关键词: 遮荫, 紫花苜蓿, 地上生物量, 化学计量特征

Abstract: The landscape dynamics of the aggradational coastal wetland in Jiangsu Province in the past three decades were studied by using Landsat images acquired in four periods (1975, 1990, 2002 and 2010). The results showed that the area of the aggradational coastal wetland in Jiangsu Province increased from 2100.18 km² to 3686.31 km² (increased by 75.52%). The artificial wetland (including agricultural/aquatural land and salina) increased from 514.97 km² to 1795.18 km² (increased 2.46 times); while the natural wetland (halophyte communities dominated by Pragmites communis, Saueda spp., Aeluropus littoralis and Spartina spp., and bare intertidal mud flat) only increased a little, and the area percentage of natural wetland relative to the total wetland decreased from 74.59% to 50.30%. In the past three decades, the average wetland width increased from 8.64±1.64 km in 1975 to 13.89±2.86 km in 2010; the artificial wetlands extended to the sea in most locations, while the natural wetland extended and retreated in different periods and locations. The succession series of wetland landscape was intertidal mud flat→ halophyte communities→ agricultural/aquatural lands. The agricultural lands were mainly reclaimed from the P. communis communities, while the aquacultural lands were mainly reclaimed from the Saueda spp. communities.

Key words: shading, Medicago sativa, aboveground biomass, stoichiometric characteristics.