Celebrating 25 Years of World Wetlands Day

The purpose of this Special Issue is to celebrate 25 years of “World Wetlands Day”. There is no other ecosystem that has its very own Ramsar Convention or such a challenge impacting ecosystem sustainability. Papers for this Special Issue provide an overview of wetland status and function within different regions of the world. The papers in this Special Issue of Land consist of three review papers, ten research articles and one perspective paper. Edward Maltby’s review paper provides us with an overview of the paradigm shift of how we value and assess wetlands over time. Ballut-Dajud et al. provide us with a worldwide perspective on factors affecting wetland loss. Finally, Jan Vymazal provides us with a historical overview of the development of water quality treatment wetlands in Europe and North America. The research papers can be grouped into four groups: 1) use of remote sensing to analyze stability and dynamic factors affecting wetlands; 2) factors affecting the wetlands’ ability to store carbon; 3) assessment of wetlands effect on water quality; and 4) understanding historical use and value of wetlands, farmer’s attitudes about wetland management, and how we can value wetland ecosystem services. Finally, Bryzek et al. remind us that, as wetland researchers and managers, we should minimize damage to wetlands even through field monitoring work

Computational study of hydro-environmental processes of Poyang Lake, China

Poyang Lake, the largest freshwater lake in China, plays a key role in regulating the hydrology, water quality and ecosystem in the middle reaches of the Yangtze River. Recent industrial development and urbanization in Jiangxi province have driven rapid increase in water consumption and deterioration of water quality, exerting pressure on water utilization in the Poyang Lake basin. In order to set up an integrated water management framework for the protection of Poyang Lake’s ecosystem and surrounding communities, an accurate and representative evaluation of the hydraulic and environmental challenges is vital. In this research, a numerical model is developed and utilized to simulate the hydrodynamics and water quality of Poyang Lake and its surrounding river networks. The study couples an in-house 1-D river network hydrodynamic and mass transport model together with a 2-D MIKE hydrodynamic and water quality model. The model is validated against field-measured data from the local water authorities. The impact of the proposed downstream barrage on Poyang Lake’s hydrodynamics and water quality is then investigated. It is concluded that: the establish integrated model is capable of simulating the hydrodynamic and water-quality processes of the Poyang Lake to satisfactory degrees; and the operation of proposed barrage has large effects on the nutrients distribution and water resources availability. The findings of the study contribute to a better understanding of the fate of Poyang Lake’s pollutants and the influence of the proposed hydraulic projects on the lake’s flow and ecosystem. Many of these findings are relevant to large freshwater lakes in other developing countries and could contribute to the fields of water engineering and water management

Afforestation and Reforestation: Drivers, Dynamics, and Impacts

Afforestation/reforestation (or forestation) has been implemented worldwide as an effective measure towards sustainable ecosystem services and addresses global environmental problems such as climate change. The conversion of grasslands, croplands, shrublands, or bare lands to forests can dramatically alter forest water, energy, and carbon cycles and, thus, ecosystem services (e.g., carbon sequestration, soil erosion control, and water quality improvement). Large-scale afforestation/reforestation is typically driven by policies and, in turn, can also have substantial socioeconomic impacts. To enable success, forestation endeavors require novel approaches that involve a series of complex processes and interdisciplinary sciences. For example, exotic or fast-growing tree species are often used to improve soil conditions of degraded lands or maximize productivity, and it often takes a long time to understand and quantify the consequences of such practices at watershed or regional scales. Maintaining the sustainability of man-made forests is becoming increasingly challenging under a changing environment and disturbance regime changes such as wildland fires, urbanization, drought, air pollution, climate change, and socioeconomic change. Therefore, this Special Issue focuses on case studies of the drivers, dynamics, and impacts of afforestation/reforestation at regional, national, or global scales. These new studies provide an update on the scientific advances related to forestation. This information is urgently needed by land managers and policy makers to better manage forest resources in today’s rapidly changing environments

Effects of biodiversity on functional stability of freshwater wetlands: a systematic review

Freshwater wetlands are the wetland ecosystems surrounded by freshwater, which are at the interface of terrestrial and freshwater ecosystems, and are rich in ecological composition and function. Biodiversity in freshwater wetlands plays a key role in maintaining the stability of their habitat functions. Due to anthropogenic interference and global change, the biodiversity of freshwater wetlands decreases, which in turn destroys the habitat function of freshwater wetlands and leads to serious degradation of wetlands. An in-depth understanding of the effects of biodiversity on the stability of habitat function and its regulation in freshwater wetlands is crucial for wetland conservation. Therefore, this paper reviews the environmental drivers of habitat function stability in freshwater wetlands, explores the effects of plant diversity and microbial diversity on habitat function stability, reveals the impacts and mechanisms of habitat changes on biodiversity, and further proposes an outlook for freshwater wetland research. This paper provides an important reference for freshwater wetland conservation and its habitat function enhancement

Self-organizing map algorithm for assessing spatial and temporal patterns of pollutants in environmental compartments: A review

The evaluation of the spatial and temporal distribution of pollutants is a crucial issue to assess the anthropogenic burden on the environment. Numerous chemometric approaches are available for data exploration and they have been applied for environmental health assessment purposes. Among the unsupervised methods, Self-Organizing Map (SOM) is an artificial neural network able to handle non-linear problems that can be used for exploratory data analysis, pattern recognition, and variable relationship assessment. Much more interpretation ability is gained when the SOMbased model is merged with clustering algorithms. This review comprises: (i) a description of the algorithm operation principle with a focus on the key parameters used for the SOM initialization; (ii) a description of the SOM output features and how they can be used for data mining; (iii) a list of available software tools for performing calculations; (iv) an overview of the SOM application for obtaining spatial and temporal pollution patterns in the environmental compartments with focus on model training and result visualization; (v) advice on reporting SOM model details in a pape

