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Ma H.,CAS Shanghai Institutes for Biological Sciences | Ma H.,East China Normal University | Chen X.-Z.,Shanghai Jiuduansha Wetland National Nature Reserve Administration | Pan H.,CAS Shanghai Institutes for Biological Sciences | And 2 more authors.
Journal of Ecology and Rural Environment | Year: 2013

To explore effects of continuous harvesting on Phragmites austrcalis-dominated wetland, growth and biomass of P. australis and variation of content of soil total nitrogen were monitored in two plots of reed wetland, one subjected to continuous harvesting for 10 years and one left intact, in Jiuduansha, Shanghai for comparison. Results show that reed harvesting significantly promoted density of P. australis (P < 0. 05), but had no much effect on shoot height and basal shoot diameter of the plants. The above-ground biomass of P. australis was significantly higher in the harvested plot than in the intact plot (P <0. 05). However, a reverse trend in below-ground biomass was observed. Reed harvesting not only significantly reduced the content of total nitrogen in the surface soil (0-5 cm), but also affected the vertical distribution of soil nitrogen. The total nitrogen content was generally lower in the harvested plot than in the intact plot in all the soil layers (0-50 cm), and the difference was especially significant in soil layers of 0-10 cm and >10-20 cm. In addition, in the intact plot, soil total nitrogen content tended to decrease with increasing soil depth, while in harvested plots, it was found lower in superficial and middle soil layers (0-20 cm) than in the other layers. Therefore, the practice of long-term continuous harvesting may affect the allocation of biomass between the above-and below-ground parts of P. australis, and reduce the content of soil total nitrogen in P. austrcalis-dominated wetland. It is advisable to develop a more reasonable strategy for harvesting reeds in the wetland.

Chen X.-Z.,Shanghai Jiuduansha Wetland National Nature Reserve Administration | Chen X.-Z.,Shanghai Normal University | Guo S.-L.,Shanghai Normal University | Zhu L.-L.,Shanghai Normal University | Wang C.-L.,Shanghai Normal University
Wetland Science | Year: 2011

In Upper shoal, Lower shoal of Shanghai Jiuduansha National Nature Reserve, according to sediment formation time and different grades of tidal creek, 17 line transects with length from 54 m to 306 m were located in the maturity tidal creeks. On each line transect, successive plots of each with an area of 150 cm × 150 cm were sampled to record the coverage of each plant species starting from the low tidal beach at the dii rection perpendicular to the tidal creek, based on the obtained data, the trends of plant coverage was analyzed, the distribution pattern of the main plants was also studied applying the method of the two-term local variance analysis, thus the plant distribution pattern under tidal creeks fine features was intuitively showed. The results showed that (1) there were 2 vegetation subtypes, herbal marsh and salt meadow vegetation, of which herbal marshes had Scirpus mariqueter and Phragmites australis, 2 formations, and salt meadow had Phragmites australis and salt-tolerant species including Suaeda glauca and Tripolium vulgare, the invasion of Spartina alterniflora formed artificial vegetations; (2) with the formation of sediments, Scirpus mariqueter and Scirpus triqueter appeared first, then Phragmites australis and other marsh plants, as hydraulic and vegetation interactive, tidal creeks are getting maturity, marsh vegetation gradually successes to salt meadow with the dominant species Phragmites australis, together with other salt-tolerant species such as Suaeda glauca, and Tripolium vulgare; (3) some local sites invaded by Solidago canadensis, Conyza canadensia, Aster subulatus and other alien plants; (4) Spartina alterniflora has been widely distributed in the survey area, across 2 vegetation subyptes ( from marsh to salt meadow vegetation), showing its broad ecological adaptability to salt and ventilation.

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