Swamp Wetland Research Articles

Assessing the Health of South Kalimantan Coastal Swamp Wetlands using Measurements of Heavy Metals in Commercial Fish Species

Heavy metals pollution damages coastal swamp ecosystems. This study’s primary purpose was to determine the amounts of heavy metals in coastal swamp waters and the tissues of three fish species (Mugil cephalus, Arius sagor and Plotosus lineatus). This study determined that the water in the coastal swamps of South Kalimantan was contaminated with heavy metals in the following order: Fe > Cu > Zn > Cr > Pb > Cd > Hg. The heavy metal concentrations found in the three commercial fish species are as follows: Fe > Zn > Cu > Cr > Pb > Cd > Hg. The bioaccumulation of heavy metals was highest in Mugil cephalus, followed by Arius sagor and Plotosus lineatus. The Fe, Cu and Cr concentrations in Mugil cephalus, Arius sagor and Plotosus lineatus exceeded the international and national MPLs. The liver tissue has the highest capacity to bioaccumulate heavy metals. Regular monitoring of these metals in fish and water sources is recommended to ensure the safety and conservation of coastal swamp wetlands.

Response of species dominance and niche of plant community to wetland degradation along alpine lake riparian.

Alpine wetland degradation threatens riparian biodiversity and ecological balance. Our study, conducted in July 2020 along the northern and eastern shores of Qinghai Lake, seeks to unravel the impacts of such degradation on plant species dominance and ecological niches, using advanced network analysis methods to explore the dynamics and survival strategies of plant species. We applied a space-to-time method to delineate three wetland degradation stage: a healthy swamp wetland, a slightly degraded wet meadow, and a degraded dry meadow. Six representative sampling points were chosen. At each point, three sample lines were randomly established, radiating outward from the center of the lake wetland, with each stage of degradation meticulously examined through three replicates to assess the plant communities in terms of species composition, plant height, coverage, and abundance. The results indicated: Species such as Kobresia tibetica and Leymus secalinus exhibit remarkable abundance across various stages of wetland degradation, indicating a robust tolerance to these conditions. This observation, coupled with the complexity of plant community structures in degrading wetlands, suggests that such intricacy cannot be solely attributed to the dominance of particular species. Instead, it is the result of a diverse array of species adapting to fluctuating water levels, which promotes increased species richness. Despite the prominence of species that exhibit rapid growth and reproduction, the ecological significance of less abundant species in contributing to the community's complexity is also notable. Changes in habitat conditions due to wetland degradation facilitate both competitive and cooperative interactions among species, highlighting the dynamic nature of these ecosystems. Our analysis shows no significant linear relationship between the ecological niche overlap values and niche widths of plant species. However, the strategies employed by dominant species for competition and resource acquisition, as observed in the ecological niche overlap networks, underscore the adaptive capacity of plant communities. These insights underscore the need for tailored restoration strategies to conserve the biodiversity of alpine lake riparian ecosystems. This research not only sheds light on the resilience and adaptability of ecosystems in the Qinghai-Tibetan Plateau but also offers valuable lessons for the conservation of similar habitats worldwide. Our findings underscore the need for tailored restoration strategies to conserve the biodiversity of alpine lake riparian ecosystems. This research not only sheds light on the resilience and adaptability of ecosystems in the Qinghai-Tibetan Plateau but also offers valuable lessons for the conservation of similar habitats worldwide.

Random Forest Classifier Algorithm of Geographic Resources Analysis Support System Geographic Information System for Satellite Image Processing: Case Study of Bight of Sofala, Mozambique

Mapping coastal regions is important for environmental assessment and for monitoring spatio-temporal changes. Although traditional cartographic methods using a geographic information system (GIS) are applicable in image classification, machine learning (ML) methods present more advantageous solutions for pattern-finding tasks such as the automated detection of landscape patches in heterogeneous landscapes. This study aimed to discriminate landscape patterns along the eastern coasts of Mozambique using the ML modules of a Geographic Resources Analysis Support System (GRASS) GIS. The random forest (RF) algorithm of the module ‘r.learn.train’ was used to map the coastal landscapes of the eastern shoreline of the Bight of Sofala, using remote sensing (RS) data at multiple temporal scales. The dataset included Landsat 8-9 OLI/TIRS imagery collected in the dry period during 2015, 2018, and 2023, which enabled the evaluation of temporal dynamics. The supervised classification of RS rasters was supported by the Scikit-Learn ML package of Python embedded in the GRASS GIS. The Bight of Sofala is characterized by diverse marine ecosystems dominated by swamp wetlands and mangrove forests located in the mixed saline–fresh waters along the eastern coast of Mozambique. This paper demonstrates the advantages of using ML for RS data classification in the environmental monitoring of coastal areas. The integration of Earth Observation data, processed using a decision tree classifier by ML methods and land cover characteristics enabled the detection of recent changes in the coastal ecosystem of Mozambique, East Africa.

