Effects Of Eucalyptus Plantation Replacing Open Pinus Massoniana Forest On Community Compositions And Soil Physical-Chemical Proprieties

With the rapidly development of eucalyptus plantation, a lot ofeconomic benefit have been brought to the social. However, a great dealof ecological problems have been emerged because of irrationallymanagement practices, Which cause more and more vehement dispute inthe academe. The focus of the argument are: (1) The problem ofbiodiversity of the understory plants in eucalyptus plantation; (2) Theproblem of decline of soil fertility. In this paper, we set three sort of plots,including E.grandis×E. urophylla plantationâ… , E. grandis×E, urophyllaplantationâ…¡and open pinus rnassoniana forest, each plot set threerepetitions. The change of community compositions and soilphysical-chemical proprieties we researched through wild investigationsand indoor analysis, in order to elucidate the influence of eucalyptusplantation on understory species diversity and soil fertility.The results of study on community compositions showed as follow:(1)Since the open pinus massoniana forest was replaced by E. grandis×E. urophylla plantation, the species of vascular plants increased51.61%～58.06%, the plant species of shrub layer increased about 52.17%,the plant species of herb layer increased 50%～75%; the trait compositionhas no significant change; (2) The dominant species of shrub layer plantsBaeckea frutescens, Rhodomyrtus tomentosa, Symplocos botryantha werereplaced by Phyllanthus reticulates, Rhodomyrtus tomentosa, Cratoxylumcochinense, Sapium discolor, Symplocos botryantha, etc.; the dominantspecies of herb layer plants were also Dicranopteris linearis, Miscanthusfloridulu and Blechnum orientale. (3) The results of study on diversityindex and species richness showed that the species diversity of understoryhas increased. (4) The biomass and productivity of the understory plantstake on down trend, the proportion of herb layer was decreased and shrublayer was increased.The results of the study on soil physical proprieties showed asfollows: (1) At 0～20cm and 40～60cm soil layer, the soil bulk density,max water holding capacity showed a no significant change, at 20～40cmsoil layer showed a descent trend, respectively; (2) At 0～20cm soil layer,total porosity showed a no significant change, at 20～40cm and 40～60cmsoil layer showed a descent trend; (3) At 0～20cm, 20～40cm and40～60cm soil layer, capillary porosity showed a descent trend,respectively; (4) At 0～20cm and 40-60cm soil layer, capillary waterholding capacity and min water holding capacity showed a descent trend, respectively; and at 20～40cm soil layer, showed a increase trend,respectively; (5) Non-capillary porosity, at 0～20cm soil layer showed aincrease trend, at 20～40cm soil layer showed a descent trend, at 40～60cmsoil layer showed a no significant change.The results of the study on soil chemical proprieties showed asfollows: (1) At 0～20cm soil layer, pH and available Zn showed a increasetrend, respectively; at 20～40cm soil layer showed a no significant trend.(2) At 0～20cm and 20～40cm soil layer, organic matter and available Kshowed a no significant change; (3) At 0～20cm and 20～40cm soil layer,total N showed a descent trend; (4) At 0～20cm soil layer, available N andtotal P showed a no significant change, at 20～40cm soil layer, showed adescent trend, respectively; (5) At 0～20cm and 20～40cm soil layer, totalK, available P, Ex-Ca²⁺, Ex-Mg²⁺ and available Cu showed a increasetrend, respectively. In a word, there is no significant and regular changeon soil physical properties or chemical properties.