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With 263 reservoir pond wetlands in Erhai Lake Basin as the research object, this study discussed the purification effects of reservoir pood wetlands on nitrogen, phosphorus and organic matter, and the influence of vegetation distribution on the purification effect of reservoir wetlands. The results showed that the removal rates of TN and TP in farmland tail water, sewage tail water and river ectopic purification pond wetland were higher than that of COD, and the removal rates of TN, and TP in three functional types of reservoir pond wetlands were higher than that of COD. The purification effect of TP and COD in dry season were higher than that in rainy season. The vegetation types of reservoir pond wetland was single, and the emergent vegetation was the main vegetation. More than 70% of the reservoir pond wetland emergent vegetation coverage ranged from 25% to 75%. Invasive vegetation was widely distributed, with a total coverage of more than 11%. The number of species and coverage were positively correlated with the purification effect, and the effect of species and coverage on TP were greater than that of TN. The effect of vegetation coverage on TN and TP removal rate were greater than the number of species. [ABSTRACT FROM AUTHOR]

The litter of Phragmites australis, a dominant species in the vegetation belt of Ulansuhai Lakeshore, was taken as the research object. The decomposition experiment of Phragmites australis litter was carried out based on the litter bag method, and the hybrid evolutionary algorithm (HEA) was used to model. The purpose of this study was to reveal and predict the decomposition process of Phragmites australis litter in lake water, and to explore the relationship between N and P released by litter decomposition and environmental impact factors by calculating threshold and sensitivity analysis. The results showed that:(1) The optimal HEA model could effectively simulate the decomposition process of Phragmites australis litter. The fitting degree between the predicted and the measured data was high (r² = 0.90-0.99), and the models of mass loss (ML-model) was the best (r² = 0.99). (2) The mass loss (ML) of Phragmites australis litter increased with the increase of water temperature (WT).The N element accumulated first and then released in litter, and low pH (pH <8.326) promoted the release of N. In the whole process, P was mainly released, when WT>= 16.978 ℃, the P in litter decreased with the increase of dissolved oxygen (DO); when WT<16.978, WT℃ was negatively related to P. The result of the present work implied that HEA model could well predict and explain the decomposition process of litter and its ecological relationship with environmental factors. They are powerful tools for identify and quantify complex ecological relationships and thresholds in data and provide theoretical support for the prevention and control of endogenous pollution in shallow grass lake. [ABSTRACT FROM AUTHOR]

The study of dark carbon fixation in estuarine wetlands is of great scientific significance for the comprehensive understanding and scientific assessment of the carbon sink potential of estuarine wetlands. Taking Chongming Dongtan as a typical study area, the effects of different wetland vegetation distributions on sediment dark carbon fixation and its key environmental control factors were studied using 14C isotope labeling technology combined with molecular biology research methods. The results showed that: the annual mean values of sediment dark carbon fixation rates in mudflat, Phragmites australis, and Spartina alterniflora wetlands were (1.27±0.66), (0.88±0.40), (1.37±0.63) mmol/(m² · d) C, respectively; there were significant seasonal differences in sediment dark carbon fixation in estuarine wetlands, in which the dark carbon fixation rates increased significantly in summer, but were inhibited by extremely high temperatures; the dark carbon fixation in sediments was promoted by Spartina alterniflora, while that in the Phragmites australis area was reduced relative to the mudflat; different vegetation influenced the dark carbon fixation in the sediment by regulating the NH4+, Fe3+, S2- and the abundance of functional genes (cbbL and cbbM). The results provide a theoretical reference to accurately assess the carbon sink potential and the influence mechanisms of the estuarine wetlands. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Scientiarum Naturalium Universitatis Sunyatseni / Zhongshan Daxue Xuebao is the property of Sun-Yat-Sen University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Mycosystema is the property of Mycosystema Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

n order to understand characteristics and significance of carbon(C), nitrogen(N), phosphorus(P)and stable carbon isotope composition(δ13C)in plant leaves of three typical aquatic plants under different growth environments, three life forms of aquatic plants including emerging plant(Phragmites australis), emersion plant(Eichhornia crassipes) and submerged plant(Ceratophyllum demersumin) of the Huixian karst wetland were selected as study objects. The differences of carbon isotope compositions of interspecies and different habitat conditions were studied, and the percentage of HCO-3 uptaken from water by aquatic photosynthesis was also estimated using the double-meta model. The results were as follows:(1)The foliar δ13C of three diffirent plant life forms ranged from -28.47‰～-21.69‰ with an average of -24.83‰. There were significant differences among species, and the sequence of relative value was Ceratophyllum demersum>Eichhornia crassipes>Phragmites australis, and among the three types of plants,Phragmites australis and Ceratophyllum demersum show the lowest and highest δ13 C, respectively.(2)For three types of halophytes,δ13C showed significantly positive correlations with foliar C, N and P. The δ13C was also positively correlated with the contents of organic matter, available nitrogen, total nitrogen, available phosphorus and total phosphorus of sediment. All types of halophytes showed a negative correlation among δ13C, C/N, N/P and C/P.(3)The foliar N/P ratio of halophytes was 10.34, indicating a co-limitation by N and P for halophyte growth in the Huixian karst wetland.(4)These results suggested that three halophytes were adapted to environment through a high water use efficiency at the expense of decreased nitrogen use efficiency, and might improve C sequestration by increasing phosphorus use efficiency in the habitat of low water availability.(5)The value of HCO-3 carbon sequestration by photosynhesis was 159.60 t·a-1·km-2 for Phragmites australis, 10.80 t·a-1·km-2 for Eichhornia crassipes, 9.24 t·a-1·km-2 for Ceratophyllum demersum, with a mean value of 59.88 t·a-1·km-2. Different plant life forms, pathways of carbon fixation in photosynthesis and micro-environment were the important factors on affecting plant foliar δ13C in the Huixian karst wetland. [ABSTRACT FROM AUTHOR]

