Mangrove forests: one of the world's threatened major tropical environments.
TL;DR: In this article, Saenger et al. reviewed the status of mangrove swamps worldwide and assessed the effect of human activities on mangroves in the coastal environment using satellite imagery.
Abstract: he mass media and scientific press have widely reported losses of tropical environments, such as fellingof rain forests and bleaching of coral reefs.This well-meritedattention has created a worldwide constituency that supportsconservation and restoration efforts in both of these threat-ened ecosystems. The remarkable degree of public aware-ness and support has been manifested in benefit rock concertsat Carnegie Hall and in the designation of ice cream flavorsafter rain forest products. Mangrove forests are another im-portant tropical environment,but these have received muchless publicity.Concern about the magnitude of losses of man-grove forests has been voiced mainly in the specialized liter-ature (Saenger et al. 1983, Spalding et al. 1997).Mangrove trees grow ubiquitously as a relatively narrowfringe between land and sea, between latitudes 25°N and30°S.They form forests of salt-tolerant species,with complexfood webs and ecosystem dynamics (Macnae 1968,Lugo andSnedaker 1974, Tomlinson 1986).Destruction of mangrove forests is occurring globally.Global changes such as an increased sea level may affect man-groves (Ellison 1993,Field 1995),although accretion rates inmangrove forests may be large enough to compensate for thepresent-day rise in sea level (Field 1995).More important,itis human alterations created by conversion of mangroves tomariculture,agriculture,and urbanization,as well as forestryuses and the effects of warfare, that have led to the remark-able recent losses of mangrove habitats (Saenger et al. 1983,Fortes 1988, Marshall 1994, Primavera 1995, Twilley 1998).New data on the magnitude of mangrove area and changesin it have become more readily available, especially with theadvent of satellite imagery and the Internet. Moreover, in-formation about the function of mangrove swamps, theirimportance in the sustainability of the coastal zone, and theeffects of human uses of mangrove forests is growing. Somepublished regional assessments have viewed anthropogenicthreats to mangrove forests with alarm (Ong 1982,Fortes 1988,Ellison and Farnsworth 1996),but reviews at the global scaleare dated (Linden and Jernelov 1980, Saenger et al. 1983).We collated and revised published information to reviewthe status of mangrove swamps worldwide.To assess the sta-tus of this major coastal environment, we compiled and ex-amined available data to quantify the extent of mangroveforest areas in different parts of the world,the losses of man-grove forest area recorded during recent decades, and therelative contributions by various human activities to theselosses.We first assessed current mangrove forest area in tropicalcountries of the world.It is difficult to judge the quality of thesedata in the published literature, because in many cases themethods used to obtain them were insufficiently described andthe associated uncertainty was not indicated. Much infor-mation based on satellite imagery is summarized in the
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TL;DR: In this paper, the main ecological services across a variety of estuarine and coastal ecosystems (ECEs) including marshes, mangroves, nearshore coral reefs, seagrass beds, and sand beaches and dunes are reviewed.
Abstract: The global decline in estuarine and coastal ecosystems (ECEs) is affecting a number of critical benefits, or ecosystem services. We review the main ecological services across a variety of ECEs, including marshes, mangroves, nearshore coral reefs, seagrass beds, and sand beaches and dunes. Where possible, we indicate estimates of the key economic values arising from these services, and discuss how the natural variability of ECEs impacts their benefits, the synergistic relationships of ECEs across seascapes, and management implications. Although reliable valuation estimates are beginning to emerge for the key services of some ECEs, such as coral reefs, salt marshes, and mangroves, many of the important benefits of seagrass beds and sand dunes and beaches have not been assessed properly. Even for coral reefs, marshes, and mangroves, important ecological services have yet to be valued reliably, such as cross-ecosystem nutrient transfer (coral reefs), erosion control (marshes), and pollution control (mangroves). An important issue for valuing certain ECE services, such as coastal protection and habitat-fishery linkages, is that the ecological functions underlying these services vary spatially and temporally. Allowing for the connectivity between ECE habitats also may have important implications for assessing the ecological functions underlying key ecosystems services, such coastal protection, control of erosion, and habitat-fishery linkages. Finally, we conclude by suggesting an action plan for protecting and/or enhancing the immediate and longer-term values of ECE services. Because the connectivity of ECEs across land-sea gradients also influences the provision of certain ecosystem services, management of the entire seascape will be necessary to preserve such synergistic effects. Other key elements of an action plan include further ecological and economic collaborative research on valuing ECE services, improving institutional and legal frameworks for management, controlling and regulating destructive economic activities, and developing ecological restoration options.
