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Swamp

About: Swamp is a research topic. Over the lifetime, 5497 publications have been published within this topic receiving 101209 citations.


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TL;DR: A global data set on the geographic distribution and seasonality of freshwater wetlands and rice paddies has been compiled, comprising information at a spatial resolution of 2.5° by latitude and 5° by longitude as discussed by the authors.
Abstract: A global data set on the geographic distribution and seasonality of freshwater wetlands and rice paddies has been compiled, comprising information at a spatial resolution of 2.5° by latitude and 5° by longitude. Global coverage of these wetlands total 5.7×106 km2 and 1.3×106 km2, respectively. Natural wetlands have been grouped into six categories following common terminology, i.e. bog, fen, swamp, marsh, floodplain, and shallow lake. Net primary productivity (NPP) of natural wetlands is estimated to be in the range of 4–9×1015 g dry matter per year. Rice paddies have an NPP of about 1.4×1015 g y−1. Extrapolation of measured CH4 emissions in individual ecosystems lead to global methane emission estimates of 40–160 Teragram (1 Tg=1012 g) from natural wetlands and 60–140 Tg from rice paddies per year. The mean emission of 170–200 Tg may come in about equal proportions from natural wetlands and paddies. Major source regions are located in the subtropics between 20 and 30° N, the tropics between 0 and 10° S, and the temperate-boreal region between 50 and 70° N. Emissions are highly seasonal, maximizing during summer in both hemispheres. The wide range of possible CH4 emissions shows the large uncertainties associated with the extrapolation of measured flux rates to global scale. More investigations into ecophysiological principals of methane emissions is warranted to arrive at better source estimates.

704 citations

Journal ArticleDOI
TL;DR: Field observation reveals that seven mangrove stands received industrial, livestock and domestic sewage as well as pollution from mariculture activities, suggesting that anthropogenic input is the main source of heavy metal contamination in Hong Kong mangroves.

607 citations

Journal ArticleDOI
TL;DR: Four lowland aquatic food webs were investigated over the course of two years, finding that extensive among—site variation in food—web parameters was associated with differences in species richness and environmental differences associated with rainfall patterns, physiography, and gross primary production.
Abstract: Observed properties of natural food webs have both important theoretical and important management implications Four lowland aquatic food webs were investigated over the course of two years: a large swamp and a small stream in Costa Rica, and a similar swamp and stream in the Venezuelan llanos Each local ecosystem differed from the three others with respect to environmental changes associated with seasonal rainfall Phylogenetic composition and diversity of biotas also varied among systems Volumetric proportional utilization coefficients from fish gut contents were used as estimates of the intensity of predator—prey interactions An annual and two or more seasonal food webs were constructed for each local community Aquatic communities were defined operationally using common fish species as consumers, and using the sink subweb associated with the top predator of each system A computer calculated a variety of food—web statistics and plotted food—web diagrams containing either (a) all observed trophic links (predator—prey interactions), or (b) subsets with weak links eliminated at prescribed thresholds Individual community food webs contained from 58 (stream, Costa Rica) to 104 (swamp, Venezuela) interactive taxonomic units and from 208 to 1243 total trophic links Food—web parameters were very sensitive to changes in level of link threshold Web connectance and related parameters converged near link threshold 004 (utilization coefficients <004 eliminated) in a variety of inter—web comparisons Despite large differences in assemblage composition and attributes of the physical environment, distributions of trophic levels calculated according to a trophic continuum algorithm were very similar among study systems Herbivores, detritivores, and their direct predators formed the largest proportions of fishes in each assemblage, followed by omnivores and secondary carnivores Fishes that fed at more than one trophic interval were extremely common in all food webs Analysis of covariance was used to compare structural features of different webs across a range of link thresholds Extensive among—site variation in food—web parameters was associated with differences in species richness and environmental differences associated with rainfall patterns, physiography, and gross primary production Seasons generally influenced food—web parameters less than did site differences Relative importance of detritus, aquatic primary production, and terrestrial production in aquatic food webs varied seasonally in each system Detritus, derived primarily from aquatic macrophytes, was an important pathway in both tropical swamp ecosystems Aquatic primary productivity comprised the largest fraction of fish diets during the wet season in the Venezuelan swamp, but it formed the major component of fish diets during the dry season at all other sites Based on comparisons using 13 webs, two—thirds of the pairings among six food—web parameters used (number of nodes, compartmentation, connectance, average number of prey per node, average number of predators per node, ratio of consumer nodes to total nodes) were positively intercorrelated Several food—web relationships previously described as constant (eg, connectance x species richness constancy, species scaling law, link—species scaling law) were not confirmed by my data These earlier food—web trends are extremely sensitive to methodological biases, especially decisions regarding the degree of taxonomic lumping of species into trophic units Although food webs have unique emergent properties and spinoff a number of potentially informative macrodescriptors, empirical studies must achieve greater precision and uniformity before analyses can be performed across different systems Several problems and potential resolutions are discussed

