A Review of Wetland Remote Sensing <s> Data and Methodology <s> Boreal and subarctic peatlands comprise a carbon pool of 455 Pg that has accumulated during the postglacial period at an average net rate of 0.096 Pg/yr (1 Pg = 1015g). Using Clymo's (1984) model, the current rate is estimated at 0.076 Pg/yr. Longterm drainage of these peatlands is estimated to be causing the oxidation to CO2 of a little more than 0.0085 Pg/yr, with conbustion of fuel peat adding °0.026 Pg/yr. Emissions of CH4 are estimated to release ° 0.046 Pg of carbon annually. Uncertainties beset estimates of both stocks and fluxes, particularly with regard to Soviet peatlands. The influence of water table alterations upon fluxes of both CO2 and CH4 is in great need of investigation over a wide range of peatland environments, especially in regions where permafrost melting, thermokarst erosion, and the development of thaw lakes are likely results of climatic warming. The role of fire in the carbon cycle of peatlands also deserves increased attention. Finally, satellite—monitoring of the abundance of open water in the peatlands of the West Siberian Plain and the Hudson/James Bay Lowland is suggested as a likely method of detecting early effects of climatic warming upon boreal and subarctic peatlands. <s> BIB001 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> Human activity is an important agent defining the contemporary hydrologic cycle. We have documented the potential impacts of impoundment, land use change and climate change on the Zambezi River system in southern Africa and found that they can be substantial. A full analysis requires construction and parameterization of a simulation for the entire catchment. This paper develops a strategy for implementing catchment-scale models of the major hydrologic processes operating within the basin. A coherent data set for calibrating the models has also been assembled. The algorithms consist of a Water Balance (WBM) and a Water Transport (WTM) operating at 1/2o spatial scale and at monthly timesteps. These models transform complex patterns of regional climatology into estimates of soil water, evapotranspiration, runoff, and discharge through rivers of various size. The models are dependent on the characteristics of the terrestrial surface, principally soil texture and land cover. A simulated river network is also required. Additional tabular data sets are essential for model testing and calibration. These include subcatchment areas; observed river discharge at selected points; flooding, storage and loss characteristics of major wetlands; floodwave translation; and, volume, surface area, withdrawal and evaporative losses from impoundments. An important design consideration for the numerous impoundments in the Zambezi requires an understanding of the seasonal variation in discharge, in particular how it might respond to climate and land use change. The research strategy offered here lays a framework for addressing such issues. Although the primary focus of this work is hydrologic, we discuss how the model can be extended to consider constituent transport and biogeochemical cycling issues at the continental scale. <s> BIB002 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> Significant progress has been made in using remote sensing as a means of acquiring information about wetlands. This research provides a brief review of selected previous works, which address the issues of wetland identification, classification, biomass measurement, and change detection. Suggested new research emphases include compiling basic spectral‐reflectance characteristics for individual wetland species by means of close‐range instrumentation, analyzing canopies architectures to facilitate species identification, and assessing the impact on composite spectral signatures of wet soils and variable depths of standing water beneath emergent canopies. These research foci are justifiable when considered in the context of environmental change / variability and the production of trace gases. <s> BIB003 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> Tropical peatlands are one of the largest near-surface reserves of terrestrial organic carbon, and hence their stability has important implications for climate change1,2,3. In their natural state, lowland tropical peatlands support a luxuriant growth of peat swamp forest overlying peat deposits up to 20 metres thick4,5. Persistent environmental change—in particular, drainage and forest clearing—threatens their stability2, and makes them susceptible to fire6. This was demonstrated by the occurrence of widespread fires throughout the forested peatlands of Indonesia7,8,9,10 during the 1997 El Nino event. Here, using satellite images of a 2.5 million hectare study area in Central Kalimantan, Borneo, from before and after the 1997 fires, we calculate that 32% (0.79 Mha) of the area had burned, of which peatland accounted for 91.5% (0.73 Mha). Using ground measurements of the burn depth of peat, we estimate that 0.19–0.23 gigatonnes (Gt) of carbon were released to the atmosphere through peat combustion, with a further 0.05 Gt released from burning of the overlying vegetation. Extrapolating these estimates to Indonesia as a whole, we estimate that between 0.81 and 2.57 Gt of carbon were released to the atmosphere in 1997 as a result of burning peat and vegetation in Indonesia. This