A Study of Forest Swamp Mapping in Hani Wetland Integrating Sentinel-1 and Sentinel-2 Satellite Images

As a unique wetland type, forest swamps play an important role in regional carbon cycling and biodiversity conservation. Taking Hani wetland in Jilin province as the research object, we integrated the application of Sentinel-1 radar and Sentinel-2 multispectral images, fully exploited the potential of Sentinel-1 multi-polarization band features and Sentinel-2 red edge index for forest swamp remote sensing identification, and applied the random forest method to realize the extraction of forest swamp distribution information of Hani wetland. The results show that when the optimal number of decision trees for forest swamp information extraction is 1200, the fusion of Sentinel-1VV and VH backscattering coefficient radar band features and Sentinel-2 red-edge band features can significantly improve the extraction accuracy of forest swamp distribution information, and the overall accuracy and Kappa coefficient of forest swamp information extraction in protected areas are as high as 89% and 0.85, respectively. The overall accuracy and Kappa coefficient of forest swamp information extraction in the protected area were 89% and 0.85, respectively. The landscape types of Hani Wetlands of International Importance are diversified, with natural wetlands, artificial wetlands and non-wetland landscape types co-existing. Among the natural wetland types, the forest swamp has the largest area of 27.1 km2, accounting for 11.2% of the total area of the reserve; the river has the smallest area of 0.7 km2, accounting for 0.3% of the total area of the reserve. The forest swamp extraction method provides data support for the sustainable management of Hani wetlands and case guidance for forest swamp mapping in other regions.

Factors Driving Wetland Herbs Distribution Range of Lake-Terrestrial Ecotone in Tibet, China

Background: Lake is a critical part of Tibet's hydrological cycle, the lake-terrestrial ecotone is the most sensitive area in the water and terrestrial ecosystem. For the ecological protection and maintenance of the lakeside zone, defining the upper boundary of the lake-terrestrial ecotone is a key issue that needs to be solved urgently. However, the ecological characteristics of lake-terrestrial ecotone made it diffcult to delimit. Wetland herbs are characteristic plants of the radiant belt toward the land of the lake-terrestrial ecotone, and their distribution range can be used to reflect the upper boundary of the lake-terrestrial ecotone. We took Baksum Lake, Yambdroktso, Namtso, Siling Co as examples, based on the spatial structure of the lake-terrestrial ecotone, used the moving split-window technology (MSWT) delimited the range of wetland herbs.Results:The results of MSWT showed the distribution range of wetland herbs in each lake-terrestrial ecotone with the natural-wetland type sampling line of Baksum Lake, Yambdroktso, Namtso, Siling Co was 51m, 56m, 33~53m, 19~31m. DCA showed number of wetland herbs species,BK1＞YT1=NT1＞NT2＞SC1=SC2. PCA, RDA showed SMO, pH, SSC, and soil nutrient content had obvious correlation with distribution range. Conclusion:MSWT was a feasible method to delimit the distribution range of wetland herbs. SMO, pH, SSC, and soil nutrient content were all-important environmental factors affect the wetland herbs distribution range of the four lakes, however, the SMO was the most important factor. Besides, compare with the lakes in the lower Yangtze Plain,the high-density population distribution,high-intensitive human activity invaded the plants' growth area, resulting in a smaller distribution range.

Three New Diatom Species from Spring Habitats in the Northern Apennines (Emilia-Romagna, Italy)