Water quality management of micro swamp wetland based on the “source-transfer-sink” theory: A case study of Momoge Swamp Wetland in Songnen Plain, China

Swamp wetlands play a pivotal role in conserving water sources, regulating river runoff, and maintaining water safety and balance. The study pioneers a new research framework in the field of pollution ecology of swamp wetlands, with a focus on the complex “source-transfer-sink” processes affecting water quality in micro swamp wetlands, an area previously under-researched. Taking the Momoge Wetland in the Songnen Plain as an example, we innovatively combined the “source-transfer-sink” theory with landscape patterns, topographic factors, and their impacts on wetland water quality. Using Partial Least Squares Structural Equation Modeling (PLS-SEM), our research quantifies and models the relationships among various environmental factors. This approach reveals how landscape patterns influence pollutant migration and water quality at a micro-scale. Our findings suggest that a 700-m buffer zone is most effective in capturing the fluctuations in water quality in arid wetlands, which is crucial for wetland management practices. We identified the main pollution sources in the Momoge Wetland, including sediment (21.60%), vegetation (24.94%), livestock and crop-related non-point sources (41.21%), and hydrodynamic factors such as water diversion (12.25%). In pollutant migration, land use emerged as the most significant factor affecting water quality (56.64%), followed by landscape patterns (25.54%). Notably, our study finds that grasslands are essential for water purification, and a uniform distribution of landscape patches significantly improves water quality. This research marks a significant stride in understanding and optimizing landscape patterns to enhance water quality in micro swamp wetlands. The insights gained are invaluable for the protection of these ecosystems and promoting their ecological value functions, providing a reference point for future wetland conservation and management strategies.

Effects of driving factors on water supply function under different basins and spatial scale in Zoige alpine wetland, China

Water supply is one of the core ecosystem services functions for wetland. Due to the important status of Zoige wetland, assessment of water supply in Zoige wetland is significant for ecological security all over the world. In this paper, Heihe and Baihe basins in Zoige wetland were taken as research objects, the water yield module of the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model was used to spatially quantify water supply, with the aims of revealing the driving mechanism of water supply under different basins and spatial scale. We observed the spatial pattern change of water yield under baseline and eleven future scenarios and used the ANOVA of repeated measures and multiple linear regression model to explore the patterns and driving factors of water supply in Heihe and Baihe rivers basins. The research results were as follow. (1) The precipitation is main factor to improve water yield, but this intensity is different in different basins and spatial scale. Topography, climate, vegetation, and percentage of wetland conditions have important impacts on water yield services. However, the impacts of these conditions on water yield were various significantly across different watersheds and spatial scales (excluding factors such as precipitation, slope, and percentage of swamp wetland). (2) The spatial pattern of water yield main was affected by land use change and the amount of water yield main was affected by future climate change. (3) Water yield in the Baihe basin was more sensitive to climate change, while the Heihe basin is more sensitive to land use changes. Wetland ecological restoration strategies can effectively improve regional water yield, especially in the Heihe basin. (4) In all scenarios, the southeast regions of the study region were both the main hot spots of water yield. Wetland ecological restoration strategies have added hot spots in the north regions of the Baihe river basin, reduced hot spots in the middle-south regions of the Heihe basin.

Variation of carbon source and sink along the environmental gradient from lakeside to highlands in Yuanchi swamp wetlands, Changbai Mountains, China.