3,750 citations
Cites background from "Mangrove forests: one of the world'..."
...The remaining sources of mangrove deforestation consist of herbicide impacts, agriculture, salt ponds, and other coastal developments (Valiela et al. 2001)....
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...Their deterioration due to human activities is intense and increasing; 50% of salt marshes, 35% of mangroves, 30% of coral reefs, and 29% of seagrasses are either lost or degraded worldwide (Valiela et al. 2001, MEA 2005, Orth et al. 2006, UNEP 2006, FAO 2007, Waycott et al. 2009)....
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...But since then, at least 35% of global mangrove area has been lost, and mangroves are currently disappearing at the rate of 1–2% annually (Valiela et al. 2001, Alongi 2002, FAO 2007)....
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James Cook University1, University of the Balearic Islands2, University of Maryland, College Park3, College of William & Mary4, University of California, Davis5, Florida International University6, University of South Alabama7, University of Western Australia8, National Oceanic and Atmospheric Administration9, University of New Hampshire10
TL;DR: This comprehensive global assessment of 215 studies found that seagrasses have been disappearing at a rate of 110 km2 yr−1 since 1980 and that 29% of the known areal extent has disappeared since seagRass areas were initially recorded in 1879.
Abstract: Coastal ecosystems and the services they provide are adversely affected by a wide variety of human activities. In particular, seagrass meadows are negatively affected by impacts accruing from the billion or more people who live within 50 km of them. Seagrass meadows provide important ecosystem services, including an estimated $1.9 trillion per year in the form of nutrient cycling; an order of magnitude enhancement of coral reef fish productivity; a habitat for thousands of fish, bird, and invertebrate species; and a major food source for endangered dugong, manatee, and green turtle. Although individual impacts from coastal development, degraded water quality, and climate change have been documented, there has been no quantitative global assessment of seagrass loss until now. Our comprehensive global assessment of 215 studies found that seagrasses have been disappearing at a rate of 110 km(2) yr(-1) since 1980 and that 29% of the known areal extent has disappeared since seagrass areas were initially recorded in 1879. Furthermore, rates of decline have accelerated from a median of 0.9% yr(-1) before 1940 to 7% yr(-1) since 1990. Seagrass loss rates are comparable to those reported for mangroves, coral reefs, and tropical rainforests and place seagrass meadows among the most threatened ecosystems on earth.
3,088 citations
TL;DR: In this paper, the authors identify key areas of uncertainty and specific actions needed to address them and identify the value of mangrove forests, seagrass beds, and salt marshes in sequestering carbon dioxide.
Abstract: Recent research has highlighted the valuable role that coastal and marine ecosystems play in sequestering carbon dioxide (CO(2)). The carbon (C) sequestered in vegetated coastal ecosystems, specifically mangrove forests, seagrass beds, and salt marshes, has been termed blue carbon. Although their global area is one to two orders of magnitude smaller than that of terrestrial forests, the contribution of vegetated coastal habitats per unit area to long-term C sequestration is much greater, in part because of their efficiency in trapping suspended matter and associated organic C during tidal inundation. Despite the value of mangrove forests, seagrass beds, and salt marshes in sequestering C, and the other goods and services they provide, these systems are being lost at critical rates and action is urgently needed to prevent further degradation and loss. Recognition of the C sequestration value of vegetated coastal ecosystems provides a strong argument for their protection and restoration; however, it is necessary to improve scientific understanding of the underlying mechanisms that control C sequestration in these ecosystems. Here, we identify key areas of uncertainty and specific actions needed to address them.