565 citations

Journal ArticleDOI
TL;DR: In this paper, the authors analyzed deforestation rates in insular Southeast Asia between 2000 and 2010 utilizing a pair of 250m spatial resolution land cover maps produced with regional methodology and classification scheme.
Abstract: Insular Southeast Asia experienced the highest level of deforestation among all humid tropical regions of the world during the 1990s. Owing to the exceptionally high biodiversity in Southeast Asian forest ecosystems and the immense amount of carbon stored in forested peatlands, deforestation in this region has the potential to cause serious global consequences. In this study, we analysed deforestation rates in insular Southeast Asia between 2000 and 2010 utilizing a pair of 250 m spatial resolution land cover maps produced with regional methodology and classification scheme. The results revealed an overall 1.0% yearly decline in forest cover in insular Southeast Asia (including the Indonesian part of New Guinea) with main change trajectories to plantations and secondary vegetation. Throughout the region, peat swamp forests experienced clearly the highest deforestation rates at an average annual rate of 2.2%, while lowland evergreen forests declined by 1.2%/yr. In addition, the analysis showed remarkable spatial variation in deforestation levels within the region and exposed two extreme concentration areas with over 5.0% annual forest loss: the eastern lowlands of Sumatra and the peatlands of Sarawak, Borneo. Both of these areas lost around half of their year 2000 peat swamp forest cover by 2010. As a whole this study has shown that deforestation has continued to take place on high level in insular Southeast Asia since the turn of the millennium. These on-going changes not only endanger the existence of numerous forest species endemic to this region, but they further increase the elevated carbon emissions from deforested peatlands of insular Southeast Asia thereby directly contributing to the rising carbon dioxide concentration in the atmosphere.

551 citations

Journal ArticleDOI
TL;DR: Introduction 307 Tolerance involving gas transport 310 Surface rooting 310 Gas-space development and diffusion 311 Root-shoot, root-rhizome and root-root junctions 315 Convective gas flows 315 Shoot and foliage submergence 319 Radial oxygen loss and the rhizosphere 322 T tolerance involving metabolic adaptation 324 Control of energy metabolism under oxygen deprivation
Abstract: It has been estimated that wetlands occupy approximately 6% of the earth’s land surfaces (Maltby 1991). They comprise fresh, brackish and salt-water marshes, inland and coastal swamps, flood plains, and lowland and upland mires (fen, bogs), as well as agricultural wetlands such as rice paddy. On a smaller scale there are constructed wetlands valued for their role in the purification of domestic, agricultural and industrial effluents (Cooper & Findlater 1990). In addition to these examples, occasional soil flooding and even a degree of submergence can be a common though unwelcome feature of non-wetland agriculture. Wetlands are usually characterized by permanent or long-term soil flooding, but often the vegetation may be wholly or partly submerged; in the lower reaches of coastal marshes this may be a daily or twice daily occurrence. Indeed, since wetlands are found world-wide and at most altitudes, flooding regimes can vary enormously; not only do the seasonal timing, duration and depth of flooding differ, but so too do light and temperature regimes and sediment type—factors which strongly interact with flooding to influence vegetation. The large numbers and wide variety of vascular plants indigenous to wetlands reflect this variety in habitat features; species range from wholly submerged aquatics of pools, rivers, coastal and lake margins through to the large tree species of the flood plain forests of the Americas and Africa. In view of this variety in both plant and habitat, a whole spectrum of flood-related stresses might be anticipated; similarly one might expect to find a number of flood-tolerance strategies.

550 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023239
2022566
2021188
2020213
2019168
2018233