The Analysis Of Diversity And Distribution Pattern Of Plant Species In Salt Marsh Wetland On Yangtze River Estuary

Salt marsh is salt water or brackish mud beach which is covered with vegetation along the coast, and affected by marine tide with cycle or intermittent. Meanwhile, the plants on coastal salt marsh are the main primary producers with high ecological and economic value. Salt marsh plant is a hot research spot, and also the basis of the salt marsh ecosystem. Jiuduansha wetland and Chongming Dongtan wetlands are the typical salt marsh in Yangtze Delta, we carried out the researches on both the flora and the fine structure of plant distribution in the tidal creek in detail with the method of field investigation. The characteristics of plant species diversity and the fine structure of the plant distribution on the tidal creek have been revealed. and the conclusion of this research as follow:1.Species composition is relatively simple. There are only 15 families 33 genera 36 species in Jiuduansha wetlands,the common species are only a dozen taxa. The most taxa almost belongs to angiosperms, which most is annual or biennial herb ,and woody plants has not yet appeared. The main reason may be that only these species could survival, which adapted in this particular inter-tidal environment.2.Shanghai is located in the northern margin of the middle subtropical, the northeastern part of eastern China of China - Japan Asia forest plants sub-region holarctic region, where the hydro-thermal climate conditions conducive the plants to settle and spread. On Jiuduansha wetlands, which still at the stage of primary succession, it is a common phenomenon that plant species which world wide living and pan-North distribution, occurs in the vanguard communities in majority.3.Jiuduansha wetlands on a well protection now, the relatively little human disturbance makes the access speed of taxa to be maintained at a relatively low level. In addition to introduce the Spartina alterniflora emerging in large-scale, the rest of plant species are natural native in Jiuduansha wetlands.4.The distribution pattern of plants is affected by elevation, the distance to the creek, the tidal channel level, conductivity and other soil factors in Jiuduansha wetlands and Chongming Dongtan wetlands. It is shown that the plant density does typically the edge effects with the distance from the tidal channel. The pattern change of Phragmites australis biomass are similar to that of Scirpus mariqueter in Jiuduansha wetlands, the trend basically decreases first, and then increases.5.The relationship between aboveground biomass and below-ground biomass is complementary in plants. In the study, amounts of data highlights this conclusion, the biomass with elevation , the distance from the tidal channel, or different tidal channel level.6.Plant biomass have the relevant with soil conductivity and ph value, great affected by the soil conductivity.The plant distribution shows great relationship with soil conductivity especially in Chongming Dongtan beaches, near the area of south bank of the Yangtze Delta, the conductivity is very low, only 0.358 - 1.476ms/cm, where Scirpus mariqueter, Carex scabrifolia and Phragmites australis predominated; while going to north, the conductivity gradually high, between 7.27-13.6 ms/cm, Spartina alterniflora gradually become dominant.Based on the results, three points should be noticed on the ecological management and protection of Chongming Dongtan Beaches and Jiuduansha wetlands as follow:1.The ecological protection of the edge of tidal channel should be intensified greatly, where a plenty of biodiversity, abundance of biomass and severity of competition, especially the protection of biodiversity in the 1-30m of area from the channel.2.By the means of the relationship analysis of between species distribution and tidal-channel level, the spread of the invasion weed, Spartina alterniflora, could be prevent from effectively, i.e. the weed should be cut with machinery in large-scale in the 20m of the 3 or 4 level of the tidal channel, could not erased where elevation higher or lower than that level, due to it hardly become large aggregation.3.For that the characteristics of ecological succession of wetland vegetation is obvious, the protection of species biodiversity and the development of ecological succession must be noticed typically, with the spreading progress of compositae, especially occurred another invasion weed, Solidago canadian, within the region.