Effect Of Interference On Natural Syzygium Hancei Communities

The Syzygium hancei community is an important part of natural vegetation in coastal ecotone of Guangxi,as a best preserved native vegetation type formations in Guangxi coastal area.In this study,three different disturbances were set up in the distribution area of Syzygium hancei species.The soil and litter samples were collected by field investigation and experiment,and the soil physical and chemical properties and the characteristics of litter were analyzed by laboratory experiment.The effects of disturbance on the community were discussed by comparing the differences in 3 sites,order to providing the basis for the restoration of coastal vegetation in Guangxi.The main conclusions are as follows:1.The species composition of the natural communities was rich,But the structure is relatively simple,the herb layer dysplasia.Three plots of arbor hancei important were the largest,but the associated species in the sample ? and? kind of the important value of the proportion is larger;the shrub layer species and important value is different.The species diversity of the three plots were shrub layer>tree layer>herbaceous layer,and the diversity of shrub layer and herb layer was greatly influenced by the canopy density of tree layer.The dominant species of tree layer of sample ? was obvious,the canopy density was the largest and the species and coverage of shrub layer were lower.However,the tree layer of the other two plots had the co-dominant species,but the dominant species of shrub layer was obvious.The species diversity of tree layer of sample ? is the highest and the coverage is the largest,and the number of herb layers in the three plots is very small.2.There were some differences between soil physical and chemical properties in different degrees of interference:(1)The soil bulk density,total porosity field capacity and the physical property index as well as other physical property were generally expressed as:?>?>?,no significant difference;(2)The level situation of the soil nutrient was:?>?>?(3)The acid of the soil of the three plots was weak,and the soil was not equally significant difference between pH value.(4)The organic content of soil was extremely low,between 0.59%and 1.14%;and hydrolysable N:20.28mg/kg?77.22mg/kg,N:0.09%?2.63%,available P:0.79mg/kg?1.97mg/kg,available K:0.13 mg/kg?0.28 mg/kg,and the difference of hydrolyzable N and total N content was significant in different samples.(5)The contents of Cl-exchangeable Ca,exchangeable Mg and exchangeable Na were both in a low level,no significant difference between the different plots.3.The litter biomass of Syzygium hancei community is related to the growth status,diversity,disturbance degree and environment of the community.Under the same geographical environment,the smaller the disturbance degree and the better the community growth and diversity,the larger the litter amount.(1)The total litter reserves were:?(11.31t·hm-2)>?(7.69 t·hm-2)= ?(7.69 t·hm-2).The variance analysis in different spots were significant.(2)The water holding capacity and water holding capacity of litter were logarithmically related to the soaking time,and the water absorption rate was exponentially related to the immersion time.The water content of litter in different locations was significant,the local water holding capacity and water holdup of mild disturbance were larger than those of interference.(3)The litter had a large nutrient storage:the N was the highest element amount of the nutrient content and the storage of nutrient of litter,the lowest element is Mg,while the storage of Ca,K and P were different for the different of environments,but the different were not significantly.4.The net photosynthetic rate,transpiration rate and stomatal conductance of Syzygium hancei under mild interference level showed advantages,which were different from other locations,and the differences of photosynthetic physiological indices were not significant under moderate and severe disturbance.The photosynthetic features were as follows:the net photosynthetic rate:?>?>?,transpiration rate and stomatal conductance:?>?>?.