[Invasion and its effects of xerarch halophytes in reclaimed tidal wetlands]

With the reclaimed tidal wetland of Chongming Dongtan in Shanghai as a case, and based on the landscape pattern analysis of colored infrared aerial photographs and field survey, this paper studied the invasion of xerarch halophytes and its effects on the original reed community in the wetland after artificial drainage. The results showed that in the test reclaimed tidal wetland area, the xerarch halophyte community with Tripolium vulgare as edificator was spreading from northeast to southwest at a high speed of 143 m per year, with the original reed patch reduced and broken sharply, causing a 22.7 times increase in patch density index and a 1.3 times increase in shape index. After the growth seasons in 2006 and 2007, the biomass of T. vulgare in the plant community reached as high as 2783.8 g x m(-2), occupying 98% of the total, and the importance value reached 88%. At the mean time, the biomass and importance value of original reed decreased 98% and 83%, respectively. The invasion process of xerarch halophytes was meaningfully correlated with the moisture content and salinity in 0-20 cm soil layer. To effectively control the rapid invasion of xerarch halophytes, the mechanisms of their invasion and the strategies of rational and dynamic drainage management should be deeply studied.