Northeast Institute of Geography and Agroecology, Chinese Academy Of Sciences
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High-efficiency breeding of early-maturing rice cultivars via CRISPR/Cas9-mediated genome editing
No full textLongitudinal and lateral variation in snail assemblages along a floodplain continuum
No full textEmerging theory suggests that biotic communities in floodplain wetlands should change longitudinally along a river's length and be affected by lateral connectivity of floodplain habitats with main river channels. However, useful invertebrate indicators of floodplain condition remain poorly developed. Snails as a group possess several attributes that should make them useful as potential environmental indicators. In this study, we sampled snail assemblages in 12 floodplain wetlands along Wusuli River (headwater, mid, and downstream reaches) in Northeastern China's Sanjiang Plain. In addition, at 10 sites, comparisons between river-connected and levee-isolated wetlands were performed. Results demonstrated that snail assemblages were concurrently being impacted by river reach, and whether the wetlands were isolated from the river, or not. Using multivariate analyses, the studied wetlands were divided into three major groups based on snail assemblages: downstream, mid, and headwater reaches. Seven snail species were significant indicators of these wetland groups. Because snail assemblages vary strongly both longitudinally along and laterally across floodplain habitats of Northeastern China, management of floodplains should recognize that landscape position plays an important role in local habitat ecologies, and that efforts to limit hydrologic connectivity across floodplains will have important consequences for resident biota
Carbohydrate metabolism during new root growth in transplanted Larix olgensis seedlings: post-transplant response to nursery-applied inorganic fertilizer and organic amendment
No full textSustainable agriculture often requires the incorporation of organic matter into cultural protocols as an amendment to mitigate problems caused by chemical inputs, but the responses of transplanted seedlings to such additions have not been well quantified. In this study, bare-root Changbai larch (Larix olgensis Henry) seedlings were applied with 100 or 200 kg nitrogen (N) ha(-1) of inorganic fertilizer with or without chicken manure added at a rate of 10,000 kg ha(-1) during nursery cultivation, obtaining four treatment combinations designated as F100+, F200+, F100-, and F200-, respectively. Over-winter seedlings were transplanted into pots and placed in a growth chamber, where the carbohydrate metabolism, biomass accumulation, root respiration, and new root number were quantified. Both initial soluble sugar and total non-structural carbohydrate (TNC) accumulation were the lowest in the F100+ treatment. However, two months later, root soluble sugar content was the highest in this treatment, while coarse-root (diameter > 2mm) carbohydrate content was the highest in the low rate of inorganic fertilizer treatment. During the two-month post-transplant period, the net carbohydrate accumulation rate (NCAR) for starch was negative for all treatments, but the NCAR value for soluble sugars was the highest in the F100+ treatment at both the root and whole-plant scales. Relative to the F200- treatment, the NCAR value for soluble sugars, final sugar content, and biomass accumulation in coarse roots, respiration rate of fine roots (diameter <= 2 mm), and new root number were all greater in the F100+ treatment, while new root number was increased by organic matter additions. In conclusion, the use of chicken manure as an organic amendment had the potential to enhance transplanted larch seedling performance by improving post-transplant new root number, but this application must be considered within the context of the interaction between organic amendment treatments and inorganic fertilizer applications
The Effect of Urban Green Spaces on the Urban Thermal Environment and Its Seasonal Variations
No full textUrban green spaces have been shown to decrease land surface temperature (LST) significantly. However, few studies have explored the relationships between urban green spaces and LST across different seasons at different spatial scales. In this study, using Changchun, China as a case study, landscape ecology and comparative approaches were employed quantitatively to investigate the effects of the composition and configuration of urban green spaces on the urban thermal environments. LST maps were retrieved from Landsat 8 Thermal Infrared Sensor (TIRS) data acquired on four dates that represented four different seasons, and detailed information of urban green spaces was extracted from high resolution imagery GF-1. Normalized differential vegetation index (NDVI) and six landscape metrics at patch, class, and landscape level were used to characterize the spatial patterns of urban green spaces. The results showed that urban green spaces did have significant cooling effects in all seasons, except for winter, but the effects varied considerably across the different seasons and green types, and seemed to depend on the NDVI and size of urban green spaces. Compared to shape metrics, the negative relationships between the LST and the area and the NDVI of urban green spaces were more significant. Both the composition and configuration of urban green spaces can affect the distribution of LST. Based on findings with one city, given a fixed area of urban green spaces, the number of green patches can positively or negatively affect the LST, depending on if the number is larger than a threshold or not, and the threshold varies according to the given area. These findings provide new perspectives, and further research is also suggested, to generate a better understanding of how urban green spaces affect the urban thermal environment
