| Coastal reclamation is an important means to alleviate our people to contradictions, while wich did not bring the land resources superiority very quickly, and had a certain influence on the ecological environment of coastal reclamation area. At the same time, We are faced with the problem of long-term land improvement.Take the Dongtai City of Jiangsu Province Coastal Reclamation Zone 2005,2009 and 2013 three different reclamation area as the research object, try to research the natural vegetation succession and growth characteristics, soil physical and chemical properties, and to explore the relationship between them, the main conclusions as follows:1. From sea to land, the vegetation distribution characteristics of reclamation area was changed from banded distribution to mosaic distribution. In 2013 reclamation area Spartina alterniflora and Suaeda salsa community was strip distribution. In 2009 and 2005 reclamation areas, different communities showed the obvious mosaic type distribution characteristics.2. Based on field investigation data, application of important value (IV), species diversity index, species growth characteristics and space-time substitution method, the quadrat survey results of plant communities in reclamation area showed that:in 2013 reclamation area, with the increasing distance from the sea, the important value of Spartina alterniflora was decreased, while Suaeda salsa was basically opposite. In 2009 and 2005 reclamation areas, different species important value spatial distribution of extreme phenomenon tended to weaken. The changes of the absolute density and cover degree maintained the consistency with species important value in a certain degree and could distinguish the differences of species in different communities. Reclamation time and distance to the sea was the influence factors of plant species diversity. Among them, with the distance to the sea and reclamation time increased the Ma index increased first and then decreased. H index, D index and JP index showed decreased first and then increased. On the whole, reclamation years about 8 years when the community structure was balanced, the highest evenness, the diversity of the best.3. The silt was the main group of reclamation soil. From sea to land, the particle size showed the characteristics of the first increase and then decreased (without bare flat). The relationship of particle size in 2013 reclamation area was bare flat> suaeda salsa Community> Spartina alterniflora and Suaeda salsa community> Spartina alterniflora community. From the sea to the land the particle size gradually became small in 2009 reclamation area, and the trend had continued into 2005 reclamation area. In vertical direction, with the increase of reclamation time surface (0-30cm) soil particle size tended to be uniform. In 2013 reclamation area, particle size vertical distribution characteristics of Suaeda salsa community was mainly bottom accumulation type. Spartina alterniflora community tended to be more uniform type, and Spartina alterniflora outside the seawall community was the same. Bare flat was intermediate or surface gathering. In 2009 and 2005 reclamation areas particle size vertical distribution was uniform type.4. From sea to land, the soil salinity was decreased generally along Spartina alterniflora, Spartina alterniflora and Suaeda salsa community, Suaeda salsa community, Imperata cylindrica in turn, but the subsequent emergence of community plots is unusual. The vertical distribution of salt was mainly surface aggregation type. Spartina alterniflora community also had both bottom poly type and uniform type in 2013 reclamation area. Compared with that, Spartina alterniflora community outside the seawall was uniform.2009 reclamation area only Imperata cylindrical community salt content was low and the distribution was more uniform.5. Reclamation soil was generally poor. From sea to land, the nutrient basically increased, but affected by species biomass difference and nutrient from the sea, the nutrient was not increasing along the sequence. In 2013 reclamation area, the effective phosphorus and organic matter in Spartina alterniflora community was the highest, K in bare flat at maximum.In 2009 reclamation area, Imperata cylindrical community had the highest nutrient than other communities. In 2005 and 2009 reclamation areas, the nutrient content were close. The vertical characteristics of the four nutrient content were varied under different vegetation types, and which mainly was surface aggregation type.6. Average particle size and clay content were significantly correlated with organic matter, total nitrogen, available phosphorus, available potassium, and the relationships between the silt and sand content with those nutrient contents were weakening. Salt was significantly positively correlated with organic matter and available potassium, while pH was negatively correlated with available potassium, and the other related was poor. Organic matter and total nitrogen, available phosphorus and available potassium showed a significant correlation, among which the relationship with available potassium was better. Total nitrogen and available phosphorus was significantly positively correlated, and available potassium is positively. Relationship of phosphorus and potassium is also very significant.7. Reclamation of vegetation and soil physicochemical properties showed that the relationship between plant species, size and distribution of maximum correlation. Different species of soil nutrient content had large differences in response, which nutrient content in Spartina alterniflora community, Suaeda salsa on the nutrient content response ability was poor. Analysis on the relationships of Spartina alterniflora and Suaeda salsa growth with soil salinity found that too low or too high of the salinity was not conducive to the growth of species. The growth of Spartina alterniflora was also influenced by the certain depth salinity difference. The growth of Suaeda salsa was affected by soil moisture. On the whole, Spartina alterniflora grew well in the middle of its community, but outside the seawall Spartina alterniflora grew better. Suaeda salsa grew worse from sea to land. |
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