This special issue on wetland research in China contains 22 manuscripts covering wetland processes and functions, wetland techniques and methods, and wetland restoration and creation. The special issue was compiled on the occasion of the 10th INTECOL International Wetland Conference held in Changshu, China, during 19–24 September 2016. The manuscripts provide an evidence-base to support the calls made through The Changshu Declaration on Wetlands for the ongoing management and restoration of wetlands globally.

The present study shows that a constructed floating wetlands (CFWs) system planted with Chinese celery (Oenanthe javanica) is a viable option for nitrogen removal from waste water during the low-temperature season (mean water temperature <10°C) and that nitrogen removal is better from CFW systems with vesuvianite as a substrate than from those without a substrate.

This study systematically investigated the characteristics of P adsorption on the sediments of the intertidal zones in the Yellow River Delta. Salinity, pH and oxidation–reduction potential significantly affected the adsorption rate and amount of P adsorbed on the sediments in these zones. In addition, a predictive model for the P-adsorption capacity of sediments was developed. Together, the results could contribute to the restoration and management of intertidal zones.

Satellite image time series (Moderate Resolution Imaging Spectroradiometer, MODIS) data collected in 2001 and 2013 were used to monitor the long-term environmental changes in 20 Ramsar sites in China. The tremendous efforts of the Chinese government contributed to effective protection for most reserves. However, unfavourable environmental conditions for some reserves still existed, primarily due to increasing water requirements outside the reserves. Therefore, a balance between economic development and ecological protection will be important in the future.

Interspecific relationships were analysed using the Chi-Square test, Spearman rank correlation coefficient and Ward’s method of hierarchical clustering on field data collected from 4 plots and 160 quadrats. The results imply that exotic species can coexist with native species and become a common species composition when they have existed for a sufficient period of time in artificial wetland forests.

Identification and understanding of human-induced wetland changes is critical for wise wetland use. This study investigated wetland changes in a rare wetland system in a popular tourist destination visited by >5 million people per year. The high number of tourists and their movement in buses have probably caused water-related changes. Determining the appropriate number of visitors is crucial for the wise use of wetlands that are tourist destinations.

Concentrations of rare earth elements (REEs) in freshwater environments are rising, but very little information is available regarding the accumulation and toxicity of REEs. Aquatic plants are known to accumulate and bioconcentrate metals. The aim of the present study was to explore the molecular distribution and assess the toxicity of yttrium in Elodea canadensis. The results indicate that Y accumulation occurred along a gradient, with the highest accumulation in cell walls, and that Y accumulation destroyed organelles and damaged the antioxidant system. This work suggests that metabolic parameters appear to be promising biomonitors of Y toxicity in aquatic plants.

Carbon sequestration rates (CSRs) and their controlling factors were determined in the Yellow River delta (YRD) and Liaohe delta (LHD) wetlands. Organic CSRs at sites above mean sea level were virtually identical in the two wetlands, but organic CSRs were much more sensitive to changes in sediment accumulation rates in the LHD wetlands than in the YRD wetlands.

Thallium (Tl) is a highly toxic heavy metal, although the mechanisms underlying its toxicity are not completely understood. In this study we investigated the physiological responses of giant reed Arundo donax to Tl accumulation in a simulated wetland. The giant reed had strong tolerance to Tl pollution, and this can probably be attributed to its root rejection and amelioration of oxidative stress, which are involved in the mechanism of Tl toxicity.

The excessive presence of dams in river ecosystems causes a series of ecological problems. The present study explored the combined effects of multiple dams on macroinvertebrate metacommunity structure and found that the direct effects of dam by limiting dispersal were greater than the indirect effects by changing environmental conditions. The results provide a theoretical basis for biodiversity conservation in river ecosystems.

An understanding of trace metal pollution due to reclamation activities is important for coastal resource utilisation and management. In the present study, although the pollution status around Yancheng National Nature Reserve was not so serious, the potential hazards may pose big threat to coastal ecosystems. Robust monitoring and sustainable land reclamation practices should be considered in coastal areas.