is equivalent to 13–40% of the mean annual global carbon emissions from fossil fuels, and contributed greatly to the largest annual increase in atmospheric CO2 concentration detected since records began in 1957 (ref. 1). <s> BIB004 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> Hydrology has been suggested as the mechanism controlling vegetation and related surficial pore-water chemistry in large peatlands. Peatland hydrology influences the carbon dynamics within these large carbon reservoirs and will influence their response to global warming. A geophysical survey was completed in Caribou Bog, a large peatland in Maine, to evaluate peatland stratigraphy and hydrology. Geophysical measurements were integrated with direct measurements of peat stratigraphy from probing, fluid chemistry, and vegetation patterns in the peatland. Consistent with previous field studies, ground-penetrating radar (GPR) was an excellent method for delineating peatland stratigraphy. Prominent reflectors from the peat-lake sediment and lake sediment-mineral soil contacts were precisely recorded up to 8 m deep. Two-dimensional resistivity and induced polarization imaging were used to investigate stratigraphy beneath the mineral soil, beyond the range of GPR. We observe that the peat is chargeable, and that IP imaging is an alternative method for defining peat thickness. The chargeability of peat is attributed to the high surface-charge density on partially decomposed organic matter. The electrical conductivity imaging resolved glaciomarine sediment thickness (a confining layer) and its variability across the basin. Comparison of the bulk conductivity images with peatland vegetation revealed a correlation between confining layer thickness and dominant vegetation type, suggesting that stratigraphy exerts a control on hydrogeology and vegetation distribution within this peatland. Terrain conductivity measured with a Geonics EM31 meter correlated with confining glaciomarine sediment thickness and was an effective method for estimating variability in glaciomarine sediment thickness over approximately 18 km 2 . Our understanding of the hydrogeology, stratigraphy, and controls on vegetation growth in this peatland was much enhanced from the geophysical study. <s> BIB005 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> Abstract Remote sensing is an important tool for mapping and monitoring vegetation. Advances in sensor technology continually improve the information content of imagery for airborne, as well as space-borne, systems. This paper investigates whether vegetation associations can be differentiated using hyperspectral reflectance in the visible to shortwave infrared spectral range, and how well species can be separated based on their spectra. For this purpose, the field reflectance spectra of 27 saltmarsh vegetation types of the Dutch Waddenzee wetland were analysed in three steps. Prior to analysis, the spectra were smoothed with an innovative wavelet approach. In the first stage of the analysis, the reflectance spectra of the vegetation types were tested for differences between type classes. It was found that the reflectance spectra of saltmarsh vegetation types are statistically significantly different for various spectral regions. Secondly, it was tested whether this statistical difference could be enhanced by using continuum removal as a normalisation technique. For vegetation spectra, continuum removal improves the statistical difference between vegetation types in the visible spectrum, but weakens the statistical difference of the spectra in the near-infrared and shortwave infrared part of the spectrum. Thirdly, after statistical differences were found, it was determined how distant in spectral space the vegetation type classes were from each other, using the Bhattacharyya (BH) and the Jeffries–Matusita (JM) distance measures. We selected six wavelengths for this, based on the statistical analysis of the first step. The potential of correct classification of the saltmarsh vegetation types using hyperspectral remote sensing is predicted by these distance measures. It is concluded that the reflectance of vegetation types is statistically different. With high quality radiometric calibration of hyperspectral imagery, it is anticipated that vegetation species may be identified from imagery using spectral libraries that were measured in the field during the time of image acquisition. <s> BIB006 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> A geostatistical contextual classifier for land-cover mapping using remote sensing data is presented. To integrate spatial information with spectral information derived from remote sensing data, a geostatistical indicator approach is adopted to determine the probability of a certain land-cover class occuring at an unsampled location given that any other land-cover classes occur at neighboring locations. The geostatistical indicator algorithm applied here is simple indicator kriging with local means. This approach can directly integrate both spatial information of ground data (hard data) and spectral information of remote sensing data (soft data) within an indicator kriging framework. This algorithm is applied to the classification of multi-sensor remote sensing data for land-cover mapping. This classification result is compared with a result obtained from a conventional