Research on Wetland Restoration Technology and Design in Resource-exhausted Areas

Due to the lack of restrictions on the exploitation and use of coal mine resources in early China,many wetland lakes were formed because of the changes in geological structure and groundwater overflows,which seriously damaged the land for production and construction.At present,the research on the key technologies and landscape design of water ecosystems and wetland repair in subsidence areas is still insufficient.By analyzing the current situation of thePan'an Lake Wetland,this paper focuses on the strategies of wetland repair and landscape design in this resource-exhausted area.Further,it discusses the enlightenment of these strategies for transforming and planning similar areas in China.

Isotopic evidence for soil water sources and reciprocal movement in a semi-arid degraded wetland:Implications for wetland restoration

Understanding water dynamics is a prerequisite for the restoration of degraded ecosystems in arid and semiarid regions.In this study,we carried out δD and δ^(18)O analyses of precipitation,unsaturated soil water,overland flow,surface runoff,and groundwater samples from a seasonally flooded wetland in the Momoge National Nature Reserve of the Songnen Plain,Northeast China,to identify the water sources and understand the mechanisms of unsaturated soil water movement.Unsaturated soil water content(W/W%)at every 20 cm along with a soil profile(0–100 cm)was collected during the growing season,and the HYDRUS-1D model was used to simulate temporal-spatial variations.The results showed that the local meteoric water line(δD=5.90δ18O-7.34,R2=0.95)had a smaller slope and intercept than the global meteoric water line because of strong evaporation at our study site under semi-arid climate.The groundwater was partly recharged by local precipitation via overland flow and unsaturated soil water infiltration.Unsaturated soil water was sourced from both precipitation and groundwater with variations at different depths.The upper soil layer at 0–15 cm was mainly sourced from limited precipitation,while the groundwater could move up to a 25 cm layer during the dry period.The unsaturated soil water content increased with soil depth in the top 40 cm,decreased at depths of 40 to 80 cm,and increased again at depths of 80 to 100 cm.The HYDRUS-1D model could simulate the unsaturated soil water dynamics well in the upper(0–40 cm)and lower(80–100 cm)sections,but poorly for depths of 40–80 cm due to the upward and downward flow.The bidirectional unsaturated soil water movement highlights the importance of capillary groundwater for wetland plants with similar climatic or hydrogeological conditions.

Phosphorus release: A biogeochemical insight from a restored lakeside wetland in the Yangtze-Huaihe region, China

The heavy intensification of agriculture in East China since the 1980s caused the decrease of lake area and water storage capacity with impediment of regulation, lake eutrophication and frequent floods. Many restoration projects have been conducted. However, the knowledge of biogeochemical factors that drive nutrient cycles during the early stage of restoration is still limited. We studied the effect of the remediation of a patch of near-shore shallow wetland on the northern bank of Chaohu Lake in the Yangtze-Huaihe region, China, which was used as rice paddy for many years, on the behavior of phosphorus. Redox potential （ORP）, temperature and dissolved oxygen were monitored in situ from May 2006 to November 2007. Samples of soil pore water were collected during this time for the determination of different forms of iron and phosphorus. ORP showed a clear transition of the wetland soil from an oxidized state in winter to a reduced state in summer. The decrease of ORP correlated with the release of large amounts of Fe and P. The maxima of total dissolved Fe and total dissolved P in the summer of the second year were （13.8 ± 6.8） mg/L and （0.88 ± 0.27） mg/L, respectively. It is worth noticing that P concentration far exceeded the critical value of lake eutrophication （0.02 mg/L）. The pressure of P release to the adjacent lake during the first two years of wetland restoration from rice fields should be taken into account by environmental policy makers.

Changes of plant species diversity and biomass with reclaimed marshes restoration

Wetland restoration had been implemented for more than two decades in Sanjiang Plain,Northeast China.To assess the restoration effi ciency of wetland vegetation,we investigated plants composition of community,plant species diversity and aboveground biomass of restored sites in a chronosequence of restoration(1,2,3,6,8,11,15 and 25 years)in the Sanjiang Nature Reserve.As comparison,we also investigated the same factors in a cropland and a natural marsh adjacent to the restored sites.The results showed that wetland plant species can invade quickly after croplands were abandoned when there were suitable hydrology conditions.On the early stage of the restoration,weeds were main plant species in the restored sites.Wetland species appeared at the same time but diff ered from the dominant species from the adjacent natural marshes.Common native wetland species could dominance the community after 3-year restoration.Species richness and diversity increased on the early stage,and then decreased to the similar level of the natural marsh with the extension of restoration.Plant biomass could restore easier than the species composition and diversity.Our results indicated that plant species composition and diversity of abandoned reclaimed wetlands can restore gradually by natural succession in Sanjiang Plain.However,25-year restoration site had similarity index of only 56%with the natural marsh,which revealed that two decades are not enough for complete restoration of vegetation.