Using light (LM, including plastid characterization on fresh material) and scanning electron microscopy (SEM), as well as a thorough morphological, physical, chemical, and biological characterization of the habitats, the present study aims at describing three species new to science. They belong to the genera Eunotia Ehrenb., Planothidium Round and L. Bukht., and Delicatophycus M.J. Wynne, and were found in two contrasting spring types in the northern Apennines. The three new species described differ morphologically from the most similar species by: less dense striae and areolae, and the absence of a ridge at the valve face-mantle transition (SEM feature) [Eunotia crassiminor Lange-Bert. et Cantonati sp. nov.; closest established species: Eunotia minor (Kütz.) Grunow]; narrower and shorter cells [Planothidium angustilanceolatum Lange-Bert. et Cantonati sp. nov.; most similar species: Planothidium lanceolatum (Bréb. ex Kütz.) Lange-Bert.]; barely-dorsiventral symmetry, set off ends, and lower density of the central dorsal striae [Delicatophycus crassiminutus Lange-Bert. et Cantonati sp. nov.; most similar species: Delicatophycus minutus M.J.Wynne]. Two of the three species we described are separated from the closest species by dimensions. Their description improved knowledge on two taxa (Eunotia minor s.l. and Planothidium lanceolatum s.l.) likely to be only partially resolved species complexes. We could also refine knowledge on the ecological profiles of the three newly-described species. Eunotia crassiminor sp. nov., as compared to Eunotia minor, appears to occur in colder inland waters with a circumneutral pH and a strict oligotrophy as well with respect to nitrogen. The typical habitat of Planothidium angustilanceolatum sp. nov. appears to be oligotrophic mountain flowing springs with low conductivity. Delicatophycus crassiminutus sp. nov. was observed only in limestone-precipitating springs, and is therefore likely to be restricted to hard water springs and comparable habitats where CO2 degassing leads to carbonate precipitation. Springs are a unique but severely threatened wetland type. Therefore, the in-depth knowledge of the taxonomy and ecology of characteristic diatom species is important, because diatoms are excellent indicators of the quality and integrity of these peculiar ecosystems in the face of direct and indirect human impacts.

Comparing Solo Versus Ensemble Convolutional Neural Networks for Wetland Classification Using Multi-Spectral Satellite Imagery

Wetlands are important ecosystems that are linked to climate change mitigation. As 25% of global wetlands are located in Canada, accurate and up-to-date wetland classification is of high importance, nationally and internationally. The advent of deep learning techniques has revolutionized the current use of machine learning algorithms to classify complex environments, specifically in remote sensing. In this paper, we explore the potential and possible limitations to be overcome regarding the use of ensemble deep learning techniques for complex wetland classification and discusses the potential and limitation of various solo convolutional neural networks (CNNs), including DenseNet, GoogLeNet, ShuffleNet, MobileNet, Xception, Inception-ResNet, ResNet18, and ResNet101 in three different study areas located in Newfoundland and Labrador, Canada (i.e., Avalon, Gros Morne, and Grand Falls). Moreover, to improve the classification accuracies of wetland classes of bog, fen, marsh, swamp, and shallow water, the results of the three best CNNs in each study area is fused using three supervised classifiers of random forest (RF), bagged tree (BTree), Bayesian optimized tree (BOT), and one unsupervised majority voting classifier. The results suggest that the ensemble models, in particular BTree, have a valuable role to play in the classification of wetland classes of bog, fen, marsh, swamp, and shallow water. The ensemble CNNs show an improvement of 9.63–19.04% in terms of mean producer’s accuracy compared to the solo CNNs, to recognize wetland classes in three different study areas. This research indicates a promising potential for integrating ensemble-based learning and deep learning for operational large area land cover, particularly complex wetland type classification.

Methane emissions from high-latitude peatlands during the Holocene from a synthesis of peatland records

<p>The sources of atmospheric methane (CH<sub>4</sub>) during the Holocene remain widely debated, including the role of high latitude wetland and peatland expansion and fen-to-bog transitions. We reconstructed CH<sub>4 </sub>emissions from northern peatlands from 13,000 before present (BP) to present using an empirical model based on observations of peat initiation (>3600 <sup>14</sup>C dates), peatland type (>250 peat cores), and contemporary CH<sub>4</sub> emissions in order to explore the effects of changes in wetland type and peatland expansion on CH<sub>4</sub> emissions over the end of the late glacial and the Holocene. We find that fen area increased steadily before 8000 BP as fens formed in major wetland complexes. After 8000 BP, new fen formation continued but widespread peatland succession (to bogs) and permafrost aggradation occurred. Reconstructed CH<sub>4</sub> emissions from peatlands increased rapidly between 10,600 BP and 6900 BP due to fen formation and expansion. Emissions stabilized after 5000 BP at 42 ± 25 Tg CH<sub>4</sub> y<sup>-1</sup> as high-emitting fens transitioned to lower-emitting bogs and permafrost peatlands. Widespread permafrost formation in northern peatlands after 1000 BP led to drier and colder soils which decreased CH<sub>4 </sub>emissions by 20% to 34 ± 21 Tg y<sup>-1</sup> by the present day.</p><p> </p>

Managing hydrology can reduce methane emissions of high-emitting freshwater marshes by half making them present-day net greenhouse gas sinks