spectral information based classification method. <s> BIB007 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> IKONOS 1-m panchromatic and 4-m multispectral images were used to map mangroves in a study site located at Punta Galeta on the Caribbean coast of Panama. We hypothesized that spectral separability among mangrove species would be enhanced by taking the object as the basic spatial unit as opposed to the pixel. Three different classification methods were investigated: maximum likelihood classification (MLC) at the pixel level, nearest neighbour (NN) classification at the object level, and a hybrid classification that integrates the pixel and object-based methods (MLCNN). Specifically for object segmentation, which is the key step in object-based classification, we developed a new method to choose the optimal scale parameter with the aid of Bhattacharya Distance (BD), a well-known index of class separability in traditional pixel-based classification. A comparison of BD values at the pixel level and a series of larger scales not only supported our initial hypothesis, but also helped us to determine an optimal ... <s> BIB008 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> The importance of accurate and timely information describing the nature and extent of land resources and changes over time is increasing, especially in rapidly growing metropolitan areas. We have developed a methodology to map and monitor land cover change using multitemporal Landsat Thematic Mapper (TM) data in the seven-county Twin Cities Metropolitan Area of Minnesota for 1986, 1991, 1998, and 2002. The overall seven-class classification accuracies averaged 94% for the four years. The overall accuracy of land cover change maps, generated from post-classification change detection methods and evaluated using several approaches, ranged from 80% to 90%. The maps showed that between 1986 and 2002 the amount of urban or developed land increased from 23.7% to 32.8% of the total area, while rural cover types of agriculture, forest and wetland decreased from 69.6% to 60.5%. The results quantify the land cover change patterns in the metropolitan area and demonstrate the potential of multitemporal Landsat data to provide an accurate, economical means to map and analyze changes in land cover over time that can be used as inputs to land management and policy decisions. <s> BIB009 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> Biomass burning represents an important source of atmospheric aerosols and greenhouse gases, yet little is known about its interannual variability or the underlying mechanisms regulating this variability at continental to global scales. Here we investigated fire emissions during the 8 year period from 1997 to 2004 using satellite data and the CASA biogeochemical model. Burned area from 2001–2004 was derived using newly available active fire and 500 m. burned area datasets from MODIS following the approach described by Giglio et al. (2006). ATSR and VIRS satellite data were used to extend the burned area time series back in time through 1997. In our analysis we estimated fuel loads, including organic soil layer and peatland fuels, and the net flux from terrestrial ecosystems as the balance between net primary production (NPP), heterotrophic respiration ( R h ), and biomass burning, using time varying inputs of precipitation (PPT), temperature, solar radiation, and satellite-derived fractional absorbed photosynthetically active radiation (fAPAR). For the 1997–2004 period, we found that on average approximately 58 Pg C year −1 was fixed by plants as NPP, and approximately 95% of this was returned back to the atmosphere via R h . Another 4%, or 2.5 Pg C year −1 was emitted by biomass burning; the remainder consisted of losses from fuel wood collection and subsequent burning. At a global scale, burned area and total fire emissions were largely decoupled from year to year. Total carbon emissions tracked burning in forested areas (including deforestation fires in the tropics), whereas burned area was largely controlled by savanna fires that responded to different environmental and human factors. Biomass burning emissions showed large interannual variability with a range of more than 1 Pg C year −1 , with a maximum in 1998 (3.2 Pg C year −1 ) and a minimum in 2000 (2.0 Pg C year −1 ). <s> BIB010 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> Periodically, reviews of our knowledge of radar-wetland relationships and detection parameters have been provided by various authors. Since the publication of these works, additional research has been completed. Five major remote sensing journals spanning the years 1965-2007 formed the basis of this review. The vast majority of significant material found its way into these mainstream journals in one aspect or another. A short history of Synthetic Aperture Radar (SAR)-wetlands discovery based on earlier reviews is followed by an update on radar-related wetland research. Although some trends emerged with regard to which wavelengths or polarizations to use, there was variation in optimum season/time of year and selection of multitemporal imagery. What is evident throughout the recent literature is that multidimensional radar data sets are attaining an accepted role in operational situations needing information on wetland presence, extent and conditions. <s> BIB011 