| Wetland ecosystems are interaction ecosystems between terrestrial ecosystems andaquatic ecosystems, which have the capability of regulation and storage of water,maintaining biodiversity and biogeochemical cycles and others. It is a ecosystem on theplanet that have most biologically diverse, most productive, and largest value of ecosystemservices. In the past few decades, in the middle and lower reaches of the Yangtze River,excessive reclamation leaded to the area of natural wetlands reduce, the water regulationand storage function degradation, the biodiversity decrease, the soil pollution increase andsoil quality degradation. Wetland ecology restoration has been an important demand for theconstruction of ecological environment in China. Returning farmland to lake is a strategicmeasure for wetland ecological restoration in China.Soils from wetlands under returning farmland to lake with different vegetationtypes(Carex maximowiczii, Rumex acetosa Linn, Phragmites australis) were sampled，toanalyze the effects of vegetation types on soil organic matter, total P and available Pdistribution in the soil profiles in Caizi Lake.Thus will provide a scientific basis for theYangtze River wetland ecological restoration and its efficient use. The main conclusionsare as follows:(1) For the test soil0~6cm profile soil bulk density was significantly lower than othersoil layers, and13~25cm,25~40cm and40~55cm soil the difference was not significant,the Carex surface soil bulk density was significantly higher than the reeds and sorrelsurface, which indicating that the vegetation types affect the bulk density of farmlandtopsoil. Same soil level in three vegetation types, the differences of soil particlecomposition were significant, and have shown the highest surface clay content, threevegetation types under40~55cm of soil, silt content were highest, which shown vegetationaffected soil particle composition characteristics in wetland. Sedge and reeds soil pHincreased with increasing depth in the same soil profile depth, the pH differences of surfacesoil between sorrel and sedge, reed were significant, the pH of sorrel surface value washigher, which shown soil pH were different in different vegetation types. Significantdifferences of soil available nitrogen in different vegetation types, in the0~6cm soil profile,sorrel (456.6mg/kg)> sedge (292.2mg/kg)> reed (261.4mg/kg), surface soil availablenitrogen content was significantly higher than at other levels, that because the available nitrogen content was closely related to organic matter; in the vertical direction, theavailable nitrogen content decreased with the increasing depth of the soil profile.(2) Selected distribution characteristics of soil organic matter affected by vegetationlitter quality and root distribution characteristics, and human activities, such as aquaculturefarm manure fertilization is also affects content of the wetland soil organic matter.0~6cmof soil organic matter content are characterized by sorrel> sedge> Reed grass reed, andthe four layers are characterized by reed> sedge> sorrel,3in total organic matter contentof the soil profile under vegetation communities were reduced with depth increasing.(3)The content of total P under all three vegetation types was high in0~6cm layersand the lowest in6~13cm layers, then increased with depth of the soil profiles, the order ofincreasing trend was sorrel> sedge>reed; soil available P content have no significantdifference in the other levels, in addition to available P of sorrel soil (0~6cm) higher thansedge and reed, Available P content decreased with depth of all profiles; Efficient of sorrelsoil (0~6cm and6~13cm) was higher than sedge and reed soil, the other levels have nosignificant difference. The analyzed results showed that the differences in litter and rootsdistribution characteristics of different vegetation communitiesLitters were the mainfactors of the distribution differences of wetland soil P in profileand, farmyard manure alsoaffected soil nutrient accumulation in surface soils.(4) Inorganic P content of Soil under different vegetation communities: sorrel> sedge>reed, the form of Ca-P was the highest content, followed was Fe-P, then was O-P, whileAl-P content wads minimum. According to the percentage of soil inorganic P formaccounted for total inorganic P: Al-P, O-P, sorrel> reed> sedge; Fe-P as reed> sedge> sorrel;Ca-P, sedge> reed> sorrel. The ratios of Al-P and O-P content accounted for total inorganicP in sorrel soil were higher than sedge and reed soil, and Fe-P, Ca-P ratios were less thansedge and reeds. Three types of vegetation communities, the trends of Al-P content weresame, decreased with profile depth increased, the range of sorrel vegetation (7.14~175.04mg/kg) was large; the trends of Fe-P in sedge and reed soil were increased early thendecreased with profile depth increased; the trends of Al-P, Fe-P, in tested soil wereincreased with profile depth increased, the first layer of sorrel was significantly higher thanthe other layers, and other layers were increased with profile depth increased; Ca-P, thechange trend of sorrel, incremented with the increment of the cross-sectional the reedsurface content.(5) The different of vegetation communities in each soil inorganic phosphorus formwith soil basic physical and chemical nature of the relationship: available phosphorus andFe-P, O-P, Al-P relations significantly with, can be considered Fe-P, O-P and Al-P wetlandsoil savailable phosphorus source; soil total phosphorus and O-P, Al-P into a highlysignificant positive correlation between Fe-P into a highly significant negative correlation between organic matter and Ca-P was not correlated with the Ca-P;Significantly negativelycorrelated with a correlation coefficient of-0.613(p<0.05), and Fe-P, Al-P showed asignificant positive correlation, the correlation coefficients were0.772,0.783(p<0.01) andOP correlation was not significant. |
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