Lacustrine wetlands have long-term carbon storage capacity and contribute significantly to regional carbon cycle, but it is unclear how its carbon sinks respond to climate change. We measured soil heterotrophic respiration carbon emissions (CO2 and CH4), vegetation carbon sequestration, and related environmental factors (temperature, water level, etc.) of five kinds of natural swamps (Phragmites marsh-L, Carex schmidtii marsh-C, Rhododendron capitatum swamp-D, Betula fruticose swamp-H, Larix olgensis swamp-LT)by using static chamber gas chromatography and relative growth equation methods, along the water environmental gradients from lakeside to highlands in Yuanchi of Changbai Mountains. We quantified the carbon source/sink function (CSS) and global warming potential (GWP) of various swamp types by estimating ecosystem net carbon balance, and revealed the variation patterns and formation mechanisms of CSS and GWP along the environmental gradients, aiming to explore the response of carbon source/sink of lakeside wetland in high altitude area to climate change. The results showed that marshes (L and C) were weak sources (-1.018 and -0.090 t C·hm-1·a-1) at the lower habitats of the water environment gradient, shrub swamps (D and H) were strong or weak sinks (1.956 and 0.239 t C·hm-1·a-1) at the middle habitats, forest swamp (LT) was strong source (-3.214 t C·hm-1·a-1) at the upper habitat. The spatial changes were promoted by water level and suppressed by soil temperature. For GWP, strong thermal radiation for marshes (from 44.682 to 59.282 t CO2·hm-1·a-1), cold radiation for shrub swamps (from -0.920 to -7.008 t CO2·hm-1·a-1), and weak thermal radiation for forest swamp (11.668 t CO2·hm-1·a-1), and their GWP was only promoted by soil temperature. Under current climate change background, marshes and forest swamp at both ends of the water environment gradient from lakeside to highlands played a positive feedback effect due to the increases of CH4 or CO2 emissions, while the middle shrub swamp still maintained a negative feedback effect in Yuanchi located the high-altitude area of the temperate Changbai Mountains.

Mapping Wetlands of Kenya Using Geographic Resources Analysis Support System (GRASS GIS) with Remote Sensing Data

Abstract Monitoring wetlands of Kenya is critical for analysis of environmental changes since they present unique ecosystems with special hydrological balance and biodiversity. In this study, the Landsat 8-9 OLI/TIRS satellite images for 2015-2022 were classified using GRASS GIS scripts to evaluate changes in the Lorian Swamp wetland, north-eastern Kenya. The results of the image analysis presented maps of land cover changes including wetlands. The study demonstrated technical effectiveness of the GRASS GIS for image analysis, and contributed to the environmental monitoring of African wetlands.

Roles of climatic and anthropogenic factors in shaping Holocene vegetation and fire regimes in Great Dismal Swamp, eastern USA

The Great Dismal Swamp wetland, spanning >400 km2 along the Virginia and North Carolina border, was shaped by a complex combination of geomorphic, climatic, and anthropogenic forcings during the last 14,000 years. Pollen, macrofossils, charcoal, and physical properties from sediment cores at seven sites provide a detailed record of the spatial heterogeneity of the wetland and the roles played by natural hydrologic variability, wildfire, and human modification of drainage in shaping vegetation and habitats. Cold-temperate forests occupied regional uplands from at least 13.5–10.3 cal ka BP. Marshes dominated by grasses and other herbaceous taxa began developing along low-elevation streams as early as 10.3 cal ka BP, resulting in accumulation of organic silts. Long-hydroperiod, peat accumulating marshes, with abundant floating aquatic plants, developed as early as 9.6 cal ka BP, as rapid rates of sea-level rise elevated the water table and facilitated wetland development and peat accumulation along stream courses. By the mid-Holocene (c. 7–6.5 cal ka BP), when local sea-level rise began slowing and reached about 12–15 m below present, shorter hydroperiod, peat-accumulating marshes dominated the landscape, with increased wildfire activity. Great Dismal Swamp vegetation shifted from marshes to peat-accumulating forested wetlands by c. 3.7 cal ka BP; these were dominated by varying combinations of Nyssa (tupelo), Taxodium (cypress), and Chamaecyparis thyoides (Atlantic white cedar). Wildfires were infrequent during this time, and the forested wetlands persisted, with minor compositional changes related to climate-driven fluctuations in stream flow, until colonial ditching and logging began in the swamp during the late 18th century. These activities decreased cypress and cedar populations, and, by the mid-20th century, expanded ditching resulted in even drier conditions and expansion of maple-gum (dominated by Acer and Liquidambar), and pine-pocosin (dominated by Pinus) forests. The distribution of these forests differs from that of the late Holocene and represents a fundamental shift in hydrology, peat structure, vegetation, and fire regime due to landscape alterations of the last few centuries.