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> The San Rossore Natural Park, located on the Tuscany (Italy) coast, has been utilized over the last 10 years for many remote sensing campaigns devoted to coastal zone monitoring. A wet area is located in the south-west part of the Natural Park and it is characterized by a system of ponds and dunes formed by sediment deposition occurring at the Arno River estuary. The considerable amount of collected data has permitted us to investigate the evolution of wetland spreading and land coverage as well as to retrieve relevant biogeochemical parameters, e.g. green biomass, from remote sensing images and products. This analysis has proved that the monitoring of coastal wetlands, characterized by shallow waters, moor and dunes, demands dedicated aerospace sensors with high spatial and spectral resolution. The outcomes of the processing of images gathered during several remote sensing campaigns by airborne and spaceborne hyperspectral sensors are presented and discussed. A particular effort has been devoted to sensor response calibration and data validation due to the complex heterogeneity of the observed natural surfaces. <s> BIB012 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> A comprehensive study using ecological engineering analysis was conducted on the influence of the hydrology process in the Yellow River Delta. It was found that water and sediment played an important role in the formation and maintenance of the estuarine wetland. Based on hydrological data (1950-2005), meteorological data (1954-2005) and landscape data produced from integrated Landsat TM images of the Yellow River Delta, the relationship among all the above factors has been analyzed. The results indicated that runoff, sediment discharge and the area of the reed marsh wetland, meadow wetland and tidal wetland had evidently decreased from 1986 to 2001. The runoff and sediment discharge into the Yellow River Delta at a rate of 200-300 x 10(8)m(3) and at 5-8 x 10(8) t, respectively, were probably the most optimal range for maintaining the stable wetland landscape pattern. Regression analysis and principal component analysis showed that there was a strong positive correlation between the area of wetland landscape and runoff, sediment discharge, whereas there was a negative correlation between the area and the temperature, and there was no significant trend with precipitation levels. The water and sediment discharge are the dominant variable factors of the wetland. Human activities also have an important influence on transformation of wetland types as well as wetland degradation. Therefore, with economic development, climate change and sustainable utilization of resources, great attention should be paid to the changes of natural landscape and their causes. (C) 2009 Elsevier B.V. All rights reserved. <s> BIB013 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> Wetland vegetation plays a key role in the ecological functions of wetland environments. Remote sensing techniques offer timely, up-to-date, and relatively accurate information for sustainable and effective management of wetland vegetation. This article provides an overview on the status of remote sensing applications in discriminating and mapping wetland vegetation, and estimating some of the biochemical and biophysical parameters of wetland vegetation. Research needs for successful applications of remote sensing in wetland vegetation mapping and the major challenges are also discussed. The review focuses on providing fundamental information relating to the spectral characteristics of wetland vegetation, discriminating wetland vegetation using broad- and narrow-bands, as well as estimating water content, biomass, and leaf area index. It can be concluded that the remote sensing of wetland vegetation has some particular challenges that require careful consideration in order to obtain successful results. These include an in-depth understanding of the factors affecting the interaction between electromagnetic radiation and wetland vegetation in a particular environment, selecting appropriate spatial and spectral resolution as well as suitable processing techniques for extracting spectral information of wetland vegetation. <s> BIB014 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> Aim Our scientific understanding of the extent and distribution of mangrove forests of the world is inadequate. The available global mangrove databases, compiled using disparate geospatial data sources and national statistics, need to be improved.Here,we mapped the status and distributions of global mangroves using recently available Global Land Survey (GLS) data and the Landsat archive. Methods We interpreted approximately 1000 Landsat scenes using hybrid supervised and unsupervised digital image classification techniques. Each image was normalized for variation in solar angle and earth‐sun distance by converting the digital number values to the top-of-the-atmosphere reflectance. Ground truth data and existing maps and databases were used to select training samples and also for iterative labelling. Results were validated using existing GIS data and the published literature to map ‘true mangroves’. Results The total area of mangroves in the year 2000 was 137,760 km 2 in 118 countries and territories in the tropical and subtropical regions of the