were reported for CH4 emissions, with low values in terrestrial ecosystems (0.22 g C m-2 yr-1), intermediate values in mangroves (1.69 g C m-2 yr-1) and high values in saltmarshes (14.2 g C m-2 yr-1). The large variability in measured CO2 and CH4 fluxes at the soil-air interface suggests that emissions are highly responsive to changes in both physical and biological parameters. Anthropogenic disturbances in particular often enhance carbon decomposition and releases from soils. With a focus on coastal wetlands, this chapter gives recommendations for the use of incubation chambers, synthesizes soil-air CO2 and CH4 flux magnitudes, discusses the biotic and abiotic parameters influencing greenhouse gas fluxes, and provides future directions to fill the knowledge gaps in coastal carbon budget estimates.
... Estuaries are recognised as regions that house some of the most productive ecosystems, sustaining a high biodiversity and complex trophic webs (McLusky and Elliott, 2004;De La Lanza Espino and Verdugo, 1998), providing habitats for many commercially important organisms (Nagelkerken et al., 2008;Cattrijsse and Hampel, 2006), stabilizing coastal sediments (Christianen et al., 2013;Friedrichs and Perry, 2001), protecting coastal regions against bad weather (Möller et al., 2014;Ondiviela et al., 2014), as well as storing large quantities of carbon ("Blue Carbon"), mainly in its sediments (Macreadie et al., 2017;Alongi, 2014). By capturing and preserving/burying significant quantities of carbon for extended periods of time, estuarine ecosystems play an important role in climate regulation, helping offset anthropogenic emissions of CO 2 and mitigating global warming (Rosentreter et al., 2018;Murdiyarso et al., 2015). ...
... Globally, the total estimated carbon stock in mangrove forest soil varies from 316.29 Mg C ha − 1 to 1485.5 Mg C ha − 1 (Perera and Amarasinghe, 2019;Boone Kauffman et al., 2017). It is estimated that mangroves cover an area of 138.000 km 2 globally (Giri et al., 2011), with an average carbon soil storage rate of 24 Tg C y − 1 (Alongi, 2014). ...
... The limitation of deposition processes directly interferes with carbon accumulation/burying in the sediment. Thus, high levels of plastic bag cover can cause irreparable damage to this ecosystem service that helps to mitigate climate change (Alongi, 2014) counterbalancing Table 1 Average values and standard deviations of organic matter and silt-clay sediment contents (%) of the treatments (control, impact) before (pre-treatment) and after (post-treatment) impact. Bold statistical values indicate significant differences (t -Student's paired t-test; pprobability values). ...
Plastic bags are among the most discarded waste items as they are generally only used once and are often improperly eliminated and transported by rivers and estuaries to the ocean. We developed an experimental design to mimic the effect of plastic bag deposition in a tropical estuary and investigated its short-term impact on benthic community structure. We observed a significant influence of the presence of plastic bags on the abundance, richness and diversity of benthic fauna after an eight-week exposure period. Plastic bags acted as a barrier and interfered in processes that occur at the water-sediment interface, such as organic matter and silt-clay deposition. Our results indicate that plastic bags, in addition to directly affecting benthic fauna, may alter processes such as carbon burying, known as “blue carbon”, thus making its storage in the sediment more difficult.
... Some carbon may be released as CO 2 or CH 4 gases, and the balance of the two being strongly influenced by salinity, oxygen availability, and the dominance of sulfate reduction. Further, global sediment carbon gases (including CO 2 and CH 4 ) emitted are 38 Tg C year −1 , while DIC and DOC export rates are 86 and 15 Tg C year −1 , respectively, in mangroves (Alongi, 2014). As a result, emitted carbon gases, DIC, and DOC account for 27.3%, 61.9%, and 10.8% of mangrove belowground C mineralization. ...