Distribution Characteristics and Genesis of Iron and Manganese Ions in Groundwater of Eastern Sanjiang Plain, China

Groundwater resources are an essential component of global water resources. Long-term consumption of groundwater exceeding the standard levels for iron and manganese can lead to chronic diseases, posing a threat to human health. The Sanjiang Plain is the largest swamp wetland area in China and has high levels of iron and manganese in the groundwater, but the cause still needs to be clarified. Based on the results of water quality tests of 41 groundwater samples in the Eastern Sanjiang Plain, this paper analyzes the distribution characteristics and causes of iron and manganese from the perspectives of the original strata environment, redox conditions, pH conditions, and hydrochemical indicator factors in the research area, using statistical methods and GIS technology. The results show that high iron and manganese content in groundwater is prevalent in the Eastern Sanjiang Plain, and the exceedance rate of manganese is higher than that of iron (87.80% and 82.90%, respectively). The primary sources of iron and manganese in groundwater are iron and manganese minerals in the original strata environment. Influenced by factors such as acidic conditions, reducing environment, and rich organic matter, insoluble high-valent iron and manganese oxides are reduced to low-valent and soluble divalent iron and manganese. At the same time, groundwater’s high mineralization and evaporation concentration are conducive to increased iron and manganese content, while the influence of human activities is small.

Prediction of Soil Organic Carbon Content Using Sentinel-1/2 and Machine Learning Algorithms in Swamp Wetlands in Northeast China

Prediction of Soil Organic Carbon Content Using Sentinel-1/2 and Machine Learning Algorithms in Swamp Wetlands in Northeast China

Evocations: A Visual Song/Poem for Canaipa

Evocations is a video work made from photographs taken at the conservation-zoned Turtle Swamp Wetlands on Canaipa (Russell Island) in southern Moreton Bay, Quandamooka Country, Queensland, Australia. The accompanying poem is a written response to the images, and evokes their sense of movement and energy.

Botanical Assessments of High-Quality Southern Shrub-Carr and Hardwood Swamp Wetlands in the Undeveloped Lowell Regional Greenspace, Kent County, Michigan

The 2019–2023 Masterplan for Kent County Parks includes the future development of acquired properties that have been designated as the Lowell Regional Greenspace (528 acres), occupying nearly the entirety of Section 22 of Lowell Charter Township in Kent County, Michigan. Four wetlands located in the same drainage basin along Karen Creek in the Lowell Regional Greenspace were inventoried for floristic quality assessments during the summers of 2016, 2018, 2019, and 2021. One of the wetlands was forested and determined to be a southern hardwood swamp community type. The other three wetlands are best classified as shrub-carr communities. In the southern hardwood swamp, we recorded 94 species, of which 87 (92%) are native. A total of 321 species were documented in the three shrub-carrs wetlands combined. The number of species in each shrub-carr site, ranging from 172 to 238, is roughly twice that for the southern hardwood swamp site. Two of the species documented are listed as Special Concern in Michigan, and two are new county records for Kent County, Michigan. A non-metric multidimensional scaling model (NMDS) was run to spatially compare similarities and differences among the sites. The Sørensen Index of Similarity, which was employed to further discern differences between pairs of individual sites, was also useful for assigning plant community types as described by the Michigan Natural Features Inventory (2016). The Floristic Quality Assessments indicate that all four of the wetlands are floristically important statewide; furthermore, the three shrub-carr communities have exceptional conservation value. We discovered that the three shrub-carr sites have a high degree of similarity in their species assemblages, whereas the southern hardwood swamp was markedly different. The high richness and significant floristic quality of the shrub-carr sites highlight the conservation value of these often-overlooked habitats. This study underscores the importance of preserving even small tracts of persisting remnant natural habitats. Our research should be of use to Kent County Parks as they approach development of the Lowell Regional Greenspace into a multiple-use recreational space, as well as to those interested in learning more about how to assess and compare habitat quality of remnant natural areas.