world. Approximately 75% of world’s mangroves are found in just 15 countries, and only 6.9% are protected under the existing protected areas network (IUCN I-IV). Our study confirms earlier findings that the biogeographic distribution of mangroves is generallyconfinedtothetropicalandsubtropicalregionsandthelargestpercentage of mangroves is found between 5° N and 5° S latitude. Main conclusions We report that the remaining area of mangrove forest in the world is less than previously thought. Our estimate is 12.3% smaller than the most recent estimate by the Food and Agriculture Organization (FAO) of the United Nations.We present the most comprehensive, globally consistent and highest resolution (30 m) global mangrove database ever created.We developed and used better mapping techniques and data sources and mapped mangroves with better spatial and thematic details than previous studies. <s> BIB015 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> Mangrove ecosystems dominate the coastal wetlands of tropical and subtropical regions throughout the world. They provide various ecological and economical ecosystem services contributing to coastal erosion protection, water filtration, provision of areas for fish and shrimp breeding, provision of building material and medicinal ingredients, and the attraction of tourists, amongst many other factors. At the same time, mangroves belong to the most threatened and vulnerable ecosystems worldwide and experienced a dramatic decline during the last half century. International programs, such as the Ramsar Convention on Wetlands or the Kyoto Protocol, underscore the importance of immediate protection measures and conservation activities to prevent the further loss of mangroves. In this context, remote sensing is the tool of choice to provide spatio-temporal information on mangrove ecosystem distribution, species differentiation, health status, and ongoing changes of mangrove populations. Such studies can be based on various sensors, ranging from aerial photography to high- and medium-resolution optical imagery and from hyperspectral data to active microwave (SAR) data. Remote-sensing techniques have demonstrated a high potential to detect, identify, map, and monitor mangrove conditions and changes during the last two decades, which is reflected by the large number of scientific papers published on this topic. To our knowledge, a recent review paper on the remote sensing of mangroves does not exist, although mangrove ecosystems have become the focus of attention in the context of current climate change and discussions of the services provided by these ecosystems. Also, climate change-related remote-sensing studies in coastal zones have increased drastically in recent years. The aim of this review paper is to provide a comprehensive overview and sound summary of all of the work undertaken, addressing the variety of remotely sensed data applied for mangrove ecosystem mapping, as well as the numerous methods and techniques used for data analyses, and to further discuss their potential and limitations. <s> BIB016 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> Ground-penetrating radar (GPR) is a non-intrusive geophysical observation method based on propagation and reflection of high-frequency electromagnetic waves in the shallow subsurface. The vertical cross-sectional images obtained allow the identification of thickness and lithologic horizons of different media, without destruction. Over the last decade, several studies have demonstrated the potential of GPR. This paper presents a review of recent GPR applications to peatlands, particularly to determine peat stratigraphy. An example study of acquisition and comparison of peatland soil thickness of a fen-dominated watershed located in the James Bay region of Quebec, using (1) a meter stick linked to a GPS RTK and (2) a GSSI GPR, is given. A coefficient of determination (r2) of 56% was obtained between the ordinary krigings performed on data gathered using both techniques. Disparities occurred mainly in the vicinity of ponds which can be explained by the attenuation of GPR signal in open water. Despite these d... <s> BIB017 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> Because of enhanced anthropogenic nitrogen input, eutrophication, hypoxia, and acidification threaten the health of aquatic ecosystems. To better understand the current state of research and emerging trends in this area, a bibliometric approach was applied to quantitatively evaluate global nitrogen research at the watershed scale. Using 9,748 articles selected from among 10,163 returned by a search in the Science Citation Index Expanded (SCI-Expanded) database from 1900 to 2011, spatial and temporal characteristics of the articles, authors, institutions, countries, and keywords are presented, and focal research areas are derived. Compared with the annual increase in all articles in the SCI-Expanded (4.5 %), the studies on nitrogen in watersheds increased more quickly (11.2 %), indicating an increasing interest in this area. The relationship between authors and their output was evaluated by a two-step function, in which 6,074 authors (26.8 %) publishing on this topic were key scientists who contributed 56.4 % of the total articles. Based on the number of authors, first authors, international collaborators, and citations, four types of authors were analyzed