This chapter discusses factors affecting processes of litter decomposition in coastal wetlands, including biotic, abiotic, as well as anthropogenic factors. A few indicators of litter decomposition are used to describe litter disappearance, including decomposition rate, mass loss percentage, half-life time, and residence time. We examine the variability of leaf litter, wood and root decomposition due to factors such as media for decomposition experiment, stoichiometry, and ecosystem types. Leaf litter decomposes at significantly higher decomposition rate in the aerial (0.06 ± 0.018 day− 1) than the aquatic environment (0.025 ± 0.007 day− 1) for mangroves, while nonsignificant differences are found for saltmarshes. There is a significant negative relationship between leaf litter decomposition rate constant and leaf litter C/N ratio for both mangroves and saltmarshes. Both leaf and root decomposition rates differ among wetland geomorphology due to differences in biotic and hydrological conditions. Relatively few studies examine the decomposition of wood compared with leaf litter and roots, but generally mangrove wood is more recalcitrant than leaf tissues. The fate of root carbon in mangroves and saltmarshes is revealed with emitted carbon gases accounting for 27.3% of belowground carbon mineralization for mangroves but unknown for saltmarsh due to the paucity of data. Sediment organic matter in coastal wetlands consists of diversified organic compounds, including carbohydrates, proteins, lipids, and phenols, which are classified into labile or humic substances. Organic matter mineralization involves the breakdown of large to small molecule weight organic compounds and eventually to carbon gases (i.e., CO2 and CH4) via various aerobic and anaerobic pathways. Free energy yields determine the likelihood of the reactions of CH4 and CO2 production. Carbon mineralization is related to a series of processes, including inorganic carbon dynamics and sedimentation in coastal wetlands.
... There are studies that try to better constrain the different components of the unaccounted carbon with more case studies. In terms of CO 2 flux rate, Alongi (2014) and Rosentreter et al. (2018) estimated slightly lower rates (43 and 56.8 mmol m −2 day −1 , respectively) in comparison with the previous review (59 ± 52 mmol m −2 day −1 ). In terms of sediment organic carbon accumulation rate, Breithaupt et al. (2012) updated the rate to reach 163 g C m −2 year −1 and revized the unaccounted carbon to be 104.3 ...
Carbon minerelization is significant to studying the whole carbon cycling dynamics and food webs in coastal wetlands. It reflects the fate of carbon from litter decomposition to greenhouse gas emission but is often less emphasized than carbon storage in the management of coastal wetlands. This chapter presents the basic concepts, the unique characteristics of carbon mineralization and current state of carbon cycling study in coastal wetlands. There is a lack of global perspective on carbon cycling in coastal wetlands except mangroves. We highlight that deciphering the factors influencing carbon mineralization is significant to determining the evolution of coastal wetlands, and enhancing understanding on the future modification of food webs and biodiversity along the coastline. Anthropogenic activities affect carbon mineralization in coastal wetlands through related physico-chemical and biological processes. The types of anthropogenic activities include deforestation, land use change, pollution, human-induce species invasion, changes in consumer control, hydrologic alteration, resources extraction and breakdown of landward margins. Coastal wetlands confront with climate change, including rising air temperature, precipitation fluctuation, sea level rise and extreme weather events. They have impact on coastal wetlands through ecosystem conversion and impact on ecosystem function and health, phenology, physiological and metabolic processes, foundation species and sediment biogeochemistry. A conceptual model of carbon mineralization in coastal wetlands is established with illustration on relevant processes, including ecosystem respiration, greenhouse gas emission from sediment- and water-air interfaces, belowground total carbon balance, as well as related processes, including bioturbation and inorganic carbon. We are motivated to synthesize research on carbon mineralization, counterbalancing the bias towards carbon storage in coastal wetlands. We highlight the necessity of systematic examination on the processes and principles of greenhouse gas production and emissions, as well as the linkage between vascular plant decomposition and greenhouse gas emission.
Intertidal wetland soils have been recognized as potential sources of greenhouse gases (GHG), including carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), and anthropogenic activities influence the quantities and patterns of the GHG emissions from wetland soils through changing the environmental settings and substrates regulating the productions of the GHGs. The impacts of various anthropogenic activities, including tidal restriction, deforestation, nutrient enrichment on the soil to atmosphere GHG fluxes in intertidal wetlands, are overviewed in this chapter. The responses of GHG emissions from wetlands depend on the species of gases and the anthropogenic activity. Generally, tidal restriction and tide re-establishment change the water saturation of wetland soils, with decomposition of organic carbon in soils altering between aerobic to anaerobic regimes, and also change the sulfate availability in soils to regulate the CH4 emissions. Mangrove clearance causes a decline in CO2 flux from soils over time, owing to the substantial loss of soil organic carbon, while CO2 flux increases with forest age as a consequence of organic matter accumulation in the soils following rehabilitation. Relative to these activities, we suggest that nutrient enrichment or nutrient pollution can largely stimulate the emissions of greenhouse gases from wetland soils, especially N2O. Pollution control and management in coastal areas are therefore essential to reduce greenhouse gas emissions to the atmosphere. Future studies are deserved for better understanding the responses of gas emissions and mechanisms behind the gas productions in wetland soils subjected to anthropogenic activities.