2,313 citations
Cites background from "Mangrove forests: one of the world'..."
...…percent loss and annual rate of loss) Percent of global Annual rate of Ecosystem loss global loss References Mangroves 20% (since 1980s) ~0.7–3% Valiela et al. (2001); 30–50% Alongi (2002); FAO (2007); (since 1940s) Spalding et al. (2010) Seagrasses 50% (since 1990s) ~7% Costanza et al.…...
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...…decline (Duarte 2002; Green and Short 2003; Duarte et al. 2005b; Waycott et al. 2009), and mangroves and salt marshes have been damaged by dredging, filling, dyking, drainage, trophic cascades, and invasive species (Valiela et al. 2001; Alongi 2002; Silliman et al. 2005; Silliman et al. 2009)....
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...2009), and mangroves and salt marshes have been damaged by dredging, filling, dyking, drainage, trophic cascades, and invasive species (Valiela et al. 2001; Alongi 2002; Silliman et al. 2005; Silliman et al. 2009)....
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TL;DR: The authors assesses the degree of resilience of mangrove forests to large, infrequent disturbance (tsunamis) and their role in coastal protection, and to chronic disturbance events (climate change).
Abstract: This review assesses the degree of resilience of mangrove forests to large, infrequent disturbance (tsunamis) and their role in coastal protection, and to chronic disturbance events (climate change) and the future of mangroves in the face of global change. From a geological perspective, mangroves come and go at considerable speed with the current distribution of forests a legacy of the Holocene, having undergone almost chronic disturbance as a result of fluctuations in sea-level. Mangroves have demonstrated considerable resilience over timescales commensurate with shoreline evolution. This notion is supported by evidence that soil accretion rates in mangrove forests are currently keeping pace with mean sea-level rise. Further support for their resilience comes from patterns of recovery from natural disturbances (storms, hurricanes) which coupled with key life history traits, suggest pioneer-phase characteristics. Stand composition and forest structure are the result of a complex interplay of physiological tolerances and competitive interactions leading to a mosaic of interrupted or arrested succession sequences, in response to physical/chemical gradients and landform changes. The extent to which some or all of these factors come into play depends on the frequency, intensity, size, and duration of the disturbance. Mangroves may in certain circumstances offer limited protection from tsunamis; some models using realistic forest variables suggest significant reduction in tsunami wave flow pressure for forests at least 100 m in width. The magnitude of energy absorption strongly depends on tree density, stem and root diameter, shore slope, bathymetry, spectral characteristics of incident waves, and tidal stage upon entering the forest. The ultimate disturbance, climate change, may lead to a maximum global loss of 10–15% of mangrove forest, but must be considered of secondary importance compared with current average annual rates of 1–2% deforestation. A large reservoir of below-ground nutrients, rapid rates of nutrient flux and microbial decomposition, complex and highly efficient biotic controls, self-design and redundancy of keystone species, and numerous feedbacks, all contribute to mangrove resilience to various types of disturbance.
1,401 citations
Cites background from "Mangrove forests: one of the world'..."
...The potential impact of climate change, regardless of whether or not it is in the range of 10e15% loss, must be kept in perspective as mangroves currently face a more predictable and insidious threat ddeforestation (Valiela et al., 2001)....
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University of Queensland1, Griffith University2, Flinders University3, Harvard University4, Alfred Wegener Institute for Polar and Marine Research5, Dresden University of Technology6, University of Florence7, United States Department of Agriculture8, University of Technology, Sydney9, Vrije Universiteit Brussel10, Institut de recherche pour le développement11
TL;DR: At a meeting of world mangrove experts held last year in Australia, it was unanimously agreed that the authors face the prospect of a world deprived of the services offered byMangrove ecosystems, perhaps within the next 100 years.