using cluster methods. The influence of the authors, institutions and countries was also analyzed in terms of publication and citation, and a co-occurrence analysis was used to assess cooperation among countries and research hotpots. The keywords were compared among countries to assist our understanding of interests of research and modes. From the analysis of the primary subjects and the co-occurrence of keywords, studies involving nitrogen's environmental effects, the nitrogen process and models are increasing, which indicates that they are likely to become a primary research focus in the near future. <s> BIB018 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> Abstract Tropical swamp forests growing on peatlands are exposed to various risks of deforestation. To assess the greenhouse gases (GHG) emission from the deforested tropical peatlands, the amount of carbon released during a forest fire needs to be accounted for. The establishment of a fuel mass data set based on a field-based approach is essential to reduce the uncertainty in estimating GHG emissions during forest fires. We estimated the fuel mass (both living and deadwood) in tropical peat swamp forests and its loss during the fire event in 2009 in Central Kalimantan, Indonesia. We also examined the relationship between the forest structure and the burning process by comparing the distribution of stem diameter in burnt and unburnt areas using a fallen wood simulation. We selected two types of peat swamp forests, mature forest and regenerated forest following a fire in 1997/98, and their neighboring burnt areas. The mean fuel mass values in mature and regenerated forest were 319.7 and 131.5 Mg ha −1 , respectively. In burnt areas of mature and regenerated forest, the mean fuel mass values were 235.8 and 89.0 Mg ha −1 , respectively, which corresponded to 73.8% and 67.7% of the values of unburnt areas, respectively. The fuel mass in burnt area comprised mainly solid deadwood. Due to the large amount of deadwood left on the ground, the estimated GHG emissions after the forest fire were larger than those during the forest fire in both forest types. The regenerated forest, which was dominated by small trees and contained a small stock of deadwood, was considered to produce a large amount of solid deadwood during the forest fire. In contrast, the mature forest, which contained many large standing trees and large amounts of deadwood, experienced a high-intensity fire over a long duration time, resulting in surface or deeply burnt deadwood. The development of a simple method to tally the surviving large trees in the burnt area (i.e., designing a study plot with a nested structure for different-sized trees) might reduce uncertainties in the estimation of fuel mass and GHG emissions in future forest fires. <s> BIB019 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> Abstract Remote sensing has got wide range of applications in the field of coastal engineering, including estimation of sea surface temperature, chlorophyll content, suspended sediment concentration, yellow substance concentration, wave characteristics, potential fishing zone (PFZ) and so on. Various satellite remote sensing data has provided rea data which can be used to monitor coastal resources. The present paper gives an overview of some of the applications of remote sensing in the field of satellite oceanography. From the present review, it can be conclude that, even though IR and microwave radiometers can be used for measuring temperatures at different depths in oceans, better choice is to use microwave data as it has got the advantage of penetrating through clouds and also it gives a clear view in all weather conditions except rain. Band ratio approach can be used for identifying different water quality parameters. In recent past, satellite remote sensing has become an ideal tool for identifying Potential fishing zone (PFZ). <s> BIB020 </s> A Review of Wetland Remote Sensing <s> Data and Methodology <s> About 80% of global wetland resources are degrading or disappearing; thus the wetland ecosystem has become one of the most seriously threatened ecosystems in the world. As an area sensitive to global changes and acting as a security barrier for the Asian ecosystem, the Tibetan Plateau has about 13.19×104 km2 of wetlands of special significance within China. With the increasing application of remote sensing technology to wetland research, Tibetan Plateau wetland research has entered a period of rapid development. This paper summarizes the remote sensing research literature of the Tibetan Plateau wetlands from 1992 to 2014, and is intended to provide references for future research into the wetlands of the Tibetan Plateau. We have reviewed monitoring methods, research topics, and existing problems. Our review has revealed the following characteristics: (1) Over the past 40 years, the research paradigm of the Tibetan Plateau wetlands has undergone dynamic changes in the monitoring of wetland areas, landscape patterns and the eco-environment based on remote sensing technology. Attention has also been focused on constructing models with an ecological system perspective and analyzing three patterns of change trends within the Tibetan Plateau wetlands. (2) The results of Tibetan Plateau wetland research based on remote sensing were as follows: (a) between 1970 and 2006, the Tibetan Plateau