Swamp Wetlands in Degraded Permafrost Areas Release Large Amounts of Methane and May Promote Wildfires through Friction Electrification

Affected by global warming, permafrost degradation releases a large amount of methane gas, and this part of flammable methane may increase the frequency of wildfires. To study the influence mechanism of methane emission on wildfires in degraded permafrost regions, we selected the northwest section of Xiaoxing’an Mountains in China as the study area, and combined with remote sensing data, we conducted long-term monitoring of atmospheric electric field, temperature, methane concentration, and other observation parameters, and further carried out indoor gas–solid friction tests. The study shows that methane gas (the concentration of methane at the centralized leakage point is higher than 10,000 ppm) in the permafrost degradation area will release rapidly in spring, and friction with soil, surface plant residues, and water vapor will accelerate atmospheric convection and generate electrostatic and atmospheric electrodischarge phenomena on the surface. The electrostatic and atmospheric electrodischarge accumulated on the surface will further ignite the combustibles near the surface, such as methane gas and plant residues. Therefore, the gradual release of methane gas into the air promotes the feedback mechanism of lightning–wildfire–vegetation, and increases the risk of wildfire in degraded permafrost areas through frictional electrification (i.e., electrostatic and atmospheric electrodischarge).

Effects of Land Use Conversion on the Soil Microbial Community Composition and Functionality in the Urban Wetlands of North-Eastern China

Urban wetlands are undergoing intensive conversion from natural wetlands to farmlands, woodlands, and even alkaline land. This study aimed to determine the effects of land conversion on soil microbial communities of urban wetlands in the hinterland of Songnen Plain, Northeastern China. Soil samples were collected from various sites of Longfeng wetland, including swamp wetland (SW), meadow wetland (MW), woodland (WL), farmland (FL), and alkaline land (AL). High-throughput sequencing followed by bioinformatic analysis was conducted to evaluate the structure, composition, and function of soil bacterial and fungal communities. The most dominant bacterial and fungal phylum among the land-use types were Proteobacteria and Ascomycota, respectively. In addition, the bacterial diversity and functions varied significantly across different land-use types. However, no remarkable differences in fungal communities were observed under various land-use types. Edaphic parameters, including exchange sodium percent (ESP) and total nitrogen (TN), remarkably influenced the abundance and diversity of soil microbial communities. These results show that land-use type shapes various aspects of soil microbial communities, including soil physicochemical properties, microbial taxa structure, potential functional genes, and correlation with environmental factors. This study provides reliable data to guide land use management and supervision by decision-makers in this region.

Assessment of Changes in Key Ecosystem Factors and Water Conservation with Remote Sensing in the Zoige

As the largest alpine peat swamp wetland distribution area in the world, the Zoige has important ecological functions, including water conservation and biodiversity maintenance. In the past 20 years, the regional ecological protection and restoration measures continuously strengthened under the leadership of the local government have led to gradual improvements in the ecological environment of the region. In this study, multisource satellite remote-sensing image data were used to carry out quantitative monitoring and assessment of the main ecological elements (vegetation and water), as well as the regional leading ecosystem service function in the Zoige. Combined with local ecological protection management policies and measures, we analyzed the characteristics and effectiveness of ecological protection. We compared the ecosystem change trends of the Zoige reserve and the county, from 2001 to 2020, and found that the fractional vegetation cover (FVC) of Zoige county has increased at a rate of 0.25%/year. The growth rate was highest between 2015 and 2020, and the growth rate of FVC in the Zoige Wetland National Nature Reserve is approximately 1.89-fold that of the whole county. The water area also shows similar variation characteristics. On the whole, the water conservation capacity of the Zoige showed a significant increase from 2001 to 2020. We used high-resolution satellite remote-sensing images to capture the details of land use changes brought about by local ecological protection policies and measures, and together with macroecological indicators, we reflected on the effectiveness of regional ecological protection measures. We observed that the ecological effects of nature reserves are more direct and rapid, and the amount of water conservation within the nature reserve is about 1 × 104 m3/km2 higher than that of the surrounding grasslands. Satellite remote-sensing images can not only capture the multiscale change information of ecological indicators, such as vegetation and water, in a timely manner, but can also help us to identify the effectiveness of conservation measures by distinguishing and analyzing the causes of these changes.