This chapter discusses carbon dioxide (CO2) and methane (CH4) gas exchange at the water-air interface in coastal wetlands. The existing literature was reviewed to report the magnitude of CO2 and CH4 water-air fluxes in mangrove, saltmarsh, and seagrass ecosystems. Based on available data, mangrove waters show a large range of CO2 (13–9726 mg CO2 m− 2 day− 1) and CH4 water-air fluxes (− 1.1–1169 mg CH4 m− 2 day− 1) and are generally a source of CO2 and CH4 to the atmosphere. Similarly, saltmarsh waters are predominantly water-air sources of CO2 (mean: 2823 ± 332 mg CO2 m− 2 day− 1) and CH4 (− 1.5–1510 mg CH4 m− 2 day− 1). In contrast, seagrass waters can act as a source or sink of CO2 (− 3168–3041 mg CO2 m− 2 day− 1) and are likely a source of CH4 to the atmosphere (1.9–4.9 mg CH4 m− 2 day− 1). High spatial and temporal variability and the large range of fluxes are linked to tidal regimes, seasonality, vegetation coverage, and complex biogeochemical processes that occur in coastal wetland sediments and waters. Various direct and indirect drivers are described that can control CO2 and CH4 concentration gradients, transport pathways, and fluxes from sediments to the water column and ultimately to the atmosphere. Finally, the three most commonly used methods to determine water-air gas exchange in coastal waters are reviewed, which are the chamber method, the gradient flux method, and the eddy-covariance technique. Using appropriate methods, more research is needed for a better assessment of long-term and large-scale gas exchange in dynamic coastal wetland waters, to quantify more accurately present and to predict future greenhouse gas trends and potential “blue carbon” offsets in mangrove, saltmarsh, and seagrasses on regional and global scale.
This chapter elucidates in detail the current knowledge on the role of biogenic structures for greenhouse gas biogeochemistry and dynamics in vegetated intertidal wetlands, i.e., mangrove forests and saltmarshes. The major types of biogenic structures formed by wetland plants and animals are portrayed and related to relevant biogeochemical processes affecting greenhouse gases. Subsequently, the impact of biogenic structures for greenhouse gas exchange is demonstrated by assessing and compiling the current knowledge on net primary production, carbon sequestration, and greenhouse gas emissions in mangrove forests and Spartina marshes. The data compilation clearly emphasizes the important role of biogenic structures (i.e., plant roots and infaunal burrows/tubes) for carbon cycling and greenhouse gas dynamics of intertidal wetlands. Emission of the greenhouse gases CO2, CH4, and N2O in mangrove forests with biogenic structures is increased 4.8, 29.9, and 3.8 times, respectively, compared with mangrove sediments devoid of these structures. Due to lack of reliable data on the role of burrow structures on greenhouse gas emission in Spartina marshes, only the impact of vegetation is available resulting in an increase of 2.7, 3.3, and 9.1 times, respectively. The strong enhancement of greenhouse gas emissions via biogenic structures largely counteracts the otherwise efficient capacity of carbon sequestration by these vegetated wetlands, leading to climate neutrality when embracing the global warming potential of the involved gases. This finding is surprising and contradicts previous estimates that indicated a distinct climate mitigation potential of mangrove and saltmarsh ecosystems.
This chapter discusses the influence of climate change on coastal wetland productivity, organic carbon burial, CO2 and CH4 production and their emissions. We reviewed studies that were performed in atmosphere-controlled greenhouses or open-top chambers to quantify the role of climate change on mangrove and saltmarsh productivity, as well as in situ studies that used the eddy-covariance method or incubation chambers at the various interfaces to quantify CO2 and CH4 flux variability with temperature, precipitation or tides. Coastal wetland productivity responses to the increases of temperature and of atmospheric CO2 concentrations will not be a simple increase but will most probably vary with the biogeographic settings and the position of the stand in the intertidal zone, both influencing pore-water salinity and nutrient inputs. The productivity of mangroves may respond more significantly to elevated CO2 than that of saltmarshes. Changes in rainfall pattern will not only have an influence on ecosystem gross productivity but also on ecosystem respiration, modifying subsequently the net carbon budget of coastal wetlands. The effect of tidal flooding will be species-specific and will depend on the prevalent climate and the position of the stand along the intertidal zone (optimum for growth or not). Eventually, enhanced cyclonic intensity may reduce the productivity of these ecosystems. Increased tidal flushing and pore-water seepage resulting from sea-level rise will limit carbon burial, while productivity and sedimentation rates will increase. However, the effect of sea-level rise in modifying soil moisture and the rate of electron acceptors renewal, will be site-specific depending on climate, soil permeability, and position along the tidal zone. Sea-level rise results in more water-saturated soils, which will limit greenhouse gas (GHG) production and emission. However, rise in temperature will enhance organic carbon mineralization. Eventually, GHG diffusion also depends on the responses of the microphytobenthos, bioturbation and aerial root density to climate change.