wetland area decreased overall at a rate of 0.23%/a, and the landscape diversity declined at a rate of 0.17%/a; (b) by contrast, between 1976 and 2009, the lake area of the inland river basins in the Tibetan Plateau increased at a rate of 0.83%/a; and (c) the change trend in the Tibetan Plateau wetlands was controlled by climate change. Current problems relating to remote sensing (RS)-based research in the Tibetan Plateau wetlands are computer interpretation accuracy and the processing precision of cloud removal, and the lack of a comprehensive overview of the Tibetan Plateau wetland system. Finally, based on the review, some key activities for future study have been proposed, as follows: (1) Strengthening the integration of the Tibetan Plateau wetland research with remote sensing research; (2) discussing the response and adaptation mechanisms of the Tibetan Plateau wetland ecosystem within the context of global change; (3) strengthening the integration of remote sensing (RS), geographic information system (GIS), and global positioning system (GPS), and promoting the construction of a Tibetan Plateau wetland information platform. <s> BIB021
The Science Citation Index Extended (SCIE) database from Web of Science BIB018 is the most comprehensive and frequently used data sources for reviewing high-quality publications and assessing scientific accomplishments so it was chosen for this study. The publications included journal papers and conference articles. To categorize and manage all the papers of wetland remote sensing and also for convenience using in analyzing, this research built a database of "wetland remote sensing" First, a "wetland" database by searching for the following keywords was built: "wetland", "peatland", "bog", "swamp", "mangrove", "marsh", "mire", "fen", or "everglades" (date of search: 11 May 2016). In total, 93,894 papers were obtained. Then a thesaurus based on the Dictionary of Remote Sensing  was built to match the wetland database and established a database named "wetland remote sensing". Intensive manual interpretation was necessary to obtain a complete set of papers of wetland research that used remote sensing. Finally, 5719 papers were selected for overview of wetland remote sensing. Figure 1 shows the published wetland remote sensing papers and the ratio of wetland remote sensing to wetland research from 1964 to 2015. Wetland-related studies are therefore of great importance to protect wetlands and mitigate climate change. Remote sensing is the major source of spatial information about the Earth surface's cover and constitution BIB006 . Different sensors capture abundant information regarding the Earth, which can be used by scientists that are interested in monitoring spatial information in a timely manner BIB007 . During the past five decades, remote sensing technology has been used in many wetland research areas such as: BIB012 land use/cover changes or mapping in wetland regions BIB006 BIB008 BIB009 BIB015 ; (2) carbon cycle and climate warming in wetland environments BIB001  ; (3) release of carbon by peatland fires BIB010 BIB004 BIB019  ; and (4) hydrology processes in wetlands BIB013 BIB002 BIB005 . Many wetland studies have used remote sensing technology and many researchers have reviewed wetland remote sensing. However, these reviews focus just on one type of wetland BIB016 BIB017 BIB020 , on one place  BIB021 , on one type of sensor BIB011 BIB014 , or on one method  . Rundquist et al. BIB003 reviewed wetland remote sensing and addressed many issues of wetland identification, classification, change detection, and biomass. However, this paper was published in 2001, hence, it does not include the relevant publications of the past 15 years, a period in which remote sensing technology and wetland research have developed rapidly. A comprehensive review of wetland remote sensing has not been reported in recent years, so the objectives of this paper are to: BIB012 provide an overview of selected approaches and findings of wetland remote sensing; (2) highlight the different types of remote sensors in wetland remote sensing; and (3) provide advice for future wetland research. The Science Citation Index Extended (SCIE) database from Web of Science BIB018 is the most comprehensive and frequently used data sources for reviewing high-quality publications and assessing scientific accomplishments so it was chosen for this study. The publications included journal papers and conference articles. To categorize and manage all the papers of wetland remote sensing and also for convenience using in analyzing, this research built a database of "wetland remote sensing" First, a "wetland" database by searching for the following keywords was built: "wetland", "peatland", "bog", "swamp", "mangrove", "marsh", "mire", "fen", or "everglades" (date of search: 11 May 2016). In total, 93,894 papers were obtained. Then a thesaurus based on the Dictionary of Remote Sensing  was built to match the wetland database and established a database named "wetland remote sensing". Intensive manual interpretation was necessary to obtain a complete set of papers of wetland research that used remote sensing. Finally, 5719 papers were selected for overview of wetland remote sensing. Figure 1 shows the published wetland remote sensing papers and the ratio of wetland remote sensing to wetland research from 1964 to 2015. 