Current situation and protection countermeasures of wetland resources in Shaanxi

In order to guide the management, protection and utilization of wetlands in Shaanxi Province, this paper analyzes and summarizes the current situation and existing problems of the protection and utilization of wetland resources in Shaanxi Province, and puts forward suggestions accordingly. There are 4 wetlands and 12 wetland types in Shaanxi Province, 308,500 hectares. The area and proportion of various wetlands are 257,600 hectares of river wetlands, 83.50%; 32,300 hectares of artificial wetlands, 10.46%; 7,600 hectares of lake wetlands, 2.46%; and 11,000 hectares of swamp wetlands, 3.58%. There are 77 families, 207 genera, 341 species and 3 varieties of wild vascular plants in the wetland, including 2 species of key wild protected species at the national level and 4 species at the provincial level. In view of the problems in the protection and utilization, such as the collaborative mechanism has not been established, the resource background has not been completely clear, and the investment is insufficient, we should build a scientific and appropriate wetland evaluation index system in Shaanxi Province, carry out the investigation and evaluation of wetland resources in the province, continue to carry out wetland ecological restoration and reconstruction projects, establish and improve wetland protection management and technical system, and formulate the protection and utilization direction of different types of wetlands.

Sedimentary environment and relative sea level changes revealed by marine biological membrane

Marine pollution has a deleterious impact, both on the conditions of the ecosystem and the biodiversity of the ocean. Researchers in the field of marine chemistry have been putting effort into the creation of efficient catalysts for the purification of seawater. There has been extensive research done on membrane technology for the activation of peroxymonosulfate, which is an extremely effective therapy for saltwater. The sediment of QX03, which was obtained from the western coast of Bohai, is located very close to the modern coastline. The uppermost 15 m of this sector were thoroughly analyzed in sedimentary petrology, grain size, shell, and sediment chroma dating to reconstruct the sedimentary environment and relative sea-level during the time period of 44.80 ka cal BP. This indicates that a sea-retreating and retreating process has taken place; VI (5.2–0 m), Terrestrial deposition, is separated into swamp wetlands (VI-1) and flood plain (VI-2). The changes in sedimentary levels had a fairly strong correlation with the changes in sea level. Within the scope of this study, we conducted an in-depth investigation of the innovative membrane technology for the treatment of seawater by means of aqueous phase advanced oxidation close to the Bohai. The results of this study present a prospective technique that could make it possible to use membrane technology in the process of environmental restoration in marine settings.

Spatio-Temporal Variations and Socio-Economic Driving Forces for Wetland Area Changes: Insights from 2008–2017 Data of Yunnan Province, China

An in-depth understanding of the associations between variations in the wetland area and socio-economic driving forces is essential owing to rapid urbanization. However, to date, no study has performed a quantitative study on the relationships between spatio-temporal patterns for wetland area variations and socio-economic driving factors in Yunnan Province. Based on Statistical Yearbook data, we found that during 10 years, different types of wetlands exhibited different change rates, with obvious spatial heterogeneity. The overall increase in wetland area in Yunnan Province was 13.35%, of which the increases in river, lake, and swamp wetland areas were 46.39%, −3.12%, and 295.56%, respectively. At the city level, the maximum decrease and increase in total wetland area were noted in Xishuangbanna (−84.30%) and Diqing (+185.22%), respectively. A total of 9 of 24 factors which were further selected according to collinearity diagnostics might help interpret changes in the wetland area of Yunnan Province according to the regression analysis results (R2 = 0.749, p < 0.01). Moreover, in different city development periods, the key socio-economic factors were different, which should be considered separately when formulating policies. Our results may clarify the socio-economic influencing factors for wetland spatio-temporal changes and help to guide policymakers.

Effects of water levels in heterogeneous habitats on sexual reproductive allocation of Deyeuxia angustifolia.