<p><span>Restoring wetlands for climate mitigation purposes could provide an effective method to protect existing soil carbon stocks, as well as act as a negative emission technology by sequestering atmospheric carbon for 100-1000s of years. However, many peatlands have low productivity limiting carbon sequestration, while high productivity marshes often emit large amounts of methane. Studies on water level management to control methane emissions have shown differing results depending on wetland type, climate, as well as measurement method and duration. Here we show with multi-year flux measurements that water level changes were likely responsible for significantly reducing annual methane emissions. To assess management impacts on annual greenhouse gas budgets, continuous high frequency measurements of fluxes are needed, such as by eddy covariance. However, this method is less suited to monitor concurrent manipulation experiments to compare treatments. </span><span> </span><span>We compared the impact of water level fluctuations by creating a second timeseries where water drawdown events were removed, which was then gap-filled by a random forest model trained only on measurements from periods when the water table was above the surface. These estimates were used to compare the annual budgets with the complete data and showed that annual methane emissions were up to 50% lower in years where water levels went sufficiently below the peat surface. This threshold was key, as only reductions in water depth above the surface were related to temporary increases in emissions. We further show that in some cases the drawdowns tipped the greenhouse gas budgets so that marshes were net greenhouse gas sinks, as long as the drawdown did not also reduce plant productivity through drought stress. In comparison, wetlands with average annual fluxes would require between approx. 50 and 200 years given current levels of net carbon uptake to offset high methane emissions and become cumulative greenhouse gas sinks.</span><span> </span></p>

Diversity and Distribution of Waterbirds across Wetlands of Eastern Uganda

Explaining patterns of diversity, and abundance across sites is a central aim of community ecology. Avian communities have been the focus of many studies on species diversity. To be able to explain patterns of waterbirds in wetlands of eastern Uganda, we conducted a rapid assessment in 48 wetlands (38 swamps, two rice paddies and eight lakes) using total counts. We examined waterbird assemblages in these wetlands in relation to wetland area, wetland type, water depth, water pH and the time of year/season. Statistical analysis were conducted using Genstat Version 8.1 (VSN Intl.2003, in which General Linear Mixed Models were used to examine the variations. In total, 9,410 birds from 64 species and 17 families were recorded. Species diversity and overall abundance varied significantly among wetland types and between seasons. Rice paddies were both more species-diverse than lakes and swamps. Wetland area had significant independent and positive effects on the waterbird community. In addition to explaining differences among wetland types in waterbird numbers, water depth had a positive effect on some aspects of the waterbird community with no significant effect of pH. These results imply that an interplay of factors is responsible for the pattern and structure of waterbird communities on wetlands in eastern Uganda.

Groundwater storage effects from restoring, constructing or draining wetlands in temperate and boreal climates: a systematic review protocol

Background Wetlands in many parts of the world have been degraded, as use of the land for food production and forestry for human needs have taken precedence. Drainage of wetlands has led to deteriorated wetland conditions and lowered water tables. Across the world, there are several programs for wetland restoration and construction, primarily to reintroduce lost habitats for wildlife, and to obtain nutrient retention functions. In Sweden, recent dry and hot summers have reinforced interest in the hydrological functions that wetlands may have, in particular as potential support for water storage in the landscape and added groundwater storage during dry periods. However, the agreement on substantial effects on groundwater is limited, and there are several critical knowledge gaps, including the extent to which such effects extend outside the wetland itself, and how they vary with local conditions, such as topography, soil, and climate. Therefore, this review will address the groundwater storage effect of restoring, constructing or draining wetlands in the boreo-temperate region. Methods We will conduct a systematic review of the evidence, drawing on both peer-reviewed and grey literature. Articles in English, Swedish, Norwegian, Danish, French, German and Polish will be retrieved from academic databases, Google Scholar, and websites of specialist organizations. We will screen literature in two stages, first at the title and abstract level and then in full text, the latter with blinded decisions by two independent reviewers for all articles. Articles will be included based on relevance criteria for a Swedish context: wetlands on previously glaciated soils in boreal and temperate climates. Data will be extracted from all included articles, including wetland type, intervention type, and hydrogeological setting. Studies will be subject to critical appraisal to evaluate their susceptibility to bias. Provided enough evidence of sufficient reliability, we will carry out meta-analyses of effect sizes in relation to various factors. The review will include a narrative synthesis in which we summarize the results of the review.