Removal of Nitrogen and Phosphorus from Fluctuating Degraded Riverine Wetland Water Using Sphagnum Floating Bed
No full textRiverside wetland in the lower reaches of Songhua River has suffered intense damage resulting in rapid degeneration of the water purification system related to human destruction and water pollution. Violent fluctuations in water levels may lead to worsening water quality effects and destruction of plant growth. Ecological floating beds provide an effective way to overcome the problems, yet limited information regarding Sphagnum purification has been obtained in the open water environment. The ability of Sphagnum survival and its correlation to nutrients enrichment in violently fluctuating riverside wetland water as applied to the ecological floating bed are investigated in this study. Ecological floating beds, with Sphagnum fallax and Sphagnum squarossum, were chosen for nitrogen (N) and phosphorus (P) enrichment. The results indicated that changes of water quality (high N low P, low N high P) resulting from water level fluctuations in test areas were beneficial for the survival of Sphagnum species, especially in flood periods that high carbon content of water could effectively stimulate the growth of Sphagnum species. Following four months of field tests, the amounts of N and P enrichment in Sphagnum squarossum were 2.29 and 0.82 mg/g dry weight, respectively, while in Sphagnum fallax were 1.98 and 0.64 mg/g dry weight. N enrichment was superior to P for both Sphagnum moss types. The release of nutrients, especially P, can be controlled effectively by harvesting Sphagnum species in early winter. This study could be useful for improved understanding of water restoration in violent fluctuating degraded riverine wetland by eutrophic Sphagnum mosses
Spatial Expansion and Soil Organic Carbon Storage Changes of Croplands in the Sanjiang Plain, China
No full textSoil is the largest pool of terrestrial organic carbon in the biosphere and interacts strongly with the atmosphere, climate and land cover. Remote sensing (RS) and geographic information systems (GIS) were used to study the spatio-temporal dynamics of croplands and soil organic carbon density (SOCD) in the Sanjiang Plain, to estimate soil organic carbon (SOC) storage. Results show that croplands increased with 10,600.68 km(2) from 1992 to 2012 in the Sanjiang Plain. Area of 13,959.43 km(2) of dry farmlands were converted into paddy fields. Cropland SOC storage is estimated to be 1.29 +/- 0.27 Pg.C (1 Pg = 10(3) Tg = 10(15) g) in 2012. Although the mean value of SOCD for croplands decreased from 1992 to 2012, the SOC storage of croplands in the top 1 m in the Sanjiang Plain increased by 70 Tg.C (1220 to 1290). This is attributed to the area increases of cropland. The SOCD of paddy fields was higer and decreased more slowly than that of dry farmlands from 1992 to 2012. Conversion between dry farmlands and paddy fields and the agricultural reclamation from natural land-use types significantly affect the spatio-temporal patterns of cropland SOCD in the Sanjiang Plain. Regions with higher and lower SOCD values move northeast and westward, respectively, which is almost consistent with the movement direction of centroids for paddy fields and dry farmlands in the study area. Therefore, these results were verified. SOC storages in dry farmlands decreased by 17.5 Tg.year(-1) from 1992 to 2012, whilst paddy fields increased by 21.0 Tg.C.year(-1)
Identifying the Salinity Thresholds that Impact Greenhouse Gas Production in Subtropical Tidal Freshwater Marsh Soils
No full textIncreasing salinity due to sea level rise is an important factor influencing biogeochemical processes in estuarine wetlands, with the potential to impact greenhouse gas (GHG) emissions. However, there is little consensus regarding what salinity thresholds will significantly alter the production of GHGs or the physiochemical properties of wetland soils. This study used a fine-scale salinity gradient to determine the impact of seawater concentration on the potential production of CH4, CO2 and N2O and associated soil properties using bottle incubations of tidal freshwater marsh soils from the Min River estuary, SE China. Potential CH4 production was unaffected by salinities from 0 to 7.5 parts per thousand, but declined significantly at 10 parts per thousand and above. Potential CO2 production was stimulated at intermediate salinities (5 to 7.5 parts per thousand), but inhibited by salinities >= 15 parts per thousand, while potential N2O production was unaffected by salinity. In contrast, soil dissolved organic carbon and NH4+-N generally increased with salinity. Overall, this research indicates salinities of similar to 10-15% represent an important tipping point for biogeochemical processes in wetlands. Above this threshold, carbon mineralization is reduced and may promote vertical soil accretion in brackish and salinity wetlands. Meanwhile, low-level saltwater intrusion may leave wetlands vulnerable to submergence due to accelerated soil organic carbon loss