Broad-Scale Patterns in CDOM and Total Organic Matter Concentrations of Inland Waters – Insights from Remote Sensing and GIS

The rise in CDOM (coloured dissloved organic matter) is likely to be relatively more pronounced in remote northern regions. However, there is a lack of monitoring to confirm this. For this reason, there is a strong incentive to develop remote sensing-based methods to map CDOM in lakes across broader geographical scales and to include geograghic contex in such analysis. There is a lack of understanding of the mechanisms behind changes in water colour (i.e. CDOM) at large scales. The CDOM variations could be due to varying drivers, such as climate and landscape patterns or catchment features. This means that currently, we do not know the extent to which aquatic ecosystems need conservation efforts, such as management of the surrounding vegetation, to prevent CDOM leakage. Thus, there is need to better understand the drivers behind CDOM changes in inland waters.Over the last few decades, remote sensing technologies and methods have developed dramatically for terrestrial ecosystems. Coupled with the broader availability of remote sensing data, free access to different data sources and the increased resolution of satellite platforms, remote sensing technology now has a significant impact on land monitoring. Due to the increasing demand for high-quality remote sensing data, the technology continues to improve, which makes remote sensing critical for reducing time and funding costs. Similar to these advances in terrestrial remote sensing, there is an increasing potential to provide information about inland waters by using remote sensing. For instance, recent advancements in designing remote sensors, such as the Landsat 8 operational land imager (OLI) and Sentinel-2 multispectral instrument (MSI), have solved past radiometric sensitivity issues and provide high spatial resolution. This thesis explored CDOM patterns on spatial and temporal scales. The overall aim was to investigate the capabilities of remote sensing (RS) and geographic information systems (GIS) to extend CDOM patterns from a regional to a broad scale. Different study sites in Europe, mainly Northern Scandinavia, including large numbers of lakes and rivers, were tested on different scales.The results shows how climate changes (from wet to dry) can result in a combination of changes in hydrology, vegetation type and productivity, which can lead to intra-annual variations in the CDOM of recipient waters. It is also shown that drought can temporarily decrease values of CDOM in boreal lakes. In addition, it is demonstrated that combining remote sensing and GIS tools is an effective way to reveal the impact of different catchment parameters and morphometry on lake CDOM concentration. Moreover, the thesis shows that utlizing long-term remote sensing records of CDOM from the last few decades is a successful approach to fill the gaps of the missing lake data from in situ assessments. Finally, the results helped to explore links between water browning and the organic matter degradation rates in temperate European rivers at a continental scale. In conclusion, this thesis demonstrates the pogential use of remote sensing for mapping CDOM in a wide range of inland waters that are situated in complex, inaccessible regions that are not well- monitored

Forest Management and Water Resources in the Anthropocene

Decades of research has provided a depth of understanding on the relationships among forests and water, and how these relationships change in response to climate variability, disturbance, and forest management. This understanding has facilitated a strong predictive capacity and the development of best management practices to protect water resources with active management. Despite this understanding, the rapid pace of changes in climate, disturbance regimes, invasive species, human population growth, and land use expected in the 21st century is likely to create substantial challenges for watershed management that may require new approaches, models, and best management practices. These challenges are likely to be complex and large scale, involving a combination of direct effects and indirect biophysical watershed responses, as well as socioeconomic impacts and feedbacks. We explore the complex relationships between forests and water in a rapidly changing environment, examine the trade-offs and conflicts between water and other resources, and examine new management approaches for sustaining water resources in the future

Assessing potential impacts of multiple stressors on riverine phytoplankton community by integrated models

Increasing pressures from both natural disturbance and anthropogenic activities challenge river ecosystem resilience. A better understanding of the ecological balancing of structure under multiple stressors is thus critical for sustainable future as well as human wellbeing. Phytoplankton are one of the important autotrophs in the river ecosystem. They are sensitively reflecting multiple filters. However, studies on how flow regime, land-use pattern, physicochemical condition and spatial factors overall affect the lotic phytoplankton community are still scarce. This study aims to examine riverine phytoplankton community structure in relation to combined abiotic gradients, and to consider the potential responses under changing status. Study area is located in a lowland catchment Treene, Germany. We establish an integrated modelling framework in combination of hydrological model with ecological models. The investigations show high spatial and temporal variations of phytoplankton community. Benthic diatom is dominant in most of the study area. Euglenophyta show higher existence percentage in the headwaters and exhibit a strong positive correlation to the share of agricultural land-use. Microcystis has found with high abundance downstream of a lake. Higher phosphorous concentration directly causes the increase of Microcystis population. Both species and traits composition more relate to hydrological and local physicochemical heterogeneity than to species dispersal, which confirm the suitability of lowland phytoplankton-based bioassessment in the study area. Due to the importance of flow regime in shaping pelagic algal community, it is necessary to include hydrological variables in biodiversity conservation. The shares of forest land-use area have outstanding explanation to the variation of species richness. Our findings emphasize the significance of preservation of forest area in protecting the aquatic algal biodiversity for maintaining the river ecosystem functioning