Soil Carbon, Nitrogen and Phosphorus Concentrations and Stoichiometries Across a Chronosequence of Restored Inland Soda Saline-Alkali Wetlands, Western Songnen Plain, Northeast China

Soil carbon(C), nitrogen(N) and phosphorus(P) concentrations and stoichiometries can be used to evaluate the success indicators to the effects of wetland restoration and reflect ecosystem function. Restoration of inland soda saline-alkali wetlands is widespread, however, the soil nutrition changes that follow restoration are unclear. We quantified the recovery trajectories of soil physicochemical properties, including soil organic carbon(SOC), total nitrogen(TN), and total phosphorus(TP) pools, for a chronosequence of three restored wetlands(7 yr, 12 yr and 21 yr) and compared these properties to those of degraded and natural wetlands in the western Songnen Plain, Northeast China. Wetland degradation lead to the loss of soil nutrients. Relative to natural wetlands, the mean reductions of in SOC, TN, and TP concentrations were 89.6%, 65.5% and 52.5%, respectively. Nutrients recovered as years passed after restoration. The SOC, TN, and TP concentrations increased by 2.36 times, 1.15 times, and 0.83 times, respectively in degraded wetlands that had been restored for 21 yr, but remained 29.2%, 17.3%, and 12.8% lower, respectively, than those in natural wetlands. The soil C∶N(RC N), C∶P(R CP), and N∶P(R NP) ratios increased from 5.92 to 8.81, 45.36 to 79.19, and 7.67 to 8.71, respectively in the wetland that had been restored for 12 yr. These results were similar to those from the natural wetland and the wetland that had been restored for 21 yr(P > 0.05). Soil nutrients changes occurred mainly in the upper layers(≤ 30 cm), and no significant differences were found in deeper soils(> 30 cm). Based on this, we inferred that it would take at least 34 yr for SOC, TN, and TP concentrations and 12 yr for RC N, R CP, and RN P in the top soils of degraded wetlands to recover to levels of natural wetlands. Soil salinity negatively influenced SOC(r =-0.704, P < 0.01), TN(r =-0.722, P < 0.01), and TP(r =-0.882, P < 0.01) concentrations during wetland restoration, which indicates that reducing salinity is beneficial to SOC, TN, and TP recovery. Moreover, plants were an important source of soil nutrients and vegetation restoration was conducive to soil nutrient accumulation. In brief, wetland restoration increased the accumulation of soil biogenic elements, which indicated that positive ecosystem functions changes had occurred.

The Countermeasures of Ecological Rehabilitation in Jinghe National Wetland Park

By analyzing the ecological status of Jinghe National Wetland Park of Qinggang,Heilongjiang,the countermeasures of ecological rehabilitation in Jinghe National Wetland Park are put forward.

Soil fauna diversity at different stages of reed restoration in a lakeshore wetland at Lake Taihu,China

Introduction:Wetland soil fauna support material cycling and restoration processes in wetland ecosystems.In our study,we observed variations in wetland soil fauna on the shores of Lake Taihu,China.We examined the relationships between fauna and major environmental factors,and looked at the short-and long-term changes in reed wetlands under restoration and in the natural reed lakeshore.Outcomes:We identified 93 groups of soil fauna in different wetlands and found significant differences in the lakeshore wetlands’soil fauna assemblages,depending on the length of the restoration period.By analyzing the soil fauna community evenness,dominance,number of taxa,and diversity,we found minimal seasonal variation in the soil fauna community diversity and abundance.The abundance of soil fauna in the sites under restoration decreased with depth below the soil surface.The reed restoration was obvious in the succession of the soil fauna groups in the long-term site.Although the restoration had an overall positive long-term effect on the soil fauna communities,there were no obvious short-term changes in the number of individuals.Conclusion:The study explored various potential measures to restore soil fauna in the Lake Taihu wetland and developed a theoretical basis for restoring the lakeshore wetland ecosystem.