Mangrove overgrowth could decrease biodiversity and increase flooding risk. Mangrove thinning has been proposed as a managerial action to solve this problem. This study found that medium thinning is the optimal strategy to meet the demand of reducing the loss of carbon sequestration capacity for mangrove management.

This study assessed greenhouse gas flux (methane and carbon dioxide) in the littoral area of a temperate reservoir. The eulittoral zone had the highest methane flux and the supralittoral zone had the highest carbon dioxide flux. The results provide suggestions for monitoring and management activities to decrease greenhouse gas emissions from reservoirs where changes in littoral areas are occurring.

We investigated the combined effects of low light and high ammonia-N stress on the submerged plant Vallisneria natans. The results suggest that the combination of ammonia-N enrichment and low light has a greater effect on submerged plants than emergent aquatic plants. We also document concentrations of ammonia-N that V. natans tolerates, with or without low light conditions, water ecological restoration.

This paper reveals the distribution features of carbon storage in Hainan Dongzhaigang mangrove wetlands in China. This study considered not only carbon storage in different communities, but also in different parts of the ecosystems. Over 80% of carbon was stored in wetland soil, and differences in carbon storage between most communities were significant.

The community structure and spatial distribution pattern of stream macroinvertebrates can reflect the health of river ecosystems. This study found that Oligochaete and Chironomidae, as representatives of pollution-tolerant species, were the dominant taxa in the study area, whereas species intolerant to polluted areas, such as Ephemeroptera, Plecoptera and Trichoptera, were rarely found. These results show that the study region is seriously polluted.

The relative importance of elevation, climatic and soil variables for Spartina alterniflora distribution was investigated across global, national and local scales using MaxEnt. The relative importance of different variables, as well as their relationship with species presence, changed across different scales. The decreasing suitable area is controlled by elevation from the global to national scale and by soil variables from the national to regional scale.

The present study reports that although constructed wetlands system planted or not with yellow iris (Iris pseudacorus) can remove nitrogen from saline waste water, elevated salinity inhibits nitrogen removal by suppressing the growth and activity of wetland plants, and by changing the microbe community composition in the substrate during the low-temperature season when the average water temperature is <10°C.

Alternanthera philoxeroides is a widespread invasive alien species in China. This study constructed a greenhouse experiment to investigate the relationship between A. philoxeroides and experimental wetland plant communities. The results suggest that both sediment type and nitrogen deposition promote A. philoxeroides growth performance and exacerbate A. philoxeroides invasion into communities. However, A. philoxeroides can increase the evenness of the wetland plant communities at a small scale by suppressing dominant species.

This study found that embankment construction in the coastal wetlands depresses the growth of smooth cordgrass and decreases leaf phosphorus content, possibly due to changes in soil salinity, moisture and organic carbon and nitrogen content. The results indicate that the decreased dry weight of the plants in the embankment-reclaimed marsh is likely to be correlated with an increase in the leaf N : P ratio.

Wetland treatment systems (WTSs) are popular for the deep purification of tailwater from sewage treatment plants (STPs). Various studies have investigated pilot constructed wetland systems, but less is known about large-scale WTSs. Thus, the aim of this study was to analyse the seasonal performance and management costs of a large-scale WTSs over the course of 1 year. The results suggest that WTSs could be used with STPs to improve waste water quality in a cost-effective manner.

Identification of the main sources of heavy metal contamination and description of their spatial distribution are essential for the control of river water pollution. In this study we investigated the concentrations and main sources of heavy metals in river waters of the Huaihe River Basin, finding significant regional variation in concentrations. These findings will help in the development of appropriate strategies for water resource management.

Plants have tight connections with microbes, especially in aquatic systems. This study investigated plant growth attributed to carbon conversion in an underwater plant–microbe interaction process. A carbon and oxygen microcycle was found between Vallisneria natans and Pseudomonas putida that may increase carbon availability to promote growth in both plant and microbe. Furthermore, the CO₂ produced by microbes may be an important source of carbon for plant underwater photosynthesis.