Abstract: At a meeting of world mangrove experts held last year in Australia, it was unanimously agreed that we face the prospect of a world deprived of the services offered by mangrove ecosystems, perhaps within the next 100 years
Mangrove forests once covered more than 200,000 km2 of sheltered tropical
1,271 citations
References
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Book•
01 Jan 1986TL;DR: The aim of this work is to contribute to the human awareness of the natural world and to contribute towards the humanizing of nature.
Abstract: Preface Acknowledgements Part I. General Account: 1. Ecology 2. Floristics 3. Biogeography 4. Shoot systems 5. Root systems 6. Water relations and salt balance 7. Flowering 8. Seedlings and seeds 9. Utilization and exploitation Part II. Detailed Descriptions by Family References Index.
2,014 citations
"Mangrove forests: one of the world'..." refers background in this paper
...They form forests of salt-tolerant species, with complex food webs and ecosystem dynamics (Macnae 1968, Lugo and Snedaker 1974, Tomlinson 1986)....
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1,600 citations
"Mangrove forests: one of the world'..." refers background in this paper
...They form forests of salt-tolerant species, with complex food webs and ecosystem dynamics (Macnae 1968, Lugo and Snedaker 1974, Tomlinson 1986)....
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...…1993; (5) Parks and Bonifaz 1994; (6) Funes 1994; (7) Jimenez 1993; (8) Stonich et al. 1999; (9) YañezArancibia et al. 1993; (10) D’Croz 1993; (11) Lugo and Snedaker 1974; (12) Odum et al. 1982; (13) Conde and Alarcon 1993; (14) Saenger and Bellan 1995; (15) Simao 1993; (16) Marguerite 1993;…...
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TL;DR: Mangroves are trees or bushes growing between the level of high water of spring tides and a level close to but above mean sea-level and the land animals found in mangrove forests include roosting flocks of fruit bats, fishing and insectivorous birds, and many insects are conspicuous.
Abstract: Publisher Summary Mangroves are trees or bushes growing between the level of high water of spring tides and a level close to but above mean sea-level Very few species of mangrove are deep rooted, or have persistent tap roots Almost all are shallow rooted but the root systems are often extensive and may cover a wide area Rhizophoraceous trees have seedlings with a long radicle which would seem well suited to develop into a tap root, but as soon as the seedling becomes established in the mud the radicle develops little further Trees of Avicennia and of Sonneratia develop several different kinds of roots The main rooting system consists of large cable roots which give off anchoring roots downwards and aerial roots or pneumatophores upwards These pneumatophores in their turn produce a large number of nutritive roots which penetrate the mineral-rich subsurface layers of the soil The land animals found in mangrove forests include roosting flocks of fruit bats, fishing and insectivorous birds, and many insects are conspicuous Of the marine animals, crabs and molluscs live permanently in the forest, and prawns and fishes come in on the tide to feed on the apparently abundant nutriment provided by the mangrove soils In South East Asia man uses mangrove areas for the establishment of ponds for the culture of fish and prawns, and for timber
881 citations
Book•
29 Jul 1992
TL;DR: Mariane ecology of the arabian region as discussed by the authors, Patterns and processes in extereme tropical environmental, Mariane ecology in arabians region, patterns and processes of tropical ecology, patterns of tropical environmental patterns, patterns, processes, and processes.
Abstract: Mariane ecology of the arabian region : Patterns and processes in extereme tropical environmental , Mariane ecology of the arabian region : Patterns and processes in extereme tropical environmental , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
412 citations
Additional excerpts
...…(22) Sidhu 1963; (23) Azariah et al. 1992; (24) Htay 1994; (25) Primavera 1995; (26) Chou 1990; (27) Menesveta 1997; (28) Turner et al. 1998; (29) Sheppard et al. 1992. around the world, but they include data collected across widely different times (1980s to present) through different methods,…...
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