Globally, mangrove forests are substantially declining, and a globally synthesized database containing the drivers of deforestation and drivers’ interactions is scarce. Here, we synthesized the key social-ecological drivers of global mangrove deforestation by reviewing about two hundred published scientific studies over the last four decades (from 1980 to 2021). Our focus was on both natural and anthropogenic drivers with their gradual and abrupt impacts and on their geographic coverage of effects, and how these drivers interact. We also summarized the patterns of global mangrove coverage decline between 1990 and 2020 and identified the threatened mangrove species. Our consolidated studies reported an 8600 km2 decline in the global mangrove coverage between 1990 and 2020, with the highest decline occurring in South and Southeast Asia (3870 km2). We could identify 11 threatened mangrove species, two of which are critically endangered (Sonneratia griffithii and Bruguiera hainseii). Our reviewed studies pointed to aquaculture and agriculture as the predominant driver of global mangrove deforestation though their impacts varied across global regions. Gradual climate variations, i.e., sea-level rise, long-term precipitation, and temperature changes and driven coastline erosion, salinity intrusion and acidity at coasts, constitute the second major group of drivers. Our findings underline a strong interaction across natural and anthropogenic drivers, with the strongest interaction between the driver groups aquaculture and agriculture and industrialization and pollution. Our results suggest prioritizing globally coordinated empirical studies linking drivers and mangrove deforestation and global development of policies for mangrove conservation.
Mangrove forests sequester organic carbon, nutrients and toxic metals sorbed to fine sediment, and thus restrict the mobility of pollutants through estuarine environments. However, mangrove removal and environmental degradation caused by industrial activity and urban growth can impact the ability of mangrove communities to provide these critical ecosystem services. Here, we use sediment profiles from an impacted tropical estuary in southwest India to provide a c. 70-year record of carbon, nutrient and trace metal burial in the context of rapid urban development and the systemic removal of mangrove communities. Our results show that carbon and nutrient accumulation rates increase sharply during the 1990's in accordance with the high rates of deforestation. Nitrogen and phosphorus accumulation rates increased fourfold and twofold, respectively, during the same period. Organic carbon accumulation was fivefold higher than the global average during this period, reflecting intense deforestation during the last three decades. The enrichment of Hg, Zn, Pb, Mo, Ni, Cu and Mn demonstrate clear anthropogenic impact starting in the 1950's and peaking in 1990. Mercury, the trace metal with the highest enrichment factor, increased sevenfold in the most recent sediments due to increased fossil fuel emissions, untreated water and incineration of medical waste and/or fertilizers used in aquaculture. Organic carbon isotope (δ¹³C) and C:N molar ratios indicate shifts to more terrestrial-derived source of organic matter in the most recent sediments reflecting growing deforestation of which may be prevalent in southeast Asia due to increasing development. This study emphasizes the critical role played by mangrove ecosystems in attenuating anthropogenically-derived pollutants, including carbon sequestration, and reveals the long-term consequences of mangrove deforestation in the context of rapidly developing economies.
We present a one-dimensional reactive transport model to estimate benthic fluxes of dissolved inorganic carbon (DIC) and alkalinity (A<sub>T</sub>) from coastal marine sediments. The model incorporates the transport processes of sediment accumulation, molecular diffusion, bioturbation and bioirrigation, while the reactions included are the redox pathways of organic carbon oxidation, re-oxidation of reduced nitrogen, iron and sulfur compounds, pore water acid-base equilibria, and dissolution of particulate inorganic carbon (calcite, aragonite, and Mg-calcite). The coastal zone is divided into four environmental units with different particulate inorganic carbon (PIC) and particulate organic carbon (POC) fluxes: reefs, banks and bays, carbonate shelves and non-carbonate shelves. Model results are analyzed separately for each environment and then scaled up to the whole coastal ocean. The model-derived estimate for the present-day global coastal benthic DIC efflux is 126 Tmol yr<sup>−1</sup>, based on a global coastal reactive POC depositional flux of 117 Tmol yr<sup>−1</sup>. The POC decomposition leads to a~carbonate dissolution from shallow marine sediments of 7 Tmol yr<sup>−1</sup> (on the order of 0.1 Pg C yr<sup>−1</sup>). Assuming complete re-oxidation of aqueous sulfide released from sediments, the effective net flux of alkalinity to the water column is 29 Teq yr<sup>−1</sup>, primarily from PIC dissolution (46%) and ammonification (33%). Because our POC depositional flux falls in the high range of global values given in the literature, the reported DIC and alkalinity fluxes should be viewed as upper-bound estimates. Increasing coastal seawater DIC to what might be expected in year 2100 due to the uptake of anthropogenic CO<sub>2</sub> increases PIC dissolution by 2.3 Tmol yr<sup>−1</sup> and alkalinity efflux by 4.8 Teq yr<sup>−1</sup>. Our reactive transport modeling approach not only yields global estimates of benthic DIC, alkalinity and nutrient fluxes under variable scenarios of ocean productivity and chemistry, but also provides insights into the underlying processes.