Taking Deyeuxia angustifolia as the research object, a representative plant of wetland in Sanjiang Plain, we analyzed the variations of individual size and biomass among the habitats of swamp wetlands, swampy meadows, typical meadows and miscellaneous grass meadows, and the relationship between reproductive components and plant biomass. We explored the effects of water level on individual biomass and reproductive allocation of D. angustifolia in different types of wetlands. The results showed that plant biomass, height and the characteristics of sexual reproduction significantly decreased with the increases of water level. The reproductive thresholds of D. angustifolia in miscellaneous grass meadow, typical meadow, swampy meadow, and swamp wetland were 0.245, 0.149, 0.148 and 0.157 g, respectively. There was a significantly negative correlation between plant size and reproductive allocation in three habitats except swampy meadow. Compared with individual size, soil water content had a stronger effect on reproductive allocation of D. angustifolia. The different investment between individual size and reproductive allocation in different habitats was the basic condition that contributes to the good ecological adaptability of D. angustifolia.

Phytoplankton in Mitika Wetland, Tibet, China:2. Characteristics of functional groups and their relationship with environmental factors

为揭示青藏高原湿地浮游植物功能群时空分布特征与环境因子的关系,本文于2019年7月(丰水期)和2019年10月(枯水期)在麦地卡湿地调查浮游植物功能群组成和生物量,并运用Spearman相关性分析、冗余分析(RDA)和典范对应分析(CCA)等方法,对麦地卡湿地浮游植物功能群时空分布特征及其与环境因子的关系进行分析.结果表明:1)根据功能群分类方法,麦地卡湿地浮游植物可划分为27个功能群,分别为A、B、C、D、E、F、G、H1、J、K、L_M、L_O、M、MP、N、P、S1、S2、T、T_B、T_C、W1、W2、X1、X2、X3和Z;在时间维度上,丰水期有26个功能群,枯水期有23个功能群;在空间维度上,河流湿地有24个功能群,湖泊湿地有23个功能群,沼泽湿地有12个功能群.2)丰水期,以功能群A、D、L_M、L_O、MP、N、P、T、T_B和X3为主,枯水期以功能群A、D、J、L_M、L_O、MP、N、P、T和T_B为主,其中A和T功能群为2个水情期的共有绝对优势功能群,功能群J仅为枯水期的绝对优势功能群.3)生态状态指数(Q)范围为1.80～4.86,平均值为3.80,表明麦地卡湿地水质状态为“好”.4)相关性分析表明,浊度、COD_Cr、总磷和硝态氮与部分优势功能群生物量具有显著相关性;RDA分析表明,盐度和总氮是影响丰水期优势功能群生物量的主要环境因子.CCA分析表明,总氮和硝态氮是影响枯水期优势功能群生物量的主要环境因子.;In order to reveal the relationship between temporal and spatial distribution characteristics of phytoplankton functional groups and environmental factors in Qinghai-Tibet Plateau in wetlands, the composition and biomass of phytoplankton functional groups were investigated in the Mitika Wetland in July 2019 (wet season) and October 2019 (dry season). The Spearman correlation analysis, redundancy analysis (RDA) and canonical correspondence analysis (CCA) were used to analyse the temporal and spatial distribution characteristics of phytoplankton functional groups and their relationship with environmental factors in the Mitika Wetland. The results showed that:1) According to the functional group classification method, the phytoplankton in the Mitika Wetland can be divided into 27 functional groups, which were A, B, C, D, E, F, G, H1, J, K, L_M, L_O, M, MP, N, P, S1, S2, T, T_B, T_C, W1, W2, X1, X2, X3, Z. In the time dimension, there were 26 functional groups in the wet season, 23 functional groups in the dry season. In the spatial dimension, there were 24 functional groups in river wetland, 23 functional groups in lake wetland and 12 functional groups in swamp wetland. 2) In the wet season, functional groups A, D, L_M, L_O, MP, N, P, T, T_B and X3 dominated. In the dry season, functional groups A, D, J, L_M, L_O, MP, N, P, T and T_B dominated. Functional groups A and T were the common absolute dominant functional groups in two hydrological periods, and functional group J was the absolute dominant functional group only in dry period. 3) Ecological status index values ranged from 1.80 to 4.86, with an average value of 3.80, indicating that the water quality of the Mitika Wetland was good. 4) Correlation analysis showed that turbidity, COD_Cr, total phosphorus and nitrate nitrogen were significantly correlated with the biomass of partial dominant functional groups. RDA analysis showed that salinity and total nitrogen were the main environmental factors affecting the biomass of dominant functional groups in the wet season. CCA analysis showed that total nitrogen and nitrate nitrogen were the main environmental factors affecting the biomass of dominant functional groups in the dry season.