Effects Of Tamarix On Ecological Environment Of Coastal Wetlands

At present, the degradation of ecological environment in coastal wetlands isincreasingly prominent in China. Restoring and improving the ecological environmentof coastal wetland is an important subject for the construction of ecologicalcivilization.Tamarisk has the characteristics of saline-alkaline tolerance andwaterlogging resistance. It is widely distributed in the north of China’s coastalwetlands. The tamarisk in Shandong Changyi National Marine Ecological SpecialReserve was selected as the research object. The distribution and change rule of soilphysical and chemical parameters under the effect of tamarix was studied through thefield sampling for one year, which plays a great role in understanding the effect oftamarisk on coastal wetland ecological environment. The main results are as follows:(1) In the exuberant growth period of tamarisk, the soil moisture content formed alow value area near the main root of tamarix and it showed an increasing trend withthe increase of the soil depth. When it came to tamarix’s growth arrest period, itshowed the opposite tendency. The soil moisture content increased with the soil depthdecreasing. It indicated that tamarisks could absorb a large amount of water and makethe soil dry in the exuberant growth period and the root system of tamarisk had theeffect of soil moisture conservation in it’s growth arrest period.(2) In the exuberant growth period of tamarisk, the soil electrical conductivity formeda low value area near the main root of tamarix and it showed an increasing trend withthe increase of the soil depth. When it came to tamarix’s growth arrest period, itshowed the opposite tendency. The soil electrical conductivity increased with the soildepth decreasing. It indicated that tamarisks absorb salt from soil in the exuberantgrowth period and then salt return to the soil through the leaves in it’s growth arrestperiod. The impact of tamarisk on coastal wetland soil salt was a process of dynamiccycle. (3) The pH of soil in study area around tamarix was between7.5and10.2. It risedwith the increase of soil depth. The value of pH near the main root of tamarisk waslower than the surrounding. It indicated that tamarisk could reduce the pH of soil andimprove alkaline soil.(4) In the exuberant growth period of tamarisk,it could decrease the total water of soilfrom7to30kg/m3in the study area. when the tamarisk grew slow or even stop, theamount of total soil moisture changed following the effect of external environmentfactor mainly.(5) In the growth period of tamarisk, soil salt could be decreased to0.02kg/m3bytamarix in the research area. The addition of salt by heavy rainfall leaching wasbetween0.04kg/m3and0.07kg/m3and the addition of salt by leaves was between0.16kg/m3and0.20kg/m3in the researching area.The annual average soil salt underthe effect of tamarix was0.09kg/m3higher than that of the control area, whichindicated that tamarix could cause the accumulation of soil salt, producing a certain"salt island effect".