To evaluate how mangrove invasion and removal can modify short-term benthic carbon cycling and ecosystem functioning, we used stable-isotopically labeled algae as a deliberate tracer to quantify benthic respiration and C-flow over 48 h through macrofauna and bacteria in sediments collected from (1) an invasive mangrove forest, (2) deforested mangrove sites 2 and 6 years after removal of above-sediment mangrove biomass, and (3) two mangrove-free control sites in the Hawaiian coastal zone. Sediment oxygen consumption (SOC) rates averaged over each 48 h investigation were significantly greater in the mangrove and mangrove removal site experiments than in controls and were significantly correlated with total benthic (macrofauna and bacteria) biomass and sedimentary mangrove biomass (SMB). Bacteria dominated short-term C-processing of added microalgal-C and benthic biomass in sediments from the invasive mangrove forest habitat and in the 6-yr removal site. In contrast, macrofauna were the most important agents in the short-term processing of microalgal-C in sediments from the 2-yr mangrove removal site and control sites. However, mean faunal abundance and C-uptake rates in sediments from both removal sites were significantly higher than in control cores, which collectively suggest that community structure and short-term C-cycling dynamics of sediments in habitats where mangroves have been cleared can remain fundamentally different from un-invaded mudflat sediments for at least 6-yrs following above-sediment mangrove removal. In summary, invasion by mangroves can lead to dramatic shifts in benthic ecosystem function, with sediment metabolism, benthic community structure and short-term C-remineralization dynamics being affected for years following invader removal.
The contribution of nonecological factors to global patterns in diversity is evident when species richness differs between regions with similar habitats and geographic area. Mangrove environments in the Eastern Hemisphere harbor six times as many species of trees and shrubs as similar environments in the New World. Genetic divergence of mangrove lineages from terrestrial relatives, in combination with fossil evidence, suggests that mangrove diversity is limited by evolutionary transition into the stressful marine environment, the number of mangrove lineages has increased steadily over the Tertiary with little global extinction, and the diversity anomaly in mangrove vegetation reflects regional differences in the rate of origin of new mangrove lineages.
An introduction to the principles of climate change science with an emphasis on the empirical evidence for climate change and a warming world. Additional readings are given at the end of each chapter. A list of "Things to Know" opens each chapter. Chapters are arranged so that the student is first introduced to the scientific method(s), examples of the use of the scientific method from other sciences drawn from the history of science with an emphasis on climate science. Climate science is treated in each chapter based on the premise of global warming. Chapter treatments on the atmosphere. biosphere, geosphere, hydrosphere, and anthroposphere and their inter-relationships are given.
Whole food-web studies of mangrove ecosystems are rare. However, several components of the flora and fauna and selected linkages from primary food sources (primary producers and detritus) and between heterotrophs have been studied in detail. Considerable attention has been given to carbon imports and exports from mangrove ecosystems in the form of Dissolved Organic Carbon (DOC), Particulate Organic Carbon (POC), and CO2. The comparatively few whole food-web studies on mangroves from different continents thus far produced fairly wide ranges (and thus few generalizations) of ecosystem level indices, including trophic efficiencies, extent of recycling, or total energy throughput.
Despite their importance in sustaining livelihoods for many people living along some of the world's most populous coastlines, tropical mangrove forests are disappearing at an alarming rate. Occupying a crucial place between land and sea, these tidal ecosystems provide a valuable ecological and economic resource as important nursery grounds and breeding sites for many organisms, and as a renewable source of wood and traditional foods and medicines. Perhaps most importantly, they are accumulation sites for sediment, contaminants, carbon and nutrients, and offer significant protection against coastal erosion. This book presents a functional overview of mangrove forest ecosystems; how they live and grow at the edge of tropical seas, how they play a critical role along most of the world's tropical coasts, and how their future might look in a world affected by climate change. Such a process-oriented approach is necessary in order to further understand the role of these dynamic forests in ecosystem function, and as a first step towards developing adequate strategies for their conservation and sustainable use and management. The book will provide a valuable resource for researchers in mangrove ecology as well as reference for resource managers.