Improvement Effect Evaluation On The Soil Nutrient Characteristics Of Different Shrub-herb Communities In Coastal Reclamation Area

Coastal wetlands are often located in the coastal and estuarine areas which are in the process of rapid urbanization, the need of land from population growth and economic development pressures make coastal wetlands reclaimed by people. Reclamation changed soil nutrient dynamic libraries, and it caused soil degradation of ecological environment. The study was located at Dongtan Wetland Park in Shanghai Chongming Island, the district had several large-scale reclamation, and appeared many new land. In a variety of measures to use reclamation land, suiting one’s measures to local conditions was very important, and the establishment of Wetland Park developed ecological tourism, it was a new mean for sustainable utilization of this new land resource. In order to understand the improvement effect in soil amendment after the establishment of the park,the study selected6typical shrub-herb communities that reclaimed10years in same time, it included: shrub-herbs(SH1/SH2/SH3),herb(H1),shrubs(S1/S2),and a bare land as control (CK) with no artificial planting vegetation. By discussing the improvement effect of the soil nutrients characteristics under different communities in reclamation area, it can judge preliminarily soil improvement effect and select excellent advantage of communities configuration, this study provided a scientific basis to restore coastal wetland.The main results were as follows:(1) The order of the average content of soil organic carbon in0-40cm soil layer under different vegetational communities from high to low was:S1,H1,SH2,S2,SH1, SH3,CK.The distribution characteristics of organic carbon content were different in different soil layer:H1was the highest content of organic carbon in the0-5cm soil surface layer, next was SH2/SH3;in the5-10cm and20-40cm soil layer, the highest content of organic carbon was S1,and it had the significant difference with other communities. In the vertical distribution,the content of SOC decreased with soil depth trend under different vegetation communities generally, the bottom was significantly lower than that in the surface content.(2) The order of the average content of soil total nitrogen in the0-40cm soil layer under different vegetational communities from high to low was:SH2,H1,SH1,S1, SH3,S2,CK.The distribution characteristics of total nitrogen content was different in different soil layer:in the0-5cm surface soil layer, SH2/H1/S2had the significant difference with CK; in the5-10and10-20cm soil layer, the content of SH2/H1/SH1significantly increased, the difference of content in the bottom under each community is not obvious. In the vertical distribution, the content of three shrub-herbs communities decreased with soil depth trend, two shrubs communities decreased first, then increased with soil depth trend. The average content of soil available nitrogen in the0-40cm soil layer under different vegetational communities from high to low in the order was:H1,SH2,S2,SH3,S1,SH1,CK. The distribution characteristics of available nitrogen content was different in different soil layer:in the0-5cm soil surface layer, the content of SH2/H1/S2were more than CK,and had the significant difference with CK; In the5-10cm soil layer,Hl and S2were more; In the10-20cm soil layer,Sl and H1were more, and had the significant difference with CK. The content had no obvious difference in the bottom. In the vertical distribution, the content of available nitrogen almost was in the0-5cm layer under three shrub-herbs communities, SI and H1almost was in the0-5cm and5-10cm layer,Sl was not obvious.(3)The content of soil total phosphorus was low under different vegetational communities, and had no significant difference with CK. The average content of soil available phosphorus in the0-40cm soil layer under different vegetational communities in the order from high to low was:S1,SH2,SH3,H1,S2,SH1,CK. The distribution characteristics of soil available phosphorus content was different in the different soil layer:in the0-5cm layer, S1/SH2/SH3had the significant difference with CK,other communities were not; in the5-10cm layer,the content of S1was the highest;in the10-20cm, the content of H1was the highest,then others were similar each other;in the20-40cm, the content of different communities were not obvious. In the vertical distribution, the content of available phosphorus under three shrub-herbs communities and two shrubs almost were in the0-5cm layer, herbs was not obvious.(4) Except total phosphorus,the study showed the correlation of soil nutrients among different vegetational communities was best. C/N ratios under different vegetation communities was far less than25.Overall, The improvement effect of the soil organic carbon and soil nitrogen were better than soil phosphorus under different vegetational communities in reclamation area, the difference of the soil nutrients content between in the surface soil and in the bottom soil was obvious. In the surface soil,Hl and SH2improved soil nutrients well generally. In the bottom soil,Sl improved soil nutrients well generally. S1improved soil available phosphorus better. In the study, SH2/H1/S1of shrub-herbs communities were excellent configuration. Comprehensive consider ation, Mixing herbaceous vegetations and shrubby vegetations can increase the effect of landscape and biodiversity, even it can effectively improve the soil nutrient characteristics.