Application of Arbuscular Mycorrhizal Inocula Might Be A Promising Method in the Restoration of Severely Degraded Wetlands

The application of arbuscular mycorrhizal (AM) inocula in severely degraded wetlands could ensure success in restoration.Mycorrhizal fungi play an important role in plant individual's survival and development in a low nutrient condition.Based on the importance that mycorrhizal fungi have to their host plants,mycorrhizal inocula have been produced and applied in terrestrial ecosystems in order to let the plants become mycorrhizal.However,mycorrhizal inocula have not been used in wetland restorations,despite increasing evidence that mycorrhizal fungi are commonly found in various wetland systems and have the ability to survive under anoxic conditions.Evidence also shows that mycorrhizal fungal inocula in the soil could have been destroyed in the degraded wetland or could be destroyed during traditional wetland restoration process.Therefore,AM inocula production is strongly recommended for wetland restoration.In this paper,I will argue that AM inocula production is required when introduced recovery is necessary,and aeroponic culture technique is a preferable method to produce AM inocula.Last,a renewed wetland restoration flow chart is summarized.

中国湿地保护修复管理经验与未来研究趋势

Wetlands are important natural resources for humans and play an irreplaceable ecological function in the terrestrial ecosystem.To curb the continued loss of wetlands globally,international organizations and many countries have taken a series of major conservation and restoration measures.This work reviews these wetland conservation and restoration measures,interprets China’s wetland conservation and restoration management policies,and proposes that future research on wetland resources in China should be conducted from the aspects of international frontiers and national strategic plans,socioeconomics,and smart services.The results show that the 27 International Wetlands Days from 1997 to 2023 provided new goals and tasks for the protection and management of wetlands.The important topics and outcomes of the 14 Conferences of the Contracting Parties to the Convention on Wetlands from 1980 to 2022 provided new directions and new challenges for wetland development.In the future,we should enhance wetland ecological functions,promote sustainable wetland development,and overcome the technical bottleneck of fragile wetland ecosystem restoration.From 1992 to 2022,China embarked on a new phase of wetland protection and restoration.The overall experience of wetland protection and restoration in China has been formed through national strategic deployment,legal policy establishment,and project planning and implementation.The needs to provide for and plan the long-term protection of wetlands at the national level,to innovate restoration and management techniques and application systems,and to effectively address the complex issues of wetland protection and restoration through collaborative division of labor among multiple departments were emphasized.Research on the future trends of wetlands should be directed towards the exploration and practice of the United Nations Sustainable Development Goals and several international conventions in support of sustainable wetland development.Wetland protection,restoration,and management services should be promoted for national strategic needs and local,high-quality social and economic development.In addition,research on cross-integration and academic innovation should be enhanced for disciplinary development,global supervision,comprehensive assessment,and smart decision making.

Restoring Wetlands

FERTILE LAND:The Qixing River Wetland in Heilongjiang Province was recently named a wetland of international importance at the Sixth Asian Wetland Symposium held in Wuxi City, east China’s Jiangsu Province, on October

Effects of salinity and clonal integration on the amphibious plant Paspalum paspaloides:growth,photosynthesis and tissue ion regulation

Aims Clonal integration can increase performance of clonal plants suffer-ing from environmental stress,and clonal plants in many wetlands commonly face stress of flooding accompanied by salinity.However,few studies have tested roles of clonal integration in amphibious plants expanding from terrestrial to aquatic saline habitats.Methods Basal(older)ramets of clonal fragments of Paspalum paspaloides were grown in soil to simulate terrestrial habitats,whereas their apical(younger)ramets were placed at the surface of saline water containing 0,50,150 and 250 mmol l^(−1)NaCl to mimic different salinity levels in aquatic habitats.Stolons connecting the apical and basal ramets were either intact(connected)to allow clonal integra-tion or severed(disconnected)to prevent integration.Important Findings Increasing salinity level significantly decreased the growth of the apical ramets of P.paspaloides,and such effects on the leaf growth were much higher without than with stolon connection after 60-day treatment.Meanwhile,leaf and total mass ratios of the connected to the disconnected apical ramets were higher at high than at low saline treatments.Correspondingly,Fv/Fm and F/Fm′of the apical ramets were higher with than without stolon connection in highly saline treatments.The results suggest that clonal integration can benefit the spread of apical ramets from terrestrial soil into saline water,and that the positive effects increase with increasing salinity.However,clonal integration did not significantly affect the growth of the whole frag-ments.Due to clonal integration,Na^(+)could be translocated from the apical to the basal ramets to alleviate ion toxicity in apical ramets.Our results suggest that clonal integration benefits the expansion of P.paspaloides from terrestrial to aquatic saline habitats via maintained photosynthetic capacities and changed biomass allocation pattern.