As a key parameter in monitoring vegetation productivity by remote sensing driven model, rapid and accurate acquisition of vegetation light use efficiency (LUE) in large area has been a key problem. Se⁃ lecting typical Phragmites australis wetland in Northeast China as study area, multitemporal Landsat OLI (operational land imager) image and the object⁃oriented classification method were used to extract Phrag⁃ mites australis wetland. Based on the principle of vegetation physiology and ecology, the relationship among LUE, vegetation indexes and chlorophyll content was analyzed, the feasibility of accurate estima⁃ tion of LUE for wetland vegetation by spectral vegetation index was discussed. Results show that areas of Phragmites australis wetland in Qixinghe Wetland, Chagan Lake Wetland and Shuangtai Estuary Wetland were 122.19, 75.29 and 439.61 km2, respectively, and overall classification accuracy was more than 82%. With the exception of EVI (enhanced vegetation index), other six vegetation indices showed the same spa⁃ tial pattern characteristics with those of three wetlands. Totally, values of vegetation indices for different land covers were: cultivated land > Phragmites australis > other wetland vegetation > water body. There exists close relationship among LUE, chlorophyll and vegetation index. NDVI (normalized difference vege⁃ tation index) was most sensitive to LUE (P < 0.01； R2 = 0.62), which was the best one to characterize LUE of Phragmites australis in this study. This study verified the theoretical hypothesis that LUE could be inversed efficiently by remote sensing vegetation index taking chlorophyll as the intermediate variable, which can provide references for the study of vegetation productivity and carbon cycle on regional scale. [ABSTRACT FROM AUTHOR]

[Objective]Soil particle size analysis of typical plant communities in oasis-desert transition ecotone on northern margin of Tarim basin can provide basis for regional vegetation restoration and effective utilization of water resources. [ Method]Based on field investigation, indoor analysis, the spatial distribution characteristics of soil particle size of the typical plant communities in the oasis-desert ecotone of the Weigan-Kuqa river delta were studied. [ Result](i)The soils in the study area were mainly coarse sand, sand and powder sand, and there were obvious differences in the contents of coarse sand grains and silt grains in different plant communities. (ii) The fractal dimension of soil was only positively correlated with the content of clay particles (P <0. 01 ) , the correlation coefficient was 0. 764. The soil fractal dimension of Phragmites australis community and Phragmites australis + Alhagi sparsifolia community soil was larger, but the soil fractal dimension of Tamarix ramasissima community and Halostachys caspica community was smaller. (iii) The average diameter of the soil in the study area was coarser, the sorting performance was poorer, the coarser and heavier degree was larger, the granularity was more dispersed, and the differences between the soil planting characteristics near the oasis and the plant communities close to the desert were obvious. (iv)The soil particles in the study area was a significant correlation between the diameter content and the fractal dimension and the particle size characteristic value. [ Conclusion]The main factors causing the differences in soil particle size of different plant communities were soil moisture content, secondary vegetation coverage, wind erosion factors, organic matter content and human factors. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of Botanical Research is the property of Bulletin of Botanical Research Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Using quantitative remote sensing and image processing techniques, a comprehensive analysis upon information about regional vegetation index and evapotranspiration of Zhalong wetland was achieved, and the temporal change and spatial variation of vegetation conditions in Zhalong wetland before and after the fire in 2001 were studied. In the course of the experiments, ratios of transpiration and vegetation index were calculated as a description for the changes of growth rate of wetland vegetations. Then, image change detection was applied to obtaining information about spatial distribution of the fire damage. Experimental results show that the Zhalong wetland ecosystem is badly damaged by the disaster and those reed marsh regions suffer the most; the growth pattern of wetland reeds has not been affected significantly though the amount is sharply reduced. Fortunately, due to the prompt water supplement measures, post-disaster restoration for the whole wetland region is satisfactory. [ABSTRACT FROM AUTHOR]